Langley's Aero Engine of 1903 
Charles M. Manly standing in the aviator's car of the partially assembled Langley Aerodrome A 
working on its engine. The Aerodrome is poised on its catapult mounted on a specially 
designed houseboat located in the vicinity of Quantico, Virginia, sometime during September 
1903. Now on exhibit at the Smithsonian Institution. (Smithsonian photo A18804.) 
S M I T H S O N I A N A N N A L S O F F L I G H T ? N U M B E R 6 
Langley's Aero Engine of 1903 
Edited by 
Robert B. Meyer, Jr. 
SMITHSONIAN INSTITUTION PRESS 
City of Washington ? 1971 
UNITED STATES GOVERNMENT PRINTING OFFICE 
WASHINGTON : 1971 
For sale by the Superintendent of Documents, U.S. Government Printing Office 
Washington, D.C. 20402 - Price $1.25 
Prologue 
How many things by season seasoned are 
to their right praise and true perfection! 
The Merchant of Venice, Act V, Scene 1 
At the turn of the century, those who dealt seriously with experi?
ments in heavier-than-air "flying machines" were regarded as an eccen?
tric fringe element, subject to derision by both the general public and 
the press. Thus, it took an extra amount of moral courage and convic?
tion for prominent men to jeopardize their professional reputations by 
attempting to advance the state of the art. Such a man was Samuel Pier-
pont Langley, third Secretary of the Smithsonian Institution, whose ef?
forts and dedication gave heart to others to also reach for the sky. How?
ever, in spite of his past accomplishments in the fields of astronomy and 
meteorology, Langley also could not escape the derision and ridicule of 
the press (Figure 1) as noted in the following skeptically flippant edito?
rial from the Washington Post of 14 November 1898, regarding the sec?
ond unsuccessful attempt to launch his man-carrying aerodrome. 
14 November 1898 
The Washington Post, Editorial Page 
"WAIT FOR THE FLYING-MACHINE?We note the published statement that 
the authorities are seriously considering the question of airships for the 
army in time of war. General Greely, of the Signal Service, proposed it, 
we believe, and now Professor S. P. Langley, of the Smithsonian Institu?
tion, the National Museum, the National Astrophysical Observatory, 
and perhaps a few other government positions which we haven't time to 
remember at the moment, has been called in to cooperate. General 
Greely, so far as we know, has never yet built and operated a flying-
machine, but he knows all about them, understands them perfectly, and 
besides has rendered illustrious public service such as trying to discover 
the north pole, and actually saving our army at Santiago. Professor Lan?
gley, however, is not only an expert in aerostatics, he has actually con-
structed an airship. He gave eight years of his time, or about that 
much, to the work, and at last he finished it. Furthermore, the ship 
really flew when tested. It flew half a mile, and, what is more, it didn't 
hurt anything or anybody except itself. Very likely it wouldn't have 
done even that if it hadn't stopped so suddenly. 
"Both General Greely and Professor Langley are convinced that the 
practicable airship is a possibility. Of course, they don't mean a thing 
that will fly only half a mile, that cannot carry passengers, and that 
alights with too great violence. Professor Langley built that ship merely 
as a demonstration of his theories. He never intended it for real use. 
But now that the government has agreed to consider the proposition in 
earnest, and General Greely has given it his official sanction, and Pro?
fessor Langley has promised to contribute to the project all the results 
of his experiments and adumbrations, the enterprise takes on a very 
hopeful aspect. As far as the Post is concerned, we are in a state of 
pleasurable excitement. The flying-machine has always been a favorite 
dream of ours. For years past we have been looking forward to a time 
when we should see other people flying about in airships and going 
from place to place without dust or heat or any other discomforts of 
travel. We have never taken a vivid interest in flying-machines that 
carried no passengers. The mere abstract demonstrations of science 
possess no charms for us. But an airship in which the inventor travels 
is our idea of a spectacular performance, and we anticipate it with an 
anxiety and a fervor far beyond all words. 
"We are not yet in a position to state the time at which the Greely-
Langley flying-machine will make its trial trip. We know only that the 
enterprise is in most capable and experienced hands, and we believe 
that, early in the next century, it will materialize. We shall do our best 
to be at the launching. We intend to practice longevity with most indus?
trious enthusiasm in the meanwhile. We should never forgive ourselves 
were we so careless as to die before the ceremony." 
Discouragement and failure haunt all pioneering efforts and Langley 
was no exception. After the second unsuccessful attempt alluded to in 
Figure 1, the machine was never launched again and when he died in 
1906, Langley was convinced that his efforts had been in vain. 
Author David Fairchild indicates Langley's reaction to the failure 
of his dreams.1 
"Professor Langley's discouragement, after the plunge which wrecked 
his only large-scale machine, is reflected in an account given me by 
1
 The World Was My Garden (New York: Charles Scribner's Sons, 1939), pp. 332-
VI 
FIGURE 1.?"The Birds Chorus: 'Wonder Which of Us Was the Model!'" The 
Evening Star, Washington, D.C, 9 December 1903. (Smithsonian photo A4411.) 
Doctor John Brashear, a noted astronomer who was for many years the 
best-loved citizen of Pittsburgh. Doctor Brashear said that he was in 
Washington shortly after the disastrous plunge into the Potomac, and 
Professor Langley sent word that he would like to see him. They had 
been very warm friends when Professor Langley was at the Allegheny 
Observatory in Pittsburgh. 
vn 
" 'As I entered his office in the Smithsonian,' Doctor Brashear said, 
'Professor Langley met me and grasped me by both hands and said, 
'Brashear, I'm ruined, my life is a failure.' He took me to the desk 
and showed me two bits of steel. They were the two triggers which had 
failed to release his machine as it slid down the ways to get its start in 
the air. Instead they had caught and held it, with the result that the 
machine dived into the water. 
" 'He cried like a child,' continued Doctor Brashear. 'You may not 
know it, but he was a very emotional man. I tried to comfort him. I 
reminded him of his discoveries in astrophysics, but he would not be con?
soled. I believe,' said Doctor Brashear, 'that he died a bitterly disap?
pointed man.' " 
Fitting recognition of Langley's aeronautical contributions came in 
1908, two years after he died, when the Smithsonian Regents estab?
lished the Langley Medal for Aerodromics which was awarded for sig?
nificant aeronautical accomplishments. The fifth recipient of this award 
was Langley's "aide in aerodromics," Charles Matthews Manly on 12 
December 1929. "The exceptional action was taken in recognition of 
the fact that the outstanding merit of Mr. Manly's invention and con?
struction of the light, radial, gasoline airplane engine has become 
more and more apparent in the last years." 2 
2
 Annual Report of the Smithsonian Institution, 1931, pp. 7-8. The recipients of 
the Langley Medal for Aerodromics, to date, are: Wilbur and Orville Wright, 1909; 
Glenn H. Curtiss and Gustave Eiffel, 1913; Charles A. Lindbergh, 1927; Charles 
Matthews Manly (posthumously) and Richard Evelyn Byrd, 1929; Joseph Sweetman 
Ames, 1935; Jerome C. Hunsaker, 1955; Robert H. Goddard (posthumously) , 1960; 
Hugh Latimer Dryden, 1962; Alan B. Shepard, Jr., 1964; Wernher von Braun, 1967. 
Vll l 
Acknowledgments 
Copies of the original manuscript were sent to Vernon W. Balzer, son 
of Stephen M. Balzer; John McK. Ballou, business associate of Stephen 
M. Balzer; Charles W. Manly, son of Charles M. Manly; and C. B. 
Veal, business associate of Charles M. Manly. 
I am particularly grateful to Mr. Vernon Balzer for giving the Na?
tional Air and Space Museum his father's papers, and to Mr. John Bal?
lou for his biography of Stephen Balzer and his comments about the 
original manuscript. 
I also wish to thank Mr. C. H. Gibbs-Smith, Keeper of the Public Re?
lations Department, Victoria and Albert Museum, London, and Lt. 
Commander W. J. Tuck, Keeper of Aeronautical Engines, Science Mu?
seum, London, for their help in preparing the present manuscript. 
Finally I take this opportunity to express my gratitude to Mr. S. Paul 
Johnston, Director, and Mr. Paul E. Garber, Assistant Director, Aero?
nautics, and Head Curator and Historian of the National Air and 
Space Museum for their advice and encouragement. 
The material contained herein is chosen for its pertinence to the de?
velopment of the Langley aero engine and to the contribution of the 
three principal participants in its development. Most of the correspon?
dence is excerpted from the originals which are on file in the National 
Air and Space Museum, Smithsonian Institution. Since all questions 
pertaining to the Langley engine cannot be answered in this brief ac?
count, additional information is available to scholars at the National 
Air and Space Museum, Smithsonian Institution, in the form of an 
index of 1,000 cards referencing the Langley papers contained in this 
Museum. Two typewritten manuscripts are also available, which elab?
orate more fully on the subject discussed here, and consist of 1,200 and 
600 pages, respectively. 
In matters of spelling and punctuation, modern usage has been intro?
duced only when the content was unclear or erroneous, in which case 
the proper terminology is supplied in brackets by the editor. Grammati-
ix 
cal lapses have been retained except in a few cases where change of a 
single letter could be classed as a correction of spelling. All proper 
names have been corrected to conform with approved spellings or us?
ages. Throughout Chapters 1 through 8 editorial comments are set in 
italics, the correspondence in roman. 
Contents 
Page 
Prologue v 
Acknowledgments ix 
Introduction 1 
Chapter 1: Influence of the Balzer Automobile Engine, 1894 . . 9 
Chapter 2: Influence of the De Dion-Bouton Automobile 
Engine, 1900 17 
Chapter 5: Balzer-Manly Aero Engine, First Stage . . 27 
Chapter 4: Balzer-Manly Aero Engine, Second Stage 84 
Chapter 5: Balzer-Manly Aero Engine, Third Stage 97 
Chapter 6: Balzer-Manly Aero Engine, Fourth Stage . . . 104 
Chapter 7: Evaluation of the Balzer-Manly Aero Engine 130 
Chapter 8: Evaluation of Balzer's and Manly's Contributions 
to the Engine 157 
Summary 184 
Epilogue . . . . 188 
List of Names 189 
XI 
Introduction 
With the advent of the successful application of power to heavier-
than-air craft by the Wright brothers in 1903, flying became a practi?
cal reality. Although Sir George Cayley of England had developed the 
first man-carrying glider, fifty years earlier, it had been without power 
and, therefore, had had little practical value. 
The genius of the Wright brothers lay in their airframe, propeller, 
and control developments, making the Kitty Hawk Flyer so aerodynam-
ically efficient that it was able to carry a man in flight powered only by 
a 200-pound 12-horsepower engine. 
A contemporary man-carrying powered airplane was developed by the 
Smithsonian Institution known as the Langley Aerodrome A. Being less 
efficient aerodynamically than the Kitty Hawk Flyer, it was abandoned 
after two unsuccessful launchings by catapult over the Potomac River 
during the last quarter of 1903. The engine, 52 horsepower and weigh?
ing 200 pounds, was of the most advanced aeronautical design in the 
world at the turn of the century. It has been on display in the Smith?
sonian Institution for the past fifty years and is known as the Balzer-
Manly aero engine to distinguish it from a model engine built by the 
same designers. 
This book presents for the first time in a comprehensive and correct 
manner the story of Professor Langley's magnificent aero engine or as it 
is otherwise known, the Balzer-Manly aero engine. For the most part 
the text and illustrations are from original source material not pre?
viously published. As a result, long-standing uncertainties concerning 
the engine are resolved for the first time. We are now able to answer 
such questions as: How was Manly able to double the engine's power 
without any design changes three weeks after he removed it from Bal-
zer's shop and started working on it at the Smithsonian? Why did 
Manly change it from an air-cooled rotary radial to a water-cooled 
static radial? Why did the Smithsonian Institution wait twenty-five 
years to award Manly the Langley Medal? Why did Balzer wait for 
1 
thirty years to press his claim? Why did the Aviation Industry wait 
thirty years before adopting the basic design features of the engine? 
The greatest mystery, however, was the lack of credit accorded to Bal?
zer. It was remarked upon by Dr. C. G. Abbot, then Secretary of the 
Smithsonian Institution, in a letter he wrote on 26 June 1933 (now in 
Smithsonian Archives). 
"We recognize that Manly followed Balzer's general design and used 
some parts and much experience that Balzer had been paid contract 
price for. We regret that Manly in his book did not give Balzer more 
credit. It would have been only fair of him to do so." [The book re?
ferred to is the "Langley Memoir On Mechanical Flight" in the Smith?
sonian Contributions to Knowledge, volume 27, number 3 (1911).] 
This lack of recognition was further attested to by Orville Wright in 
his letter of 28 January 1942.3 
"Several years [ago]. . . I read in the New York Times of October 
25, 1931, a story that a Mr. Balzer, of New York, was the author of the 
basic designs of the motor. Smithsonian publications apparently repre?
sented these as being the work of Mr. Manly. As to the merits of the 
claims made on both sides I had no personal knowledge. But a year 
after the appearance of this story in the New York Times, Dr. Abbot 
made the following revealing and significant statement: 
" 'Mr. Balzer, however, though very co-operative, after exceeding his 
contract time on the large engine by many months, did not succeed in 
producing more than 8 horsepower. His engine was fully paid for by 
Langley and removed to Washington. There Charles M. Manly, Lan?
gley's engineer, made certain alterations in it, whereby he raised its out?
put to 21 horsepower. Calculations indicating that this was insufficient, 
Manly designed and constructed an engine on similar lines to Balzer's, 
but with some features from European engine practice, and some of his 
own invention.' " 
It is important to realize that the engine would not have existed 
without the combined efforts of three men: Samuel Pierpont Langley 
who created the need, determined the specifications, and saw to it that 
the money was provided; Stephen Marius Balzer who designed, built, 
and developed the engine in its original configuration; and Charles 
Matthews Manly who redesigned and rebuilt the engine greatly increas?
ing its horsepower and improving its reliability. Each man had 
brought to the task his unique set of qualifications. 
3
 The Papers of Wilbur and Orville Wright, volume 2 (New York: McGraw-Hill 
Book Company, Inc., 1953), p. 1170. 
FIGURE 2.?Samuel P. Langley. Photograph is a gift of Mrs. Charles W. Manly. 
(Smithsonian photo A512.) 
SAMUEL PIERPONT LANGLEY 
Born in New England, Samuel Pierpont Langley (1834-1906) be?
came especially interested in astronomy and mathematics as a student 
3 
in various private schools. The necessity of earning a living, however, 
prevented his going to college. He studied civil engineering and archi?
tecture on his own and worked mainly in Chicago and St. Louis as an 
architect. 
Returning to New England in 1864, he abandoned his profession, 
and spent several years building telescopes in his spare time. After a 
year in Europe, he joined the Harvard Observatory, and became a pro?
fessor of mathematics and was in charge of the observatory at Annapo?
lis. Shortly afterward he became professor of astronomy and physics at 
Western University, Pennsylvania, and Director of the Allegheny Ob?
servatory. In order to buy equipment for the Observatory he sold "ac?
curate time" to the Pennsylvania Railroad. Twice a day the master 
clock in his observatory synchronized the exact time to every station on 
the rail lines extending for 8,000 miles. 
By 1880 he had invented the bolometer, an instrument so sensitive to 
heat that for the first time accurate discriminations could be made be?
tween various narrow portions of the solar spectrum. It was soon 
adapted by astronomers and physicists for their experimental work. 
In 1887 he became Secretary of the Smithsonian Institution, and be?
fore long had established an astrophysical laboratory. He is best known, 
however, for his aeronautical experiments. Rescuing from skepticism 
this subject, which has now become so important, he made careful in?
vestigations of the physics of mechanical flight. As early as 1896 he 
built steamdriven aircraft models of about thirteen-foot wingspan 
which made repeated flights of one-half to three-quarters of a mile. 
STEPHEN MARIUS BALZER 
Upon the death of his father in 1873, Stephen Marius Balzer 
(1864-1940) emigrated with his mother from Hungary to New York. 
Serving an apprenticeship at Tiffany's as a watchmaker, he became a 
journeyman in 1883 and specialized in repairing chronometers. 
The next year he left Tiffany's to work for the Davids Machine 
Works of New York City, later becoming its superintendent. While at 
Davids he studied engineering at Cooper Union night school. In 1889 
he invented a counting register for which, three years later, his com?
pany was awarded the Gold Medal of Superiority by the American In?
stitute. In 1893 a United States patent was assigned to the company cov?
ering Balzer's register. It is the most widely used of all his inventions, 
being found in nearly all speedometers for automobiles today. 
By 1894 he had designed and built the first automobile to run in 
New York City. It was powered by a three-cylinder, rotary, air-cooled 
FIGURE 3.?Stephen M. Balzer. Photograph is a gilt of Mr. John McK. Ballou. 
(Smithsonian photo A49987.) 
382-902 O - 71 - 2 
FIGURE 4.?Charles M. Manly. Photograph taken by Underwood & Underwood; gift 
of Mrs. Basil Manly. (Smithsonian photo A50114.) 
gasoline engine, which has been on exhibit in the Smithsonian Institu?
tion since the turn of the century. 
That same year he left the Davids Machine Works, and concentrated 
on developing his inventions. One was a backing-off mandrel to be used 
in any lathe for machining formed milling cutters. He was issued a pat?
ent in 1895, and received the John Scott Gold Medal in 1896 from the 
City of Philadelphia upon the recommendation of the Franklin Insti?
tute. 
In 1898 Balzer's engine-building ability came to the attention of Lan?
gley who had wisely decided that a gasoline engine would be more prac?
tical for his proposed man-carrying airplane than a steam power plant. 
CHARLES MATTHEW MANLY 
As a youth in Greenville, Virginia, his association with a Cornell 
graduate in charge of the local electrical plant determined Charles Mat?
thew Manly (1876-1927) to become an electrical engineer. 
After a year at the University of Missouri, he entered Cornell as a 
sophomore, and was said to have had the best preparation in mathemat?
ics ever brought to that University. Specializing in electrical and me?
chanical engineering, he was among the early experimenters in the 
transmission of high-voltage currents. 
When Langley had determined to construct a man-carrying airplane, 
he asked Professor R. H. Thurston, Dean of the School of Engineering 
in Cornell, to recommend the best young engineer he knew to assist 
him in this undertaking. Dr. Thurston selected Manly, who was allowed 
to go to Washington immediately, receiving his Cornell degree of Me?
chanical Engineer in absentia. 
As a result of Langley's driving force both Balzer and Manly overex?
erted themselves. The former spent twice the contract price of the en?
gine, using up all of his working capital in a vain effort to fully develop 
it, and the latter permanently impaired his health while rebuilding it. 
Their combined efforts, however, produced the first modern full-size 
aeronautical engine. In its first stage it anticipated the rotaries of the 
1900s, and in its second and subsequent stages it preceded the radials of 
the 1920s. 
Chapter 1 
Influence of the Balzer Automobile Engine 
1894 
/
n order to understand the significance of the Balzer Automobile 
Engine of 1894 to the later development of the Langley aero en?
gine, the difference between a rotary engine and a static radial engine 
should be clear. A rotary engine, (generally known as a rotary) and 
the static radial engine (generally known as a radial), both have 
cylinders arranged around a circular crankcase like the spokes of a 
wheel. In the former case the cylinders, pistons, and crankcase revolve 
around a stationary crankshaft; and in the latter case none of these 
elements revolve; however, the crankshaft rotates, and the pistons 
reciprocate. 
When run as a rotary, the cylinders and crankcase rotate about one 
center, and the pistons and connecting rods rotate about another center. 
This eccentricity, caused by the throw of the crankshaft, permits the 
pistons to reciprocate relative to the cylinders, but not in the absolute 
sense. 
Since there is no absolute reciprocation all of the parts move in the 
same direction with a smoothness approaching that of a turbine. In a 
properly balanced rotary the only noticeable vibrations come from its 
power impulses. A good characteristic of the rotary, therefore, is its 
smoothness of operation. Another advantage is the flywheel effect of the 
rotating parts which lessens the chance of stalling. With cylinders re?
volving, adequate air cooling was provided both on the ground and in 
the air, and this eliminated bulky and heavy xuater-cooling systems. Ad?
ditional weight was saved over inline engines by the short crankshaft 
and crankcase of the radial design which also resulted in a more com?
pact engine, hence a more maneuverable airplane. 
Disadvantages of the rotary engine were: limitation on revolutions 
per minute due to centrifugal stress, the windage losses caused by the 
rotating cylinders, design limitations imposed by rotation of all parts 
but the crankshaft, a rather strong gyroscopic effect on the airplane dur?
ing turns, the necessity of frequent overhauls, high fuel and oil com-
sumption, and excessive throwing of oil by centrifugal force thus mak?
ing the airplane dirty and a fire hazard. 
In spite of these disadvantages the rotary was the best possible design 
for the state of the art as it existed at the turn of the century. It was 
produced in quantity through World War I, and powered many fighter 
planes. 
The automobile went on exhibit at the Smithsonian Institution on 
12 January 1899. It is presently displayed in the Automobile Hall of 
the National Museum of History and Technology. 
16 May 1899?Stephen Balzer to Professor Langley 
At the suggestion of Mr. J. E. Watkins I take great pleasure in pre?
senting to the National Museum my first automobile carriage. It was 
built in the year 1894 and ran successfully for six months. I believe it 
to be the first road carriage driven by a rotating * gasoline engine with?
out water jacket. 
20 May 1899?Memorandum from George C. Maynard, Curator of the 
Department of Mechanical Technology, United States National Mu?
seum describing Balzer's automobile. 
This Balzer machine is a four-wheeled, rubber-tired vehicle, 5 feet 
6 inches long; 2 feet 9 inches wide; 3 feet 2 inches high; gas pipe frame; 
wooden seat and foot-rest. Extra rotary engine with the wagon. 
As shown by the accompanying memorandum the wagon was placed 
in the old Fisheries Hall 12 January 1899 and is still there.5 
1 September 1899?Waste book 6 entry by Manly 
I have today received from Mr. Balzer a small flywheel and a small 
box of fittings which belong to his "second engine," and have put 
Pierce to work fitting the engine up. As soon as I can find the time I 
4
 Refers to a rotary engine. 
6
 Another memorandum written by Maynard on 18 November 1905 indicated that 
an extra Balzer automobile engine was officially given to C. Manly on 5 September 
1899. It was used by Manly to familiarize himself with Balzer's design and to con?
duct aeronautical experiments. 
"Langley's name for notebooks in which he and his staff kept records of their 
experiments. 
10 
FIGURE 5.?Balzer Automobile of 1894. Now on exhibit at the Smithsonian 
Institution. (Smithsonian photo A45576-C.) 
will have a small carbureter built, so that I can use this engine to 
drive one of the 2y2 meter propellers, and thus get some idea of the 
power required to obtain a given number of revolutions of them. This 
engine of Balzer's is said to have developed between 214 and 3 horse 
power. I will run it first to make a brake test with a series of R.P.M.'s 
11 
o 
OH 
C 
?a 
a 
1 
12 
and will then attach the propeller to it and note the number of 
revolutions, and comparing them with the number obtained dur?
ing the brake test, I will be able to determine the horse power required 
to drive the propeller at a given speed. After having once obtained data 
of this kind, I feel very safe in making rough extra-polations up to 15 
or 20 horse power, as it is at present we know nothing at all of the 
power required to drive the propeller at any speed whatever and conse?
quently are unable to say whether or not Balzer's engine would drive 
the propellers at as high a speed as 500 revolutions, even should it de?
velop as much as 20 horse power. I am rather inclined to think that 
Balzer's engine will not drive both the propellers at 500 revolutions, 
even should it come up to as much as 20 horse power. 
12 September 1899?Another reference to Balzer's spare automobile en?
gine appeared in a letter Manly wrote to Balzer 
The fly wheel and fittings for the second engine were received in due 
time, and I thank you very much for having sent them on, and having 
placed the engine at my disposal. I am now having the engine fitted up 
and hope to have it running within a few days. I shall, however, have 
to have a carbureter built for it, and would like very much to try the 
plan we were speaking of when I saw you last, that is, to have a small 
carbureter made out of wired discs and supplied from an ordinary tin 
vessel. However, as I have had very little occasion to construct carbure?
ters, I would be very glad if you would, just as soon as possible, make a 
rough sketch showing a tank holding about 1 gallon, with its carburet?
er, which should be large enough to supply the gas necessary for this 
"second engine." I do not wish a scale drawing, but would like to have 
you just take a pencil and make a rough sketch, showing a few of the 
dimensions, so that I can give it in a rough way for the present purpose. 
I would also be glad if you would write a letter addressed to Mr. J. 
E. Watkins, in his official capacity as Curator of Mechanical Technology, 
U.S. National Museum, directing that the second engine be delivered 
to me at the Institution. I have already secured the engine, but merely 
want this letter sent to Mr. Watkins so that the official form may be 
gone through with. 
31 March 1900?A final reference to Balzer's spare automobile engine 
appeared in a letter Manly wrote to Balzer 
In regard to your request that I write up a sort of report of your wagon 
engine, and send it to Mr. E. Molson, 411 West 147th Street, New York 
City, I explained to you over the long distance telephone that it would 
13 
FIGURE 7.?Cylinder details of Balzer automobile engine of 1894. Left to right: 
Automatic intake valve spring, make and break ignition return spring, and 
exhaust valve spring. (Smithsonian photo A417.) 
be impossible for me to render an official opinion upon the engine, as 
this would be contrary to the wishes of the Secretary at the present 
time, owing to the fact that he wishes the matter kept quiet until after 
the official test. However, I stated to you over the 'phone that I would 
be very glad to speak in a personal way, and as a Mechanical Engineer, 
with regard to your wagon engine, but owing to my official connection 
with the Institution I prefer not to write to Mr. Molson direct, though 
14 
FIGURE 8.?Cylinder details of Balzer automobile engine of 1894. Left to right: 
exhaust ports, exhaust tube, intake tube, and ignition wire. (Smithsonian photo 
A416.) See Figure 7. 
if you desire you may show him this letter, calling particular attention 
to the remarks which I make below concerning it. 
I first examined one of your engines during the latter part of Novem?
ber, 1898, and the opinion which I then formed that it was built upon 
thoroughly correct (both thermodynamic and mechanical) principles 
has been, I think, entirely justified by what I have seen of your engines 
since that time. 
I consider the principle of the rotating cylinders which you use in 
15 
their construction as making them particularly well adapted for auto?
mobile work, the revolving cylinders making it possible to build an en?
gine for a given horsepower of a very much lighter weight than on any 
other principle that I know of. 
Balzer's automobile engines of 1894 had several features in common 
with the first stage of the Balzer-Manly Rotary Aero engine of 1900?the 
first full-size gasoline airplane engine. They are described in Patent 
Number 573,174 issued to Balzer on 15 December 1896, and are as fol?
lows: (1) Rotary radial design, (2) Odd number of cylinders, (3) Air-
cooled cylinders, (4) Automatic (suction operated) intake valves, (5) Ex?
haust valves operated by a cam concentric with the crankshaft, (6) Low 
tension make-and-break ignition system, (7) Ball and socket joints 
(pistons to connecting rods), (8) Slipper bearings (connecting rods to 
crankshaft), (9) Surface carburetion, (10) Four-stroke cycle operating 
system. 
As described in the next chapter, another automobile engine also in?
fluenced the design of the Balzer-Manly engine. This was the De Dion-
Bouton engine discovered by Langely and Manly while they were in 
Europe during 1900 seeking an improvement over the Balzer-Manly ro?
tary engine. 
16 
Chapter 2 
Influence of the De Dion-Bouton 
Automobile Engine, 1900 
13 May 1899-"The DeDion-Bouton Tricycle," by E. Bernard, Scien?
tific American, vol. LXXX (19): 307-308. 
Nowhere has the development of automatically propelled vehicles 
reached a more advanced stage than in France, where, on account of the 
fine roads and pavements, the most favorable conditions are found for 
their operation. Carriages and tricycles operated by gasoline motors are 
now among the ordinary sights in the streets of Paris. Among the latter 
the tricycle DeDion-Bouton is most extensively in operation, and may 
be considered as typical of this class of vehicles. 
The motive power used is that of a small hydrocarbon motor, operat?
ing on the same principle as the gasoline engine, the gas being fur?
nished by the evaporation of gasoline contained in a vaporizing cham?
ber, and then mixed with air to form an explosive mixture, which is 
then conducted to the chamber of the motor, and which by its explosion 
at proper intervals operates the piston. 
The action of the motor will be seen by referring to the diagram 
shown in Fig. 1 [Figure 13]. To the left is the vaporizing chamber or 
carbureter, in which the gasoline contained in the lower half is brought 
into contact with the air entering by the tube, A, and made to pass be?
tween the horizontal plate, B, and the surface of the liquid; the carbu?
reted air then rises, as shown by the arrows, and enters the double valve, 
C, shown below in detail, by which it is mixed with an additional 
quantity of air, which enters by the orifice, D, at the top; the mixture 
then passes to the motor by means of the tube, E. The admixture of air 
is regulated by the handle on the left, and the supply of gas by that on 
the right. The float, F, serves to indicate the level of the gasoline in the 
17 
^ ? "(fl 
FIGURE 9.?De Dion-Bouton engine. View of driveshaft end. 
(Smithsonian photo A232-C.) 
carbureter by means of a rod which passes through the tube of admis?
sion; and the tube itself is arranged to slide up and down in order to 
maintain a constant difference between the horizontal plate and the 
surface of the liquid, this plate being attached to the lower end of the 
tube. In order to avoid the cooling of the gasoline by evaporation, it is 
warmed by means of the tube, G, through which passes a portion of the 
hot gas escaping from the motor. By this means a nearly constant tem?
perature is obtained for a given speed of the motor. 
The cylinder, H, of the motor is of cast steel, with projecting flanges 
which serve to increase its radiating surface and prevent overheating; 
above is the chamber, J, in which the explosion of the gas takes place; 
at the top of the chamber is the valve, K, which admits the gas coming 
from the carbureter; the valve is normally closed by means of the 
spring, S, whose pressure is regulated so as to allow the valve to open 
upon the descent of the piston. Opposite is the exhaust valve, L, which 
permits the waste gasses to escape after the explosion; to the valve, L, is 
attached a rod which passes through the cover of the exhaust chamber 
and engages with a cam, M, by pushing up the rod, opens up the valve 
at the proper instant, this valve being normally closed by the spring r. 
At W is shown the igniter, consisting of two copper rods passing 
through an insulating bushing and so arranged as to allow a spark from 
the induction coil to pass in the interior of the chamber for the ignition 
18 
FIGURE 10. De Dion-Bouton engine. View of ignition end. (Smithsonian photo A232. 
19 
FIGURE 11.?De Dion-Bouton engine. Crankcase section (ignition side) showing 
exhaust valve cam and cam follower. (Smithsonian photo A4474A.) 
of the gas. The piston, O, is a hollow steel casting provided with three 
packing rings, and carrying the wrist-pin. The piston is connected with 
the enclosed fly-wheels, Q and R, and with the shafts, S and T, by 
means of the piston rod, P. The shaft, S, carries a pinion which engages 
with another of twice its diameter, operating the small shaft above, t, 
which carries two cams; the cam on the right serves to open the exhaust 
valve once in every two revolutions, while that to the left acts upon the 
lever arm, U, carrying the contact, V, of the induction coil, by means of 
20 
FIGURE 12.?De Dion-Bouton engine. Left to right: crankcase section (ignition side), 
cylinder, piston, cylinder head, crankshaft with connecting rod and flywheel unit. 
(Smithsonian photo A4474.) 
which a spark is caused to pass at W, thus igniting the gas contained in 
the chamber of the motor. 
This induction coil is operated by four dry piles. From the preceding 
description the action of the motor will be readily understood. When 
the piston descends, it produces a vacuum in the top chamber, by ac?
tion of which the valve, K, opens, admitting the detonating mixture 
from the carbureter; when the piston rises, it compresses this gas, and 
the valve of admission closes. At the instant of the second descent of the 
piston the cam actuates the lever, making contact with the induction 
coil, upon which a spark passes, causing an explosion of the gas, which 
pushes the piston with sufficient force to cause it to pass twice through 
the same position; when the piston rises after its descent, it compresses 
the residual gasses of explosion, and at this instant the cam, M, lifts the 
exhaust valve and the gas leaves the motor by the exhaust pipe, Y. 
When the piston redescends, this valve closes and the upper valve 
opens, as before, to admit a fresh supply of gas, and so on. 
The action of the motor is thus determined by four different periods, 
which may be characterized as (1) introduction of gas, (2) compres?
sion, (3) explosion, (4) evacuation of the products of combustion. 
Figs. 2 and 3 [of Figure 13] show the tricycle complete. In Fig. 2 the 
handle, D, serves to open or close at the proper time the cock shown in 
the diagram, Fig. 1, at Z, which permits the piston to ascend and de?
scend freely when starting the motor. The handle, A, displaces the sup 
port of the contact of the induction coil in order to vary the instant of 
ignition with relation to the introduction of gas; the handles, B and C, 
serve respectively to regulate the admission of gas to the motor and the 
introduction of air to the carbureter. The pedal, P, operates the main 
axle of the tricycle and at the same time starts the motor, which is 
21 
382-902 O - 71 - a 
ICYCLI MOTOH. 
Fig. 2 . _ T H E Itk. UlOM-flut'lMN 
FIGURE 13.?Illustrations from "The De Dion-Bouton Tricycle," by E. Barnard, 
Scientific American, 13 May 1899, LXXX(19): 307. (Smithsonian photo A20939-A.) 
geared to the same axle. The tricycle may be operated by the pedal 
alone in case of accident or in mounting steep grades. 
Figs. 4 and 5 [of Figure 13] show the motor dismounted and pro?
vided with a frame for securing it to the tricycle. A is the admission 
valve; B, igniter; C, exhaust pipe; D, rod and spring of exhaust 
valve; E, contact, cam and binding posts. 
The maximum speed of the tricycle is 24 miles an hour, and grades 
of eight to ten percent may be mounted without the aid of the pedals.7 
7
 It developed 2y? horsepower. 
22 
The Waltham Manufacturing Company of Waltham, Massachusetts, 
will exclusively sell the product of DeDion-Bouton and Company in the 
United States, and in addition to selling the regular machines now 
manufactured by DeDion-Bouton and Company they will import the 
DeDion motors and make a complete line of "Orient" motor cycles and 
motor carriages. They are now building tricycles, trailers and attach?
ments, tandems, and a light carriage, and will add other vehicles.8 
2 October 1900?Langley memorandum (in part), Paris, France 
I went out to Puteaux to see Mr. Bouton of the De Dion-Bouton 
firm. Bouton, I was told, is the original engineer and inventor, and De 
Dion the man of business, although he had learned a good deal of engi?
neering on the way. 
Bouton was to be there shortly, but when [we] got out there he had 
not arrived, and I entered into conversation with a resident engineer 
whose name was Lecoeur. I got nothing out of him that was practical. 
He thought that the firm would try to build something if I wished it, 
though they would not undertake it in a commercial spirit and not at 
any fixed price, that is, attempt a machine of 20 horsepower weighing 
80 kilos [1 kilogram = approximately 2.2 pounds]. 
He proposed to show me the parts that were actually in use for the 
light motors. I went up to the warehouse where the pieces were all ar?
ranged. 
I understood that in the ordinary way of business, these are only to 
be bought by those who have machines already, and that the machines 
themselves cannot be got for a long time, because there are so many or?
ders in advance. 
Mr. Lecoeur agreed to deliver to me here tomorrow morning at 9:30 
o'clock, completely boxed, the entire engine outfit of a bicycle or tricy?
cle engine. It was to be complete, including the batteries, carbureter 
and every incident of part. I do not remember the size of the cylinder, 
but it was I think 314 inches. 
He remarked that the 2i/2 horsepower could be extended with a 
somewhat more effective cooling than was obtained by the radiation. 
8
 It is ironical to note that this copy of Scientific American was available to 
Langley before he left for Europe. In Langley's words the only useful information 
regarding aeronautical engines garnered by Manly and himself during the European 
trip was data about the DeDion-Bouton engine plus the fact that one of these 
engines was imported by the Smithsonian. 
Advertisements for the DeDion-Bouton "Motorette" appeared in Scientific Ameri?
can for 18 and 25 August and 1 and 8 September 1900. It was called, "The standard 
automobile motor of the world." Over 20,000 were in actual use. 
23 
The whole thing was to be 600 francs, and I undertook to take it as it 
stood, away with me in the carriage, but he said that it would take 
some time to box it up and that I might rely with absolute confidence 
of its being here in the morning. 
I was to pay 600 francs in the form of a letter on the banker. 
3 October 1900?Langley diary (in part) 
The DeDion-Bouton 3 HP engine is delivered at the hotel this morn?
ing & S.P.L. pays the carrier 600 francs, getting a receipted bill 
[$115.80]. 
1 November 1900?Manly waste book entry (in part) 
I today had the small DeDion-Bouton engine taken apart and the 
various important parts weighed. 
The most notable thing about the whole engine is the lightness of 
the pistons, the wall of the piston being only 2i/2 millimeters thick, and 
the head only 4 millimeters thick; the piston rings fit very loosely in 
their grooves, there being only three rings. 
10 November 1900?Wells diary 
The account of the DeDion-Bouton Motorette Company for $52.00 
was sent them today, also a letter and copy of regulations of the U.S. 
Treasury requesting them to forward the necessary certificate of author?
ity enabling the proper officer to sign vouchers. 
13 November, 1900?Wells diary (in part) 
The Secretary was reimbursed to the amount of $115.80 for the small 
De Dion-Bouton engine which he bought of the manufacturers in Paris 
in October. 
18 January 1901?Wells diary (in part) 
The De Dion-Bouton motor is mounted on a testing frame in the 
lower room of the South Shed, and this morning ran about 4,000 rpm. 
Voucher No. 405-Page 21-1901 
January 25th-To 5 Spark Plugs 9-$2.00-$ 10.00 
De Dion-Bouton Motorette Company 
37 th and Church Lane, Brooklyn, New York 
Signed by Langley and Manly 
9
 The De Dion-Bouton used one spark plug, however, Langley's aero engines 
used 5 spark plugs. 
24 
20 February 1901-F. W. Hadley in Washington, D.C, to the De Dion-
Bouton Motorette Company, 37th and Church Lane, Brooklyn, New 
York. 
I am authorized by the Secretary to inquire whether you can furnish 
the Institution with some of the porcelain stems as are used in the 
sparking plugs. 
A great deal of difficulty has been experienced at the Institution from 
these porcelain portions of the plug getting broken, and what is wanted 
is either the separate porcelain stem or the stem with merely the pla?
tinum wire cemented into it. 
If you can furnish these please let the Secretary know as soon as possi?
ble, and at what price. 
Voucher 468-Page 112-1901 
To: De Dion-Bouton Motorette Company 
37th and Church Lane, Brooklyn, New York 
Feb. 28th?5 Porcelains for sparking plugs .20?$1.00 
May 8th?15 Porcelains for sparking plugs .20?$3.00 
May 24th?20 Porcelains for sparking plugs .20?$4.00 
$8.00 
[Signed] S. P. Langley 
/ May 1901?Wells diary (in part) 
The large engine is run considerably today by the attached De Dion-
Bouton engine in the process of "wearing" the new pistons. 
It is found later today that this D. B. [De Dion-Bouton] engine heats 
up too rapidly so Mr. Manly has one of the electric motors attached to 
the engine in its place. 
No further mention is made of additional experiments using the De 
Dion-Bouton engine. Two features of the De Dion-Bouton engine were 
used in Manly's development of the Balzer-Manly engine; the light?
weight pistons and the ignition system. 
On 18 February 1901, according to the Wells diary, piston castings 
were received from the Erie Foundry Company, and were installed on 
29 April 1901. Apparently from this time onward only the De Dion-
Bouton type of piston was used. Figure 12 illustrates this type of piston 
which is still in general use today. It is readily distinguished from the 
design Balzer employed by the fact that it uses a piston pin as opposed 
to the ball and socket bearing employed by Balzer which is illustrated 
in Figure 18. 
25 
The ignition system is discussed in detail in the affidavits of Hewitt 
and Newham of 22 and 23 May 1933 (pages 179-183). A quotation fol?
lows from the Newham affidavit. 
"The make and break ignition system with which said original en?
gine had been equipped by Balzer was not satisfactory, and Mr. Manly 
instructed us to make a copy of the De Dion jump-spark system that 
was installed on an engine he had purchased in France from the Comte 
De Dion. This ignition system was successful." 
Balzer had planned to use a high-tension or jump-spark system, but 
he changed his mind and with Manly's approval installed low-tension 
ignition. 
The Balzer-Manly aero engine underwent modifications for five 
years through four principal stages of development. These stages may be 
defined by the horsepower achieved at the end of each modification 
stage. 
The first stage reached a culmination in 1900 when the engine devel?
oped 8 horsepower as an air cooled rotary. During the second stage 
when the engine was changed to a static radial and cooled with damp 
rags it reached 18 horsepower in 1901. The third stage was reached in 
1902 as a result of modern design light weight pistons which permitted 
the development of 25 horsepower; and 1903 marked the culmination 
of the fourth stage when 52 horsepower was attained after the engine 
was equipped with larger cylinders. This progress is charted on Figure 
44 (page 185). A detailed description of the stages is given in the fol?
lowing three chapters. 
In addition to power-producing modifications, there were two other 
important improvements which greatly increased the engine's endur?
ance: the addition of permanent water jackets, instead of damp rags, to 
keep the cylinders cool; and the use of a master and link rod system to 
replace a less advanced method of joining the pistons with the crank?
shaft. 
26 
Chapter 3 
Balzer-Manly Aero Engine, First Stage 
T\uring the entire first stage, the engine was in Balzer's machine 
JLJshop, and its features reflected his thinking. Developed as an 
aircooled rotary radial, the engine was the simplest, lightest, and most 
practical form at this state of the art. Although this type became very 
popular from 1910 through 1920, Balzer was unable to fully develop 
his own version of the rotary. 
22 October 1898?Langley's first entry in his record book 
I mean to use this book as a strictly private diary of the more impor?
tant or to me more interesting parts of what goes on in connection with 
Aerodromics. 
At the time I write, I have had some conferences with the Board of 
Army and Navy officers appointed by the Secretaries of War and Navy. 
A copy of their report is in a large envelop in a drawer of my private 
desk. Nothing has come of it, and nothing may come. 
I have decided, however, to go on with the large aerodrome as far 
as the limited means allow, if I can get a gas engine built within the 
terms of the proposed contract with the American Motor Company, of 
New York. 
The American Motor Company, after offering to build such a gas en?
gine as I would want, have since then withdrawn from their proposal, 
and asked a higher price, which was acceded to, and finally after six 
months delay, have decided they will not undertake. I am about writ?
ing to the Pope Manufacturing Company.10 
The sketch plans for the large aerodrome have been made. The 
10
 The above paragraph emphasizes the importance of the engine. It was consid?
ered to be the major unknown quantity. The American Motor Company gave up 
when it could not find anyone willing to cast the cylinders. 
27 
S1DC E L C V A Y l O N . 
DRAWINGS OF PROPOSED MAN-CARRYING AERODROME, 1898 
FIGURE 14.?Three views of proposed man-carrying aerodrome drawn by W. L. Spei-
den on 11 June 1898 under supervision of Langley and Manly. Sent to American 
Motor Co. From "Langley Memoir on Mechanical Flight" Smithsonian Contribu?
tions to Knowledge, vol. 27, no. 3 (1911), pi. 32. (Smithsonian photo A33322.) 
28 
French tubes are all ready, and the brass thimbles for uniting them at 
least temporarily so that the machine can be set up, are nearly done.11 
5 November 1898?Letter from Rathbun to Mr. Stephen M. Balzer, at 
370 Gerard Avenue, New York City. 
The Smithsonian Institution is desirous of promoting the construc?
tion of specially light gasoline engines, and the Secretary directs me to 
inquire whether you would accept an order for one of 12 brake horse 
power weighing not over 120 pounds, fly wheel, water-jacket and water, 
or substitutes for water (such as special radiation) and every accessory 
included. The weight would include a crankshaft but not a bed plate 
engine mount. 
By way of explanation, I might say if it is thought desirable, there 
may be as many as 6 cylinders as a substitute for the fly wheel or other?
wise and that the engine would need to be guaranteed to run three 
hours without heating. Many usual considerations may be sacrificed to 
weight. 
7 November 1898?Waste book entry by Langley 
Lieutenant J. N. Lewis, recorder of the Board of Ordnance and For?
tification wrote me on the 2nd of November on the part of the Ord?
nance Board. He called Saturday, and I showed him the shop and 
loaned him the photograph of the aluminum ballon with a group of 
Prussian officers. 
He says the Board has had two talks over the report of the Army and 
Navy officers. He thinks they will be willing to approve the $50,000 if it 
need not all be given at once. I asked him to prepare them not to ex?
pect to see an actual flight of the model (5 or 6) this year. I am to go 
before the Board on the 9th at 12.12 
11 November 1898?John F. Stout in New York City to Langley in 
Washington, D.C. 
Replying to your esteemed favor of the 5th inst. would say that we 
" T h e three-view drawing (Figure 14), previously published in the 1911 
Langley Memoir on Mechanical Flight, shows the aerodrome powered with two six-
cylinder inline engines mounted on outriggers, each one directly driving a propeller. 
This arrangement had the advantage of simplicity; however, it was a heavier instal?
lation than having the engines mounted inboard and driving the propellers by 
means of chains or shafts. It was presently decided that the additional weight of the 
bracing needed to support the engines when mounted on outriggers was too great a 
penalty to pay. As a result all of the later designs show inboard mounted engine (s). 
12
 Langley did go before the Board as scheduled, and received an immediate ap?
propriation of $25,000. 
29 
would undertake to build a gasoline engine that would develop 12 
brake horse power and not weigh more than 120 pounds, and would 
take an order for one, providing that we can get a satisfactory price. 
You will of course understand that as it would have to be made spe?
cially it would be quite expensive, but we would guarantee it in every 
particular and give a fine mechanism. There is no question but that it 
will not heat if run 24 hours and at a high speed. 
We would be pleased to hear from you further on this subject and 
would esteem it a great honor to secure your order. 
12 November 1898?Rathbun in Washington, D.C, to Stout in New 
York City. 
Your letter of the 11th instant, in regard to the proposed small gaso?
line engine, has been received, and, in reply, the Secretary directs me to 
say that the engine desired must fulfill the following specifications: 
The engine is to be an Otto cycle, six cylinder gasoline engine, 
capable of developing 12 brake horse power at from 600 to 800 revolu?
tions per minute, but working efficiently at any speed between 400 and 
1,200 revolutions per minute, of a total weight not to exceed 120 pounds, 
including crank-shaft, flywheel, water-jacket and water, or substitutes 
for water (such as special radiation) and every other accessory except 
bed-plate. 
The 12 brake horse power in question shall be developed continuous?
ly, with ordinary careful handling, by an ordinary engineer, and the 
engine must be capable of being run continuously for three hours with?
out overheating. The engine must be capable of burning ordinary 
gasoline, and the fuel consumption is not to exceed one pound per 
horse power per hour. 
I am further directed to say that only responsible parties have been 
written to with reference to this proposed engine, and, if it be decided 
to build it, that the contract will be let to the lowest bidder, with the 
understanding that it will not be received until a rigorous and satis?
factory inspection has been made of everything used in the construc?
tion of and the workmanship on the engine, as well as of its fulfillment 
of the preceeding condition under tests. 
The engine must be completed and ready for the official test within 
four months from the date of the contract, and this test shall be held in 
Washington, in the presence of three experts, one to be appointed by 
each party and the third by mutual agreement. 
If you care to enter into a contract containing the above specifica?
tions, an illustrative drawing will be sent you showing the method of 
30 
support and general disposition of the cylinders. However, in order to 
enable this illustrative sketch to be prepared, you should send a sketch 
showing the approximate dimensions of the cylinder and the length of 
the stroke which you would use. If you care to, further make an esti?
mate on a still lighter engine, specifying weight and price. 
9 May 1898?Langley in Washington, D.C, to R. H. Thurston in Ith?
aca, New York. 
I mention in especial confidence that official enquiries from the Army 
and Navy lead me to think it possible (I can hardly say probable) that 
an aerodrome capable of a speed of 30 miles an hour maintained for 
three hours, carrying an "aeronaut" and possibly some missiles may be 
attempted. I think it practicable though not to be realized without 
trial. I should try to have some form of gas engine. Have you any young 
man who is morally trustworthy ("a good fellow") with some gump?
tion and a professional training.13 If nothing comes of this, I have 
still some work for such a one in experimenting here, on aerodynamic 
data, etc. 
26 November 1898?book Entry by Langley 
The Balzer engine (mounted on a tricycle) arrived yesterday after?
noon and Manly is testing its hp today.14 
/ December 1898?Manly and Watkins to Langley 
In connection with the accompanying memoranda, I beg to recom?
mend that unless some better offer should be received for the gas engine 
from other manufacturers, the contract be closed with Mr. Balzer, if he 
will accept it on the terms already proposed, and if his price is reasona?
ble. 
30 November 1898?Memorandum from Manly to Langley (in part) 
Mr. Balzer had come down to bid on a gas engine of 12 horse power 
weighing not over 120 pounds and fulfilling the other conditions incor?
porated in the letter to him of November fifth. Mr. Balzer now finds 
that the weight is limited to 100 pounds for 12 horse power, and he is 
13
 Dr. Thurston chose Charles Matthews Manly who did not even wait to be grad?
uated properly?his diploma was granted in absentia. On 1 June 1898, he reported 
(sight unseen) to Langley in Washington, D.C, signed the pay roll for $1,000 per 
annum, and presently became "aide in aerodromics." 
14
 Langley, Manly, and Balzer became directly involved on the aero engine project 
for the first time. From this consortium evolved the most advanced airplane engine in 
the world at the turn of the century. 
31 
therefore, at the present moment unprepared to put in his bid without 
further calculations of weights, cost, etc. Mr. Balzer s intention was to 
construct the engine upon the principles of the other engines which he 
sent down here, the only difference being that he now proposes to use 5 
cylinders instead of 3. By using 5 cylinders he is able to obtain 5 ex?
plosions for 2 revolutions of the engine, thus leaving no portion of the 
stroke dead. This latter construction would be quite a gain, since the 
engine will run very much smoother. 
In the construction of his 5 cylinder engine Mr. Balzer proposes to 
make the cylinders 41,4 inches in diameter, with a 6 inch stroke. The 
cylinder proper are to be made of ]/l6 inch soft steel, with a cast iron 
FIGURE 15.?Jacobs engine of 1914 illustrating the use of both spiral and parallel 
types of cooling fins. (Smithsonian photo A607.) 
32 
bushing 1/g inch thick. On the outside of these steel cylinders he will 
turn screw threads, to facilitate cooling by radiation. The object in 
turning a screw thread on these cylinders, instead of parallel rings, is 
that the screw thread will tend to conduct the heat from the hot end of 
the cylinder to the cooler end, whereas the rings would not do so.15 In 
building his engine for 120 pounds weight Mr. Balzer had expected 
that the cylinders would weigh 8l/? pounds each, and that the pistons 
would weigh about 1 pound each. The length of the bearing surface of 
the piston would have a square section. Mr. Balzer expects to cut down 
the weight of these cylinders now, in order to bring the weight of the 
engine within 100 pounds. This he will do by making the steel less 
than 1/16 of an inch in thickness. He does not care to cut down the thick?
ness of the cast iron bushing, because the cast iron, being a porous 
metal, absorbs oil, and thus lubricates the piston, and he fears that less 
than I/3 of an inch will not be a sufficient thickness for this purpose. 
This 5 cylinder engine will have no [fly] wheel surrounding it at all, 
being in this respect similar to the first engine which Mr. Balzer sent 
on here. 
Mr. Balzer says that the premature explosion occurs when the cylin?
ders reach a temperature of about 650 Fahrenheit]. He also says that 
he is not worried at all in regard to keeping the cylinders cool without 
the use of a water jacket; his idea in arranging these cylinders in a cir?
cle, and allowing them to revolve, is to obviate this very difficulty. 
Mr. Balzer expects to obtain a pressure of 350 pounds to the square 
inch at the beginning of the explosion. This will necessitate very accur?
ate fitting of the pistons to the cylinders. He proposes to use 5 cast iron 
packing rings on the piston, the centre ring being a bull-ring. 
The cylinders of the engine will describe a circle about 33 inches in 
diameter. The central drum on which the 5 cylinders are to be 
mounted will be about 12 inches in diameter, and will be constructed of 
steel, and every precaution will be taken to make it as light and at the 
same time as strong as possible. 
Mr. Balzer does not propose to use a coil for sparking the cylinders, 
but will construct a small high voltage dynamo which will be placed on 
the same shaft with, and very close to, the engine. The dynamo itself 
will weigh about 5y2 pounds, and it will cost him about $100.00 to 
have it built. He will have the dynamo built outside by an electrical 
concern, but after his own designs. 
15
 The reference is to different types of cooling fins, one featuring a spiraling type 
such as used on some air-cooled machine guns, and the other a series of parallel 
rings as used on all modern air-cooled aero engine cylinders. 
He does not now use a "wiping contact" for igniting the charge in 
the cylinders, but uses instead an arrangement by which he gets a spark 
at the proper time.16 
Mr. Balzer was unable to give me an exact estimate as to the time 
required to build the engine under the modified conditions, but he said 
that it would require between 3 and 4 months. 
Owing to the fact that the cylinders of the engine will sweep through 
a circle of something more than 30 inches diameter, I beg to advise, for 
several reasons (which we have already discussed), that the engine be 
so placed in the aerodrome that the plane of the circle described by the 
cylinders will be in the direction of motion of the aerodrome. If the 
engine is thus placed it will present a surface of only about 1 square 
foot, perpendicular to the direction of motion of the aerodrome, since 
the engine will be only about 5 inches wide. If the engine is placed di?
rectly on the propeller shaft it will present a surface of nearly 6 square 
feet, perpendicular to the direction of motion of the aerodrome. Mr. 
Balzer does not feel certain that he can guarantee the 12 brake horse 
power without providing for possibly more, as no skill or knowledge 
will enable one to calculate the horse power of a gas engine accurately 
in advance. The horse power depends so much on the degree to which 
compression of the explosive mixture is carried, and compression de?
pends so much on the tightness of the pistons in the cylinders, that it is 
very difficult to say just what horse power will be developed with a 
given size of gas engine running at a given speed. 
I add a rough sketch to illustrate the principle of construction which 
Mr. Balzer employs in his gas engines.17 
If the crank is fixed, the cylinders kick themselves and the support?
ing-drum backwards, and if the cylinders are fixed the crank is kicked 
forward, so that no matter which is fixed, power may be obtained from 
the other. 
I consider the principle of construction which he employs in his en?
gine as both mechanically and thermodynamically correct, and I beg to 
say that my opinion is that the engine which you desire can be con?
structed very much lighter on this principle than on any other which I 
have seen. 
I find Mr. Balzer a practical mechanic who can build (and perhaps 
will build) this engine with his own hands, and who appears to under-
16
 By "wiping contact" Manly means a low tension ignition system. The implication 
is that Balzer proposed a high tension or spark plug ignition system which is the 
modern practice. 
17
 Not reproduced here. 
34 
stand and appreciate the thermodynamical and mechanical principles 
involved in the construction of gas engines. According to his statement 
(confirmed by Mr. J. E. Watkins) he has a large and well equipped 
shop which is devoted to the manufacture of a number of engineering 
appurtenances, but which is capable of being used in the construction 
of gas engines. Mr. Balzer is evidently desirous to build this engine and 
appears very much interested in the work. You have seen Mr. Balzer 
and will perhaps agree with me the favorable impression that he has 
made on Mr. Watkins and myself. 
5 December 1898?Balzer in New York City to Langley in Washington, 
D.C 
My interview with Mr. Watkins and Mr. Manly about the proposed 
engine. Would say I would be willing to build a fine revolving cylinder 
gas engine of my own design, developing at five hundred revolutions 
twelve brake horse power weighing not over one hundred pounds for 
the sum of $1,500. The workmanship can be passed upon by any me?
chanic you may appoint. To be delivered ten weeks from date of con?
tract. Hoping this will meet with your approval. 
10 December 1898?Rathbun in Washington, D.C, to Balzer in New 
York City 
In reply to your letter of December 5, containing your bid on the 
proposed 100 pound, 12 horse power, gasoline engine, I am directed by 
the Secretary to say that your bid will be accepted upon the signing of 
the enclosed contract and your furnishing the bond for the advance 
payment therein mentioned. 
As soon as you sign the contract please return it and it will be prop?
erly signed here and a certified copy will be immediately sent to you. 
As the Secretary is about leaving Washington for some weeks, and 
wishes to dispose of the matter before going away, allow me to request 
that you attend to the matter as soon as is possible. 
12 December 1898?Balzer in Nexo York City to Langley in Washing?
ton, D.C. 
Find enclosed contract signed. I will forward bond in a few days. 
Have also put work on engine in hand. Hoping this will meet with 
your approval, and thanking you for your valued contract.18 
"Realizing that Balzer had signed the contract, Langley wrote the Board of 
Ordnance and Fortification on the same day accepting the invitation to build a man-
carrying aerodrome. 
35 
17 December 1898?Langley entry in waste book 
Yesterday received the following telegram from Lieutenant Lewis, re?
corder of the Board of Ordnance and Fortification: "Board approved 
letter. You are given fullest discretion in the work." 
Immediately proceeded to arrange, as far as possible, for the work of 
the New Year. 
23 December 1898?Rathbun to George Wells 
The Secretary directs me to notify you that as part of your new duties 
you will have immediate care, under the direction of Mr. Manly, of the 
books, manuscripts and other papers in the Aerodromic Room, and will 
also attend to pasting in the scrap books the clippings relating to aero?
dromics. 
The Secretary also wishes me to remind you that your new duties 
will ordinarily call for a longer day's work than the old ones, as your 
hours will necessarily be nearly the same as those of the workshops, 
where you will have frequently to be rather than those of the Parent 
Institution. 
11 January 1899?Langley in Washington, D.C, to Balzer in New York 
City 
I herewith enclose you, in compliance with your verbal request, a 
sketch showing the general disposition of the engine. You will observe 
that the sketch provides for the possibility of two engines, but the sec?
ond engine, if ordered, will come later, and you will notice (1) that 
the one with which we are concerned at present, must run both propell?
ers if desired; (2) possibility of this second engine must be arranged 
for so that the propellers can be run by the second, if wished. 
As I understand the construction of your engine, it does not, without 
modifications, admit of the cylinders rotating and yet driving a shaft 
which is run through continuously in the way here shown, or in some 
way which will be equally simple and especially equally light. 
These are the principle points which I have thought it best to refer 
to you, who are the designer of the engine and know best how to adapt 
it to such a condition as here presents itself. I may add incidentally 
that a desirable provision, but not an absolutely indispensable one, 
would be to enable the engineer to employ one engine on one propeller 
wheel, and not on both, if occasion arose. I suppose, however, that this 
might add weight enough to be prohibitory.19 
19
 Langley was apparently trying to increase maneuverability by being able to speed 
up one propeller relative to the other. 
36 
58m*m*m*00&m>
 t<t?e*^>*. 
.***. t = ; 
ZKuabtlti'^- ortZtf asre? rur/~ 
FIGURE 16.?Sketch authorized by Manly, drawn by Speiden, approved by Langley, and 
forwarded to Balzer on 11 January 1899 showing proposed mounting of engine. 
(Smithsonian photo A4480-C.) 
It will also be noted that the bearings for supporting the engine shaft 
are not shown, as these are details which will have to be arranged for 
later, when the exact dimensions of the engine, shaft, etc., are known. 
The sketch, which is merely to illustrate in a general way the length 
of the shaft that will be required to transmit the power from the engine 
to both propellers, is fully labeled, and arrows indicating the direction 
of motion of the propellers have been added. The distance between the 
tubing which forms the cross frame has been made 36 inches, based upon 
your statement made when you were in Washington, that the diameter 
of the circle swept through by the engine cylinders would be about 33 
inches. If this distance of 36 inches is not great enough to accomodate 
your engine you should let me know immediately, so that in making up 
the drawings this can be altered. 
The distance between the tubes of the main frame is seen to be 36 
inches and it is hoped that this width will accommodate two engines of 
your design, including their sparking dynamos, but if not let me know 
by return mail. 
37 
382-902 v - 71 - 4 
Please let me know as soon as you can the diameter of the circle 
which the cylinders will sweep through and also the width of the en?
gine complete, including the dynamo, as I must have these dimensions 
in order to complete certain important drawings which are now under 
way. 
I trust that the enclosed sketch will give you all the information 
which you desire.20 
7 February 1899?Langley in Washington, D.C, to Balzer in New 
York City 
I hope to shortly hear from you that the engine is ready for trial 
here, but as I would like it tried as far as possible under the identical 
circumstances to which it will be applied in practice, I shall probably 
send you in a day or two a drawing of its exact position, indicating the 
work which it is to do and the possible disposition of a second engine, 
if your first gives satisfaction. The drawing, which will be a working 
drawing, will show the disposition of a frame of very light steel tubing, 
in which your engine will rest and the shafts and gears which transmit 
its motion to a propeller wheel. 
I may ask you to fit up at my expense the driving shafts, gears and 
accessories (which form no part of your stipulated weight) and also the 
frame of steel tubing which holds them, and I shall in this case, send 
you the necessary gears cut, and finishing yourself the minor accessories, 
so that your engine can be tested under the conditions of actual work, 
and I can better judge the possible desirability of ordering a second en?
gine. The engines will, of course, be paid for, when the stipulated test 
is met, but there is something more than this, and perhaps I may add 
(what I believe you already understand), that these engines are for a 
very special and confidential purpose. 
If they turn out a success, (and success can only be proven by a trial 
under the conditions of actual motion through the air) I shall think it 
fair to you, to give as full publicity as I can to the fact that you were 
the builder, but until the trial under the conditions of actual flight has 
been made, I shall not feel that success has been proven. Everything 
that lies in my power will be done to hasten the time when this can be 
20
 On 16 January 1899 Balzer sent Langley a full size drawing of the engine. Un?
fortunately it has been lost; however, a good deal is known about the engine as 
it left Balzer's shop more than a year later due to photographs, patent office draw?
ings, written descriptions by Manly, and studies of Balzer's model aero engine and 
his automobile engine of 1894. 
38 
determined, but until then, I will ask you to join me in keeping the 
details of this matter as a confidential trust. 
9 February 1899?Balzer in New York City to Langley in Washington, 
D.C 
Your favor of the 7th inst. received, and in reply I would say I expect 
to give the engine a trial next week. So far all work is satisfactory and 
hope the engine will fit all requirements. As to the other work you men?
tion, I would be pleased to receive any work that you may entrust to 
me, and will give it my fullest attention to make it satisfactory. And I 
can assure you all work done by me will be kept strictly confidential as 
you requested. 
26 February 1899?Langley waste book entry 
Mr. Manly reports Balzer's engine likely to develop 20 or more horse. 
The entire central part of the frame from Pope tube steel with gears is 
to be built by Balzer, and is likely to be ready for testing here under 
actual conditions of support by March 20. The delay arises from the 
construction of this frame. 
29 March 1899?Langley at the Metropolitan Club, New York 
City, to Rathbun in Washington, D.C 
Say to Manly I have seen Balzer's engine and am much pleased by it. 
Balzer wants the frame strengthened by some bracing and modification 
of the piece carrying the propeller shaft, and is addressing me a letter 
here, which I will perhaps forward tomorrow. 
If time press, this modification may be made, if Manly approve, espe?
cially as Balzer believes his engine can be worked for ten or fifteen min?
utes up to 30 horse. 
He will have it on (he says) next week. 
9 May 1899?Manly memorandum to Langley 
Mr. Balzer called me up over the phone yesterday afternoon at 
about 5:30 o'clock. He said that he was going to run his shops until 10 
o'clock last night and finish up the frame work, and that he would ship 
it (that is, the frame work) early this morning. The engine is not quite 
complete, as he finds he will have to put the radiating fins on the cylin?
ders and explosion chambers in order to keep them cool during the 3 
hour test. He says that he thinks it will take about a week to complete 
the engine. He himself is coming down on the train which reaches here 
at 8 p.m. today. I will see him tonight, and will bring him down to the 
Institution in the morning. 
39 
M
"\ 
- -ft-r^ 
41 
bi-Ll \.m i 
A Kl ft4% AM?^ fcu. Os**/??A-Iy 
.v7 ,?,.., ,ufK u^A cL ???/// \ 
FIGURE 17.?"Preliminary sketch of Great aerodrome made under instructions from 
the Secretary. "Drawn by Speiden, 5 May 1899. (Smithsonian photo A50245.) 
23 June 1899?Manly in Washington, D.C, to Langley in Europe 
(in part) 
Nothing further has been heard from Balzer since my last communi?
cation to you, but I hope to stir Balzer up now in a short time by in-
40 
quiries made in a personal way. He seems to have no idea of the value 
of time, and I hope to impress on him the fact that if he hopes to get 
any glory out of his engine, that time is growing more precious every 
day. This engine of his must be made to do the work, if it necessitates 
bringing it here to finish it. / / he cannot build it, I know of no com?
pany in this country that would be able to do it. It is a larger and 
harder affair than Balzer had any suspicion of. However, I have hopes 
that he will yet fulfill his contract on it. 
9 July 1899?Manly in Washington, D.C, to Langley in Europe 
(in part) 
I beg leave to submit the following report on the condition of the 
work in aerodromics on July 8th 1899: 
On July 8th I received a personal letter from Mr. Balzer with refer?
ence to the progress he is making with the engine and give you below a 
copy of it. 
"Your favor of July third received and am more than pleased that 
you have again broken the long silence. 
No doubt you know under what difficulties I am laboring. I have 
been obliged to place the backing-off device for sale in order to raise 
the neccessary capital to continue work on the engine, and I hope to be 
successful in doing so. 
As far as the engine is concerned, for you, I find that it is necessary to 
have two three inch cylinders instead of one four and three sixteenths 
in order to get greater radiating area, and avoid all angles in ports; all 
ports in cylinders must have an easy entrance without angles to avoid 
the accumulation of heat; it is not necessary to change any other part of 
the engine but the cylinders, placing two three inch cylinders side by 
side with one connecting rod and only one exploding chamber for the 
two cylinders, the pistons of the two cylinders will be connected to?
gether; it is also necessary to have very large ports and valves to get the 
high speed required. As far as the power of the engine is concerned it 
will go even beyond my expectations and I will endeavor to do my best 
and strain every point to deliver the engine to you this month." 
As the above is somewhat obscure, I will endeavor to explain it to 
you. What Balzer means by using two 3 inch cylinders instead of one 
4yi6 inch diameter, is that whereas he originally built the engine with 
five cylinders, of 4 3/16 inches in diameter, arranged equidistantly on the 
circumference of the supporting drum, he now finds that he will have 
to substitute ten cylinders, of three inches in diameter, with them ar?
ranged in pairs, and placed at five equidistant points on the same drum. 
41 
With this arrangement he will have ten pistons and piston rods and five 
connecting rods, two piston rods being connected together and working 
on one connecting rod. 
If the above is a correct interpretation of what Balzer intends doing, 
I must say that I somewhat question the advisability of such a mechani?
cal construction. However, I prefer not to render final opinion on the 
matter without seeing Balzer and finding out exactly what he intends 
to do. Again, I have been quite concerned for some weeks as to whether 
Balzer was acting fairly about the matter and I have been trying to ar?
range matters here, so that I could run up to New York and see just 
what he is doing. However, the work at Quantico has been progressing 
so very slowly and so little has been accomplished in the time allotted 
for its completion, that I have felt that no time could be spared for at?
tending to Balzer, until the experiments with the aerodromes were 
brought to a close, but as it now appears that this may be some time 
longer, I have decided to go to New York tonight and see Balzer tomor?
row, returning to Washington Monday night or early Tuesday morn?
ing in order that no time may be lost from the Quantico work. 
The "Backing-off device" which Balzer says he has placed on the mar?
ket is a patented mandrel of his for relieving the teeth of milling cut?
ters. What he says about "having had to place it on the market to raise 
capital to complete the engine', is all "stuff" and means nothing. 
14 July 1899?Manly in Washington, D.C, to Langley in Europe 
(in part) 
I beg leave to make the following report of the condition of the work 
in aerodromics on July 14, 1899: 
In my report of July 9th, I informed you of my intention to go to 
New York to investigate the condition of the engine which is being 
built by Mr. Balzer. I left Washington on the night of July 9th, arriv?
ing in New York on the following morning and went immediately to 
Balzer's shops. I had intentionally not informed Balzer of my coming, 
and so of course my visit was entirely unexpected. I found him at work 
with two assistants on his 4 hp engine which he uses in his automobile. 
He was at that time carrying on some investigations with different 
forms of sparking devices, and informed me that he had been doing so 
for some weeks. 
The engine which he has been building for you was in exactly the 
same condition as on my previous visit of April 29th. 
Mr. Balzer told me that the cause of delay is that before putting the 
sparking devices for your engine in the explosion chambers he felt it 
42 
necessary to make some further experiments using one of his heavier en?
gines, and that this was what he had been doing for the last few weeks 
and which he had now about completed. He said that he did not wish 
to bore into the very light explosion chambers of your engine until he 
had satisfied himself as to what was the best form of sparking device, as 
the engine would require almost a total rebuilding if he should happen 
to find afterwards that the sparking device should have been put in dif?
ferent positions in the explosion chambers, and also that he was not 
completely satisfied as to just what is the best form of sparking device to 
use. 
Mr. Balzer's original intention was to use a "jumping" spark for ig?
niting the gas in the explosion chambers, and when he first undertook 
the building of the engine, I advised him against this as my experience 
has been that the "jumping" spark is not so reliable as the "wiping" 
spark, but as Mr. Balzer had had a great deal more experience with gas?
oline engines, and especially with this form of his own, I of course at 
that time yielded this point to him. However, Mr. Balzer has now 
found that the "jumping" spark will not be at all satisfactory for this 
engine, and he has determined to put in a "wiping" spark as I had orig?
inally advised him to do. It is on this very point that he has been mak?
ing his experiments, and also lately he has been continuing his experi?
ments to try to secure a "wiping" spark which would be absolutely 
reliable at the very high number of revolutions at which the engine 
would be required to run to produce the required power.21 
I found out, however, that the carrying out of these experiments, 
which are necessary, but at the same time which could not possibly 
have consumed all of Mr. Balzer's time since my last visit there, was not 
the principal cause of the delay in the completion of your engine. This 
delay is principally due to the fact that Mr. Balzer is at a complete fi?
nancial standstill. He has no mechanics at all at work in his large shops, 
except the two which he had assisting him in the above experiments. 
He has a large number of orders, which he showed me, for his auto?
mobiles, but he has no money to stand the expenses of the shop and 
buy the necessary materials for their construction. He informed me 
that he had spent all of his capital, outside of a private income all of 
which he required for his living expenses, on the development of his 
engine and the automobile. He stated, however, that he expects to 
21
 The "jumping" or "high tension" ignition system offered a greater development 
potential; however, the "wiping" or "low tension" system offered greater reliability 
at that time. In its final form the engine was equipped with a "high tension" 
system. See also footnote 16. 
43 
have some money coming in very soon and that he would then push 
your engine to completion as rapidly as possible. I then told him that 
he had been promising the completion of the engine for several months, 
and that you had left this country under the impression that the engine 
would certainly be delivered before the latter part of May, and that 
you would be returning now very soon, and would be expecting to find 
the whole thing completed, and I therefore wanted to urge upon him 
the necessity of letting me have the engine as soon as possible, as I 
must get things in shape before your return. After talking to him 
awhile on this line, he promised me most emphatically that he would 
certainly push the engine through and have it delivered before the 
first of August, even though it proved necessary to change the con?
struction of the engine by using the ten small cylinders instead of the 
five larger ones, the plan of which I informed you in my last communi?
cation. I fear, however, very greatly, after having been disappointed by 
him as to the date of delivery so often, that he will not have it finished 
by that time. 
Mr. Balzer wanted to know if it would be possible to have some more 
money advanced to him, to be secured by a bond, but I informed him 
that it was contrary to the rules of the Government to pay any money 
for materials or work until the actual delivery of the same; and that the 
money which you had advanced to him at the beginning of the work 
had been advanced from a private fund, and to do this again would be 
impossible now. 
To sum the whole matter up, Balzer is evidently very anxious to com?
plete the engine, but has not the money to carry on the work, and un?
less he can get it from outside, or can secure some job work of some 
kind, the running of his shops will be impossible for some time. He is 
trying to secure partnership with someone having the necessary capital 
for the placing of his automobile on the market, and although he has 
had several offers from "promoters" to form the necessary company, yet 
he is not willing to go into that kind of a company, as he fears that he 
will not only lose his time, but also his very valuable patents which he 
holds on his engine and his automobile. He is evidentally "waiting for 
something to turn up". That the man is a master mechanic there is no 
doubt, and that he has a very wonderful engine there is also no doubt, 
but he seems utterly lacking in business ability, and is afraid to enter 
into the formation of any very large company, but desires to deal with 
some one man who has the necessary capital for the development of the 
work. As this man seems to be lacking, his very excellently equipped 
shops are consequently at a standstill. I hope that he may be able to se-
44 
cure the necessary money to complete the engine by the first of next 
month, but I must confess that I have very little grounds for expecting 
that it will be accomplished. 
21 July 1899?Manly in Washington, D.C, to Langley in Europe 
(in part) 
In my communication of July 14th, in referring to the condition in 
which I found the engine which Mr. Balzer is building, I neglected to 
state that while I was in New York City with Mr. Balzer, I urged him 
to at least put together one cylinder of the engine, attaching it to the 
crankshaft, and to make an experiment with it so as to be able to deter?
mine immediately and definitely whether the present cylinders which 
he has will be suitable for the engine, or whether it will require the 
rebuilding of the cylinders. Mr. Balzer promised that he would do this 
and would let me know the results of the test by Wednesday, July 12th. 
Thursday, July 13,1 received the following note from Balzer: 
"It was my intention to send you a few lines last evening, but was 
unable to finish the one cylinder and advise you of the result. It was too 
late today when we got through with it and we had very little time to 
give it a thorough test. I think the cylinders I have are going to answer 
the purpose, only the ports are a trifle small to give good results. 
Tomorrow I put on the drag power and after adjusting all parts will 
again give it another test and will report results to you.22 
I have had my wagon out twice, and it runs most satisfactorily." 
I have heard nothing further than the above from Mr. Balzer so am 
unable to state what results were obtained with the one cylinder. I have 
written to him again to let me know immediately if possible, what re?
sults he obtained. 
I am rather at a loss to explain how it is that one day Mr. Balzer 
thinks the present cylinders will work, and the next day he thinks that 
the engine will have to be rebuilt,?neither of these opinions being sup?
ported by any test whatever. If the ports are too small to allow the ex?
ploded gases to enter and leave the cylinder with a great enough rapid?
ity at the very high speed, then all the cylinders will have to be rebuilt, 
but whether the ports are too small or not can only be determined by 
test, and this test is the thing I am trying to get Mr. Balzer to make 
immediately. He had abandoned work on the engine, claiming that he 
found that the ports were too small and that the cylinders would have to 
be rebuilt, but he had made no experiment whatever, and in fact had 
22
 This means he was going to put the engine on a prony brake to test its brake 
horsepower. 
45 
not even attached the valve gear to any of the cylinders to see what they 
would do. 
As I have stated before, I am convinced, in order to have the engine 
completed immediately, some arrangement will have to be made by 
which Mr. Balzer can be advanced some more money to carry on the 
work. Of course this seems like bad business policy, but at the same 
time, under the circumstances, I think it will be absolutely necessary. 
28 July 1899?Manly in Washington, D.C, to Langley in Europe 
(in part) 
As I informed you in my communication of July 21st, I wrote an?
other personal letter to Mr. Balzer urging him to make the test on the 
one cylinder of the engine as soon as possible so that I might know im?
mediately something definite in regard to it. 
On July 26th, I received the following telegram: "Can make cylin?
ders do. Will write." 
I have not yet received this letter so am at present unable to say any?
thing further in regard to the matter. I will communicate to you the 
contents of Mr. Balzer's letter immediately upon receipt of it. 
In regard to the possible necessity of falling back on the steam en?
gine, I must say that I have no fears of such a contingency. A suitable 
gasoline engine not only can but must and will be built. It may prove 
necessary to add to the combustion chambers of the engine some small 
water jackets, and have a small condenser which will handle a very 
few pounds of water, but this would be as nothing compared to the ne?
cessity of constructing a steam engine with its complicated generating 
and condensing auxiliaries. A gasoline engine which will mark the 
greatest advance in explosion motor construction will be built for the 
machine. 
Allow me to assure you that your expression of confidence in the con?
duct of the work entrusted is most highly appreciated. 
4 August 1899-Manly in Washington, D.C, to Langley in Europe 
I have today received the following letter from Mr. Balzer with refer?
ence to the engine: 
"Yours of the first instant is at hand, I am now hard at work complet?
ing the engine being perfectly satisfied with the result of running the 
cylinder, it seems as close as I can come to it that the compression is 60 
and the explosion 180. The explosion chamber does not overheat, but 
the head of the cylinder gets so hot that I have premature explosion in 
about 15 minutes but I am quite certain that after the radiating fins 
46 
are attached the circulation of air will reduce the temperature of the 
cylinders for their continuous working: the engine in all its construc?
tion is perfectly strong enough and I doubt very much whether you 
will need another engine as this one cylinder develops 4 hp." 
What Mr. Balzer means by saying that "the compression is 60 and ex?
plosion 180" is that he gets a compression of 60 pounds to the square 
inch, and that the pressure at the instant of explosion is 180 pounds to 
the square inch. He does not say at what speed the one cylinder was 
working when he obtained the 4 brake horsepower from it, so that I am 
unable to apply any check on the calculations to see whether he has 
over-estimated the result or not. If one cylinder working by itself has 
developed 4 horsepower, then with 5 cylinders working, (owing to the 
fact that with 5 cylinders you have no dead points to the stroke) he 
should obtain slightly more than 20 horsepower. If Mr. Balzer had not 
given me reason to rather fear that he over-estimates good results, I 
would feel perfectly safe in saying that this one engine when completed 
will be able to furnish all the power which will be required. What I am 
trying to do now is to make him complete the engine so that you can 
immediately know exactly what is to be expected of it, and I consider 
the completion of the engine as the most urgent part of the work now 
on hand. If the engine will run in a close space for fifteen minutes be?
fore premature explosion occurs, it will certainly run indefinitely if it 
is allowed to travel with its machine through the air, and I shall there?
fore spare no effort to force the completion of it immediately.23 
21 August 1899?Waste Book entry by Manly (in part) 
On Monday morning August 21, I went out to Mr. Balzer's shop at 
370 Gerard Avenue, New York City having intentionally not informed 
him of my coming. I found Mr. Balzer at work assisted by two mechan?
ics turning up the valves for the combustion chambers of the engine. 
The engine was mounted on two heavy cast iron bearing plates which 
were in turn bolted to the large square drill press which was bolted to 
the floor. The gasoline tank and carbureter had been disconnected, 
and being the ones belonging to his automobile, had been replaced in 
it. The electric connection for the sparking device had also been discon?
nected. The engine, however, was as it had been when he made his test 
of the one cylinder of it, the cylinder which had been fitted up with its 
23
 Both Balzer and Manly should have added that since the engine was designed 
to be run as a rotary, vastly improved cooling would be realized upon completion 
of the entire engine. Manly's prediction that the engine had a potential of more than 
20 h.p. was actually realized at his hands as will be seen in Chapter 4. 
47 
valve being held fast, and pointing directly downward by clamping up 
the bearings. On that part of the shaft which is connected with the 
flange of the supporting drum, was placed a large flywheel about 3 feet 
in diameter, and weighing perhaps 250 lbs. Out beyond this was a small 
wheel of perhaps 12 in. diameter with a 1 in. face, which he had used 
for applying his Prony brake.24 
Mr. Balzer first turned the engine over once or twice by hand, and 
the steam gauge which he had attached to the combustion chamber 
showed a compression of 65 lbs. when turned by hand, the needle of the 
gauge going the same place every time he turned the cylinder so as to 
get compression. 
I had him turn the cylinders of the engine so that I could see the 
head of the cylinder which had been run, and found that it was some?
what "purpled" by the excessive heating which it had experienced dur?
ing the preliminary trials which Mr. Balzer had made sometime pre?
vious, a record of which he sent me, and a copy of his letter having 
been transmitted to the Secretary in my communication of August 4, 
1899. 
The combustion chamber and sides of the cylinder showed no effects 
of heating whatever, and Mr. Balzer stated that they did not become 
seriously heated during the run. 
Mr. Balzer proposes to arrange a kind of "oil feed" so that the pis?
tons, connecting rod bearing, crankshaft, and in fact all parts requiring 
lubrication will be oiled from one point. He will do this by making a 
small "oil vein" which he will place on the inner side of the drum, and 
which will lead to all parts requiring oil. 
Mr. Balzer states that the engine in its present shape weighs 103 lbs. 
However the hollow shaft which is part of the flange of the supporting 
drum is about 8 in. longer than it need be so far as Mr. Balzer's con?
tract is concerned. 
Mr. Balzer again emphasized his financial difficulties and the conse?
quent delay of the completion of the engine on this account. However, 
I will not go into this as a complete summary of the matter is given in 
my letter of August 22, 1899 to Mr. Rathbun, also in my letter of Au?
gust 25th to the Secretary, and of the same date to Mr. Rathbun "Q.V." 
As there was very little time to be lost I told Mr. Balzer to meet me 
24
 A device for ascertaining horsepower consisting of a band brake attached to a 
wheel driven by the engine being tested. The braking force is measured by a scale 
from which the engine's torque can be ascertained. The revolutions per minute of 
the engine is also determined. From these two variables the horsepower can be de?
rived. See Figure 24. 
48 
early the next morning at my hotel, and I would go with him to see Mr. 
John W. Weed, 62 William Street, New York about the furnishing of a 
bond to secure a second advance of $500 on the contract price of $1,500 
for the engine, I advising such an advance to be made. 
On August 22nd I spent the morning with Mr. Balzer in going to see 
Mr. Weed about the furnishing of a bond and getting the matter ar?
ranged by one o'clock. I then took Mr. Balzer to lunch. After which he 
went back to Mr. Weed's office to sign the bond and forward it to Mr. 
Rathbun that evening. 
On August 23rd I again went out to Mr. Balzer's in the early morn?
ing, and found the engine in running condition before I reached there. 
On my arrival Mr. Balzer started up the engine, which he stated had 
been running a short while before, and the one cylinder which had 
been fitted up worked very nicely under the circumstances. The com?
pression as shown by the gauge attached to the combustion chamber 
was 60 lbs. per sq. in. regularly. The explosions were 110 per minute, 
and varied all the way from about 120 lbs. clean up to more than 240, 
the gauge reading to only 200 lbs., but the needle being thrown clear 
around at times until it struck the guard pin at the zero mark, and on 
one or two occasions the needle was bent very severely. I was unable to 
make a brake test, as the Prony brake was not in shape, but from what I 
saw I feel very much encouraged, and am rather inclined to believe that 
the one cylinder will develop 4 hp., and if this is the case the 5 cylin?
ders ought to develop more than 20 hp. allowing for the power which 
will be consumed in the rotation of the cylinders, and the resistance to 
be overcome on account of this rotation, and the added resistance of 
the radiating ribs. 
The head of the cylinder, however, heated up so in about 5 minutes 
that premature explosion occurred unless some waste which had been 
soaked in water was shoved between the head of the cylinder and the 
flange of the supporting bearings. As soon as this dampened waste was 
pressed against the head of the cylinder the premature explosion was 
practically overcome; however, the water evaporated very quickly, and 
the waste had to be continually wetted. As to whether the radiating ribs 
which Mr. Balzer proposes to place on the head of the cylinder will 
keep it cool or not, I confess I am unable to say, bu; I feel that it is best 
at any rate to complete the engine as at present planned as we can tell 
nothing about what will happen until it is completed and tried, and as 
there remains now very little to be done, I consider it on the whole, 
without question [advisable] to complete it immediately and try it. 
I am going to have Mr. Balzer send on the remaining parts of the 
49 
"second engine" which is now lying over in the National Museum, and 
expect to put it in working shape, and attach one of the large 2i/2 ft. 
propellers to it, and drive the propeller around, and if possible, deter?
mine the thrust, and knowing the thrust, and number of revolutions I 
can very readily determine the horsepower expended, and from this I 
will be able to calculate very closely as to what the propellers will do 
when used on the great aerodrome.25 I will have him send the parts im?
mediately so that I can, if possible, make this test before the Secretary 
returns. This engine is capable of developing about 2i/2 or 3 hp., and 
will I think do very nicely for the work I wish to employ it in. 
I left Mr. Balzer with the understanding that I would see that $500 
of the contract price was advanced to him immediately, and that he 
would spare no effort to push the work forward, so that if possible the 
engine would be completed and ready for trial before the Secretary re?
turns. Mr. Balzer stated that he would certainly have it finished in two 
weeks. However, Mr. Balzer has been promising the engine "next week" 
every week for the last five months, but I am inclined to believe that 
[although] we may expect to find that he may not be able to keep the 
cylinders cool we will have it here at work before the close of next 
month. 
12 September 1899?Manly to Langley in Washington, D.C. (in part) 
The engine for the great aerodrome is as yet unfinished, but Mr. Bal?
zer promises to be ready with it by the 22nd of the present month, at 
the very outside. In order to use the engine on the great aerodrome, 
provision will have to be made for supporting it and attaching it to the 
frame, and Mr. Balzer was expected to have made these supports while 
he was constructing the traverse frame last spring. However, it was not 
done then, although I gave Mr. Balzer instructions as to how I wished 
the work executed, and he promised me on my last visit to him on Au?
gust 21, 1899, that he would put some extra men at work on these sup?
ports and complete them immediately. 
It will also be necessary to have made a clutch, by means of which the 
engine can be started up under "no load," and when it has gotten up its 
speed, the load can then be thrown on by means of a clutch. Mr. Balzer 
is now at work on this clutch, and will, I think, have it completed and 
ready for delivery with the engine. 
It will be necessary to provide two sets of bevel gears of about 3 in. or 
4 in. diameter, and 8 pitch, to be used in transmitting the power from 
the engine to the shafting, which in turn transmits it to the propellers. 
" T h i s refers to the spare engine which came with Balzer's quadricycle of 1894. 
50 
These gears had better be provided by Mr. Balzer, who will turn up the 
blanks for them, and send them to Bilgram, of Philadelphia, to be cut. 
Before the engines can be used on the aerodrome, a specially light 
carbureter, of a capacity of about three gallons, will have to be made, 
and this had also best be done by Mr. Balzer. 
21 September 1899?Manly in Washington, D.C (quoting from Balzer's 
letter) to Langley in Boston 
Yours of the 12th received, and in reply to the same would say that I 
have been so busy that I have been unable to give the carbureters any 
time. I have found that my first idea of the wick system would not 
work. 
Please find enclosed a rough sketch of one with which I have been 
partly successful, and which I intend to use on your engine. 
The work on the engine is progressing slowly, as we have had a great 
deal of trouble in bending the tubes of the feed and exhaust pipes. We 
now have all the valves set on the engine, and we are finishing up the 
spark mechanism and the lubricating channels, and I expect no later 
than Saturday, to give you a full report of the working of the engine 
with five cylinders. 
26 September 1899?Balzer in New York City to Langley in Washing?
ton, D.C. Langley was in Boston, and Manly forwarded the letter 
Your telegram of today, to Mr. Weed, has been handed over to me, 
and in reply would say that I have had the engine running with five 
cylinders, and after running for sometime the crankshaft froze tight, 
making it necessary to take the engine apart and replace the brasses 
which we are doing now with most possible haste. It is very difficult to 
get the proper mechanics, at the present time, to do this work, as New 
York is turned up-side down on account of Dewey's Day.26 
I am personally at this work, and if things run smoothly, I will have 
the lubricating cups and all accessories to the engine finished by Thurs?
day, the 28th, but as Friday and Saturday are two holidays I will be 
unable to get any one to do the work. 
All parts of the engine work satisfactory, and as for the horse power, I 
cannot give you that until I have had the engine run fully a day, or so 
as to run the piston rings and the cylinders down smoothly, as we dare 
26
 It will be recalled that Mr. Weed was Balzer's bondsman. Manly had sent him a 
telegram to put pressure on Balzer. This is an important date as it marks the first 
time the engine was run in its entirety. Dewey's Day was 30 September 1909. 
51 
not use any emery in fear of cutting them. I will also advise you of the 
progress of the engine tomorrow at the same time. 
3 October 1899?Waste book entry by Manly (in part) 
I left Washington on Tuesday afternoon for New York arriving there 
that evening, and the next morning went out to see Balzer. I found him 
at work on the engine assisted by 5 or 6 men, and he was then finishing 
up some of the parts for the valves of the engine. 
I spent the day with Balzer going over the work on the engine, and 
laying out designs for the bed-plates for supporting it. These bed-plates 
are to be so made that in case it becomes necessary to have another en?
gine, both engines can be very easily held within the present frame 
without any very serious changes being made. 
I called on the Secretary at 4:30 o'clock in the afternoon at the Met?
ropolitan Club, and laid before him very plainly the conditions of the 
work. 
8 October 1899?Waste book entry by Manly 
I met Mr. Balzer at 7:25 this morning at the station and after taking 
him to breakfast went immediately to the Institution where we have 
been at work talking over the question of the engine, frame work, etc. 
I have also taken Balzer out to the South Shed so that he may see the 
traverse frame again and get it clearly fixed in his mind. 
About 11 o'clock the Secretary arrived at the building, and after dis?
cussing the matter with him and informing him of Mr. Balzer's visit, I 
have been able to get him to come to a definite conclusion about the 
matter, and to write me a letter authorizing me to give the work to Mr. 
Balzer under contract. 
I have given Balzer drawings of the bed-plates, bearings, supports for 
bearings, etc., and he left this afternoon at 4 o'clock. 
13 October 1899?Telegram from Langley in Washington, D.C, to 
Balzer in New York City 
I find that it will be necessary to have the engine, even in its uncom?
pleted state, in Washington by October 17th, and I desire therefore, 
that you will ship it so that it may reach here by that time. 
I am also desirous of seeing you here at the time that the engine is 
sent on, and if you can come here on the evening of October 16th, and 
remain a day or so, I will be very glad to have you reimbursed for the 
expenses incurred for your travel and subsistence on account of this 
visit. 
52 
14 October 1899?Telegram from Balzer in New York City to Manly in 
Washington, D.C 
Your telegram received this noon. I will ship all the parts of the en?
gine Monday noon, and will follow myself on the 4 o'clock train but 
will be unable to have the engine complete by that time. I am doing 
the best I can. 
17 October 1899?Waste book entry by Manly (in part) 
I met Mr. Balzer at the depot last night at 8:30, and spent the eve?
ning with him discussing the engine, bed-plates, etc., going over the 
question of the radiating cooling fins ribs, the proportion that their 
thickness should bear to the thickness of the cylinder walls of the 
engine. 
Balzer has about finished up the engine; the only things remaining 
now to be done are to finish up some of the valve rods for the feed and 
the exhaust connections, and to make preliminary runs until he can get 
the cylinders properly worked in. This will probably require a week or 
so more. I think the whole thing would have been completed ready for 
a short run by October 24 had the Board not changed the date of their 
inspection. 
The engine, bed-plates, etc., were shipped at noon yesterday by Mr. 
Balzer, and will therefore probably arrive in Washington this morning. 
As soon as they arrive they will be placed in their proper position in the 
traverse frame and the whole ready to be turned over by hand. 
The engine, bed-plates, etc., arrived by express at 11 o'clock, and 
were immediately placed in the frame. I have been busy with Mr. Bal?
zer all day. 
19 October 1899?Waste book entry by Manly 
While talking with Mr. Balzer I brought up the question of the 
building of a small engine of about \y2 horse power for use on the pro?
posed new and larger model of the great aerodrome. Balzer thinks the 
engine can probably be built for about 12 lbs. weight, but is unwilling 
to accept contract for such an engine, and in fact, will not undertake 
the engine under any circumstances until the large engine is completed. 
I have today been again discussing with the Secretary the question of 
the probability of having Balzer build the \y2 hp. gasoline engine for 
the new model of the great aerodrome, and the Secretary is very desir?
ous of securing the engine, and if the engine is successful, will cer?
tainly have the new model built.27 
27
 This model gasoline aero engine is in the National Aeronautical Collection. 
53 
382-902 O - 71 - 5 
The Secretary has also had Balzer look over the sketch of his appa?
ratus for controlling the movements of the Penaud rudder, and Balzer 
agrees to make a rough working drawing of the same, the drawing to 
indicate the general method to be pursued in making a model of it. 
The engine, bed-plates, etc., were today boxed so that they may be 
returned to Balzer tomorrow for completion. Balzer left this afternoon 
at 4 o'clock, it being now certain that the Board of Ofrdnance] and 
F[ortification] will make no inspection for the present. 
/ November 1899?Waste book entry by Manly 
The model of the device for securing automatic equilibrium in the 
great aerodrome was received from Balzer today. Balzer, however, mis?
understood the directions of the Secretary with reference to it, and the 
model is consequently not what was desired. I expect to draw out in de?
tail the plans for this apparatus, and will construct it here, as it will 
require constant supervision while it is being made.28 
15 November 1899?Balzer in New York City to Manly in Washington, 
D.C. (in part) 
This is the first chance that I have had to dictate a letter and report 
on the progress of the engine since I left you three weeks ago. 
One of the "I" beams of the engine, as I have written you, buckled 
up and had to be replaced with a new one, but the tubing that I tele?
graphed for yesterday was a mistake on my part. Instead of making one 
of the supports in the center and the other 314 in. from the center, I 
made them both alike. 
There has been a great deal of detail work on the engine, small and 
no end of fitting, but now we have the engine complete with five cylin?
ders, all connections made, and the starting bar finished, but have not 
had any time to put on the attachment to throw the spark ahead, that 
is, shifting the ignition cam, of which I spoke to you. The inlet of the 
engine is 1% in. pipe, but I do not know at what angle you want the 
pipes to lead, yet I have so arranged them that you can put them in any 
position. The connecting rods and gears are all hardened and ground, 
but I have still to make the carbureter, the tank and the moving device 
of the igniting cam. 
I am going to give the engine a test tomorrow morning, with the five 
cylinders working complete, and will report the result to you tomorrow 
?that is give vou the speed, horse power and time of premature explo?
sion if any. For this test I will use the wagon tank, and if the time 
28
 This early autopilot was built but not tested. 
54 
should be so short that I will not be able to make a new tank for you 
and [a new] carbureter, I would advise you to use this [the wagon 
carbureter] and I will bring it on. I think that we can make a satis?
factory test of it. 
I trust that you have completely recovered from your cold which you 
had when I was down there, and hope that you are feeling better than 
I, for I am simply over-worked trying to get this work out. 
20 November 1899?Waste book entry by Manly 
I met Mr. Balzer at the depot last night at 8:30 o'clock and went with 
him to his hotel. We spent the evening discussing the possible improve?
ments in the engine. 
This morning Mr. Balzer came down to the building at 9 o'clock and 
went to the South Shed to get things ready for the engine which arrived 
about 11 o'clock. The carbureter, however, did not come, although it 
was shipped at the same time as the engine, and I have sent George 
Wells over to the Express (Adams) Office to see that proper steps are 
taken to have it here by tomorrow morning. 
The engine is, so far as mechanical construction is concerned, practi?
cally complete with the exception of the oiling ring with the special 
aluminum cup, which is to be used for keeping the crank shaft, pistons, 
etc., properly lubricated, the "cam" for varying the time of ignition, the 
possibly necessary radiating ribs on the ends of the cylinders, and the 
carbureter. The carbureter which Balzer had sent on but which had not 
yet arrived, was one belonging to one of his automobiles, and is too 
small for supplying sufficient gas when the engine is run to its maxi?
mum power. 
21 November 1899?Waste book entry by Manly (in part; refers to an 
inspection by the Board of Ordnance and Fortification) 
Judge Outhwaite, Captain Lewis, Capt. Wheeler, Capt. Davis, Mr. 
Bell, and Mr. Walcott called at the Institution building at 2:30 o'clock, 
and after a short talk with the Secretary came out to the South Shed to 
look over the progress of the aerodromic work. After spending about an 
hour at the South Shed appearing very much interested and pleased at 
the progress of the work and at the intricacy of the problems connected 
with it, they all with the exception of Mr. Walcott went to the house 
boat at the 8th Street Wharf to see it. They were there shown No. 5 
with its wings, rudder, etc. mounted, and also the working of the lower 
launching apparatus. 
After inspecting the inside of the boat, they all went on top to see the 
turntable, etc., after which they departed. 
55 
21 November 1899?Wells diary, (in part; same event as above) 
They appeared to be very much pleased with the condition of things, 
and especially with the engine. Balzer receiving the congratulations of 
the party for turning out such a magnificent piece of work. 
Owing to the failure of the Express Company to deliver the carburet?
er, the engine could not be run by gasoline, but was turned over by 
hand, which seemed to be sufficient for the occasion. 
23 November 1899?Memorandum from Langley to Manly 
You know my extreme desire to have a brake horse test of Mr. Bal?
zer's engine, now here. 
I understand from Mr. Balzer that the following things are to be 
made before this can be properly done: 
1. A carbureter and copper tank. (This represents about a week's 
work.) 
2. The sparking device (which is within about 3 days of being fin?
ished.) 
3. The special aluminum oil cup which will oil all five cylinders at 
once. 
4. The starting device. 
Mr. Balzer thinks that with good fortune he may have these ready in 
a fortnight. 
With the above four things the engine will be entirely ready to turn; 
but before the horsepower test is made, it ought to be run (Mr. Balzer 
says) 3 or 4 days under the eye of the maker, to be sure that the cylin?
ders will not cut. While it is running, the maker can determine 
whether there is danger of premature explosion from overheating, and 
whether it will be necessary to put on the radiating ends (which may 
take a week more time). 
You will please see that everything is ready for the brake tests before 
the close of next week. This includes the strengthening of the tubes in 
the aerodrome frame immediately about the engine, so that it may be 
tested in the frame itself. The completion of the heavy rolling 
carriage 29 on which the whole frame is to be mounted during the test, 
the providing space for doing this while carrying the wheels [propel?
lers], the provision of a suitable single Prony brake (which Mr. Balzer 
is ready to take the risk of applying to one side of his engine only, with 
the whole of the power), the provision of the requisite apparatus for 
testing the thrust and, at the same time, testing the speed of the propel?
lers, I desire that all the above shall be, as far as possible rehearsed; that 
20
 This is a device to measure static propeller thrust. 
56 
is to say, the frame actually mounted in place; the wheels [propellers] 
put on and actually turned, if only by hand; and every portion so that 
it will be sure that everything is there and ready in its proper position. 
3 January 1900-Telegram from Manly in New York City to Langley in 
Washington, D.C 
Arrived last evening at Balzer's shop. Now he has had engine run?
ning light up to eight hundred revolutions without overheating, but 
sparking device must be slightly changed before brake test can be made. 
Will make test tomorrow. 
4 January 1900-Telegram from Manly in New York City to Langley in 
D.C 
Have had shop running until eight tonight. Will certainly make test 
by noon tomorrow. Arrive Washington Friday evening. 
10 January 1900?Manly in Washington, D.C, to Balzer in New York 
City 
I have arranged to have a further advance of $400 made to you and 
the check with the accompanying letter will be mailed tomorrow. 
I have had to practically guarantee this amount myself and further 
assure the Secretary that the engine will be ready for its official test by 
the third of February. 
Now pray don't disappoint me in this matter as I have staked a great 
deal on your being certain to allow nothing to interfere with the com?
pletion of the engine by February 3rd. 
I will send the pieces of tubing to you by mail tomorrow. 
Please send me that Vi6 in- roller that you used in the construction of 
the bedplates for the engine. I mean the one for grooving the tubing. I 
enclose a franked and addressed envelope in which you can enclose it. 
By the way, I find I will have to hasten things here at double speed 
and am going to double my force. However, I can guarantee a man for 
only three months work, though I may need one longer. Do you think 
that the man you spoke of would like to come under these conditions at 
$3.00 per day with hours from 8 a.m. to 4 p.m., and full pay for legal 
holidays. If he cares to come please let me know with his name and ini?
tials by return mail, as I expect to fill all of the places by the close of 
this week. 
12 January 1900?Langely in Washington, D.C, to Balzer in New York 
City 
Referring to your oral request, made through Mr. Manly on his last 
57 
visit of inspection of the condition of the gasoline engine, that owing 
to the number of changes which had proved necessary in the engine, 
and to the additional expense incurred thereby, you be advanced $400 
more of the contract price of $1,500 for the engine, making $1,400 in all 
of this contract price which has been advanced, I desire to say that 
owing to the extreme urgency of the matter, I will authorize that a fur?
ther advance of $400 of the contract price be made you, upon condition 
that you will allow nothing to interfere with the immediate completion 
of the engine. 
Mr. Manly informs me that as a result of the recent preliminary 
trials which you have made on the engine, it has been found that it 
will not be necessary to add the radiating ribs on the heads of the cylin?
ders and the explosion chambers, in order to prevent premature explo?
sion, as you have so far had no trouble on this point. I am gratified 
to learn this, but regret that the procuring of a suitable sparking ar?
rangement has caused so much experiment and consumed so much 
time, thus causing a very serious delay. However, I trust that with this 
additional advance which I now authorize, you will spare no effort to 
complete the engine at the earliest possible date, allowing no outside 
work to interfere with it, and that you will certainly have the engine in 
Washington for its official trial by the 3rd of February. 
15 January 1900?Memorandum by Manly to Langley (in part) 
CONDITION OF AERODROMIC WORK ON DECEMBER 3 1 , 1 8 9 9 
Mr. Balzer has completed all of the different parts and has assembled 
it and had it running light on two or three occasions, but has each time 
found troubles existing in the sparking arrangement which have de?
manded the dismounting of the engine, and the design and construc?
tion of suitable variations in the sparking arrangement. The difficulties 
which have been met in the sparking arrangement have not existed in 
the mere contact points, but have arisen with what is known as the 
"spark shifter," a device which must so control the spark as to enable 
the operator to cause the explosion at any designated point of the 
stroke. This is absolutely necessary, as the engine upon first starting up 
must be exploded just after the cylinder [piston] passes the dead cen?
ter, whereas the point of explosion is gradually made to occur earlier 
in the stroke as the speed goes up until, running at about 500 or 600 rev?
olutions, the proper time of explosion is found to be at a point about 
30? before the cylinder [piston] reaches its dead center. However, it is 
encouraging to be able to state that Mr. Balzer has now found a very in-
58 
genious shifting device which I think will, after a few slight changes, 
prove entirely suitable for the present case, and I am now encouraged to 
think that the engine will not only fulfill its contract, but perhaps under 
favorable circumstances show as much as 18 to 20 brake horsepower. 
The greatest difficulty in the way of immediate completion of the en?
gine is the fact that Mr. Balzer who has already expended two or three 
times the contract price of the engine in its construction, has practically 
no means, outside of a small income required for personal living expen?
ses, at his disposal for carrying on the work. 
4 February 1900?Balzer in New York City to Manly in Washington, 
D.C. 
Your cable received?would say that you can depend on twenty horse?
power at 500 rev., and I will ship engine about Thursday this week. 
Wright will report to you tomorrow and I will send you another man 
about the middle of the month. Will write tomorrow. 
5 February 1900?Wells diary (in part) 
F. F. Wright, formerly with Balzer in N.Y.C. as a machinist, reported 
here for work this morning. 
14 February 1900?Langley in Washington, D.C, to Balzer in New York 
City 
Mr. Manly has communicated to me your letter of the 13th which is 
just received. I am sorry to hear that you have had trouble with the 
ball-joint of the connecting rod, but am prepared by what Mr. Manly 
tells me not to feel surprised that you have found it necessary to run 
the exhaust pipes around the carbureter.30 
Please send the other mechanic you speak of, on the same terms 
which I have offered Wright, and if you know of still another please 
send him also. 
Please be good enough to write me by Saturday or Sunday what prog?
ress you have made with the engine since your letter of the 13th to Mr. 
Manly. 
19 February 1900?Wells diary 
Austin H. Philbrook, a machinist from Balzer, reports for duty this 
morning and is set to work in Stable Shop with Wright, another of Bal?
zer's men. He is to receive $3.25 per day. 
30
 The piston was joined to the connecting rod by a ball and socket joint in con?
trast to the modern practice of using a piston pin. Apparently it had been necessary 
to "run the exhaust pipes around the carbureter" in order to increase the vapori?
zation of the fuel. 
59 
FIGURE 18.?Crankshaft, connecting rods, and pistons assembly from Langley's 
model aero engine illustrating slipper crankshaft and ball joint piston bearings as 
used in the original version of the full size engine. Now on exhibit at the Smith?
sonian Institution. (Smithsonian photo A-4425.) 
20 February 1900?Langley to Wells both in Washington, D.C. 
I take pleasure in informing you that, in recognition of your efficient 
services, your compensation has been fixed at the rate of $60.00 a 
month, beginning February 15, 1900. 
5 March 1900-Wells diary 
G. D. MacDonald and R. S. Newham, two machinists procured from 
Balzer in New York by Mr. Manly last week, report for work this morn?
ing. 
MacDonald put at work in upper laboratory, and Newham in stable 
shop. 
20 March 1900?Manly in Washington, D.C, to Balzer in New York 
City (in part) 
The Secretary realizes the difficulties under which you have been 
60 
working, and the great amount of reconstruction of parts of the work 
that you have had to do, and he thoroughly appreciates the spirit in 
which you have met all the difficulties, his appreciation having been 
shown by the way in which he set aside precedent and rule in doing all 
that was possible for him to do in a financial way. However, you must 
realize that it is nothing but natural that he is now very uneasy con?
cerning the ultimate success of the large engine, the entire machine for 
which it was intended being now about complete, and having con?
sumed not only thousands of dollars, but also a large portion for the 
last two years of his available time from his multitudinous official du?
ties. This will be made more clear to you when you note the fact that 
the entire frame work which you have seen, will be entirely worthless 
should it become necessary to undertake the construction of a different 
type of engine which would necessarily mean the entire change of de?
sign and reconstruction of all this frame work, and such a reconstruc?
tion would inevitably mean a further delay for many months and the 
expenditure of several thousands of dollars. 
As I have said to you during conversation recently, the Secretary 
stands ready to not only give you all credit for your part in the work 
and to insure this will be properly recognized by the public generally, 
but will, I am certain, recognize your success in a pecuniary way. 
Now I must say in a personal way, and I think you will agree with 
me, that there is no one who more thoroughly recognized the difficulties 
with which you have had to contend, or who more thoroughly appreci?
ates the difficulty of the work which you have undertaken, and I have at 
all times done my best to render you all assistance possible. Our rela?
tions from the very beginning of the work have been of the most pleas?
ant nature, and at no time has there been any change in this relation, 
and I hope and expect that there will never be any occasion which 
would cause such a change. However, you must realize that there is a 
limit to the number of times that a man of the Secretary's experience 
will allow himself to be given assurance that everything is progressing 
as well as possible, and then after waiting several months, things are in 
practically no better shape than they were before, without losing confi?
dence in the person giving him such assurance, and I fear that unless 
this large engine is completed very soon that it may be the means of the 
Secretary losing all confidence in my judgment and advice. 
I hope you understand the matter as I have tried to explain it to you, 
and will do all in your power to see that such a state of affairs as I have 
last mentioned will have no reason to arise. 
61 
6 April 1900?Langley to Manly both in Washington, D.CS1 
Referring to the terms of my contract with Mr. Balzer, to your letter 
of April 4th, to my visit to Mr. Balzer yesterday, and to the doubt 
which we both feel whether he will deliver this week the engine fulfill?
ing even the terms of the contract (not to speak of the greatly higher 
power which we anticipated), I feel that the matter is serious and that 
I shall have to decide finally this week what expedient to adopt. I do 
not forget that from the beginning I have reckoned, as in my letter of 
June 21, 1898, on using two engines developing from 10 to 12 horse?
power each at a weight of 100 pounds apiece. If Balzer's engine then 
gave only 10 brake horsepower for 100 lbs., he would still be doing 
what I first expected as the largest probable achievement in this direc?
tion, but his engine has now been delayed over a year with experi?
ments on experiments, and in that year we might have constructed the 
engine if we had known nothing better was to be had. 
I understand it to be your belief that most of the difficulties are in?
troduced by making the engine itself revolve so as to be its own fly?
wheel, and that you think it might give very much more than the 12 
horsepower contracted for if the question of weight did not enter in, 
and if the engine did not revolve, but had a fly-wheel to help it pass 
dead center. I have suggested as worth trying a small light fly-wheel, 
giving it a very high rate of speed. 
The second difficulty, of course, is the cooling of the cylinders when 
they are not revolving. This would be a matter for subsequent consider?
ation. If we could run them for fifteen minutes surrounded with a wet 
cloth or some such device for momentary action, we could in that time 
do everything that might be necessary to insure the success of the test, 
which has never been definitely put, but which I will suppose to be the 
carrying of a man something like a mile in two or three minutes, re?
turning to the start in safety. To provide a new rotating engine at a 
high cost will involve waiting at least ten weeks or more, and an ex?
penditure, I suppose, at a minimum of $1,500, but probably much 
more. Please give me your opinion on the advisability of experimenting 
on a stationary engine with a small fly-wheel. If neither of the plans 
81
 This memorandum marked the beginning of a loss of faith in Balzer and the 
rotary engine by Langley and Manly. From this point onward, Manly's influence 
with Langley increased and he became fully responsible for the engine's development. 
A trip to Europe shortly afterwards convinced both Langley and Manly that rotary 
engines were not practical. Therefore, upon Manly's return, he converted the engine 
from a rotary to a static radial in which form its evolution continued. 
62 
work, the gas engine seems to be condemned. It is to be hoped then that 
one or the other of them will do. 
I will still hope that Balzer's engine will arrive next week, developing 
more than the contracted horsepower, but if it does not, I have come to 
a crucial point where I must finally take one of the different roads that 
open, the least desirable of all being the adoption of the steam engine 
instead of the gas engine. I cannot bring myself to contemplate this last 
possibility. 
I desire that you will take everything that I have said into considera?
tion, and shall be pleased to have you express your own opinion as to 
what is to be done if Balzer's promise is broken, as so many of his prom?
ises have been. 
12 April 1900?Balzer in New York City to Langley in Washington, 
D.C. (in part) 
Replying to Assistant Secretary Mr. Rathbun's letter of the 11th, I re?
gret very much to say that I was unable to ship the large engine to you 
on Tuesday as I promised, as I have been unable to get the proper ma?
terial in time to finish the same. Also I have discovered since your visit, 
that the connecting rods must be re-hardened. 
When I made the promise to ship the engine to you I was in hopes of 
getting the proper workmen to help me out, but I have been unable to 
secure men who do accurate and fine work as they are now scarce. And 
while we are making all efforts by working over time, it is almost im?
possible for me to have any work done by the men, unless I help them 
by giving my personal attention, and this I am doing. The men when 
alone are simply afraid that the work is too light, therefore progress is 
very slow. 
Mr. Manly asked me over the telephone if the engines could be oper?
ated by revolving the cylinders, and also by revolving the crankshaft: 
This can be done without injury to any parts as they are strong enough 
to stand the strain, but the engines will run steadier if the cylinders are 
revolved. 
9 May 1900?Langley to Manly both in New York City 
After calling with you on Balzer this morning and finding that there 
are neither efficient preparations made for the brake test, nor that any 
can be made within two days, I have decided that you must stay here til 
they are made, and desire that you will see that they are made with the 
greatest possible dispatch. I wish at least three different speeds tested, 
63 
and something definite ascertained. Balzer may work his force over 
time, if necessary, in putting in bushings where the thing has heated, or 
in other ways, and you, if you judge fit, may pay him for his men's over 
time, or for the outside work, to the extent of $100. 
I am going to leave town for Washington tomorrow, and hope to see 
you after another interview with Balzer, bringing him down with you 
to this hotel at half past five this afternoon. 
11 May 1900?Langley in Washington, D.C, to Balzer in New York 
City (in part) 
Referring to my visit to your shop on Wednesday, the 9th instant, I 
desire that you will construct immediately the wheels and brakes neces?
sary for a Prony brake trial of the large engine. 
I will meet the necessary expenses connected with this construction so 
that the brakes may be brought on and kept permanently here. 
15 May 1900-Wells diary 
The Secretary telegraphs to Mr. Manly instructing him not to leave 
until he receives letter from Secretary. 
Secretary writes to Mr. Manly asking for final report on engines 
which will decide the Secretary as to whether he will throw Balzer over 
or not. 
The Secretary calls Mr. Manly up on long distance telephone this af?
ternoon about 2:20 in regard to work on engines. 
The Secretary receives a letter from Mr. Manly in New York today 
stating that he had made three brake tests of the large engine, each one 
being very unsatisfactory as regards the hp. obtained. 
Discusses difficulties in way of engine reaching requisite hp. Will pro?
cure a new carbureter and make another trial tomorrow morning. 
Though, if he is unable to procure carbureter, he will leave New York 
for Washington this afternoon at 3:25 unless he hears from the Secre?
tary to the contrary by telegraph. 
19 May 1900-Wells diary 
The Secretary receives a letter from Mr. Manly today dated the 18th, 
and acknowledges the Secretary's letter of the 16th. Expected to make a 
test of large engine by today and another test Monday. Mr. Manly says 
that it is his firm conviction that Balzer's engine offers more chance of 
success for purposes intended than any other plan of construction with 
which he is acquainted. Thinks that minor faults in engine which pre?
vents good results in hp. tests will be overcome very shortly. 
64 
19 May 1900?Langley in Washington, D.C, to Manly in New York City 
(in part) 
I received your interesting letter of the 18th this morning. I desire 
that you will still remain, at any inconvenience to the work here, until 
you can advise me certainly as to the performance of the engine under 
the brake meeting the requirements (I mean the requirements as to 
horse power; for those as to time and other conditions, concessions 
might be made upon). 
I have never doubted, after the careful examination you first gave it, 
that the non-success of the engine was not due to faulty mechanical or 
thermodynamic principles. At the same time I believe I mentioned that 
I was warned by people of experience that the combination of minor 
difficulties, such as cannot be forecast or certainly overcome, has hith?
erto prevented entire success with any gas engine at all; at least with 
one so light as I am trying for. 
Now I cannot contemplate continuing these experiments indefinitely 
or in your absence. You must stay then, until you get something defi?
nite one way or the other; or if you do not see your way to getting 
something definite (I mean a satisfactory brake test), that itself is a 
conclusion. 
I do not want you to be hampered by lack of money. I sent you, on 
May 11th, $100; I sent Balzer $300 through your hands; and am send?
ing you tonight $100 more. You understand, and Balzer will under?
stand, that I have got no more to send until I get news that the engine 
has fulfilled its contract, at least the horse power part, without reference 
to time and other conditions; and that as soon as this is done I can ask 
the Ordnance Board to grant more money, and will if you recommend 
it. 
20 May 1900-Wells diary 
The Secretary receives a special delivery letter this morning from Mr. 
Manly in New York in regard to work on large engine, dated the 19th 
(Sat.). 
States that he has made four more tests of large engine under differ?
ent conditions from those of last Monday. Gives results of tests. 
Engine developed approximately 8 hp. at 700 R.P.M. and 7i/2 hp. at 
500 R.P.M. Says will work on engine today at shops. 
Says results of tests are to him (C.M.M.[anly]) very encouraging. 
Everything possible being done to expedite work. 
21 May 1900-Wells diary 
A telegram received from Manly at 3 o'clock this p.m. "Men have 
65 
quit work on account of inability to pay back wages. Recommend 
Wright, Philbrook, and Newham be sent on tonight and kept on our 
pay roll rest of month. Answer." 
The Secretary approves this recommendation of Mr. Manly's and has 
G. B. Wells notify men mentioned to leave 10 o'clock tonight for New 
York and report to Balzer's shop first thing in the morning. Furnished 
transportation orders for the three men to New York. Also advances 
$5.00 to get their breakfasts in New York and pay car fare to Balzer's 
shop where they will meet Mr. Manly. 
G. B. Wells notifies Mr. Manly by telegraph of Secretary's approval of 
recommendation. 
24 May 1900-Wells diary 
The Secretary receives a letter from Mr. Manly this morning stating 
that he fears engine tests will not be made until Friday on account of 
delay caused by making new piston rings. 
Speaks in regard to premature explosions of engine. If requisite 
power is not obtained Friday morning, corrections will be made, and 
further tests will be made Saturday or Sunday. 
30 May 1900-Wells diary 
The Secretary receives a private letter from Mr. Manly in regard to 
condition of things at Balzer's shops. Men refuse to work, etc. States 
that he has advanced Balzer money out of personal funds. 
3 June 1900-Wells diary 
The Secretary receives a special delivery letter from Mr. Manly this 
morning. Has had some very discouraging and exasperating delays in 
connection with anticipated test of Saturday, and expects to be busy all 
day Sunday with tests. Find that there is still some leakage.32 This has 
been the most exasperating thing that has come up in the work. 
States that if it were not for the large amount of delay which would 
be entailed by abandoning this gas engine to take up construction of 
different type of engine, he would not for one instant attempt to keep 
up the mental and physical strain which the work on Balzer's gas en?
gine has been causing him. 
The Secretary writes a personal note to Mr. Manly today cautioning 
him not to overtax himself in the work on the engine and sympathizing 
with him in regard to the way the work is going. 
32
 Leakage was of compression around the contact points of the make and break 
ignition system. 
66 
4 June 1900-Wells diary 
Secretary receives letter from Mr. Manly today dated June 3, report?
ing that as a result of trial of Sunday, it is found that there is still 
much leakage of the compression around contact points, and that it will 
be necessary to construct some metal cups to fit around contact points. 
This will take about five days work, which he says will be undertaken 
rather than fail on some temporary arrangement. 
Hopes that construction of steam engine will not be necessary. 
Has made arrangements to procure three new machinists immedi?
ately, two taking the place of Wright and Philbrook and the third in 
the place the Secretary authorized in his letter of May 30. Will each re?
ceive $2.75 per day for his actual work. Gives account of money sent 
him while in New York. 
13 June 1900?Manly in New York City to Langley in Washington, 
D.C. 
It was past noon today before the first run could be made on the large 
engine, owing to the slipping of the contact rods (for the make and 
break ignition system) and consequently the necessary making of taper 
pins to hold these rods. However, at two o'clock everything being in 
readiness, the engine was started up. After only two turns by hand, it 
continued to revolve under its own power. Owing to some slight defect, 
however, it was found impossible to increase the speed above 400 revo?
lutions per minute because of some trouble seeming to lay in the vibra?
tion of the brush which bears on the commutator and supplies the 
sparking current. During this test, however, it steadily maintained a 
pull of 30 lbs. on the 4' lever, running at a speed of 360 revolutions per 
minute, which is equivalent to 8 horse power. 
Although this result was not as good as was expected, it was very en?
couraging, for although the engine in one of the previous trials pulled 
down only a slightly less number of pounds at a considerably greater 
speed, it did not do it regularly. That is, it did not maintain this power 
continuously in the previous trial. In this first test of today, however, 
the compression was perfect, though the exhaust gases were very black, 
indicating that the regulating valve [of the carbureter] was allowing 
too much gas and too little air to enter the combustion chambers. At 
the same time, the exhaust was sharp and quick, and it was the very ir?
regular fluctuation in the sound of the exhaust, and the fact that the 
brush was seen to be sparking at the commutator, which led me to be?
lieve that the vibration of the brush was due to a certain amount of 
unavoidable shaking of the frame work, which caused the inability to 
67 
increase the speed above 400 revolutions, regardless of the load. 
If the engine had not heretofore on one occasion run at a speed as 
great as 600 or 700 revolutions per minute,33 I would have thought it 
possible that the valves were incapable of working at such a high speed; 
but the fact that they had worked at this high speed previously made 
me look for some other cause. Heretofore there has been no trouble at 
the commutator, and this defect at present may be caused by the fact 
that in enlarging the sleeve, to allow the larger supply of gas to enter 
the engine, it was necessary to greatly increase the diameter of the com?
mutator; and where there is a constant vibration in any running part, 
it also manifests itself to a very much greater degree as the diameter of 
the part is increased. 
In order to make sure that the valves were working properly two 
more tests were made after the one above referred to, the stiffness of the 
springs on the valves being changed just previous to each of these tests. 
The results of both of these tests were practically the same as those 
noted, the exhaust remaining quick and sharp, the exhaust gases 
(though the [carbureter] regulating valve was turned to the limit of its 
adjustment) remaining black and dirty, and the report of the exhaust 
being still irregular at a speed as great as 350 revolutions, but becoming 
more uniform as the speed was reduced. 
Immediately upon the completion of the last two tests, I started the 
men to work making a brush which will bear at three points of the 
commutator, and since the three arms of this brush will be of different 
periods of vibration, I hope that it will cure the trouble with the irreg?
ularity of the exhaust by insuring that at least one brush will always be 
bearing on the commutator. This brush will be completed in the morn?
ing, and I therefore expect to get several more tests during the course of 
the day. 
It now seems that about all of the faults of construction have been 
remedied, and that it remains to endeavor to bring the engine up to the 
requisite power by making such changes in the adjustment of the differ?
ent parts as the tests indicate to be necessary. 
15 June 1900-Wells diary 
The Secretary receives letter from Mr. Manly this morning dated the 
14th. Stated that found this morning (the 14th) another special spark 
coil would be needed, and half a day spent in procuring a suitable one, 
one working at about 4,000 to 5,000 sparks per minute. 
But not under load. 
68 
Got two runs on engine late in afternoon, both rather unsatisfactory. 
Expects to change cams and valves to overcome minor difficulties. Ex?
pects to make further tests on the 15th. 
15 June 1900?Langley in Washington, D.C, to Manly in New York 
City 
I have your letter of the 14th and note what you say regarding the 
proposed further experimentation with a view to minimizing the 
amount of minor defects in the engine in the hope of obtaining the re?
quired horse power. I infer from it that the work is getting into the way 
which I apprehended it would and wrote about in my letter of May 
19th. Please re-read that and you will see what I said about contemplat?
ing continuing these experiments indefinitely, and that while I wanted 
you to stay until you had a satisfactory brake test (I mean one develop?
ing the contract horsepower), that if you could not do that, that was in 
itself a conclusion. 
We were then talking as if the matter would be settled in one way or 
another in a week or ten days, and I hope you felt and feel that I 
wanted to stand by you, but now each day has brought its new hope 
and its new failure in the way we know so well in the work here; until 
finally when you receive this, nearly six weeks of experiment will have 
elapsed, and (perhaps owing to my unfamiliarity with gas engines) I 
do not derive from what you say any absolute confidence that we are 
materially nearer a result than we were when you obtained 8 horse?
power when first using the improved carbureter. 
I have no question in my mind whatever, that you are doing all that 
it is possible for anyone in your position to do, and are working on this 
as if your own future were at stake with it. Do not misunderstand me 
then when I ask you, after re-reading our correspondence and remem?
bering that it is impossible that I should continue this work indefi?
nitely, if you can give me any positive assurance when the work will be 
done. I presume that you cannot, and that no man can. 
I am leaving for Europe next week and I want to see you here before 
I go. I will therefore ask you to please come on next Monday at the lat?
est, unless you prefer to be here Sunday. Telegraph early tomorrow. 
Let me renew the advice given in my private letter of June 3rd, that 
you do not let the condition of things worry you, or over-tax your 
strength by trying to accomplish impossibilities before you return, and 
believe me. 
69 
382-902 O - 71 -
15 June 1900?Manly in New York City to Langley in Washington, 
D.C 
Four more tests of the engine were made today, the conditions pre?
vailing in each test being somewhat varied each time. In the first test 
this morning, made at about 8 o'clock, the old cam was used, and a "re?
bound spring" was inserted back of the exhaust valve to make sure 
there was no sticking of the valve at the high rate of speed. The results 
of the test were practically the same as those of the previous one, of 
which I wrote you last night. 
The second test was made just after noon, the old cam being replaced 
by the new one, the other conditions remaining practically the same. 
While the horsepower developed in this test was very little more than 
the 8 hp. procured in the test yesterday, the pull on the spring balance 
was very much more steady and uniform, the pointer varying at the 
maximum only about three or four pounds. The appearance of the 
heavy black smoke from the exhaust, while very much less than yester?
day, was still observable. It was still found impossible, however, to raise 
the speed of the engine, even when running with no load, above 410 rev?
olutions per minute, and the maximum power was again obtainable at 
the speed of 350 revolutions per minute. 
The three or four tests were made under practically the same condi?
tions as those prevailing in the second, except that the tension of the 
springs on the valves was increased each time, and the results obtained 
were practically the same. 
If we assume a mean effective pressure of 70 lbs. per square inch 
(which is about what we would expect from a stationary engine of the 
same dimensions as this, that is 5% in. stroke by 43/16 in. diameter) 
and calculate what the indicated horse power would be at a speed of 
350 revolutions per minute (which in the case of the present engine 
would mean 875 explosions per minute) we obtain as a result approxi?
mately 12 horse power; and multiplying this by the mechanical 
efficiency of 75 per cent, which is also about what we would expect in 
the present case, we obtain as a final result 9 brake horse power, which 
is very little more than the last tests have given. 
Now, it is easily seen that if the valves can be made to work fast 
enough so that we obtain approximately the same mean effective pres?
sure at a speed of about 530 revolutions per minute, we should get 
slightly over 12 horse power; and, of course, theoretically, the power to 
be obtained is only limited by the speed at which the valves will work 
without decreasing the mean effective pressure, the capacity of the inlet 
70 
passages to convey sufficient gas in the short period of time in which 
they would have to act, and the danger of overheating due to an exces?
sively large number of explosions within a limited time. 
There are at present on each engine [cylinder] three valves, the first 
or main valve, which opens directly into the combustion chamber; sec?
ond, the inlet valve opens into the sub-chamber and also communicates 
with the combustion chamber through the same main valve. The main 
valve is raised at the proper time by means of a cam, which is so geared 
that it makes 100 revolutions while the engine is making 400 (this 
ratio being due to the four cycles used), and the closing of the valve is 
caused by a spring which compels the roller, through which the main 
valve is actuated by the cam, to follow the "drop off" point and thus 
make the action of the valve independent of centrifugal force. 
The exhaust and inlet valves are of the true "poppet" type, the inlet 
opening whenever there is a suction in the sub-chamber, and closing 
whenever there is pressure there; and the exhaust valve operating in ex?
actly the reverse sense; that is, opening whenever there is a pressure, 
and closing whenever there is a suction in this sub-chamber. Now, it is 
easily seen that the exhaust and inlet valves are powerless to act unless 
the main valve is in its proper position, the main valve opening at the 
end of the stroke to allow the exhaust gases to be forced out on the re?
turn stroke, and remaining open until the engine has made one com?
plete revolution, when it closes, the engine cylinder being then full of 
gases, since the back stroke of the engine forced the gases out and the 
second half of the revolution, or forward stroke, sucked the fresh gases 
in. 
It is furthermore essential that this main valve should open at such a 
time as to cause the "point of release" to come at the proper place on 
the indicator diagram; that is, a small fractional part before the end of 
the stroke, and that it should close it exactly at the end of the suction 
stroke, so that none of the gases will be forced out through the exhaust 
valve when the piston starts to compress the charge preparatory to the 
next explosion. 
I have dealt at some length with this matter of valves, since that is 
where the trouble now is; and I desire that you understand as far as 
possible the exact difficulties which I am attempting to overcome. It is 
possible that it may be necessary to put in a positive motion cam; that 
is one which will not only raise the main valve, but which will also jerk 
it down to its seat at the proper time, as it seems that the spring does 
not cause the roller, through which the main valve is actuated by 
the cam, to follow the contour of the cam at the opening and closing 
71 
CYLINDER & COMBUSTION CHAMBER 
Large Balzer Engine 
Cylinder 
FIGURE 19.?Schematic drawing of valve system employed by Balzer. Drawing by 
Harry T. Hart (Smithsonian photo A4517.) 
points.34 Were it possible to make such a change as this in a day's time, 
I would, of course, not hesitate to do so; but as it may involve a delay 
of more than four or five days, I think it best to strive to overcome the 
difficulty in the way in which I am now experimenting, especially since, 
34
 Manly is suggesting desmodromic valves such as used successfully by certain 
post-World War II Mercedes sports/racing cars. 
72 
as you know, that slight, but necessary changes are being made after 
each trial, and as suggested by such trials. 
Your telegram with reference to the tubing was received this after?
noon, and I will attend it. 
19 June 1900?Manly to Langley both in Washington, D.C. 
Referring to our conversation of this morning with reference to 
procuring a motive power for the great aerodrome, and in response to 
your oral request, I give the following brief statement of the present 
outlook in this direction. 
The gasoline engine which was contracted for on the 12th of Decem?
ber, 1898 by Mr. Balzer can neither be accepted nor condemned at the 
present moment, since in the recent trials made upon it, it developed 
steadily and regularly 8 horsepower at 350 revolutions per minute with 
the valves working improperly, and while it cannot be accepted from 
the fact that it has not developed the 12 horsepower required, I do not 
think it best to condem it until it has been proven beyond question 
that no more power can be obtained from it even with the valves work?
ing as they should. 
If there were a large number of defects in the mechanical principles 
employed in the construction of the engine, which would necessarily 
take an indefinite time to overcome and correct, I would of course rec?
ommend that work be immediately begun on a steam engine with its 
necessary boilers, condensers, burners, pumps, etc., but as this is not the 
case, and as I still believe most implicity that when the few defects now 
remaining, which prevent the proper amount of gases from entering the 
cylinders and being properly held there after they have exploded, have 
been corrected, that the engine will develop regularly and steadily a 
minimum of 12 horsepower. 
I make this statement fully realizing that at present all manufacturers 
of gasoline engines are having more or less difficulty with their ma?
chines, but the very difficulties which these manufacturers are now 
having are the ones which have been entirely overcome in this engine 
during my recent visit in New York City, and I am firmly convinced that 
an engine suitable for the great aerodrome will be more quickly and 
surely procured by continuing the work on this present engine than 
by any other means, for the very defects which now remain are those 
which can be surely and certainly corrected. 
While of course it is impossible for anyone to guarantee that the en?
gine will be successful within a certain specified time, I desire to say 
that if it were a mere question of money loss instead of the much more 
73 
serious loss of time, I would not hesitate to stand accountable for any 
financial loss occasioned by continuing the attempts to correct the few 
faults now remaining in the engine. As I have said before, the engine 
has already cost Mr. Balzer more than $3,000 above the price which he 
will receive for it when it is complete, and of course all further experi?
ments which he will make on it have been and will be a continual loss 
to him, but so great is his confidence in the engine, that he is deter?
mined to make it meet the requirements of the contract before he ceases 
work on it, and he will not abandon it even though the present con?
tract with him be declared void. 
In view of your wish that I go abroad for a few weeks to investigate 
all the different motors which may possibly afford some hope of being 
utilized for the great aerodrome, I recommend that Mr. Balzer be au?
thorized to continue the work on the large engine, with the understand?
ing that four machinists for this work will be carried on the O. and F. 
roll, and that they will at all times be kept employed making such 
changes in the details of construction, and that he be allowed to procure 
the materials for his work not to exceed the sum of one hundred 
($100) dollars sending the vouchers here so that they may be paid in 
the regular way. 
As forty days' time work of one man will complete all the work on 
the great aerodrome and its appurtenances that can be completed until 
my return, and as it is desirable that the present force of machinists be 
kept together if possible as they will all be needed when the engine 
does come, I recommend that McDonald and Newham, both of whom 
are good conscientious workmen, be sent to New York to work on the 
large engine, their names being continued on the O. and F. pay roll and 
they being used as two of the four men I have above recommended to 
work under the direction of Mr. Balzer. The two additional machinists 
of these four I can engage in New York City at a rate of $2.75 per day, 
there being two good men there now who have worked for me pre?
viously. 
I may presume that I will be back within six weeks, and these recom?
mendations are made on that assumption. 
In regard to the one hundred dollars which I recommended be ad?
vanced Balzer for materials in connection with changes on the engine, I 
do not think that Balzer will need any money beyond this. 
My reason for advising this advance to him is my belief that it is al?
most the one best thing to do in the interests of the Government. It is 
founded partly on my knowledge that he has spent nearly three thou?
sand dollars on the engine outside the contract, and my absolute moral 
74 
confidence that he will do the best he can to finish it in the next six 
weeks, and my belief that if it can be done by anyone it will be done by 
Mr. Balzer under these conditions. 
20 June 1900?Langley to Manly both in Washington, D. C 
Referring to my conversation of this morning with you with refer?
ence to the engine which Mr. S. M. Balzer is now building for the great 
aerodrome, and to the necessity of immediately taking under consider?
ation the procuring of some other motor for the aerodrome in case this 
engine of Mr. Balzer's fails there having already been a delay of more 
than fifteen months since the contract called for the completion of the 
engine, I desire that you go abroad on June 27th to make as thorough 
examination as possible of such light engines as are now being con?
structed in both England and on the Continent. I desire that you will 
proceed to New York City in time to have a consultation with Mr. Bal?
zer on June 26th and to give him final directions as to the course of the 
work on the large engine during your absence, and that you take a pas?
sage for Europe on the "Germanic" sailing from New York for Liver?
pool on June 27th. 
After examining the light engines in England, both gasoline and 
steam, you will proceed to France, going first to Paris and examining 
the engines there on exhibit and if necessary in any other cities in 
France. If time permits, you will visit Berlin, and if necessary, other cit?
ies in Germany which you may think advantageous, returning to Liver?
pool in time to take passage on the White Star Steamer "Cymric," sail?
ing from that port on August 3rd. 
Upon returning to New York City, you will investigate the progress 
which Mr. Balzer has made with the engine during your absence, and 
upon the completion of this duty you will return to Washington. 
I desire that you take as copious notes as possible during these inves?
tigations, so that upon your return you may be able to give me a com?
plete and definite report on the subject. 
Your necessary expenses for travel and subsistence will be refunded to 
you upon the presentation of the proper vouchers therefor. 
If in the course of the investigations you deem it necessary to employ 
the services of an interpreter, you are authorized to do so, and any such 
expenses will also be refunded to you. 
25 June 1900?Manly in Washington, D.C, to Balzer in New York City 
(in part) 
I will leave Washington at 12:45 Tuesday by way of the Penna. R.R. 
arriving at the 23rd Street Station at 6 p.m., and will go direct to the 
75 
Netherland Hotel. Please arrange to meet me at the hotel at 7:30 to 
dine with me. 
Please make a rough sketch indicating what changes you think had 
best be made in the engine that can certainly be completed by four 
men, and the engine ready for trial again, within 30 days. I mean such 
changes as the making of new cylinder heads with new sub-chambers, 
the substitution of a positive motion cam, etc., so that we can discuss 
the matter very thoroughly Tuesday evening. 
27 June 1900?Langley to Balzer both in New York City 
Referring to the recent tests on the large engine in which the maxi?
mum power developed was 8 horsepower at 350 revolutions per minute, 
and to your conversation with Mr. Manly of June 26th, I desire that 
the two machinists McDonald and Newham, that I have just ordered to 
report to you at your shop, be put to work immediately under your di?
rection on the construction of a five section commutator. This commu?
tator should be so constructed and the brush which supplies the current 
so attached that the brush will be at all times shifted as the sparking 
lever is thrown the one way or the other. 
As soon as this commutator is completed, the engine should be given 
a test to see whether the change has corrected the premature burning of 
the gases in the cylinder which now appears to occur at the moment, 
just preceding the compression stroke. 
As it is possible that this five section commutator may not allow the 
contact points the proper rest, as soon as the test is completed and this 
point determined, and in case the desired rest is not secured, another sec?
tion commutator revolving with the actuating gear and supplied from 
the second commutator revolving on the rotating cylinder should be 
built. 
Upon the completion of these two changes in the engine and the pro?
per tests as to the effect of the changes, and in case the engine still fails 
to come up to the required power the sub-chambers should be so ar?
ranged that the valve which is now the exhaust valve, will be made the 
inlet valve, and a new valve of larger dimensions made for the exhaust 
valve, and to be placed in the position which is now occupied by the 
inlet valve. When this change in the sub-chamber and valves is made, 
the inlet pipes which connect the sub-chamber and the rotating sleeve 
should be enlarged to at least \y8 in. internal diameter (li/2 in. being 
preferable if the space will allow). Upon the completion of this change 
in the valves and inlet pipes, a brake test of the engine should be made 
to determine the power developed. 
76 
As it will certainly be possible at times to expedite the work by work?
ing more than two men in the making of the changes mentioned, and 
in immediately completing the small engine along with the large one, 
you are authorized until further notice to employ two additional men 
at a rate not exceeding $3.00 per day, with the understanding that the 
compensation for their services will be obtained by your sending their 
time to the Disbursing Officer of the Institution who will enter their 
names on my pay-roll and forward the checks to you for their services at 
the proper period. 
27 June 1900?Langley diary 
Sailed from pier 48, North River, N.Y.C. at 12 o'clock today on "Ger?
manic" for Liverpool, having C. M. Manly and G. B. Wells with me. 
S. P. L[angley] has stateroom 19, starboard side. C. M. Manly and G. B. 
Wells have berths in stateroom 62, port side. Weather very warm. 
10 July 1900?Memorandum (in part) by Langley after a visit to H. S. 
Maxim, #18 Queen's Gate Place, London. 
Mr. Maxim does not like the idea of the cylinders revolving on ac?
count of the difficulties it must necessitate in oiling and in sparking. 
Assuming that the Otto cycle is employed under ordinary conditions, a 
cylinder 3 inches in diameter and giving a 7 inch stroke, not only should 
but can and habitually does give 1,500 revolutions and 3 brake horse?
power. An engine built by Count de Dion gives 3 brake horsepower at 
1,500 revolutions, and 4 such cylinders would give 12 horsepower, and 
Mr. Maxim thinks it only a reasonable demand that they should be 
built for 100 lbs. weight. A smaller cylinder 2^4 inches in diameter, is 
in use by Mr. Walters, one of Maxim's employees, for an engine he has 
running a tricycle. The cylinder is 21/4 in. diameter and gives 214 
brake horse. He did not dwell on the question of cooling except to say 
that if it were cooled directly by water, about !/7 the water for a steam 
engine would be needed. It is absolutely necessary that the speed should 
be more like 1,500 revolutions rather than 350, even 600 revolutions ac?
cording to Mr. Maxim, would be most injudiciously slow. Everything 
otherwise depends on the judicious mixture of the gasses, and conse?
quently on the carbureter as well as on the conditions of compression 
and the period in the cycle at which the spark is made. 
11 July 1900?Langley in London to Manly in London (in part) 
I repeat what I have said in our conversation, that whether the Bal?
zer engine be or be not a failure, I desire that you will act in your visit 
77 
here as though it was, and as though I must obtain a new gas engine of 
from 20 to 24 brake horsepower, fulfilling the conditions of the Balzer 
contract, including the condition of fitting the present frame. You will 
ascertain where and how in Europe it can be obtained, getting specific 
information as to solvency and reputation of contractors, as to time and 
price, and such entirely definite statements as will be necessary for me 
to act on in making such a contract. 
My judgment is that you can best do all this in Paris, and that it will 
be better for you to leave here before the close of the week, being there 
on the 13th at the latest. I enclose a letter of introduction for me from 
Mr. Maxim to the Comte de Dion, which please return. 
Please give me a minutely exact statement with a drawing if possible 
from which one of the Comte de Dion's cylinders can be built in Wash?
ington or in New York. Please see if I can get one of them in Paris and 
at what cost. Perhaps I should say that when I ask you to act as though 
the Balzer engine was entirely abandoned, I mean that the chief object 
of your visit is to get something that can be absolutely relied on in its 
place, and it is hardly necessary to say that if you see incidentally any 
ways of amending it, I should like to know them, but I repeat here that 
the course of experiments on the engine in New York will need to abso?
lutely come to an end with what is now being done there. 
Knowing you to be so fully possessed of my wishes from our conversa?
tion, I will add nothing more. 
19 July 1900?Manly in Paris to Langley in London (in part) 
I shall be here for several days after you arrive, so will not trouble 
you now with a written digest of the motor situation, as I have not yet 
had an opportunity to visit the factories which are out of the city. 
Nearly all of the gasoline engines used by the twenty or thirty differ?
ent automobile companies are made after the general plan of the De 
Dion-Bouton engine, the only change being in some slight details of 
construction, and I think it will therefore be best to wait until you ar?
rive, before attempting to make arrangements for the construction of a 
light engine, as you can then use your letter of introduction to Count 
De Dion and probably get the matter arranged more quickly. 
30 July 1900?Langley memorandum 
After two or three mischances, I obtained an interview this morning 
with Comte de Dion, 46 Avenue de la Grand Armee, introducing my?
self with letters from the Embassy and from Maxim. I took Mr. Manly 
with me. 
78 
De Dion is an intelligent man conversant with each detail of the sub?
ject and apparently a real inventor. He speaks excellent English. 
He condemns the system of having the cylinders revolve, he having 
tried it himself several years ago and given it up. 
The principal trouble comes from the centrifugal force piling up the 
oil at the end where it burns and fouls the gases. He would certainly 
recommend placing the cylinders side by side. He states specifically that 
his cylinder 10 cm. in diameter and with 11 cm. stroke develops contin?
uously 7 brake horsepower at 2,000 revolutions. I do not understand 
clearly whether it would do this without limit unless there were special 
precautions against overheating. 
This type, but using more than one cylinder so as to form a balanced 
machine, he thinks recommendable, and if something is to be done at 
once, to produce a 20 horsepower engine, he would recommend four 
cylinders of the same type side by side. If four such cylinders are to be 
used he would recommend that they be arranged to explode in the 
order 1-2-3-4, 1-2-3-4. 
He believes, however, that there is a limiting possible weight for 
efficient work in this way, and that this 20 brake horse engine would 
involve at least 110 kilos of weight without cooling water or flywheel, 
both of which he thinks indispensable. He has a patent for cooling the 
water by tubes and radiators at one end of the cylinder where the water 
and steam are under a pressure which is self regulated by the rate of 
radiation and cooling. This pressure is something like 5 kilos to the 
centimeter. His system then, keeps the cylinder cool by using the same 
water over and over and employing consequently very little. 
He has employed an alloy of aluminum largely, and strongly favors 
the use of it in all cases where such a metal is applicable. 
He thinks of making an engine for a flying machine himself next 
year. 
He is constantly experimenting and hopes in three or four months to 
have something very much lighter and more efficient than he has yet 
got, but would not care to give any drawings for work that is inces?
santly being modified. 
He has no engine to sell. 
He said that in this, which is the substance of his talk, he had given, 
he believed, the gist of what he could in the way of advice. His own 
successes have been obtained at the cost of incessant experiment in de?
tail and of numberless failures, and as for my work, like any other in?
ventor's work, he believes there is nothing for it but time and patience. 
79 
30 July 1900?Langley in Paris to Manly in Paris (in part) 
In view of the advice of Mr. Maxim against a rotary engine and the 
strongly confirmatory opinion of the Comte de Dion in our interview 
this morning, of which I enclose you a memorandum, in view also of 
the fact that you have been unable to find anything better than the De 
Dion machine in London, Paris or Berlin, and in view also of your 
proximate return to New York and Washington, I decide as follows: 
First, that further work on the original Balzer engine is to be discon?
tinued when the experiments in actual construction are finished, which 
should be within a week or ten days. 
Second, that Balzer should be paid for the contract price of the en?
gine, $1,500, and the engine be taken to Washington and submitted to 
a brake test under the actual conditions, and again when stationary and 
driving the shaft with the aid of a flywheel improvised from the pro?
pellers by placing a rim on them. 
I anticipate that this will cause a prejudicial shake, but if it be 
ineffective, some other arrangement for a flywheel can be derived. 
I do not wish to make the preceding instructions absolutely manda?
tory, for in case that some very strong reason presents itself to you for 
modifying them, I will not attempt to make them absolute when I can?
not tell from this side of the ocean what change may present itself. 
You will, of course, do nothing without consulting Mr. Rathbun. 
21 August 1900?Manly in Washington, D. C., to Langley in Europe 
(in part) 
I landed in New York safely on Monday morning August 13th, the 
boat having reached the harbor too late Sunday night to move into its 
dock. I found the "Cymric" most pleasant there being practically no 
rolling or pitching perceptible, and the staterooms were very commodi?
ous and comfortable, while the table was as good or even better than 
that of the "Germanic". In fact, I was so very much pleased with the 
"Cymric" that I would without question choose it for any trip where 
the difference of a day or two in the length of a voyage is not impor?
tant. 
Immediately upon reaching New York, I went to my hotel and from 
there to Balzer's shop to investigate the progress that had been made 
during my absence. The two men, MacDonald and Newham, from the 
O. and F. roll, who had been working there since the day we left, had 
been employed the whole time in making the new and larger supply 
pipes and changing the combustion chambers so that these larger pipes 
could be connected thereto. As soon as I saw the engine, which required 
80 
FIGURE 20.?Balzer-Manly engine. First stage, 8 hp, exhaust side, August 1900. 
(Smithsonian photo A49438.) 
only a short while for adjustment before making a test, I felt certain 
that the changes which had been made would amount to practically 
nothing in increasing the power, and I accordingly told Balzer to get 
the engine ready for its last and final trial on Tuesday morning. 
On Tuesday morning, everything being in readiness, I made a test of 
the engine with the result that only about six horsepower was obtained, 
owing to the cylinders not working properly, but as I was satisfied that 
any further time spent in adjustment would be utterly wasted, I di?
rected Balzer to box the engine and all its accessories, the tools used in 
its construction, the framework for supporting it, and in fact, every?
thing connected with it and ship the entire affair to Washington imme?
diately. 
I am now making preparations to test the large engine with the cylin?
ders stationary and with a temporary arrangement for a water-jacket 
for keeping the cylinders cool, the cylinders of course being mounted in 
the circle as they have always been, and the only change being that the 
drum which supports them will be held stationary and the crankshaft 
allowed to revolve with a temporary flywheel on it. Upon the result of 
this test will depend my next step, for if the power and speed be ob?
tained in this preliminary test, I will then construct permanent water-
81 
FIGURE 21.?Balzer-Manly engine; First stage, 8 hp, view showing valves and ignition 
system, August 1900. (Smithsonian photo A49438-A.) 
jackets either using the De Dion principle or a specially light con?
denser, and if it does not prove successful, the next step I will take will 
doubtless be to dismount the cylinders from the circular arrangement 
and mount them side by side, this last arrangement requiring five 
cranks on one shaft, and of course necessitating an increased weight on 
the shaft. The only difficulty which I anticipate in this first test which I 
expect to make will be with reference to the oiling of the uppermost 
cylinders, but I am having made a temporary arrangement for this. I 
now have all of the workmen engaged on the construction of the special 
clamps necessary for holding the drum which supports the cylinders and 
firmly attaching it to the bedplate upon which the cylinders will be sta?
tionary and the crank will revolve. This construction will probably re?
quire the remainder of this week and I think it possible that I may ob?
tain this first test with the cylinders stationary by the beginning of next 
week, and will in any event communicate with you by next Wednes?
day's steamer. 
No further attempts were made to develop the engine as a rotary. 
Under Manly it became a static watercooled radial?a more compli?
cated, heavier, and bulkier engine?but it immediately met the horse-
82 
power requirements. Stage one, therefore, terminated with Balzer's loss 
of design control over the engine on 21 August 1900. During that year, 
the horsepower output had dropped from 8 to 6, indicating that Balzer 
had retrogressed in spite of valiant efforts to improve the engine. 
Chapter 4 
Balzer-Manly Aero Engine, Second Stage 
r 'he most dramatic increase in power occurred during the second stage (between 21 August to 11 September 1900), when output 
rose from 6 to 16 horsepower. Manly had merely changed the engine 
from a rotary radial to a static radial by fastening the crankcase to a 
fixed object and allowing the crankshaft to rotate. Since the cylinders 
no longer rotated, they had to be cooled, temporarily with damp rags. 
This encouraging horsepower increase not only indicated to Manly 
in what direction to further develop the engine, but also assured him 
that the Balzer engine could be retained as the basic structure. Stage 
two, therefore, set the course of the engine's future development. 
3 September 1900?Langley in Carlsbad, Austria, to Manly in Washing?
ton, D.C 
I have your letter of the twenty-first and while glad to hear of your 
safe return, I need hardly say it is with regret that I receive its bad news 
with regard to the Balzer engine. 
I am too far from being an expert in such matters to insist on a line 
of conduct against your counsel, but I have an impression that unless 
your early efforts in remodeling the Balzer engine meet with success, it 
will be better not to continue them, but to let the whole thing go and 
to extract from it the teaching of this dearly bought experience that it 
is better in such things to keep in the common road where the experi?
ence of such as have found practical success seems to show that 
efficiency is connected with not only a very much higher speed than 
ever was expected from the Balzer engine, but with a form of side by 
side cylinders with a well worked out sparking device, from which a de?
parture in the smallest details opens unknown chances of difficulty. 
84 
This at least I understand to be the gist of the counsel of both Maxim 
and De Dion. 
In case you can certainly build a small engine of the De Dion type 
for the model at Washington, for something like the equivalent of the 
sum of seven hundred dollars which you tell me has disappeared in Bal?
zer's hands, I think it had better be done there and that this work 
should go on independently of the other whatever may be done with 
the large one. 
If you are not entirely confident of your ability to do it successfully 
without any new experiment, on the De Dion type so efficiently as to be 
an essay and model for the large one, I should like to seriously consider 
the building of it on this side in hands actually experienced in the 
work. 
I shall be in England probably a month from now and I may possibly 
be able to arrange with Maxim for the use of a skilled workman or 
workmen to undertake this task of the small De Dion engine and get 
out the results which Maxim says have actually been obtained in an en?
gine made under his eye, and which I detailed to you. I have not these 
details by me now, but I think they represented in the particular one of 
Maxim's construction, something like 21/2 brake horse for a cylinder 3 
inches in diameter. 
If you are confident of your ability to do it directly (I mean without 
indefinite experiment) please commence the small engine in Washing?
ton (if you have not already done so) at once. If you have any doubts 
on this point, then in your next letter please write me whether in your 
judgment it is possible or desirable to do anything in England about it 
(the small engine). 
In case you favor this course, write me fully with plans on the ordi?
nary De Dion type, adapted to the frame and conditions of mounting of 
the small engine, for I might possibly have the time to arrange to start 
it in London before I return, though I by no means like to do this. I 
should like to have you let me have your opinion as to the possibility of 
building the large engine even here. 
I consent if you recommend, to build this small engine at Washing?
ton. I do not absolutely refuse to consider the idea of building the large 
one there, but if there is one thing which I am more reluctant than an?
other to contemplate, it is the prospect of entering on a course of exper?
iment in engine building in our shops, and I should be glad to hear 
where else you think it can be done and by whom. 
85 
382-902 O - 71 
8 September 1900?Manly in Washington, D.C, to Balzer in New York 
City 
Please, as soon as possible, send me by mail in the enclosed "Frank," 
the pattern of the five pointed hub from which the brass crank shaft 
bearings of the engine are made. 
I am having some changes made in the engine, and everything is 
progressing very nicely and as soon as I obtain the results I expect I will 
let you know the full details. 
I am also expecting to make some experiments with a slightly differ?
ent form of carbureter and if there is any of that Tupelo wood left I 
would like for you to send it to me by Express. Please, however, send 
the hub pattern tomorrow if possible, as I want to use it immediately. 
I trust that the wagon engine is now in good working order and hope 
to see you sometime soon and talk over the affairs of the company.35 
11 September 1900?Manly in Washington, D.C, to Langley in Europe 
I have only time for this short note to let you know that I am exceed?
ingly glad to be able to state that the results which I am now obtaining 
from the engine are of a very encouraging nature. 
I made the first preliminary run on Friday, September 7 th, and al?
though the engine was not working as well as I was certain it would do 
later, I obtained 750 revolutions per minute with the horsepower vary?
ing between twelve and sixteen. I made another test on Saturday, hav?
ing changed the conditions with the expectation of obtaining more 
speed, and although I was unable to get a brake test reading, due to one 
of the bearings overheating early in the test, yet I was much gratified at 
obtaining a speed of 800 revolutions with the assurance from the run 
that the speed could be brought still higher.36 
Both of these tests were made using the temporary water-jacket ar?
rangement with the cylinders stationary.37 I am at the moment of writ?
ing this, just completing adjustments for another test this afternoon, 
but as it will be too late when I complete the test to get the letter off 
on tomorrow's steamer, I am sending this personal note to relieve, as 
much as possible, any anxiety you may feel in reference to the work. 
35
 Manly is referring to an automobile company that Balzer was attempting to form. 
36
 On 3 January 1900 Balzer ran the engine at 800 rpm. With the cylinders made 
stationary, the engine's automatic valves, freed from centrifugal and inertial forces, 
operated properly for the first time, hence the increased power. 
" T h e "temporary water-jacket arrangement" was the use of damp cloths wrapped 
around the cylinders such as Balzer had used on 23 August 1899 when demonstrating 
the running of a single fixed cylinder to Manly. 
86 
As soon as I can get a good and entirely satisfactory test both of the 
highest speed obtainable and the maximum power at some certain 
speed, I will write you officially. If the results of the present tests justify 
me in believing that with the cylinders stationary and properly water-
jacketed, as much as eighteen or twenty horse power may be obtained, I 
will immediately start the men at work on the permanent water-jackets. 
These water-jackets and their accessories will probably require between 
three weeks and a month for their completion, and I, therefore, wish to 
be very certain of sufficient power being obtained from this one engine 
before I start this construction. 
12 September 1900-Telegram from Manly in Washington, D. C, to Bal?
zer in New York City 
Please send by express, immediately, tools and mandril for making 
large inlet pipe elbows and washers for bending tubes. 
Circa 15 September 1900?Rathbun in Washington, D. C, to De Dion-
Bouton Motorette Co. in New York City 
I am returning to you by express this afternoon, the spark coil which 
was received from you a few days ago, and which upon examination has 
been found to be out of order. From the weakness of the spark which it 
gives when properly connected, it would seem that the circuit at some 
point in the secondary is partially broken, and as it is urgently needed 
in the work here, I beg to request that you will either repair it or send 
another in its place immediately. 
18 September 1900?Manly in Washington, D. C, to Langley in Europe 
Your letter from Carlsbad, of September third, acknowledging the re?
ceipt of mine of August 21st, was received last Thursday. The several 
questions which you have asked regarding the engines have been dwelt 
upon in the letters which I have written you since August 21st, but 
which, of course, you had not received at that time. 
However, to make certain that you thoroughly understand just what 
I am doing with the engines, I will say that in the first place I have 
entirely abandoned Balzer's idea of the rotary cylinders, and that all 
the work which has been done on the large engine since my return and 
the arrival of the engine in Washington, has been with the cylinders 
held stationary and cooled by temporary water-jackets, and in the sec?
ond place, that with the arrangement just described the results which 
I have obtained have encouraged me to hope that it will be possible 
to so modify the present engine as to obtain from it as much as 
18 or 20 horse power for a weight not exceeding 200 pounds, in-
87 
eluding water-jackets, cooling water, condenser, flywheel and all other 
appurtenances.38 
In my letter of last Tuesday, September 11, I stated that I was then 
just about to make another test on the [large] engine. The engine was 
started up on Tuesday afternoon but too late to get a test. However, a 
run was made on Wednesday, September 12, the result being that at a 
speed of 800 revolutions, the power varied from 12 to 16 horsepower, 
or about the same as the previous test. The reason of the variation in 
the power is due to the manner of making the brake test, the fly-wheel 
used being so small that as soon as the prony brake begins to heat from 
the absorption of the work it binds irregularly, and requires a great 
deal of care in properly regulating it. 
I have made no more runs on the large engine since last Wednesday, 
as I have found it necessary to construct an arrangement to prevent the 
exhaust from going down on the bedplate as it does at present. This 
construction is now about complete, and I expect to make another run 
either tomorrow or the day following. 
With reference to your questions regarding the advisability of seeing 
what can be done in England, in the way of securing the construction 
of the large engine and possibly the small, I will say very frankly that if 
you can find anyone willing to undertake the work, I would recom?
mend that contracts be immediately entered into for the engine but at 
the same time, I will be very surprised if any very great assistance 
out of the difficulty is found in this way. At the same time, it can cer?
tainly do no harm to enter into contracts, and of course there may be a 
possibility of good being thus accomplished. 
28 September 1900?Manly in Washington, D. C, to Balzer in New 
York City 
I had hoped to have a chance ere this to see you and talk over the 
affairs of the motor company, but I have been so very busy both with 
the previous work and the additional caused by the two engines, that 
this has been impossible. 
I have heard nothing from you regarding the outcome of the wagon, 
but I feel very certain that my fears regarding it have been entirely jus?
tified. Since bringing the two engines to Washington, I have made a 
most thorough and careful examination of them, and to be entirely 
frank with you, as I have always been, I must say that I am now thor-
38
 By converting Balzer's rotary engine to a radial Manly was able to double its 
horsepower?from 8 to 16?thus exceeding the contract requirements. This answers 
one of the problems posed in the Introduction. Later it will be seen, however, that 
Manly made this change for the wrong reason. 
88 
oughly and absolutely convinced that the rotary cylinder will never 
prove a success no matter how much money or time may be expended 
on it. The main reason why it will never be a success has escaped you 
and I must confess that up to the time I returned from Europe, it had 
escaped me, and my reasons for not having written you earlier was that 
I wished to be absolutely certain that I was right before calling your 
attention to it. 
In the familiar type of stationary cylinder gasoline engine, the explo?
sion which occurs when the piston is at the beginning of its stroke 
produces a pressure on the crankshaft the tangential effect of which is 
very small until the crank has moved through a few degrees, the pres?
sure on the piston tends to send the crank on around in its circle, and, 
of course, the further the crank has moved until it reaches the mid 
stroke, the greater this tangential force becomes. In other words, the 
piston is at all times moving in the exact direction in which the force 
of the explosion tends to send it. Now in the rotary cylinder this is not 
the case, for in this case the explosion which occurs between the head of 
the cylinder and the piston would tend to send the cylinder directly 
out, and this, of course, produces an enormous strain on the bedplate 
and from the very fact of the rotary motion of the cylinder at no time is 
the cylinder moving in the direction in which the explosion tends to 
send it, and even at mid stroke the tangential force is almost nothing. 
Now in the stationary cylinder engine at mid stroke the crank is per?
pendicular and the tangential force on the crankshaft (neglecting the 
angularity of the connecting rod) is equal to the full pressure on the 
piston, whereas in the rotary cylinder at no time is the tangential force 
on the cylinder equal to the pressure on the piston, and in fact it is 
never even equal to one half this pressure. In other words, in the rotary 
cylinder the explosion is at all times tending to send the cylinder di?
rectly away from the center of the shaft, whereas the rotary drum com?
pels it to move in a circle, and it was this very thing which has made it 
impossible to speed the large engine above 375 revolutions as a 
maximum.39 
39
 Manly had devised an erroneous theory to explain the operation of the rotary 
engine, the conclusion of which was that the rotary only developed one half as 
much power as a radial of the same size. When he actually got twice as much 
power (16 h.p.) from the engine as Balzer had (8 h.p.) , Manly considered his theory 
proven; yet basically all he had done was convert the engine from a rotary to a 
radial. The theory of operation of a static radial or rotary engine is identical for 
both types of engine. The added efficiency was due to a function of the valves. It 
should also be noted that Balzer had the engine running at 800 rpm on 3 January 
1900 (see page 57) . 
89 
Wishing to be absolutely certain about this point before bringing the 
matter to your attention, I have made some very radical changes in the 
large engine, and am now making some still further changes. The first 
changes were made immediately upon arrival of the engines in Wash?
ington, and before the close of the second week after their arrival here 
(that is before the last of August), I had obtained more than double 
the power which the engine had ever previously developed, and had ex?
perienced absolutely no difficulty in obtaining more than 800 revolu?
tions per minute. 
I need hardly say that there is no one who is more anxious to see you 
succeed or is more willing to be of any assistance possible, and it is this 
very reason which causes me to say to you very frankly now, that before 
the wagon can be a success, either from an engineering or commercial 
point of view, it is absolutely necessary that the rotary cylinder be aban?
doned. 
If you see any reasons that cause you to think my above conclusions 
regarding the engine are at fault, do not hesitate to write fully and 
freely to me about it, because I am fully aware of the difficulty that one 
always meets in giving up a thing on which one has spent six of the 
best years of his life.40 
I must close now but hope you will write me fully and freely about 
the affairs of the company, and I trust will hear from you by Sunday 
night or Monday morning. 
29 September 1900?Langley in Paris to Rathbun in Washington, D. C 
(in part) 
It is clearly impossible to carry on a written correspondence any 
longer at the eleventh hour. I have already cabled you to get a clear 
written statement which may decide me. 
I now add that, on receipt of this, if such a clear statement has not 
been already given that Mr. Manly should through you, cable me some?
thing more positive than is contained in his letter just received [Sep?
tember 18]. In other words, it is just that the responsibility of the deci?
sion should rest on him, and that he express it one way or the other, 
either saying that he will build something in Washington which will 
do the work, or that I had better abandon hope of his doing so, and 
attempt to buy on this side with all the difficulties in the way. There is 
no middle course, and he as an engineer, and on the ground, must take 
40
 On 14 October 1900 Balzer wrote to Manly disagreeing with his rotary engine 
theory; and on the 18th Manly wrote back to him reaffirming his faith in the 
erroneous theory. 
90 
the responsibility of advising, and say in substance, "I can build here 
in reasonable time" or, "I give it up". I have got nothing yet of the 
builders here. 
If Mr. Manly has not already written positively let him cable a few 
words which I shall get before it is too late to make some arrangement 
here. 
9 October 1900?Cable from Manly in Washington, D. C, to Langley in 
London 
Manly can build here in reasonable time. 
27 October 1900-Wells diary 
Mr. Manly orders some platinum wire today from Lambie to replace 
that in the sparking plugs for the large engine.41 
30 October 1900?Manly waste book entry (in part) 
The change in the sparking plugs being completed, they were put in 
place and a preliminary run with a tachometer was made to see if the 
change in the sparking plugs would overcome the trouble from the lu?
brication short-circuiting the plug. The engine started up without any 
difficulty, only one or two turns being necessary, and was allowed to run 
for two or three minutes. 
It was found that the sparking was perfect, the engine never since it 
was built having run so smoothly.42 
31 October 1900?Manly waste book entry 
I this morning had the two lower cylinders taken off and cleaned out 
with gasoline, and it was found there was quite a bit of burned graph?
ite and oil in both of these cylinders. All the piston oil cups were then 
filled with oil, the two lower cylinders replaced, and the water jackets 
41
 Langley Memoir on Mechanical Flight (pages 221 and 222) ; Considerable difficulty 
was at first experienced with the spark plugs from a coating of soot (resulting from 
the incomplete combustion of the gas and oil in the cylinder at the time of explo?
sion) which formed on the porcelain and thereby caused a short-circuit, preventing 
the plug from working properly. This was overcome by extending the metal 
portion of the plug for some distance into the cylinder, and for something like 
three-quarters of an inch beyond the end of the porcelain insulator. The terminal 
which passed through the insulator was also extended for something like half an 
inch beyond the porcelain and bent to a proper extent to co-act with a piece of 
platinum wire inserted in the interior wall of the plug which formed the other 
terminal. After making this improvement in the plugs practically no difficulty was 
experienced from short-circuits caused by soot. 
" T h i s change undoubtedly refers to the spark plugs. See footnote 41. 
91 
put on ready for a trial, the carbureter having had about a gallon of 
gasoline put in it. About 10 o'clock an attempt was made to start the 
engine, and upon its failing to start, and after making sure that every?
thing else was correct, the carbureter was examined and found to be 
filled with gasoline. The superfluous gasoline was emptied back into 
the can, and upon again starting the engine, everything was found to 
work perfectly. After a short run of only about two minutes premature 
explosion set in due to the present temporary water jackets being so 
soaked with oil that they did not hold water. 
The engine was accordingly shut down, and some fresh cloth was got?
ten and new jackets made from it. At two o'clock, the new jackets being 
completed and adjusted to the cylinders, a run was made in which the 
maximum recorded revolutions was about 650 with only four of the cyl?
inders working. The run lasted several minutes, but it was useless to 
prolong it until all the cylinders were working, and the engine was ac?
cordingly shut down and it was found that one of the sparking plugs 
was not working properly. This plug was repaired and the engine was 
immediately gotten ready for another trial. 
Three more runs were made with practically the same result, there 
being first trouble with one cylinder and then with another, due to ei?
ther water or surplus oil having gotten down into the cylinder and in?
terfered with the sparking, to the secondary wires working loose from 
the plugs, etc. 
I am having McDonald remove the springs from the main valves and 
will have him wind some new springs the first thing in the morning 
from some stiffer wire, the present springs I have being too weak at the 
start, and having become weaker due to the excessive heating of the cyl?
inders. I shall also have the valve stems of these main valves bored out 
so as to lighten up the valves, thus insuring quicker and more certain 
closing of the valves. 
2 November 1900?Manly waste book entry (in part) 
The drilling out of the valve actuating rods and the valves was com?
pleted about 11 o'clock this morning and the valves with their springs, 
etc., were put back into place and preparations made for a run this af?
ternoon, the joints being adjusted to the cylinders. The valve actuating 
rods with the rollers formerly weighed 87 grammes and the main valve 
weighed 52 grammes. The valves now weigh 43 grammes, and the ac?
tuating rods 61 grammes. This is inclusive of the springs and nuts. 
The connection was repaired, the water jackets wetted down, and an-
92 
other run with practically the same results was obtained, the Secretary 
witnessing both runs. 
Immediately after luncheon I made another run with the Prony 
brake in place and the propeller off, to see whether the present sparking 
arrangement will allow the engine to speed up to its former free rate of 
850 rpm. After two short runs it was found that the engine even run?
ning free does not speed over 700 rpm, and I will therefore investigate 
the cause of this later. 
4 November 1900?Manly waste book entry 
I have this morning broached the subject to the Secretary of the con?
struction of a new and more powerful engine for the large Aerodrome. 
He, however, seems very much opposed to it on the ground that the pre?
sent engine had been delayed almost two years while it was in the 
hands of Balzer, and that all during that time it was a source of aggra?
vation and almost despair, and that it was only after I personally took 
the responsibility of producing a suitable engine, and made such a com?
plete change in the present one to bring success out of failure, and that 
he is therefore willing to "let well enough alone", and to depend on 
using the present engine.43 However, I am still strongly in favor of the 
construction of a new and more powerful engine, and shall not be con?
tent until work on it actually commences. 
7 November 1900?Manly waste book entry (in part) 
McDonald will make some new caps for the pistons of the large en?
gine. These new caps for the pistons of the large engine are to deter?
mine what effect raising the compression will have on the work of the 
engine as I shall want to raise the compression slightly when I make the 
new and lighter pistons for the engine. At present the compression 
space in the large engine is about 40 per cent of the volume swept 
through by the piston. These new caps on the pistons will reduce the 
compression space to about 25 per cent of the volume swept through by 
the piston which should raise the mean effective pressure to between 75 
and 80 lbs. which also means a slight increase of power; but it may also 
increase the vibration of the engine, and in case this is so, it will proba?
bly be best not to raise the compression so much. However, it is impos?
sible to say just what the effect will be until I make a trial with the 
increased compression. 
43
 The "complete change" consisted of changing the engine from a rotary to a 
radial. This was done after a consultation with Balzer who indicated that it would 
be practical. 
93 
14 November 1900?Manly waste book entry (in part) 
I will then put him [Newham] to work in the lower room, South 
Shed getting out some disks l/8 in. tfiick which will be placed on the 
ends of the pistons of the large engine, to see what effect the increased 
compression will have on its running. 
14 November 1900?Manly waste book entry (in part) 
Russell has now about completed the stuffing boxes for the water 
jackets, and should be ready to fit these to the cylinders and jackets by 
tomorrow. Before any further work is done on the jackets, however, I 
shall have Russell cut the bay window jackets from the piston chambers 
of the cylinders and insert circular pieces in their places so as to have 
the water jackets encircle the cylinders and the combustion chamber at 
a uniform distance. These bay window projections were put on in New 
York on the first of last June to enable the wiping spark to properly 
work, but are now not necessary, and merely serve as a receptacle for 
burnt gasses.44 
If the sparking plugs in the heads of the cylinders of the small engine 
demonstrate that there is no trouble from their becoming fouled more 
rapidly than when they are in the combustion chamber, I shall proba?
bly change the sparking plugs in the large cylinders to the heads, 
change the inlet valves in the caps of the combustion chambers, and en?
tirely do away with the valve chambers on these cylinders. The object 
of this change would be twofold; first in order to get rid of the valve 
chambers, and second in order to get the sparking plug where the com?
bustion would be more nearly instantaneous than when it has to travel 
through the present inadequate ports in order to ignite the main charge 
in the cylinder proper. The main valve would then become the exhaust 
valve, and the present exhaust valve would be entirely done away 
with.46 
26 February 1901?Wells diary (in part) 
A preliminary run obtaining 700 rpm was made on the large engine 
late this afternoon. Other runs will be made in the morning. 
1 March 1901-Wells diary (in part) 
The Secretary goes to Lower Room, South Shed this afternoon about 
44
 Manly is referring to necessary changes since the ignition system of the engine 
was modified from low to high tension. 
44
 An excellent idea?This change simplified the engine, reduced its weight, and 
permitted it to breathe more freely. 
94 
3:30, but does not wait to see test of large engine which when started at 
4 o'clock by Mr. Manly runs 3 minutes at approx. 800 rpm which indi?
cates 24 hp. This was with propeller attached. 
2 March 1901-Wells diary 
A Prony brake test of the large engine running at 600 rpm was made 
this afternoon, which showed the engine developed 18 hp at this speed. 
5 March 1901?Langley to Captain Lewis both in Washington, D. C 
Referring to my letter of February 23rd, I would say that if you care 
to see a brake test, I could have one for you any forenoon this week 
which you may indicate. 
I am in hopes to show you 18 horsepower at the brake for an engine 
which with cooling water and all complete, weighs less than 200 
pounds. It has actually done this, and if it is not fractious, will do it in 
your sight I hope, though I have not yet got it to run with absolute 
uniformity. 
12 March 1901?Wells diary entry by Manly (in part) 
Made 4 runs on large engine, each of which was of short duration 
due to the breaking of the water connections, but the engine working 
favorably and showing slightly over 40 lbs. on the brake at 700 rpm 
with each cylinder working intermittently. 
Started 5th run in the afternoon and found cylinder # 1 full of 
water. The engine was dismantled and cylinder taken off, and upon 
putting hydraulic pressure upon the water jackets, it was found that the 
asbestos packing under the cap was broken and had sprung a leak. New 
packing put in and assembling the engine preparatory to trial first 
thing in the morning left in charge of McDonald. 
Unless some unforseen difficulty arises the engine should be in proper 
working order so that Captain Lewis can see it when he comes down 
tomorrow. 
13 March 1901?Wells diary (in part) 
Captain I. N. Lewis, Recorder of the Board of Ordnance and Fortifi?
cation, War Department, came down at the Secretary's request this 
afternoon at 1:30 to see a brake trial of the large engine, and look at 
the work in progress. 
He saw both the large and small engines running. The large one did 
not work well owing to the non-working of a cylinder, but gave a pull 
on the scale of from 25 to 30 lbs. 
95 
The small engine worked exceedingly well after a short trouble in 
the beginning. 
The maximum output of 18 horsepower was developed in the stage 
two configuration on 2 March 1901. This was more than twice the pow?
er that Balzer had been able to obtain in over one and a half years. 
The only major design change over stage one was the addition of the 
water jackets. Therefore, although Balzer's engine had had the poten?
tial to meet the contract requirement for 12 horsepower, it was Manly 
who earned the credit for doing so. 
96 
Chapter 5 
Balzer-Manly Aero Engine, Third Stage 
O n 28 June 1901, the engine developed 25 horsepower and main?tained this level during 1902. The major design change in stage 
three was discarding Balzer's heavy "ball and socket" pistons for the 
modern light-weight "piston pin" type, which is universally used to 
this day. 
15 March 1901?Langley waste book entry 
On the 13th Captain Lewis, Recorder of the Board, came by my invi?
tation to see a brake test of the actual engine. It was a failure. 
In answer to my subsequent questions I obtained from Mr. Manly 
the following memorandum. 
Mr. Manly says in relation to the trial of yesterday that the present 
engine, which has yielded 21i/2 hp at the brake, is but a patched up 
thing, and cannot be counted on. Independently of this the 5 cylinder 
engine can never in theory be a perfectly balanced one; and the weight 
of the present pistons considered, it is certain that even if it ran, the 
vibration would be too great for the actual frame.46 
Mr. Manly would like to do three things, two of them immediate and 
practical: 
1. To put into the present patched engine as it exists, light pistons 
with the present patched up water jackets, these pistons to weigh per?
haps 4 lbs. instead of the present 61/?> lbs. This first change (which is 
now under way) is purely experimental, and will be completed in a 
week or ten days. 
2. If the vibration cannot be cured by lightening these pistons, it 
49
 The 5-cylinder configuration in radial form is a perfectly valid one from the 
standpoint of balance, and the heavy pistons were not a liability when the engine 
was run as a rotary as there was no absolute reciprocation. 
97 
will next be- in order to make entirely new castings for pistons which 
will give decreased compression in the present cylinders, these new pis?
tons being also of the lighter weight; and an attempt made to obtain 
sufficient power by making up in the speed of the engine what was lost 
in the explosive pressure. The engine in its final form is held up until 
these experiments with the pistons are complete, though the work is 
going on on the cylinders for them. 
This second stage of experiment can only be met, with the engine de?
signed to be completed in June, on the engine itself; that is, with the 
new cylinders, and if this fails to control the vibration, we are at the 
end of any possibility we can now see of using the 5 cylinder engine. 
3. If the 5 cylinder engine does not work satisfactorily, Mr. Manly 
can suggest nothing but the building of the 6 cylinder one, which will 
almost necessarily run without prejudicial vibration, but which it may 
be practically impossible to undertake with our time and means. 
In Manly's belief the chances of success with the 5 cylinder engine 
are good enough to warrant the continuance of the work on it, leaving 
the other questions open. 
16 March 1901?Memorandum by Langley and Manly 
I wrote and telephoned to Captain Lewis that he could see a brake 
trial of the engine this afternoon, if he could come down at a little 
after one o'clock. He replied that he could not get here until 3:30. I 
said that the trial would be ready for him to see at that hour, but that I 
had an engagement which would prevent my being present. He came, 
and Mr. Manly reports as follows: 
"Captain Lewis arrived promptly at 3:30, and was met in the recep?
tion room by Mr. Manly, and went immediately to the Lower Room of 
the South Shed, where the trials are being held. 
The [large] engine was started up immediately, and a continuous 
run of about 12 or 15 minutes was made. The brake varied slightly, 
being a trifle higher than the reading recorded below at the beginning, 
but falling off toward the middle of the run owing to the imperfect lu?
brication of the cylinders when the lubricating oil commenced to be 
carbonized by the excessive heating, the circulation in the water jackets 
being imperfect during this run. The least or commercial reading of 
the brake was 35 lbs. at 750 rpm on a Prony brake arm of four feet, and 
this result was maintained during the entire run, and as stated above, 
was slightly more at the beginning and represents a minimum of some?
what over 17 horsepower. 
The imperfection in the circulation of the cooling water being re-
98 
medied, a second run was started, but it was found that excessive heat 
had melted two of the sparking plugs. However, others were immedi?
ately substituted and the engine again started up without any difficulty. 
The results of this second run were practically the same as those of the 
first, and it should be noted that in the second run, all of the lubricat?
ing oil in the piston oil cups had been used up and the lubrication of 
the cylinders was therefore not so perfect as in the first trial. In this sec?
ond run the water inlet pipe on cylinder # 2 developed a fracture and 
began to seriously leak. 
The break in the water connection of cylinder # 2 was temporarily 
repaired by some cloths, and a third and short run made to demonstrate 
the extent of the reliability of the engine. The engine was started up 
immediately without any difficulty, only one or two turns being made 
by hand in order to take in gas from the carbureter. The result of this 
third run was practically the same as that of the first and second, and 
the engine was several times speeded up during the run in order to 
demonstrate the very high speed at which it was possible to work it. 
It is particularly to be noted that at all these trials the cylinders were 
dirty from lack of the considerable time needed to dismount them to 
clean them, but that when clean and fresh they have been known to 
give a great deal more, the highest ever having been obtained being 
24 horse and 21 on several other occasions. 
The result of these trials was that the engine had actually given a 
minimum of 17 horse under the imperfect conditions in which it was 
tried. 
Captain Lewis expressed himself as greatly pleased with the results, 
which he considered to show much the most considerable advance in 
engine building that has ever been made. 
22 March 1901? F. W. Hadley in Washington, D. C, to the De Dion-
Bouton Motorette Co., 37th & Church Lane, Brooklyn, New York 
I am authorized by the Secretary to inquire if you can furnish the 
Institution with a small quantity of the cement which you use in ce?
menting into place the long platinum wire in the sparking plugs. 
The cement is wanted in some special research work now in progress 
at the Institution, and if you can furnish it, please send about a table-
spoonful, together with your bill, under the enclosed frank. 
29 April 1901-Wells diary 
Mr. Manly is reassembling the present large engine, putting in the 
new light pistons which have been made for it and for the new engine, 
99 
and expects to run it after these pistons have been "worn" in the old 
cylinders for 2 or 3 days. 
/ May 1901?Manley in Washington, D. C, to Balzer in New York 
From your telegram of the 26th instant, I judge that you are back at 
work at the shop, though I have not yet received the letter which you 
said in your telegram you would write me. 
I find that the crankshaft in the large engine has gotten slightly bent 
owing to the excessive power which I have been obtaining from it. 
When you first started to build the engine you turned up one crank?
shaft for it and had it about half complete when you noticed a small 
flaw in the wrist pin, and the crank was therefore discarded and a new 
one made. When I was at the shop last spring I noticed this old un?
finished crankshaft lying near the carpenter bench in the upper room, 
and my recollection is that the flaw in the wrist pin was a very small 
one indeed. 
If you have not destroyed this crankshaft and can get it out of the 
shop for me, I wish you would send it to me (addressing it: Smith?
sonian Institution, O. and F. acct.) by express as soon as possible and I 
will see that you are paid what is proper for it. 
Let me hear from you regarding the affairs of the Company, as you 
well know I am very deeply interested in them. 
2 May 1901-Wells diary 
The large engine with the new pistons has been running all of today 
under the power of an electric motor, and it will probably soon be in fit 
condition to run under its own power. 
28 June 1901-Wells diary (in part) 
Mr. Manly made several runs on the large engine with the new pis?
tons, and with it drove the 2 meter propeller at a speed varying from 
850 to 875 rpm. The average power developed in the various runs was 
between 25 and 30 horsepower, which compared with the power devel?
oped on March 16, when Capt. Lewis witnessed the test, shows for a 
speed of 850 rpm 8i/2 hp more than at that time shown on the brake, 
the brake showing very much less power than the calculations based on 
the work of the propeller, which at that time was 22i/2 hp and which 
would make the present test show a horsepower of over 30, or to be 
more exact 3334. This increase in power is entirely due to the latest 
changes in the pistons which Mr. Manly has made. 
100 
1 January 1901?Manly to Langley both in Washington, D.C. (in part) 
When I assumed the responsibility of producing an engine suitable 
for the aerodrome, I fully expected that it would be necessary to con?
struct an entirely new and larger engine, for I deemed it unsafe to 
launch the aerodrome with an engine which could develop the mini?
mum power required only when it was working at its very best. I have 
since found that by constructing a new set of cylinders of a larger diam?
eter (including of course new pistons, piston rods and crank) it will be 
possible to provide an engine which will furnish when working at its 
very best at least 25 or 26 horsepower, which it would therefore be safe 
to depend on developing, under the conditions of actual flight, ample 
power. I never expected to utilize the present engine except for experi?
mental purposes, so that when I did undertake a new engine there 
would be no experiment connected with it; and I now feel that al?
though there are still some things which may be learned from the pre?
sent cylinders, yet owing to the pressure for time, it will be better to 
immediately construct the new set of cylinders and thus have the final 
engine in a finished condition as soon as possible. It should also be re?
membered as stated in the earlier part of this report that I am design?
ing the new cylinders in such a way that none of the essential parts of 
the engine as it exists at present (such as the circular bed-plate, spark?
ing arrangement, valve rods, etc.) will be altered and it will thus be 
possible at all times, in case it is required, to use either set of cylinders 
and thus have always on hand a reserve engine. 
I may recall in this connection the fact that the French engine build?
ers are very much opposed to the steel cylinders having a cast iron lin?
ing, they maintaining that it is impossible to rely on such a construc?
tion, although they recognize that it is in this direction that the great?
est saving in weight can be made. This same opinion on the subject 
would probably be confirmed by engine builders of this country, and if 
cylinders giving satisfactory results had not already been constructed in 
this way, it would be best to accept their judgment in the matter. How?
ever, it is impossible to give this work out under contract since I know 
of no shops outside of Mr. Balzer's which are well enough acquainted 
with this kind of work to do it properly, and as Mr. Balzer is at present 
engaged in other work, it is impossible for him to do it; so that if it is 
to be done, it must be done in our own shops and under the most care?
ful supervision. Of course, if there were no other work to be done, the 
present equipment of machine tools would serve to rapidly complete the 
engine, but the present equipment will certainly be taxed to its utmost, 
as it has always been, in completing other essential parts of the work. It 
101 
382-902 O - 71 - 8 
will therefore be necessary in order to complete these cylinders, includ?
ing their pistons, water jackets, etc. within the time when they will be 
required, to install at least two additional lathes, and employ at least 
two additional skilled machinists who are accustomed to this kind of 
work. Regardless of whether the present cylinders or new ones are used, 
it will be necessary to construct a light condenser and pump capable of 
taking care of the water required for cooling the cylinders. It will also 
be necessary to provide the carbureter and tank for the fuel, as well as 
new propeller and transmission shafts for the frame, as the shafts at pre?
sent in place will probably not prove strong enough. Outside of minor 
accessories for the engine, such as providing means to allow the aero?
naut to properly regulate the engine from his seat, the above is about 
all that can be at present anticipated with reference to the engine.47 
14 November 1900?Manly waste book entry (in part) 
Manly already knew exactly how he would construct the new cylin?
ders as this partial quotation indicates. 
While in New York last Saturday at the Automobile Show at Madi?
son Square Garden, I noticed that Janney, Steinmetz and Company are 
now making cylinders from 5 in. to 16 in. in diameter of cold drawn 
steel which are closed at one end by circular domes, the domes and 
walls all being in one solid piece. Since seeing these cylinders I am 
thinking very strongly of taking the present large engine and making 
new cylinders for it by turning out a 5 in. tube to 51/s in. internal di?
ameter, lining it with a 1/16 in. extra iron, and brazing the combustion 
chamber to the side of the cylinder. By using the cylinders closed at one 
end the most tedious part of the construction of new cylinders would be 
done away with since the heads and combustion chambers as formerly 
made from the solid could now be superseded by the plain combustion 
chamber, all of the work on which would be simple lathe work. With 
the present supporting drum and a new crank, for a longer bearing sur?
face for the piston rod brasses, the engine should develop not less than 
25 hp., and I feel very sure it would develop as much as 28. However, I 
do not care to consider construction until I have made the further ex?
periments on the present engine to determine the advantage or disad?
vantage of the sparking plugs being in the heads of the cylinders and 
the amount of space by which the water jackets should be separated 
from the cylinders in order to obtain just sufficient water to keep the 
cylinders cool, and also until I have made a brake test of the engine 
47
 See entry of 4 November 1900 (p. 93) regarding the first time Manly broached 
the subject of building a 'new" engine to Langley. 
102 
and determine exactly and directly how much power it is now develop 
ing. 
However, if the tests on the present large engine do show that it will 
be advisable to construct larger cylinders, I think these new cylinders, 
built as above described, can be without question completed by 5 men 
in 4 weeks time, and a new crank, and all other necessary changes could 
be made by one extra man in the same length of time, so that if these 
points are determined by the first of January, 1901, there should cer?
tainly be no delay caused by having this work done in outside shops. 
To summarize, the major phases of development during the third 
stage were: (1) The use of new light weight pistons permitted a higher 
rpm and a higher compression ratio. These pistons of the De Dion-Bou?
ton type raised the engine's power from 16 or 17 horsepower to about 
25 horsepower. (2) Another feature copied from the De Dion-Bouton 
engine was the modern high tension rather than low tension ignition 
system which allowed the engine to run more smoothly at the higher 
rpms. (3) A permanent cooling system was devised consisting of cylin?
ders with full length water jackets, a circulating pump, and a radiator 
composed of finned tubes. This in theory permitted runs of hours in?
stead of minutes, and was therefore a great improvement over the pre?
vious water-soaked rags. On the other hand had the original rotary 
design (stage one) been retained and developed as such, the weight and 
complications of a water cooling system would have been eliminated. 
103 
Chapter 6 
Balzer-Manly Aero Engine, Fourth Stage 
T\etween 14 and 19 November 1900 Manly received permission from 
JLJ Langley to order new larger cylinders for the engine, thereby in?
creasing its displacement from approximately 380 cubic inches to 540 
cubic inches. This change constituted stage four and by 23 March 1903, 
52 horsepower was developed. 
19 November 1900?Manly to Janney, Steinmetz and Company, Drexel 
Building, Philadelphia, Pennsylvania 
I am authorized by the Secretary to inquire at what price and how 
soon after receipt of order you can furnish five seamless steel tubes 
closed at one end, 5 inches internal diameter with a 1/g inch wall and 
12 inches long. 
The closed end which is drawn from the solid and joined to the tube 
without any seam, should have a radius of curvature of about twice the 
diameter of the tube. 
Please also state what difference in the internal diameter at the two 
respective ends of the tubes should be expected and allowed for. 
6 February 1901?Manly in Washington, D.C, to Balzer in New York 
I have been making some further changes on the original cylinders of 
the large engine and want to borrow the taper mandril which you used 
in making them and which fitted the inside of the cylinders. I think 
you will understand what I mean. I am not certain whether this 
screwed on to the spindles of the lathe or whether it was bolted to the 
face plate, but in either case I think I shall have no trouble in using it 
here, and if you will be good enough to ship it to me by express, 
charges collect, as soon as possible, I will thank you very much. 
104 
I would also like to know the name and address (Pugsley, I think) of 
the man who was agent for the Franklin Stock Cylinder Oil, as I shall 
probably want to order some from him right away. 
I am sorry you have been having so much trouble with the wagon 
now in hand, but hope that everything connected with it is now in 
good shape. Let me hear from you when you can find time to write. 
18 February 1901?Wells diary 
The piston castings for the new engine received this morning from 
Erie Foundry Company and sent to lower room South Shed. Patterns 
returned with them. 
20 February 1901?Manly in Washington, D.C, to The Erie Foundry 
Company, Erie, Pennsylvania 
The piston castings were received on February 18th, and so far as 
they have been examined, prove to be unusually sound. 
I enclose a sketch of two patterns from which I would like to have 
you submit an estimate for some castings. Twelve castings of pattern 
No. 1 are to be made, and as these castings are to be used as linings for 
gas engine cylinders, and will not be more than y16 in. thick when 
they are machined and shrunk in, they must be of a good close grained 
gray iron of medium hardness, (slightly harder than the piston castings 
and yet not too hard) and entirely free from all blow and pin holes. 
Eight castings of pattern No. 2 are to be made, and as they are to be 
used as piston rings, they must also be of good gray iron of a little 
closer grain and slightly harder than the above linings, and entirely 
free from all blow and pin holes. 
The castings from pattern No. 1 weigh approximately 35 lbs. each, 
and from No. 2 approximately 15 lbs. each, and I desire that you will 
let me know immediately at what price per pound you can furnish the 
entire lot of castings, and also the shortest time that you can make ship?
ment after receipt of patterns. 
20 August 1901?Manly in Washington, D.C, to Langley in Newport, 
Rhode Island 
I have all of the accessories connected with the large engine now 
fully in hand, and am completing them as rapidly as possible, and am 
also getting the necessary materials on hand for making as rapid repairs 
as possible to the frame and power transmission parts, in case there is 
any breakage or mishap when the large engine is put to work in its 
frame. 
I have been somewhat hampered for some weeks now by first one 
105 
man being sick and then another, due to the effects of the heat, but all 
of the men are back at work now, and on the whole, I feel very well 
satisfied with the progress of the work. 
3 September 1901?Manly in Washington, D. C, to Langley in Baddeck, 
Nova Scotia (in part) 
I beg leave to submit the following brief report on the present condi?
tion of the aerodromic work. 
The work on the large engine and its accessories including the water 
cooling system of jackets, condenser and pump is progressing as well as 
might be expected, considering the very great delays which have been 
experienced in it, caused by having to set aside this work for several 
weeks this summer in order to use the few large lathes we have to rush 
certain repairs and changes which have been necessary in the small 
aerodrome and its engine. The finishing cut is now being taken in the 
steel shells for the large cylinders, and this cut should be completed and 
the cast iron liners shrunk into place by the close of the present week. 
As soon as the liners are shrunk in, the jackets, which have already 
been fitted to the cylinders are to be brazed into place and the cylinders 
then bored out and finished up. These latter two operations will proba?
bly require from now until the twentieth of September for their com?
pletion. By this time, however, I hope to have all necessary accessories, 
such as carbureter, tanks, specially designed prony brake for absorbing 
and measuring the power of the engine without endangering it, and 
the new propeller and transmission shafts with their larger gears com?
pleted so that the brake trials can be had without delay and the engine 
then put to work in the aerodrome frame.48 
11 September 1901?Wells diary 
Ludewig is making patterns for the large dynamometer to be used in 
connection with the new engine when it is completed. 
12 September 1901-Wells diary 
Russell is at work under Mr. Manly's directions shrinking a liner in 
one of the new cylinders, and brazing the water jacket on cylinder. 
25 September 1901?Wells diary (in part) 
The shrinking in of the remaining cast iron liners was done by 
McDonald under Mr. Manly's direction. The whole 5 cylinders of the 
WA water absorption type of dynamometer was used for measuring power. Two 
more years were to pass before the engine was put to the acid test! Balzer's delay 
now seems more understandable. 
106 
new large engine are being pushed to completion now, the liners being 
bored out, and the water jackets being attached. 
26 September 1901?Wells diary (in part) 
Mr. Manly [is] brazing the water jackets on the new cylinders today.49 
2 October 1901?Wells diary 
Mr. Manly puts the water pressure on the new water jackets today 
and finds that two or three of them leak badly which will necessitate 
the making of new water jackets for these cylinders, and as some of the 
leaks are in the cylinder head itself, the linings will have to be taken 
out, and consequently new castings will have to be ordered and bored 
as well as new water jackets made, and three new steel shells will also 
be ordered from Janney, Steinmetz and Company to replace the cylin?
ders themselves. 
8 November 1901?waste book entry 
January 1,1899-October 15,1901 
Large aerodrome: 
Old Engine - In assisting Balzer - 1900 - $350 - T. $350 
Old Engine - Reconstruction and experimental tests in S. I. 
Shops - 1900 - $650 - 1901 - $1,050 
New and larger engine (engine proper) - 1901 - $1,450 
Condenser - 1901 - $130 
Dynamometer - 1901 - $60 
Paid Balzer on contract - $1,500 
$5,190 
9 November 1901?Wells diary 
Hewitt, Newham, and McDonald are all at work finishing up the new 
large cylinders, and Mr. Manly hopes to have this new large engine fin?
ished, assembled, and ready for shop trials in the near future. 
13 November 1901?Wells diary (in part) 
Mr. Karr gives the Secretary a recommendation as requested by the 
49
 Perhaps the most difficult operation in building the engine was brazing the 
water jackets onto the cylinders, since the engine had been designed for aircooling 
rather than watercooling. As a result, large areas of metal had to be brazed. The 
intense heat required tended to warp the thin jackets and they invariably failed the 
water pressure tests. Finally, when Russell, one of the best mechanics, failed to solve 
the problem, Manly undertook to do the brazing himself. After enduring intense 
heat at close quarters for many days, thereby permanently impairing his health, 
Manly succeeded in accomplishing the task. 
107 
T. 
T. 
T. 
T. 
T. 
$1,700 
$1,450 
$ 130 
$ 60 
$1,500 
latter in regard to funds for the continuance of the aerodromic work; 50 
that what is known as the Bell Fund of $5,000 and the Kidder Fund of 
$5,000 be both set aside (making $10,000 in all) and jointly forming a 
fund to be called the "Bell and Kidder Fund" and to be disbursed in 
connection with the aerodromic work in the regular form pursued in 
regard to the routine Smithsonian accounts. The Secretary approves 
this recommendation. 
6 January 1902?Wells diary 
All of the men away on leave reported for work this morning 
(McDonald, Hewitt, and Newham) and Mr. Manly makes another 
trial of the engine, but the push rods for the exhaust valves still smash 
up causing the abandonment of the run, and Mr. Manly decides to 
make certain changes in the exhaust cam mechanism. 
8 January 1902?Wells diary 
Mr. Manly makes another trial of the large engine today with the 
slant on the exhaust cam greatly reduced, and finds that the push rods 
which lift the exhaust valves now stand up to their work; but owing to 
the "wobbling" of the dynamometers due to their flimsy supports, he is 
unwilling to let the engine run at full speed and holds it down to about 
400 rpm for a 5 or 6 minute run. 
Mr. Manly decides to add further balance weight to the flywheels, 
and puts one machinist at work fitting this additional balance weight. 
The balance weights on the flywheels now merely balance the crank 
brasses, and 1/2 the weight of the piston rods. 
9 January 1902?Wells diary 
Mr. Manly makes another run on large engine today with the extra 
balance weights on the flywheels to counteract the effect of one piston, 
and finds the vibration greatly reduced; but owing to the flimsy con?
struction of the wooden bracing which supports the dynamometers, con?
siders it unsafe to allow the engine to run at full speed, and therefore 
holds it down for 5 or 6 minutes run to a speed of about 500 rpm, the 
dynamometers recording a pull of about 50 lbs. each. 
11 January 1902?Wells diary 
The extra wooden bracing for testing frame of large engine being 
completed, and the bearings for the dynamometer lined up with the en?
gine, the dynamometers were coupled up to the engine shaft this morn-
50
 The $50,000 allotted by the Board of Ordnance and Fortification had been spent. 
108 
ing preparatory to making a run on the engine. The engine was started 
up at 2 o'clock, started at the first turn after the current was thrown in, 
and a run of 10 or 12 minutes at a speed of from 900 to 950 rpm was 
made. The outer drums of the dynamometers still bind in their bear?
ings so that the spring balance readings are inaccurate, for the readings 
of the scale show the same pull of 50 lbs. at 500 rpm that they do at 950 
rpm, whereas the scale readings at 950 rpm should be nearly 4 times 
what they are at 500 since the pull goes up as to the square of the speed. 
Engine ran perfectly without a stop, all of the cylinders working in pro?
per order, though the run was stopped to repair the primary sparker, 
one of the brushes of which got out of line, and cut during the run. 
The primary sparker being repaired, Mr. Manly expects to make an?
other run on Monday. 
Mr. Manly was exceedingly well pleased with the results of the trial. 
16 January 1902?Wells diary 
First test today at 11:30 a.m.?450 rpm?pulled down 270 lbs. on scale. 
Too much water in dynamometer. Ran off some water in dynamometer 
and at 1:30 got a run of 500 rpm, scale reading 225 lbs. One of balance 
wheels being out of true, tests had to stop. [Horsepower developed, 25.] 
Mr. Manly then sets to work having balance wheel trued up. 
17 January 1902?Wells diary (in part) 
Engine taken apart, and pistons being lightened up to decrease vibra?
tion, and increase speed. Reinforcing specially built balance wheels, 
which had weakened from high speed. 
On taking engine apart, all working parts found to be in extraordi?
nary good condition, which ranks it far above the old Balzer engine. 
23-24 January 1902-Wells diary 
The new nuts for the spokes of the flywheels being finished, and the 
wheels reassembled, Mr. Manly has engine connected up to the dyna?
mometers for a trial in the testing frame. The engine starts up readily 
upon making a few turns to draw in the gas, and flywheels appear to be 
holding true. Engine had been developing about 25 hp at 600 rpm for 
about 10 minutes when there was a sudden jerk on the port dynamome?
ter, the scales recording a pull of about 350 lbs. and the engine drop?
ping down in speed but tending to turn at about 200 rpm, when Mr. 
Manly shuts off engine to ascertain what has happened. Upon investiga?
tion he finds that a piece of steel about 1/2 in. long by % in. diameter, 
which through the carelessness of the workmen had been left in the dy-
109 
namometer in reassembling it, had gotten wedged between the rotary 
and stationary plates of the dynamometer thus causing several of the 
sectors of one of the rotary plates to be twisted, bent and broken, thus 
wedging the dynamometer. 
The port dynamometer being repaired and reassembled, Mr. Manly 
makes another run on engine in testing frame. Engine starts up readily 
and has been running about 4 minutes when suddenly engine com?
mences to smash itself all to pieces on the inside, and Mr. Manly shuts 
it off immediately. Upon investigation it is found that three of the five 
crank pin brasses which fasten the piston rods to the crank have broken, 
allowing the crank to smash them into the sides of the cylinders, and 
upon first examination three of the cylinders appear almost irreparably 
damaged. Engine is immediately dismantled and upon closer investiga?
tion, it is found that cylinder No. 5 has been smashed by its own piston 
rod, and that of No. 4 being forced into the lower inch of length, strip?
ping and splitting the steel, and smashing the cast iron lining. Cylinder 
No. 4 has lower inch strip and liner bottom smashed to pieces. Cylinder 
No. 3 same as No. 4. Cylinder No. 1 lower inch strip in one piece, and 
liner has small piece broken, but will not need to be pieced. Cylinder 
No. 2 uninjured. 
25 January 1902?Manly to Langley both in Washington, D.C 
I have verbally reported to you the success of the new engine which 
has been developing 25 hp right along, and more than 30 hp at its best. 
I have run it as high as 950 rpm, but last night while running it at a 
rate of 675 rpm the wrist pin bearings which bind the wrist pins to the 
connecting rods apparently gave away, and four cylinders out of five 
were wrecked, though not beyond repair. 
Where the steel has been drawn out of shape I have got to draw it 
back into shape, and I will give you next week an approximate estimate 
of the time I think it will take to put the whole thing in order again. 
Following your instructions, I have ordered four more steel shells. 
These cost approximately $8.00 apiece, and with the special tools which 
we have for them, perhaps a couple of hundred dollars more apiece for 
fitting them up. 
The making of new brasses and a heavier set of wrist pins will make 
a greater weight. 
8 March 1902?Wells diary (entry by Manly) 
Mr. Manly makes first run on large engine in frame of Great Aero?
drome, this being the first time engine has been started up since the 
110 
smash up on January 27th. Engine started up on first few turns of start?
ing mechanism shaft, but bevel gear on starboard transmission shaft 
loosens up before engine gets fairly started and Mr. Manly immediately 
shuts off sparking current stopping engine. The bevel gears which are 
being used are the ones which were made originally for use with Balzer 
rotary cylinder engine which required that starboard and port gears 
should both be threaded left hand, while present engine requires that 
gears on starboard shafts should be right hand, and gears on port shaft 
be left hand. In order to save time and cost of making new gears for 
starboard shafts, which would also require that new shafts having right 
hand threads be made, Mr. Manly has put jamb nuts (right hand 
thread) on starboard shafts to keep gears on, but jamb nut on propeller 
shaft did not hold gear, apparently from nut not being jammed hard 
against gear. Nut will be jammed hard up against gear on Monday, 
and another run made, as it was six o'clock when the above accident 
stopped run. New type globular carbureter used in run. 
10 March 1902?Wells diary (entry by Manly) 
Bevel gear on starboard transmission shaft tightened up and nut 
jammed hard and sweated. Large tank carbureter connected to gas sup?
ply pipe.51 Mr. Manly starts up engine with starting mechanism. Before 
engine gets fairly started, the starboard flywheel goes to smash, eleven 
of the twenty-four wire spokes breaking off short at the hub. Mr. Manly 
immediately stops engine before flywheel does any further damage. 
Upon inspection it is found that the bevel gear on the starboard trans?
mission shaft has again loosened up, though the jamb nut has not 
moved. More seriously still the starting mechanism worm and worm 
wheel are found to be somewhat smashed up from outboard bearing of 
starting shaft having given way, allowing worm and worm wheel to get 
out of alignment. From same cause inboard thrust bearing of starting 
shaft has twisted and bent part of bedplate to which it is attached. Fly?
wheels will be strengthened by putting in larger spokes, and all other 
parts immediately repaired. Flywheels had evidentally been strained in 
the serious smash up of January 27th.52 
22 March 1902?Wells diary (entry by Manly) 
The starting mechanism and flywheels being repaired, and the large 
engine reassembled in the frame of the large aerodrome, the transmis?
sion and propeller shafts were coupled up and everything gotten in 
" T h i s appears to be the Balzer type of carbureter. 
62
 Actually 23-24 January (see page 109) . 
I l l 
readiness for a trial at 4:40 p.m. Mr. Manly starts up engine unassisted, 
the engine starting readily upon his giving a few turns of the starting 
shaft to draw in the gas. Starboard flywheel writhes and buckles and 
appears very dangerous as though it would certainly go to pieces at 
even a moderate speed, and Mr. Manly therefore shuts off engine im?
mediately before allowing it to speed up to examine flywheel. He finds 
one spoke very loose and another somewhat so, but decides to risk run, 
and immediately restarts engine. Starboard flywheel again writhes and 
twists, but seems to get no worse, at any rate, as engine is speeded up. 
However, before engine has speeded up to more than 200 rpm (a sound 
is heard) being as though the bevel gears are slipping, and it is found 
upon closer observation that the port propeller is apparently running 
only about one half as fast as the starboard one, which means that its 
gears are slipping. Mr. Manly immediately shuts down engine and 
finds that owing to workmen failing to put washer between port trans?
mission shaft and engine shaft all of the strain from the gears has come 
on port 3 pronged bearing, buckling it out and thus allowing gear on 
transmission shaft to spring out of mesh with gear on propellar shaft. 
Teeth on gears are slightly bent and 3 pronged bearing seriously bent. 
29 April 1902?Waste book entry by Langley 
April 29 of last year, Mr. Manly reckoned that his new engine to de?
velop 25 hp. would be done in June, that is June of 1901. The ten 
months have passed in incessant experiments and on the whole in im?
provements. A considerable part of this delay was represented by the 
failure of the contractors to deliver the steel shells and linear castings 
for the engine cylinders. These were received sometime in June, in?
stead of January as promised. Another delay arose from the difficulty in 
applying the water jackets; but by the first of January of this year, 1902, 
the engine was substantially complete as regards the conditions under 
which it was undertaken. A little later in January an accident occurred 
due to defective crank brasses which caused the engine under trial to 
seriously injure four of the five cylinders, thus delaying the work a 
month from this cause. 
The engine was first carried up and placed in the frame of the large 
aerodrome about February 15, 1902, and three trials have been made 
with it there, in each of which trials the transmission gears and bear?
ings of the frame proved insufficient, thereby preventing the engine get?
ting up to its full speed, and consequently not giving a full test as to 
the strength of the frame itself. 
There have been many improvements which have brought the engine 
112 
FIGURE 22.?Schematic drawing circa 1900 from Smithsonian Institution Archives illu?
strating master rod (top cylinder) with its bearing completely surrounding the 
crankshaft throw as designed by Manly, and Balzer-type of slipper bearings for the 
link rods (other cylinders) . (Smithsonian photo A52558.) 
above the 25 or 30 hp for which it was originally designed. Mr. Manly 
thinks the most important of these is a new crank bearing of his own 
invention which gives 4 times the former bearing surface on the crank?
shaft for each piston.53 At the same time the new radiating condensers 
have been built and attached to the aerodrome frame. Almost every 
63
 G. H. Corliss patented a master and link rod system in 1857 and built a stream 
pump utilizing this principle in 1875. Manly was forced to develop a similar system 
after greatly exceeding the horsepower for which the engine was designed. Balzer's 
slipper bearings (connecting rod to crankshaft) appear to have been satisfactory, 
however, up to 12 horsepower. 
113 
part of the guy wire system has been tested and strengthened. To di?
minish the shaking of the engine in the frame two flywheels have been 
applied, adding 20 pounds including the balance weights of 4 pounds. 
These have made the engine run, if not with ideal smoothness, yet so 
that the aerodrome with the engine at work can probably be mounted 
upon the [strengthened] uprights of the launching carriage with safety. 
There have also been built 2 special "water friction" dynamometers 
[Figures 23, 24] for making the all-important determinations of the 
actual power given off at the brake by the large engine and its results 
with these have been most satisfactory. 
The above refers to the machinists' work, but Reed and Darcy have 
been occupied, while at times assisting the machinists with small fit?
tings for the frame, in completing the front part of the wings according 
to the drawings given elsewhere in this book, and in similar things 
which it is not easy to briefly summarize. 
However, after this long delay, the finally greatly gratifying result is 
to be found in the following letter of Mr. Manly to me under date of 
April 28, 1902. 
"In the shop test at which you and Captain Lewis were present Satur?
day, one of the five cylinders of the large engine was not working pro?
perly. However, the other four ran the two dynamometers, each of 
Casing 
Water 
FIGURE 23.?Schematic drawing of hydraulic dynamometer by Harry T. Hart. 
(Smithsonian photo A4517-A.) 
114 
FIGURE 24.?Water absorption (hydraulic) dynamometer used for testing Balzer-
Manly engine. (Smithsonian photo A308.) 
115 
which has a lever arm of 13 inches, at a speed rising from 700 to over 
1,000 rpm near the end of the run, at which point the coupling connect?
ing the port dynamometer to the engine shaft was sheared off, the pull 
on each spring balance rising from 75 to over 100 pounds, the latter 
pull occurring just before and at the time when the coupling sheared 
off. The horsepower developed is calculated from the following for?
mula: 
HP equals 2Pi G X A X N/33,000, 
where G equals the total pull on the two dynamometers in lbs. 
A equals the length of the lever arm in feet 
N equals number of revolutions per minute. 
"In this test, where G equals 200 lbs.; A equals 13/12 ft.; and N 
equals 1,000 rpm we have from the formula, hp equals 41 plus. 
"While I am not willing at the present time to make a definite state?
ment as to the maximum power which the engine will develop, yet I 
consider it safe to now run the engine continuously (that is with safety 
as regards the engine itself) at a speed which renders 40 horsepower, 
though of course it is understood that I designed the engine with the 
view to having it furnish 25 horsepower, working under the conditions 
imposed by the aerodrome frame already constructed, and the system of 
gearing through which the large and low speed propellers are driven; 
and that the higher horsepowers of 40 or more are obtained at much 
higher speeds than I think would be possible to drive the propellers un?
less their size is somewhat reduced. It is also yet uncertain whether the 
frame of the aerodrome will be strong enough to hold the engine devel?
oping 25 horsepower, to say nothing of 40 horsepower, unless it is 
greatly strengthened; and in order to test this matter I placed the en?
gine in the frame during the first part of the month of February, hop?
ing to then make the test on this point; but in three successive tests 
the transmission gears and bearings proved insufficiently strong to stand 
the strain long enough for the engine to even reach full speed, so that 
I had to abandon these tests of the engine in the frame until I could 
complete the new and stronger transmission gears and bearings, which 
I am now doing, and which I expect to have complete within the next 
ten days. 
"The actual weight of the engine, including all parts necessary to its 
operation, is 130 pounds, the engine not requiring any flywheels, so far 
as its mere running is concerned. However, in order to properly balance 
the moving parts, to reduce as far as possible the vibration, I have 
found it necessary to add two very specially constructed flywheels, in-
116 
eluding the balance weights, weighing approximately ten pounds each.54 
Though it is impossible to say definitely what will be the minimum 
amount of water required for properly cooling the engine when it is 
working in the frame and actually propelling the aerodrome through 
the air, yet from a careful perusal of similar engines on high speed au?
tomobiles, I have inferred that 25 pounds of water, rapidly circulated 
through the water jackets and the radiating condensers, will properly 
cool the engine in flight. This amount of water will, I think, keep the 
water jackets at an average temperature of about 95 degrees Centigrade, 
which I consider the best and most advantageous working temperature. 
With the engine working in the shop, and with no provision for cool?
ing the water, but merely pumping it from a tank through the water 
jackets and back into the tank, 25 lbs. would not remain below the tem?
perature of 95 degrees Centigrade more than for 3 or 4 minutes; but 
since the aerodrome should certainly be launched within 3 minutes 
after starting up the engine, I have no great fear of any serious trouble 
from the overheating of the engine cylinders. 
"The flying weight of the engine, including all accessories, I think 
will come very close to 200 pounds, of which 130 pounds is for the ac?
tual engine itself, 20 pounds for the two flywheels, 25 pounds for the 
cooling water, 17 pounds for the condenser, 1 pound for the pump, 3 
pounds for the sparking coil, 9 pounds for the sparking dynamo or bat?
tery, besides a few minor water connections, electrical wires, etc." 55 
17 June 1902?Manly to Langley both in Washington, D.C. (in part) 
The new five cylinder engine was completed during the first week of 
January, 1902, and since that time numerous tests of it have been made, 
using the water controlled dynamometers which were especially in?
vented and constructed for it.56 The objects of these tests have been, 
(a) to determine the brake horsepower developed when the engine is 
working at its best and also when under conditions such as may possibly 
occur while the engine is driving the aerodrome through the air, when 
the carbureter may not give exactly the correct mixture of gases, the 
time of the electric spark may not be quite correctly adjusted, or one or 
more cylinders may not be quite correctly adjusted, or one or more cyl?
inders may not furnish power, due to various causes, (b) To improve 
M
 Had the engine been left as a rotary, there would have been no vibration 
problems so that the 20 pound weight of the flywheels could have been eliminated. 
55
 Had the engine been left as a rotary, perhaps with finned cylinders, 43 "cooling" 
pounds would have been saved with a slight decrease in horsepower due to the 
windage of the rotating cylinders. 
86
 Water absorption dynamometers were used as early as 1865. 
117 
382-902 O 71 
FIGURE 25.?Balzer-type carbureter. Now on exhibit at the Smithsonian Institution. 
(Smithsonian photo A18081.) 
the carbureter [Figure 25] which has been especially invented and con?
structed for the engine, and to render it as nearly absolutely reliable as 
possible under varying conditions of temperature and wind velocity.57 
(c) To reduce to a minimum the vibration due to unbalanced recipro?
cating parts and to reverse torque, by adjustments of the balance 
weights and by the reduction of the inertia of the moving parts.58 
The general results of these tests were, (a) that at 950 rpm and with 
all accessories of the engine working properly, the dynamometers re?
corded a pull of 265 pounds on a 13 inch lever, which is equivalent to 
51 brake horsepower, that at 875 rpm the engine gave 45 bhp, that at 
800 rpm the engine gave 40 hp, and that at 750 rpm and with one cylin?
der not working, the engine gave 28 bhp. (b) The vibration has been 
reduced to a point where it appears reasonable to expect that it will not 
cause any serious strains in the frame of the aerodrome, or any great 
inconvenience to the aeronaut. I hope to be able to still further reduce 
57
 This was similar to the original Balzer carbureter, but enlarged to accommodate 
the enlarged cylinders of the "new" engine. 
68
 Had the engine been left as a rotary, these problems would not have occurred. 
118 
the vibration as soon as the engine is working the frame, where I can 
study more minutely the effects of different changes I propose making, 
(c) The carbureter has been steadily improved in its reliability and I 
expect to have it thoroughly satisfactory very soon after I get the engine 
working in the frame, where I can utilize the currents of air from the 
large propellers to study the effects of wind on it. 
The engine proper complete weighs 125 pounds, or a little less than 
214 pounds per horsepower, if we take as a basis the power developed 
under perfect working conditions, which is the custom of all builders of 
engines for such purposes. Including cooling water, pump, condenser, 
sparking coil, batteries, carbureter, tanks and all such accessories neces?
sary to the proper working of the engine, it weighs just 200 pounds, or 
slightly less than 4 pounds per brake horsepower for its "flying weight." 
A new type of crank bearing, to enable the five piston rods to work 
en a single crank and at the same time to give each one its full crank 
pin bearing, has been invented and constructed, and has been used in 
all of the tests since March, and has proved to be absolutely perfect, 
solving completely the very difficult problem of proper lubrication, 
which had given me the greatest concern since the beginning of the 
construction of the engine. 
3 July 1902?Manly in Washington, D.C, to Langley in Europe 
(in part) 
I now have the large engine working in the aerodrome frame and de?
livering the power of [to] the propellers through the newly designed 
and constructed transmission shafts, gears, etc., and everything so far has 
worked very well. The vibration of the engine is very small indeed con?
sidering the power developed but it is not so small as I wish it to be, 
and I am now just starting experiments running the engine in the 
frame, as a result of which I hope to be able to reduce the vibration 
still further. 
18 July 1902?Manly in Washington, D.C, to Langley in Europe 
(in part) 
A few minutes after writing to you on July third, I started up the 
large engine in the frame to begin the measurements of the actual thrust 
or "lift." 59 The engine had been working about three minutes at 550 
revolutions and driving the 21/2 meter unit pitch propellers and devel?
oping a thrust of 280 pounds, when I noticed that the top cylinder was 
68
 This was accomplished by securing the frame to a carriage mounted on a track. 
The thrust developed by the propellers was measured by a spring scale. 
119 
getting almost red hot. I immediately shut down the engine and found 
that the cooling water supply for the top cylinder had, in some unex?
plained way, gotten choked off, and upon removing the top cylinder, 
found that the excessive heat had caused some of the brazed joints to 
come loose, which necessitated the removal of the jacket on the top cyl?
inder in order to repair the damage. The extra cylinders not being yet 
complete, there have, of course, been no further tests on the engine 
working in the frame since that time; but I am now completing the re?
pairs on the top cylinder and expect to have the engine working again 
in the frame and on the launching car during the early part of next 
week. 
/ August 1902-Manly in Washington, D.C, to Langley in Europe 
(in part) 
Since my letter of July 18th, I have completed the repairs to the top 
cylinder which was injured in the previous run, and have also com?
pleted one of the extra cylinders and have had the engine again work?
ing in the frame on the launching car. I regret to say, however, that on 
Monday, July 28th, while the engine was running in the frame, the 
port propeller suddenly twisted off at the hub but fortunately the bro?
ken part flew in the direction of the floor and did not injure the frame. 
The large bevel gear on the port propeller shaft had four teeth broken 
out of it and, of course, requiring a new gear. The repairs, however, are 
now about completed and I expect to make another run tomorrow. 
15 August 1902?Manly in Washington, D.C, to Langley in Europe 
(in part) 
I am pleased to be able to say that after considerable delays, caused 
by first one part and then another of the frame breaking, I now have 
the engine working regularly in the aerodrome frame and have been 
letting it run up as high as thirty-five brake horsepower. Quite a bit of 
the delay has been due to the propellers breaking under the strain of 
the work, but I am now building some new and stronger ones, all of the 
ones on hand having gone to pieces. All of the work is progressing in a 
satisfactory manner, except for continual set-backs due to various causes 
to which the work, as ever, has been particularly subject. 
18 August 1902?Langley in Germany to Manly in Washington, D.C 
I have I think, answered your previous letter of July 18, and have 
now to acknowledge yours of August 1st. 
The injury to the propeller and bevel gear is only in the normal 
120 
course of accidents. Perhaps we ought to be glad rather than sorry that 
they have happened in the shop instead of a thousand feet above itl But 
as the time for flight draws very near I confess my anxieties, for the in?
calculable play of what is all but chance, increase. I admit that I feel 
almost a shrinking from the time of trial which I suppose is now so 
near. 
29 August 1902?Manly in Washington, D.C, to Langley in Europe 
(in part) 
I have to acknowledge with thanks your very kind letter of August 
18th from Karlsbad, where I am pleased to note that you then were, 
and the visit to which I trust has been of much pleasure and benefit to 
you. 
Since my letter of August 15th I have been making a series of experi?
ments with the engine working in the frame under artificially produced 
air drafts acting on the carbureter, to imitate as far as possible the ac?
tual conditions under which the carbureter will work when the aero?
drome is in flight, and to determine beforehand, as far as possible, the 
changes in adjustment that the carbureter will require in the few sec?
onds of greatly changed conditions when the aerodrome starts from a 
position of rest and is rapidly accelerated in its travel to the end of the 
track where it becomes free in the air. This question of the change of 
conditions seriously affecting the carbureter, and consequently the 
working of the engine, is the cause of more anxiety to me than any?
thing else which I anticipate may happen to cause a failure at the first 
launching of the machine, and I shall not feel that we are sufficiently 
prepared for the first trial until I can obtain more information, than 
I have yet been able to do, with the machine working under condi?
tions artificially produced and as nearly similar as possible to those to 
be actually met. 
9 September 1902?Langley in London to Manly in Washington, D.C. 
I have your letter of the 29th and am not surprised that my pessimis?
tic forecast as to the time has been partly justified. I think you are very 
prudent to imitate the actual conditions under which the carbureter 
will work when the aerodrome is in flight, in its first few critical sec?
onds. 
I have changed my steamer and do not expect to sail now until the 
25th hoping to reach Boston on October 3rd. With goodwill and sympa?
thy in your disappointments. 
121 
17 September 1902?Manly in Washington, D.C, to Langley in Boston 
(in part) 
The continual breakage of the propellers, which was totally unex?
pected, as I had thought for a year or more that the propellers we had 
on hand would be amply strong for the work expected of them, has al?
ready delayed the work at least four or six weeks and has completely 
upset all of my calculations as to when I would be ready to start the 
houseboat with everything on board down the River, and until I over?
come this trouble with the propellers, I can give no idea of when the 
aerodrome will be ready for trial. However, I am getting all of the 
other work in shape as rapidly as possible with the expectation of start?
ing down the River at the earliest possible time, so that I trust you will 
not worry regarding the delays which are now being experienced. 
26 September 1902?Manly in Washington, D.C, to Langley in Boston 
(in part) 
Since my letter of September 17th I have been continuing the tests 
with the engine working in the frame and on September 19th met with 
another serious breakdown. This time the propeller shafts which had 
been in use for sometime and which had withstood all the usual strains 
which had heretofore broken the propellers, twisted and buckled under 
the strain of driving the propellers, the buckling and twisting being so 
serious as to require the construction of new shafts. However, I have 
gotten the new shafts complete and am just now putting them in the 
frame and expect to have everything in working order again tomorrow. 
10 November 1902?Langley in Washington, D.C, to Captain I. N. 
Lewis, Fort Casey, Washington (in part) 
I tell you privately that the engine for which we owe so much to Mr. 
Manly is finally showing itself perhaps the best anywhere at present, for 
he reports it running at forty horsepower, while weighing, with cooling 
water and every accessory, about two hundred pounds, though part even 
of this weight is due to flywheels and weights (on the spokes of the fly?
wheels) required by the light frame. Working on the bench, including 
cooling water, its weight is less. 
Everything is ready, and were there still time this season, a flight 
would be made, but I do not expect one until after the ice has gone; 
then I, who has never known any great initiatory trial without some 
mischance, look for what I call our "first smash." When every human 
care has been taken, there remains the element of the unknown. There 
may well be something that forethought has not provided for, and I ex-
122 
pect it and fear it, but excepting for the fact that a human life is now 
in question, I could make it without fear at all. 
4 January 1903?Langley memorandum 
Mr. Manly says in substance? 
"Since December I have been prepared to make a flight. The whole 
machine including the sustaining surfaces, and seat, and the whole of 
the houseboat and apparatus for launching, is ready to the last degree, 
except those things which are necessarily left to the day or two proceed?
ing the actual trial. In particular, the engine is actually delivering 
(after the deductions from the use of the bevel gears) 45 brake hp at 
the propellers. This, however, still demands an incessant personal atten?
tion, though not so imperatively as formerly, since it may run fifteen 
minutes without attention, but may also run less, or it may stop alto?
gether. Each month the thing grows more under control, but I can 
never expect to be free from anxiety as to what will happen in the first 
few seconds of the launch. That over, and the machine once in the air, 
if the engine works satisfactorily at the end of the first ten seconds, I 
have no fear of its not continuing. 
"I have improved the carbureter and other points until I have had it 
running without any personal interference for fifteen or twenty min?
utes, developing the same amount. The whole question, however, (now 
that the other things have been made so nearly right) is that of the sup?
ply of gas from the carbureter. There is no certainty that it will work 
well or ill, or work at all without my personal attention. To put it in 
such a condition that it will work under any conditions or with an?
other man, requires still an indefinite time. I will not guarantee that 
three months will do this. 
"It is in this work that the large staff of men is still employed, and in 
the building of the three extra cylinders which you have wished to 
have; so that with the three on hand belonging to the Smithsonian In?
stitution, there may be at any time more cylinders than enough to re?
construct the present engine." 
23 March 1903?Manly to Langley both in Washington, D.C. 
I have your letter of this date. Your understanding as to the condi?
tion of the work is correct. 
I add that I have repeatedly had the engine running in its actual po?
sition on the frame driving the 21^ meter propellers, with a power of 
over 45 brake horse, with entire smoothness,?the engine running at 745 
123 
FIGURE 26.?Manly (in aviator's car) and Reed (below with straw hat) making 
adjustments to partially assembled aerodrome frame in place on its catapult during 
the latter part of September 1903. (Smithsonian photo A18782.) 
revolutions per minute, and the two propellers at 575, developing 
jointly a thrust of over 300 lbs. 
Every part of the aerodrome and guys has been minutely tested. The 
carbureter works so that I am not apprehensive of any failure of the 
124 
FIGURE 27.?Manly and Langley during the latter part of September 1903 with 
aerodrome on its catapult in the background. (Smithsonian photo A18824.) 
first rush, and I am prepared to risk myself with it in actual flight, 
as soon as the final adjustments, balancing, etc., are made. 
I may add that the engine proper, including all necessary working 
parts, and comprising everything that is intrinsically a part of it, 
weighs 120 lbs., and develops on test 52 brake horsepower, or at the rate 
of 1.05 kilograms per brake horsepower. 
125 
FIGURE 28.?Langley aerodrome poised on its catapult-houseboat during the latter 
part of September 1903. (Smithsonian photo A18840.) 
On 7 October and 8 December 1903 two unsuccessful attempts were 
made to launch the aerodrome. In each case the airframe suffered exten?
sive damage from the moment of launching, however, the engine 
worked perfectly, and was recovered from the bottom of the Potomac 
River after each trial in undamaged condition. Its future was doomed, 
however, because of the aerodrome's failures. 
The engine was separated from the airframe in order to prepare it 
for the St. Louis Exposition contest and has, subsequently, maintained 
its own identity as the crowning achievement of the entire aerodromic 
program. It is exhibited separately at the Smithsonian Institution; re?
cently a dummy reproduction of it has been installed in the aerodrome. 
23 May 1904?Manly to Langley both in Washington, D.C. 
Referring to our conversation in the early part of April when I men?
tioned the subject of the entrance of the large engine in the competi?
tion for the prize for light weight motors at the St. Louis Exposition, I 
now beg to again bring the matter to your attention. 
126 
SAMUEL PIERPONT LANGLEY 
19 03 
FIGURE 29.?Three-view drawing of Langley aerodrome in its 1903 configuration. 
(Smithsonian photo A38167.) 
The prize is provided for under Section II (Motors for Airships or 
Dirigible Balloons) of the rules governing the secondary contests, 
which is as follows: 
"A first prize of Twenty-five Hundred Dollars ($2,500.00) and a sec?
ond prize of One Thousand Dollars ($1,000.00) are offered for the air?
ship motors other than the exact machine winning the grand prize, hav?
ing the least weight and greatest efficiency in proportion to their power." 
"The first test will cover one hour's run to determine power, and the 
second test a continuous run of ten hours for ascertaining the reliabil?
ity and durability of the apparatus." 
As the motor winning this prize will no doubt be considered the 
lightest per horsepower in the world, and as I think it very certain that 
no one else has one so light as this one which I have invented and 
127 
FIGURE 30.?Glenn H. Curtiss in aviator's car of modified aerodrome during May 
1914. Note automobile-type radiator and carbureter. Note the addition of floats 
and the modification of the propellers toward the Wright Brothers-type. (Smithsonian 
photo A52394.) 
built, I should regret it very much if an inferior construction were per?
mitted to receive the credit which seems to belong here. 
I have estimated that the expense of making the tests at St. Louis (in?
cluding transportation and subsistence for myself and a machinist and 
the wages of a machinist) will be something like five hundred dollars. 
This I am prepared to bear personally if the permission is granted me 
to enter the engine in the contest. 
It appears to me that the interest of the aerodromic work and of the 
Institution itself would be furthered by an exhibition of what has been 
accomplished and I therefore beg to ask your permission to enter the 
engine in the competition. 
The idea of entering the engine in these contests had not occurred to 
me until suggested and urged by several men whose opinions in such 
matters are of importance.60 
00
 Permission was granted and money was allotted to exhibit the engine and enter 
it in the contest; however, the following telegram was received from the Exposition, 
"On account of lack of competition engine tests abandoned." 
128 
As a result of an agreement between Secretary Walcott of the Smith?
sonian Institution and Glenn H. Curtiss, the last attempts to power the 
Aerodrome model A with its original engine were made in April 1914. 
The machine was shipped to Curtiss at Hammondsport, N.Y. in 
April. Dr. Zahm, the Recorder of the Langley Aerodynamical Labora?
tory and expert witness for Curtiss in the patent litigation [with the 
Wright Brothers], was at Hammondsport as official representative of 
the Smithsonian Institution during the time the machine was being re?
constructed and tested. In the reconstruction the machine was changed 
from what it was in 1903 in a number of particulars as given in Dr. 
Wright's list of differences which appears later in this paper. On the 
28th of May and the 2d of June, 1914, attempts to fly were made. After 
acquiring speed by running on hydroplane floats on the surface of Lake 
Keuka the machine lifted into the air several different times. The 
longest time off the water with the Langley motor was approximately 
five seconds. Dr. Zahm stated that "it was apparent that owing to the 
great weight which had been given to the structure by adding the floats 
it was necessary to increase the propeller thrust." So no further attempts 
were made to fly with the Langley 52 HP engine.61 
Stage four marked the engine's highest performance peak and assured 
it an undisputed title of the most advanced and most powerful airplane 
engine in the world at the turn of the century. 
61C. G. ABBOT, "The 1914 Tests of the Langley 'Aerodrome' " Smithsonian 
Miscellaneous Collections (Washington: Smithsonian Institution) , vol. 103, no. 8, 
pp. 1-2. 
129 
Chapter 7 
Evaluation of the Balzer-Manly Aero Engine 
/
n addition to the Balzer-Manly aero engine, there are two other full 
size gasoline engines on display in the National Air and Space 
Museum which first powered aircraft in 1903. A comparison of these 
engines reveals the state of the art at the turn of the century, and the 
preeminence of the Balzer-Manly engine. 
The Wright Brothers Engine of 1903 62 
The heaviest of these engines for its horsepower (approximately 16 
lbs for each hp) was the one Orville and Wilbur Wright designed 
themselves and built with the help of their machinist, Charles E. Tay?
lor in the remarkably short time of three months. 
They began to build it in December 1902, and the first tests were run 
on February 12, 1903. On the 13th dripping gasoline caused the bear?
ings to freeze, and this broke the engine body and frame. It was neces?
sary to order a new aluminum casting which was received on April 20, 
1903. The rebuilt motor was shop tested in May. In a description of the 
motor by Wilbur Wright dated February 28, 1903, he had this to say: 
We recently built a four-cylinder gasoline engine with 4" piston and 4" stroke, 
to see how powerful it would be, and what it would weigh. At 670 revolutions per 
min. it developed 8i/? horsepower, brake test. By speeding it up to 1,000 rev. we 
will easily get 11 horsepower and possibly a little more at still higher speed, though 
the increase is not in exact proportion to the increase in number of revolutions. 
The weight including the 30-pound flywheel is 140 lbs. 
"
2
 ROBERT B. MEYER, JR., "Three Famous Early Aero Engines" Annual Report of 
the Board of Regents of the Smithsonian Institution, 1961, (Washington: Smith?
sonian Institution) pp. 357-371. 
130 
A description of the rebuilt motor by Orville Wright dated 28 June, 
1903, follows: "Since putting in heavier springs to actuate the valves on 
our engine we have increased its power to nearly 16 horsepower, and at 
the same time reduced the amount of gasoline consumed per hour to 
about one half of what it was before." 
By November 5, 1903, the engine had been tested in the Wrights' first 
powered airplane, the "Kitty Hawk Flyer." Considerable trouble was 
experienced with the propeller shafts. Finally, new ones had to be 
made, and so the engine did not become successfully airborne until 
December 17, 1903. 
A detailed description of the motor follows. It consists of quotations 
from The Papers of Wilbur and Orville Wright, edited by Marvin W. 
McFarland. 
This historic motor is described by Orville Wright in an undated typewritten 
memorandum among the Wright papers in the Library of Congress: The motor used 
in the first flights at Kitty Hawk, N. C, on December 17, 1903, had (four) horizonal 
cylinders of 4-inch bore and 4-inch stroke. The ignition was by low-tension magneto 
with make-and-break spark. The boxes inclosing the intake and exhaust valves had 
neither water jackets nor radiating fins, so that after a few minutes' run the valves 
and valve boxes became red hot. There was no float-feed carbureter. The gasoline was 
fed to the motor by gravity in a constant stream and was vaporized by running over 
a large heated surface of the water jacket of the cylinders. Due to the preheating of 
the air by the water jacket and the red-hot valves and boxes, the air greatly expand?
ed before entering the cylinders. As a result, in a few minutes' time, the power 
dropped to less than 75 percent of what it was on cranking the motor. 
The crankcase and water jacket were cast in a single block of aluminum alloy. 
The crankshaft was made from a block of machine steel l5/s inches thick and had 
five babbitted main bearings. A 15-inch, 26-pound flywheel was attached to the rear 
end of the shaft. A chain drive on the front end drove the camshaft, which operated 
the breaker arms and exhaust valves. A boxwood idler, l i^ inches in diameter, 
without flanges, created tension on the chain. 
The valve heads were made of cast iron. The stems were of steel. The intake 
valves operated automatically. Neither the cylinders nor the pistons were ground. 
The connecting rods were seamless steel tubes screwed into brass big ends. 
The motor was started with the aid of a dry-battery coil box. After starting, 
ignition was provided by a low-tension magneto, friction-driven by the flywheel. 
This magneto?permanent horseshoe magnets with exciting coils?weighed 18 
pounds. Insulated ignition electrodes in the cylinder heads were connected by a 
strap of copper. The speed of the motor was regulated on the ground by retarding 
the spark. A small lever on the leg of the motor controlled the timing of the 
spark by altering the position of the camshaft. There was no way to regulate the 
speed of the motor in flight. 
Lubrication was supplied to the cylinders by a small oil pump driven by a worm 
gear on the camshaft. No pump was used in the cooling system. The vertical sheet-
131 
steel radiator was attached to the central forward upright. Gas feed was controlled 
by a metering valve, not adjustable during flight. A shutoff valve, made from an ord?
inary gaslight pet cock, was placed conveniently near the operator. The fuel tank had 
a capacity of 0.4 gallon. The fuel line was copper. 
The weight of the 1903 engine is given as 161 pounds dry in Orville 
Wright's letter to Charles L. Lawrance, November 15, 1928, or 179 
pounds with magneto. Complete with magneto, radiator, tank, water, 
fuel, tubing, and accessories, the powerplant weighed a little over 200 
pounds. 
Additional information about this engine was furnished by Charles 
E. Taylor in an article that appeared in the May 1928 issue of the jour?
nal Slipstream.63 A partial quotation follows: 
Orv and Will then asked me to help them build the motor for their 
first power-driven machine. They had a little workshop where they built 
and repaired bicycles at 1927 West Third Street. As I recall we first hit 
upon the idea of an air-cooled motor but we decided after some figur?
ing that it would weigh more per horsepower than a water-cooled type 
so we settled upon the latter. I do not know but that if we could have 
secured the light alloys available today we would have gone ahead with 
the air-cooled job. 
The first thing we did as an experiment was to construct a sort of 
skeleton model in order that we might watch the functioning of the 
various vital parts before venturing with anything more substantial. 
Orv and Will were pretty thorough that way?they wouldn't take any?
thing for granted but worked everything out to a practical solution 
without too much haste. I think that had a lot to do with their later 
success. 
When we had the skeleton motor set up we hooked it to our shop 
power, smeared the cylinders with a paint brush dipped in oil and 
watched the various parts in action. It looked good so we went ahead 
immediately with the construction of a four cylinder engine. I cut the 
crankshaft from a solid block of steel weighing over a hundred pounds. 
When finished it weighed about 19 pounds. We didn't have spark plugs 
but used the old "make and break" system of ignition. The gas was led 
in and made to spread over the chamber above the heated water jackets 
and this immediately vaporized it. Of course, we had real gasoline in 
that day?fully 76 proof and you could count on it going into action at 
the least excuse. 
The cylinders of that first motor were made of gray iron as were the 
63
 Fred Marshall, "Building the Original Wright Motor," Slipstream (May 1928). 
132 
pistons. As I recall those cylinders were from 1/$ inch to 3/16 inch in 
thickness. So far as I know that was the first four cylinder engine ever 
built. The automobile manufacturers were out of the picture then and 
the Oldsmobile firm was the only one I was familiar with at that time. 
We tried to get a motor built there but they couldn't make one near 
the low weight we wanted. The old one-lunger auto engines of that day 
really weighed more than our entire flying machine with the first motor 
installed. 
When the engine was ready for block test we rigged up a connection 
with natural gas, put on a resistance fan and made several block runs in 
this manner. Later we used gasoline fuel and found the motor would 
run satisfactorily. That first motor developed around 18 h.p. and 
weighed around 190 pounds. We were all highly pleased at being able 
to hold down the weight to this figure but a short time afterward we 
built another motor that produced around 45 h.p. and which weighed 
about the same as the first one. 
When we installed the first motor in the original machine it lay on 
its side to right of the pilot and in such a position that the pilot's 
weight partially offset that of the motor. The radiator was made from 
speaking tubes flattened to reduce the capacity. 
Yes, I must admit there wasn't much to that first motor?no car?
bureter, no spark plugs, not much of anything but cylinders, pistons 
and connecting rods, but it worked. 
SPECIFICATIONS 
Cylinders 
Cooling 
Carburetion 
Ignition 
Horsepower 
Bore and stroke 
Displacement 
Dimensions 
Weight 
Weight/h.p. ratio 
Country of manufacture 
? 4 horizontal in-line 
? Water 
? Surface type?no float 
? Low-tension magneto with make-and-
break spark 
? 12.05 at 1,090 r.p.m. 
? 4 x 4 in. 
? 201.1 cu. in. 
? 13% in. high x 23%2 in. wide x 3 0 % 
in. long 
? Slightly over 200 pounds including cool?
ing water. 
? Approximately 16.6 lb. per h.p. 
? U.S.A. 
133 
382-902 O - 71 - 10 
On 7 June 1903 Wilbur Wright wrote to George A. Spratt:Gi 
"About Christmastime we began the construction of the motor, which 
is of four cylinders, four-inch bore and four-inch stroke. We had esti?
mated that we would require a little over eight horsepower to carry 
our weight of 625 lbs. of machine and man. At this weight we would 
be limited to two hundred lbs. for our motor. Our motor on completion 
turned out to be a very pleasant surprise. Instead of eight horsepower, 
for which we hoped but hardly expected, it has given us 13 [non-
continuous] horsepower on the brake, with a [dry] weight of only 150 
lbs. in the motor." 
Although the 1903 Wright brothers' motor was heavier for the horse?
power it delivered than those of Santos Dumont or Professor Langley 
(respectively two and four times as heavy), it nevertheless fulfilled its 
function. On April 12, 1911, Orville Wright wrote: "We look upon reli?
ability in running as of much more importance than lightness of 
weight in aeroplane motors. We attempt to design our flyers of such ef?
ficiency that extremely light motors are not needed." 
Since the Wright brothers did not have the wealth of Santos Dumont 
or the Government grant of Langley, it was necessary for them to build 
their own engines [Figures 31-33]. It therefore had to be of practical 
and simple design. A logical procedure was to adapt the automobile en?
gine to the requirements of the airplane, which is what they did. 
The next heaviest of these engines for its horsepower (approximately 
(8 lbs for each hp) was the French designed and built Clement motor 
(made by Adolphe Clement, who later founded the famous Clement-
Bayard firm). It powered the Brazilian Santos Dumont's airship No. 9 
during the summer of 1903. To quote from his book, My Air-ships: 65 
I determined to build a small airship runabout for my pleasure and 
convenience only. . . . So I built my number 9, the smallest of possible 
dirigibles, yet very practical indeed. As originally constructed, its bal?
loon capacity was but 7,770 cubic feet, permitting me to take up less 
than 66 pounds of ballast; and thus I navigated it for weeks, without 
inconvenience. Even when I enlarged its balloon to 9,218 cubic feet, the 
balloon of my number 6, in which I won the Deutsch Prize, would have 
made almost three of it, while that of my Omnibus is fully eight times 
its size. As I have already stated, its 3 horsepower Clement motor 
84
 MEYER, op. cit., p. 367. See also MARVIN W. MCFARLAND, Editor, The Papers 
of Wilbur and Orville Wright (New York: McGraw-Hill Book Company, Inc., 1953) , 
vol. 1, p. 313. 
65
 A. SANTOS-DUMONT, My Air-Ships (New York: The Century Co., 1904), p. 313. 
134 
FIGURE 31.?Wright Brothers engine. Left front view showing automatic intake 
valves, rocker-arm actuated exhaust valves, fuel induction system, timing chain, and 
spark advance lever. (Smithsonian photo A41898-A.) 
weighs but 261/?> pounds. With such a motor one cannot expect great 
speed; nevertheless, this handy little runabout takes me over the Bois 
[Paris] at between 12 and 15 miles per hour, and this notwithstanding 
its egg-shaped form, which would seemingly be little calculated for cut?
ting the air. 
Further information is given in "The New Santos-Dumont Airships," by 
the Paris correspondent of the Scientific American, 11 July 1903:66 
The new Clement gasoline motor used on the number 9 has proved 
especially satisfactory. The little motor with its cylinders joined in the 
form of a V to a round aluminum crank box seems like a toy and 
weighs but 26y2 pounds, although it will develop 3 horsepower. The 
weight per horsepower (8.8 pounds), the smallest that has yet been 
reached, is the result of long experience in racing cars, where weight 
must be cut down to a minimum. Current for the spark is supplied by a 
battery and induction coil of the motor-bicycle pattern. The motor is 
connected through a light friction clutch to the long shaft which passes 
back to the propeller. A bicycle wheel with a heavy rim [without tire] 
66
 Volume 89, no. 2, p. 25. 
135 
FIGURE 32.?Wright Brothers engine. Underside view showing flywheel, oil pump, 
exhaust valve camshaft, rocker arms, and valve springs, and ignition system cam?
shaft. (Smithsonian photo A41898-C.) 
forms the flywheel and lies next to the motor. . . . An air-bag of 60 
cubic yards lies along the inside of the ballon at the bottom, forming a 
pocket which can be filled out with air by a fan [blower] mounted on 
the motor shaft. The balloon is [therefore] always kept in shape as the 
gas escapes. 
Cylinders 
Cooling 
Carburetion 
Ignition 
Horsepower 
Bore and stroke 
Displacement 
SPECIFICATIONS 67 
? 2 arranged in the form of a V. 
? Air. 
? Automobile-type carbureter 
? Battery, induction coil, spark plug (high-
tension) 
? 3 
? 214 x 23/4 in. 
? 21.8 cu. in. 
67
 MEYER, op. cit., pp. 358-359. 
136 
FIGURE 33.?Wright Brothers engine. Right rear view as mounted in the airplane, 
showing the flywheel, magneto, propeller drive chains, automatic intake valve 
springs, and open-ended can surface-type carbureter. (Smithsonian photo A38388.) 
Dimensions ? 17 in. high x 9i/2 in. wide x 9 in. long 
Weight - 26i/2 lb. 
Weight/hp ratio ? 8.8 lb. per hp. 
Country of manufacture ? France. 
The Clement engine had two tasks to perform: the propulsion of a 
lighter-than-air craft, and the operation of a blower (fan) to aid in 
maintaining the rigidity and therefore the structural integrity of the 
dirigible's envelope (balloon). 
As Santos Dumont stated above, this motor would propel his diminu?
tive airship up to 15 mph. Forcing it much beyond this speed would 
not have been practical because of the envelope's great resistance to the 
passage of the air. If a considerably more powerful engine had been in?
stalled, it would have weighed so much that little or no ballast could 
have been carried. This would have prevented safe aerial navigation. 
The blower, as mentioned above, merely forced air under low pres?
sure into a flexible compartment on the underside of the gas bag. This 
compensated for any reduction in stiffness of the airship's envelope due 
to a loss of lifting gas caused by leakage or purposeful releasing of the 
137 
FIGURE 34.?Clement engine. Rear view showing cylinders, valve mechanisms, fly?
wheel, clutch, and blower. Now on exhibit at the Smithsonian Institution. (Smith?
sonian photo A46816-B.) 
138 
FIGURE 35.?Clement engine. Left side showing the left cylinder and its valve 
mechanism, spark-timing system, flywheel, clutch, and blower. Now on exhibit at 
the Smithsonian Institution. (Smithsonian photo A46816-A.) 
139 
FIGURE 36.?Clement engine. Right side showing the right cylinder and its valve 
mechanism, spark-timing system, carbureter, clutch, and flywheel. Now on exhibit, 
at the Smithsonian Institution. (Smithsonian photo A46816.) 
140 
gas. Probably only a fraction of one horsepower was needed for this 
purpose. 
This particular engine [Figures 34-36] was apparently designed for 
the Clement Autocyclette motorcycle which was sold in 1903. However, 
its light weight and reasonably good weight/power ratio made it an 
ideal engine for the diminutive airship. 
The Balzer-Manly Engine of 1903 
The lightest of these engines for its horsepower (approximately 4 lbs 
per hp) was the engine which is the subject of this book. Manly de?
scribes it in the following excerpts from, "The Langley Memoir on Me?
chanical Flight" 68 now out of print and largely unavailable. 
The main requirement in an engine for an aerodrome?aside from re?
liability and smoothness of operation, which are necessary in an engine 
for any kind of locomotion?is that it shall develop the greatest amount 
of power for the least weight. It is, therefore, desirable to reduce the 
weight and number of parts of the engine to the very minimum, so far 
as this can be done without sacrificing reliability and smoothness of 
running. Furthermore, since the strongest metal for its weight is steel, 
and since the greatest strength of steel is utilized when the stress acting 
on it is one of tension, it is advisable to design the engine so that parts 
which sustain the greatest strains shall be of steel and, as far as possible, 
meet with strains which are purely tensional ones. 
In designing the new engine for the large aerodrome it was, there?
fore, planned to make it entirely of steel, as far as this was possible. The 
only parts which were not of steel were the bronze bushings for the 
bearings, the cast-iron pistons, and cast-iron liners of the cylinders. Pre?
vious experience had shown that, while it is possible to use a cast-iron 
piston in a steel cylinder or even a steel piston in a steel cylinder, pro?
vided the lubrication be kept exactly adjusted, yet the proper lubrica?
tion of the piston and cylinder of a gas engine is difficult under the 
most favorable conditions, owing to the fact that excessive lubrication 
causes trouble from the surplus oil interfering with the sparking appa?
ratus. It was, therefore, determined not to risk serious trouble by at?
tempting to have the pistons bear directly on the steel walls of the cyl?
inders. 
Smithsonian Contributions to Knowledge, vol. 27, no. 3, pp. 234-246. 
141 
k 
FIGURE 37.?Balzer-Manly engine, exhaust side. Now on exhibit at the Smithsonian 
Institution. (Smithsonian photo A54409.) 
142 
The engine cylinders consisted primarily of a main outer shell of 
steel one-sixteenth of an inch thick, near the bottom of which was 
screwed and brazed a suitable flange, by which it was bolted to the sup?
porting drum or crank chamber. These shells, which were seamless, 
with the heads formed integral, were designed to be of sufficient 
strength to withstand the force of the explosion in them, and, in order 
to provide a suitable wearing surface for the piston, a cast-iron liner 
one-sixteenth of an inch thick was carefully shrunk into them. Entering 
the side of the cylinder near the top, was the combustion chamber, 
machined out of a solid steel forging, which also formed the port which 
entered the cylinder and was fastened to it by brazing. The water jack?
ets, which were formed of sheet steel .020 inch thick, were also fastened 
to the cylinder by brazing. 
* * * * * 
The engine consists primarily of a single crankshaft provided with a 
single crank pin, the shaft having bearings in a drum which consists es?
sentially of two heads. Arranged around the crankshaft and attached at 
equidistant points of the drum are five cylinders. Mounted on the port 
side of the crankshaft and close to the crank arm is a small gear, which 
through suitable gears mounted on the port head of the drum drives a 
double-pointed cam which has a bearing on the exterior of the hub of 
the drum. The ratio of these gears is such that the cam is driven at 
one-quarter the speed of the crankshaft, and in the reverse direction. 
Mounted on the exterior side of the port head of the drum are five 
punch rods, the upper ends of which are within a sixty-fourth of an 
inch of being in contact with the exhaust-valve stems of the cylinders, 
and on the lower end of these rods are hardened-steel rollers which rest 
on the double-pointed cam?this one cam thus serving to operate the ex?
haust valves of all five of the cylinders. The port head of the drum is 
connected to the port bed plate, by which it is supported, by means of a 
flanged bushing in which are formed tongues and grooves which fit into 
corresponding grooves and tongues formed in the hub of the drum, it 
being necessary to have a certain amount of space between this bed 
plate and the head of the drum to provide room for the exhaust-valve 
cam and its co-acting punch rods. The starboard bed plate is fastened to 
the starboard head of the drum by bolts which draw the web of the bed 
plate against the face of the drum. The sparking gears are driven by 
means of a gear formed on a sleeve which telescopes over the hub of the 
starboard drum, and has a bearing thereon, the end of the sleeve termi?
nating in a ring which is fastened to the crankshaft. 
Since the five connecting rods must center on the one crank pin, the 
143 
FIGURE 38.?Balzer-Manly engine, ignition side. Now on exhibit at the Smithsonian 
Institution. (Smithsonian photo A49990-B.) 
144 
FIGURE 39.?Balzer-Manly engine, exhaust side showing starting crank, piston, and 
water radiator. Formerly exhibited at the Smithsonian Institution. (Smithsonian 
photo A26484.) 
145 
bronze shoes in which they terminate can occupy only a portion of the 
circumference of the pin, and with the relative proportions which here 
existed between the length of a stroke of crank and the length of the 
connecting rod, the circumferential width of the connecting-rod shoes 
was slightly less than sixty degrees, thus leaving uncovered a crank 
space of about one-sixth of the circumference, which it was necessary to 
have in order to provide room for the change in relative position of the 
shoes due to the angularity of the connecting rods. In the experimental 
engine the connecting-rod shoes were all given their bearing directly on 
the crank pin, as heretofore described, being held in contact therewith 
by means of cone nuts, which were screw-threaded to the crank pin, the 
taper of the cones permitting adjustment for wear. This method of con?
necting these parts to the crank pin is the usual plan of con?
necting three or more connecting rods to one crank pin. So much trou?
ble had been experienced with the water jackets and with minor defects 
in the experimental engine that no long runs had been possible with it, 
and consequently no trouble had been experienced because of the 
small amount of bearing area provided by this method of joining the 
connecting rods to the crank pin. When, however, the new engine was 
completed it was found that after working at high power for a few 
minutes the connecting-rod shoes heated so rapidly that it was impossi?
ble to run the engine for more than ten or twelve minutes, the exces?
sive heating of the shoes causing a great diminution in power besides 
the danger of serious damage if the tests were continued longer. At 
first this defect seemed almost fatal, as there appeared to be no way of 
providing sufficient bearing area for the five connecting rods on one 
crank pin. Happily, however, the writer was able to overcome this de?
fect by an improved design which enables all five connecting rods to 
operate on the one crank pin, and at the same time provides each with 
the full amount of bearing area which it would have were it the only 
connecting rod operating on the crank pin. This arrangement consists 
essentially of a main connecting rod formed of a steel forging termi?
nating in a sleeve which encircles the crank pin and is provided with 
a bronze lining for giving a proper bearing surface between the con?
necting rod and the crank pin, both the steel sleeve and the bronze 
lining being split, but at right angles to each other, to permit assem?
bling them on the crank pin. This steel sleeve, the upper half of which 
is formed integral with the main connecting rod is rounded off to a 
true circle on its exterior circumference, except at the point where the 
rod joins it. The other four connecting rods terminating in bronze 
shoes are then caused to bear on the exterior of this sleeve, being held 
146 
Cylinder SttyttX t' f Stir I 
End Elcrolio?{P.rts<*) 
FIGURE 40.?Balzer-Manly engine showing exhaust side. (From "Langley Memoir 
On Mechanical Flight," Smithsonian photo A19874-A.) 
in contact therewith, and permitted to have a sliding motion thereon 
sufficient to take care of the variation in angularity of the connecting 
rods, by means of the cone nuts which are screw-threaded to the sleeve 
and locked thereto by means of the jam nuts, as shown in the draw?
ings. The main connecting rod, of course, acts in the same way as in 
the ordinary case where each cylinder has its separate crank pin. The 
other four connecting rods deliver their effort to the crank pin through 
the sleeve in which the first connecting rod terminates, and they, 
therefore, do not receive any of the rubbing effect due to the rotation 
of the crank pin, except that of slipping a very short distance over the 
circumference of the sleeve during each revolution, the amount of 
slipping depending on the angularity of the connecting rod. This 
improved type of bearing was successful from the time of its first trial; 
and even in later tests in which the engine was run for ten consecutive 
hours at full power it showed no signs whatever of overheating. 
147 
The lubrication of the main crank-shaft bearing and of the crank pin 
was effected by means of a small oil cup, fastened to the port bed plate, 
which fed oil through a hole in the hub of the drum to a circular 
groove formed in the bronze bushing in the hub. The crankshaft being 
hollow, a hole was drilled through it in line with the groove in the 
bushing, and the oil was then led from the interior of the crankshaft 
through a pipe connected to the plug in the end thereof, and through 
a hole drilled in the crank arm to the hollow crank pin. Small holes 
through the crank pin permitted oil to pass to the exterior thereof and 
thus oil the bearing of the main connecting rod. Small holes through 
the sleeve and bushing of the main connecting rod fed oil under the 
shoes of the other four connecting rods, the small holes being placed in 
oil grooves formed in the interior of the bronze bushing. The lubrica?
tion of the pistons was effected by means of small crescent-shaped oil 
cups fastened to the outer wall of the cylinders, which distributed the 
oil equidistantly around the circumference of the pistons, through 
small tubes which projected through corresponding holes drilled in the 
cylinder wall. These oil cups for the cylinders were, while small, of suf?
ficient size to furnish a supply for approximately one hour, and were so 
positioned on each cylinder as to have a gravity feed. It may be men?
tioned here that while there were many parts of the engine which were 
of unprecedented lightness there was nothing which excelled these oil 
cups in this respect, as they were made of sheet steel .003 of an inch 
thick, riveted and soldered up. The crankshaft bearing in the star?
board drum was oiled from an oil cup mounted on the outside of the 
bed plate and connected by a pipe to a hole in the inner wall of the 
drum, which was connected to the oil grooves in the bronze bushing in 
the hub of the drum. 
The first set of pistons for this engine were similar in design to those 
shown in the assembled drawings, [not reproduced herein], except that 
they had side walls and heads which were twice as thick as those shown. 
These lighter pistons were constructed later, and were just as good as 
the earlier and heavier ones. It will be noted that the pistons have two 
deep but thin ribs reinforcing the head. The pistons were slightly ta?
pered from the middle, where they were .005 inch smaller than the cyl?
inder bore, toward the outer end, where they were .0075 inch smaller 
than the bore. The outer piston ring was .0035 inch narrower than its 
groove, the second one .003 inch, and the third .0025 inch, and the 
inner one .002 inch narrower than its groove. The rings were bored 
one-sixteenth inch off center with the exterior surface, and had one-
eighth inch diameter of spring. They were of the lap-joint 
148 
r~\ 
cszaii 
Jcrodrome jf. 
J* Cjllidcr JSnglnt ffTilllItt) 
Top Plan. 
EAOINEOF AEflOOKOME . 
FIGURE 41.?Balzer-Manly engine, top view. (From "Langley Memoir On Mechanical 
Flight," Smithsonian photo A19874-D.) 
type, with the sides of the laps carefully fitted and only one-sixty-
fourth-inch clearance at the ends of the laps to allow for thermal expan?
sion. As no grinding facilities were obtainable in Washington, the 
cylinders were carefully bored smooth and free from taper, and the pis?
tons were worn in to a perfect fit by running them in by a belt for 
twenty-four hours, with copious oil supply. 
The main connecting rod was 7/8 inch diameter and solid, while the 
other four were of the same diameter but with a y8 inch hole in them. 
The gudgeon pins in the pistons were hollow steel tubes % inch diame?
ter and case-hardened, and were oiled entirely by the oil thrown off by 
centrifugal force from the crank-pin bearing, the oil running along the 
connecting rods and through suitable holes at the heads into oil grooves 
in the bronze bushings in these heads. 
Since on an engine for an aerodrome the best plan for releasing the 
exhaust gases from the engine is to get rid of them as soon as possible, 
149 
382-902 O - 71 - 11 
so long as they are released behind the aviator and do not interfere 
with his view in the direction of motion, it was decided to have the 
gases exhaust immediately from the combustion chambers; but in order 
to prevent their playing on and heating the main bearing of the crank?
shaft in the port drum the combustion chambers were each provided 
with a chamber below the exhaust-valve seat, with a side outlet there?
from. The manifold pipe through which the gaseous mixture was sup?
plied to the inlet valves of the engine consisted of a tube bent to a 
circle and having five branch tubes, each leading to one of the automatic 
inlet valves, which fitted removable cast-iron seats fastened by a nut in 
the upper part of each combustion chamber. The very small amount of 
clearance between the engine and the frame necessitated that this pipe 
be cut in three places and joined by flanges in order to properly assem?
ble it on the engine when the latter was mounted in the frame. The 
carbureter, which was placed near the rear of the aviator's car, was con?
nected through suitable pipes to this circular inlet pipe, at a point hori?
zontally in line with the center of the shaft. The auxiliary air valve 
consisted of a sleeve rotatably mounted on the vertical pipe leading 
from the carbureter to the manifold, holes in the sleeve being brought 
to coincide more or less with holes in the vertical pipe, by the operator, 
when more or less air was required or when he wished to vary the speed 
of the engine. The cooling water for the jackets of the cylinders was led 
to them through a circular manifold pipe on the starboard side con?
nected by a vertical pipe with the centrifugal pump situated at the 
lower point of the lower pyramid of the aerodrome frame. The heated 
water was led from the jackets through another circular manifold pipe 
on the port side, through two connections to the radiating tubes at the 
front and rear, respectively, of the crossframe. These radiating tubes, 
which were provided with thin radiating ribs soldered to them, finally 
led the cooled water to the tank situated in the extreme rear of the 
aviators car, a suitable pipe from the bottom of this tank being con?
nected to the inlet side of the centrifugal pump. The centrifugal pump 
was driven by means of a vertical shaft connected to the crankshaft 
through a set of bevel gears which drove it at three times the speed of 
the engine. The bearings through which these gears were connected 
were mounted on the port bed plate, and in order to allow for a certain 
amount of vibration between the engine and the pump this vertical 
connecting shaft had a telescoping section connection through suitable 
splines. 
The sparking apparatus comprised, first, a primary sparker similar to 
the simplest form of such devices which have since come into common 
150 
use, where a cam driven by the engine co-acts with a pawl on the end of 
a spring, but in this case, as the sparker was used for all five cylinders, 
the cam was driven at a speed of two and one-half times that of the 
engine shaft, thus making and breaking the primary circuit five times 
in each two revolutions of the engine. Second, a spark coil, the primary 
terminals of which were connected to the primary sparker and to a set of 
dry batteries. Third, a secondary distributor consisting of a disc carrying 
5" Cf/indrr i]Si" gln/it Snyne 
Sextnn thnayh CwJindrr tjfrwm. 
FIGURE 42.?Balzer-Manly engine, cross-section view. (From "Langley Memoir On 
Mechanical Flight," Smithsonian photo A19874-C.) 
151 
a contact brush and driven at a speed of one-half that of the engine, 
this brush being constantly connected through a contact ring to one of 
the terminals of the high-tension side of the spark coil and running over 
the face of a five-section commutator, each of the sections of which was 
connected to a spark plug, the other high-tension terminal of the spark 
coil being, of course, grounded on the engine frame. This sparking ap?
paratus was first constructed by using blocks of red fibre for insulation. 
After the engine was completed and was being tested difficulties were 
met with in the sparking apparatus which at that time appeared in?
explicable. After a great deal of annoyance and loss of time it was 
finally discovered that the red fibre was not as good an insulating me?
dium as it was supposed to be, owing to the zinc oxide used in making 
it. In damp weather the sparking apparatus absolutely refused to work, 
and it was found that the moisture in the air caused he zinc oxide in 
the fibre to nullify its insulating qualities. This trouble, after being lo?
cated, was cured by substituting hard rubber for the red fibre. 
At the time when this engine was built, as well as earlier when the 
experimental engine was built, it was impossible to procure any wire 
which had been properly insulated to withstand the high voltages neces?
sary for the connections between the high-tension side of the spark coil 
and the secondary distributor, and from the secondary distributor to 
the spark plugs in the cylinders. While at this time this appears a very 
simple matter, yet the trouble experienced and the delays caused by the 
lack of such small accessories which are now so easily procurable were 
very exasperating, and it was finally necessary to insulate these 
wires by covering them with several thicknesses of ordinary rubber tube 
of different diameters telescoped over each other. 
In the early tests of this new engine, which were made with it 
mounted on a special testing frame and delivering its power to the 
water absorption dynamometers, the engine was operated without any 
flywheels, and, so far as its smoothness of operation was concerned and 
its ability to generate its maximum power, it did not require any. 
After the completion of the tests on the testing frame the engine was 
assembled in the aerodrome frame, which was first mounted on the 
floor of the launching car. The car itself was mounted on a short track 
in the shop, which arrangement provided a smoothly rolling carriage 
which could be utilized for measuring the thrust of the propellers by 
merely attaching a spring balance between the rear of the car and a pro?
per holding strap on the track. In the first tests of the engine under 
these conditions, it was found that while the engine itself did not re?
quire any flywheels, yet the lack of them caused trouble with the trans-
152 
mission and propeller shafts, which, while it had never been antici?
pated, was easily understood when it was encountered. This difficulty 
was caused by "reverse torque," which fluctuated from a maximum to a 
minimum five times during each double revolution of the engine, and 
which set up fluctuating torsional strains of such magnitude in the 
transmission and propeller shafts that the shafts themselves became ex?
ceedingly hot after a few minutes operation of the engine, and under 
more prolonged periods of operation these fluctuating torsional strains 
caused a permanent twisting and bending of the shafts. 
* * * * * 
Upon calculation it was found that by providing specially light fly?
wheels the major portion of this reverse torque could be eliminated for 
a less increase in weight than would be occasioned by sufficiently in?
creasing the thickness of the transmission and propeller shafts to safely 
stand it. 
It will be recalled that in starting up the engine on the quarter-size 
model, the initial "cranking" necessary with a gasoline engine was ac?
complished by having two of the mechanics turn the propellers. While 
this same plan might have been followed in the case of the large aero?
drome, yet it would have involved some danger to the mechanics and 
would also have left the aviator without any means of restarting the en?
gine should it for any reason stop while in the air. Believing it to be 
very important to provide means for enabling the aviator to restart the 
engine in case it stopped in the air, the writer devised the starting 
mechanism shown [See Figures 39 and 40]. 
* * * * * 
This starting mechanism was a success from the first, and the engine 
was never started up in any other way. 
* * * * * 
The reason for building the engine with five cylinders instead of 
some other number, and for arranging them radially on a central drum 
using only one crank pin may not appear quite obvious. The advan?
tages gained by such a construction, however, are very great, and may 
be briefly summed up as follows: 
First, since in a gas engine of the four-cycle type there is only one ex?
plosion in each cylinder every two revolutions, and the crankshaft and 
crank pin therefore are loaded only one-quarter of the time for each 
153 
FIGURE 43.?Balzer-Manly engine, ignition distributing and timing system. (From 
"Langley Memoir on Mechanical Flight," Smithsonian photo A19874-B.) 
cylinder, it is obvious that by having four cylinders arranged radially 
around a central drum the load on the bearings of a single crankshaft 
and crank pin may be kept very uniform. However, with four cylinders 
thus arranged it is impossible to have the cylinders explode and exert 
their effort on the crank at uniform intervals. With any odd number of 
cylinders the explosions will occur at equal intervals in the cycle. It is 
therefore seen that there is a great advantage in smoothness of opera?
tion and uniformity of torque of the engine through having an odd 
number of cylinders instead of an even number. 
Second, it is readily apparent that the greater the number of cylin?
ders, provided the number is an odd one, the more uniform the torque 
will be. There is considerable fluctuation of the torque in each revolu?
tion of the engine with five cylinders, but this fluctuation of torque is 
more easily smoothed out by the use of very light flywheels than by in?
creasing the number of cylinders, and thus adding to the complication 
of the engine. 
Third, the strongest point in favor of the radially arranged cylinders 
is the reduction in weight and complication which it permits. The 
crankshaft is reduced to the very minimum, there being only one crank 
pin with two main bearings which can, without any difficulty whatever, 
be kept absolutely in line with each other and thus prevent binding 
and loss of power. Again, the use of a single-throw crank not only re?
duces the cost and weight of the crank itself, but makes it very much less 
liable to damage; long crankshafts with several crank pins being 
154 
frequently twisted by improper explosions in the cylinders. The sup?
porting drum or crank chamber is likewise reduced to the very mini?
mum, both in weight and simplicity, the drums being perfectly sym?
metrical with no lost space either inside of them or on their ex?
teriors. 
The radial arrangement of the cylinders is thus seen to give not only 
an engine with the smallest number of parts, each of which is as far as 
possible worked to a uniform amount during each complete revolution 
of the crankshaft, but it also gives a very compact and readily accessible 
mechanism with its center of gravity coincident with its center of 
figure, and with the liability of damage to it, in case of a smash of the 
vehicle on which it is used, reduced to the minimum from the fact that 
the greatest weight is located at the strongest part. 
Fourth, and of almost as great importance as the reduction in weight 
which the five-cylinder radial arrangement permits, is its unusual quali?
ties as regards vibration. It is sufficient to call attention to the fact that 
in an engine having five cylinders arranged radially, all of the recipro?
cating parts are balanced for all forces of the first, second and third 
orders. As it is only the reciprocating parts which give any trouble in 
balancing any engine, the unbalanced rotating parts being readily bal?
anced by placing an equal weight at an equal distance from the center 
of rotation, and on the opposite side thereof, it is readily seen that the 
properties of balancing which are inherent in this type of engine are 
unusual. While this is true, as regards the vibration due to mov?
ing masses, it is still more impressively true as regards vibration 
due to reaction arising from the force of the explosions in the engine 
cylinders, especially when the engine is running slowly and having 
heavy explosions. 
This concludes the excerpts from, "The Langley Memoir on Me?
chanical Flight." 
The engine was completed in December 1901 and was tested in Janu?
ary 1902; however, it did not reach its full horsepower capability until 
March 1903. Subsequently, under a Prony brake load of 52.4 hp at 950 
rpm, it ran continuously for 10 hours during three separate tests. The 
net dry weight of the engine proper was 124.2 lb. with 20 lb. of cooling 
water, flywheels, batteries, and accessories, the total weight of the pow?
erplant was 207.5 lb., or 3.96 lb. per hp.69 
155 
SPECIFICATIONS 
Cylinders ? 5 in radial configuration 
Cooling ? Water 
Carburetion ? Surface type, no float 
Ignition ? Battery, induction coil, spark plug (high 
tension) 
Horsepower ? 52.4 at 950 rpm 
Bore and stroke ? 5 x 5.5 in. 
Displacement ? 540.2 cu. in. 
Dimensions ? 37-in. diameter and 19-in. width 
Weight ? 207.5 lb. including cooling water 
Weight/hp ratio ? 3.96 lb. per hp 
Country of manufacture ? U.S.A. 
The Balzer-Manly engine was superior to the Wright brothers en?
gine in total horsepower developed (4 times as much), in weight I 
horsepower ration (4 times lighter), and in reserve power (one-half of 
total power compared with one-third). 
According to the "Langley Memoir on Mechanical Flight,"70 28 
horsepower was needed to power the aerodrome in its final configura?
tion. This could easily be provided with one cylinder inoperative. The 
Wright brothers calculated that the "Kitty Hawk Flyer" needed 8 
horsepower to fly.71 
The Balzer-Manly engine was also superior to the Clement engine in 
total horsepower developed (17 times as much), and in weight jhorse-
power ratio (2 times lighter). We do not know what Santos Dumont 
considered the reserve power of his Clement engine to be. 
89
 This information and the specifications following are from MEYER, op. cit., p. 362. 
70
 p. 224. 
" MARVIN W. MCFARIAND, editor, The Papers of Wilbur and Orville Wright (New 
York: McGraw-Hill Book Company, Inc., 1953), vol. 1, p. 313. 
156 
Chapter 8 
Evaluation of Balzer's and Manly's 
Contributions to the Engine 
AS mentioned in the Prologue, Manly was awarded the Langley 
X~? Medal posthumously. This presentation was largely due to a 
statement by Mr. Charles L. Lawrance, President of the Wright 
Aeronautical Corporation, before the International Civil Aeronautics 
Conference held in Washington, D.C, 12 to 14 December 1928.72 
I wish particularly to call your attention to this engine, for if the 
Wright brothers were geniuses in the science of aerodynamics, as well as 
in the engineering judgment and good sense which characterized the 
conduct of their successive experiments, and if Glenn Curtiss was the 
practical type of engine designer most likely to succeed, Charles Mat?
thews Manly was certainly the outstanding genius of early powerplant 
design. When we consider that the most popular type of airplane en?
gine of today is almost identical in its general detail and arrangement 
with the one evolved by Charles Manly in 1902, we are lost in admira?
tion for a man who, with no data at his disposal, no examples of simi?
lar art on which to roughly base his design, and no workmen capable of 
making the more difficult parts of his engine, nevertheless, through the 
processes of a logical mind, the intelligent application of the science of 
mathematics, and the use of his surprising mechanical skill, succeeded 
in constructing an engine developing 52.4 hp for a weight of 125 lb., or 
a weight of 2.4 lb. per hp.,73 which stood up under severe tests, once 
even going through a full power, non-stop run of ten hours. 
72
 CHARLES L. LAWRANCE, "The Development of the Airplane Engine in the United 
States," Mechanical Engineering, vol 51, no. 3 (March 1929) , pp. 186-192. 
73
 With 20 pounds of cooling water, flywheels, batteries, and accessories, the total 
weight of the powerplant was 207.5 pounds, or 3.96 pounds per horsepower. 
157 
After giving many details Mr. Lawrance concluded: 
Everything had to be specifically made, the ignition system, the car?
bureter, and even the spark plugs. This engine may indeed be charac?
terized as the first 'modern' aircraft engine in the world, and the fact 
that it was produced years ahead of any other modern engine, and by 
an American engineer, should be a matter of pride to all who are inter?
ested in the advancement of American aeronautics and the mechanical 
genius of the American people. 
The Langley Medal was awarded for "specially meritorious investiga?
tions in connection with the science of aerodromics and its application 
to aviation." The awarding of the Langley Medal to Manly started a 
controversy between Balzer and the Smithsonian and involved active 
correspondence over a two year period. A lot of effort was wasted on 
both sides in overclaiming, and in trying to prove prior art. Some posi?
tive good did result, however, in that the engine label was corrected to 
reflect Balzer's contributions, and several affidavits were written by me?
chanics who had served under both Balzer and Manly. These affidavits 
have been a great help in determining Balzer's and Manly's contribu?
tions. 
1 June 1931?Stephen M. Balzer in Andover, New Jersey, to Dr. Charles 
G. Abbot at the Smithsonian Institution. This letter started the con?
troversy. 
Last winter it came to my attention that Mr. Charles M. Manly had 
been signally honored by the Smithsonian Institution for his work in 
"designing and building" the engine with which Secretary Langley's 
Aerodrome was powered. It was my privilege for several years to be 
closely associated with Secretary Langley as well as with Mr. Manly, 
and it gave me great pleasure to see that Mr. Manly's hard work had 
been recognized by the Institution he had so ably served. 
That pleasure, however, was somewhat dampened since the achieve?
ment for which he was especially honored was not his but my own. Fur?
thermore I feel sure that had Mr. Manly been alive he would have seen 
to it that I received credit for the design of the motor, however much 
he may have achieved in other lines for the science of engineering. 
Although not perhaps of as wide general interest, it appears to me 
that there is a parallel between the Smithsonian's act in this matter and 
its actions in the controversy with Orville Wright, since in that quarrel 
158 
Professor Langley had no part, so in this question Mr. Manly has no 
part.74 
These are the facts, and here are the proofs: 
HISTORY The motor wagon on exhibit in the Institution, in the 
same room with the "Manly engine," was completed by me in 1894. 
This wagon is equipped with the same type of wood filled carbureter as 
was used in the Aerodrome. In 1895 I built another motor wagon, simi?
lar in all respects but somewhat improved. In 1896 I built still another, 
but with the cylinders of its engine water cooled. In my preliminary 
dealing with the Smithsonian Institution preparatory to the signing of 
the contract, the engine from this wagon was shipped to the Institution, 
and tested in the presence of Mr. Watkins, Curator, both as a rotary 
and as a static radial, the crankshaft being provided with a flywheel. 
The ignition system on this engine was of the make and break type, 
and it, like its predecessors was a three cylinder. The jump-spark type of 
ignition, including platinum wire electrode spark plugs was used on 
other of my rotary and radial engines prior to the signing of the Smith?
sonian contract. In 1898 I contracted with Secretary Langley "for the 
Institution" for the design and construction of the engine that was used 
in the Aerodrome, and later for the design and construction of the 
smaller engine that is at present on exhibit in the Institution in the 
quarter size model of the Aerodrome. 
PROOF I have a number of letters from both Secretary Langley and 
Mr. Manly showing not only that I designed and built the motor but 
showing further that in increasing the horespower to meet the increased 
requirements of the Aerodrome, owing to its unexpected weight from 
strengthening the frame, Mr. Manly sought and received my help in 
carrying out the original and at that time unique work of shrinking the 
liners in his large size cylinders. We found that the original engine 
frame and various other parts were strong enough with plenty of factor 
of safety to take the 5 inch bore, with the same stroke. Finally, the pat?
ents for the engine are in my name and were applied for by me before I 
had the pleasure of meeting either Secretary Langley or Mr. Manly. 
Even a superficial examination of the "Manly engine" in the Institu?
tion and the Balzer engine in the wagon, also in the same room of the 
Institution, will show a striking likeness between the two. I would be 
only too glad to furnish you with any further proofs that you may call 
upon me for. 
It has taken me many months to come to the decision that it is due 
" T h i s controversy is summarized by C. G. Abbot, "The 1914 Tests of the 
Langley 'Aerodrome'," Smithsonian Miscellaneous Collections, Vol. 103, no. 8, 1942. 
159 
my reputation as an engineer and designer, and at the urgent requests 
of my friends, to write you, since the two men most concerned, Secre?
tary Langley and Mr. Manly are dead. While work was progressing on 
the engine, Secretary Langley requested that I keep all information re?
garding it a confidential trust until the Aerodrome had been success?
fully flown, at which time he assured me that he would have my part 
in the project given full publicity. I have faithfully kept this trust, and 
it is only the fact that the honor for my work has been conferred on 
another that prompts me to write you. 
11 July 1931?Abbot at Smithsonian Institution to Balzer in Andover, 
New Jersey 
Since receiving your letter of June 1, I have been closely engaged in 
preparing the manuscript of Volume V of the Annals of the Astrophy-
sical Observatory, so that it is only in the last week that I have been 
able to give attention to the matter of the engine. 
I have read all the letters received by the Institution from you and 
all the letters sent by the Institution to you, as well as many reports, 
which at that time were confidential, from the Institution to the Board 
of Ordnance and Fortification, from Manly to Langley and from Lang?
ley to Manly, bearing upon the subject. I have also read in full Chap?
ters VIII and X of Manley's "Langley Memoir on Mechanical 
Flight." 75 I think there can be no question but that, as you claim, the 
engines which were used in the large and small aerodromes in 1903 re?
sembled in appearance the type of your general design. You will be in?
terested, however, in the quotations, which I append and make a part 
of this letter, from these formerly confidential sources to which I have 
referred, and which are enumerated in the following paragraph, as well 
as in the drawings and description of the final large engine given by 
Manly in Chapter X above cited: 76 
It seems to me that the accomplishments of Mr. Manly: (a) in pass?
ing from a brake horsepower of 8 to one of 20 by modifying the large 
engine which you contracted for and on which you had spent 18 
months; and (b) in achieving reliability and a horsepower of 52 in the 
new engine made here under his direction which was actually used in 
the large aerodrome, with a total weight including cooling water and 
75
 Smithsonian Contributions to Knowledge, vol. 27, no. 3, 1911. 
76
 Balzer to Langley, 5 December 1898 (page 35) ; Langley to Manly, 20 June 1900 
(page 75) ; Rathbun to Captain Lewis, 6 September 1900 (page 161) ; Manly to 
Langley, 1 January 1901 (page 162) ; and Report on Progress of Smithsonian 
Institution to Ordnance Board (page 165) . 
160 
flywheel of only 207 pounds; and (c) his accomplishment in passing 
from a horsepower of less than 1 to between 2 and 3 by modifying the 
small engine of your construction which was used with the quarter-
sized model: and this at a time when neither the makers in this country 
nor in Europe could encourage Dr. Langley to hope for success as re?
gards sufficient lightness and reliability of action for use in the aero?
dromes; all these achievements entitled Mr. Manly to receive the award 
which was made by the Institution. 
At the same time, I am appreciative of the fact that your relations 
with Dr. Langley and Mr. Manly were always of the most cordial and 
helpful sort and that you spent upon your contracts not only your own 
time and thought but, as Mr. Manly states, $8,000 or $10,000 of your 
own money beyond that which, according to the contracts, you were 
paid. I am very ready, therefore, to consider what acknowledgment on 
the part of the Institution would seem to give you proper credit in the 
premises. Would it meet your view, for instance, if the Institution 
should publish a pamphlet quoting your letter of June 1 with such 
modifications as you might now wish to make, and including quota?
tions from the confidential reports of the Institution by Manly and 
Langley written at the time, such as I am enclosing? Such a publication 
might be introduced by a statement from myself acknowledging on be?
half of the Institution its appreciation of your efforts in this connec?
tion. 
Here follow various enclosures mentioned in the above letter which 
have not already been included in the text; see footnote 76. 
6 September 1900?R. Rathbun in Washington, D.C, to Captain L.N. 
Lewis, Recorder, Board of Ordnance and Fortification, Washington, 
D.C. 
Mr. Powell telephoned me on Tuesday that you were about prepar?
ing the annual report of the Board of Ordnance and Fortification, and 
desired to include in it a brief statement of the progress of the aero?
dromic work during the year just closed. As Mr. Langley is still abroad 
and will probably not return before the latter part of October, I have 
thought it best to give you the following notes, which are merely sup?
plemental to the report of Mr. Langley of October 14, 1899, and which 
I have obtained from Mr. Manly, leaving it to your discretion how to 
use them. 
Generally speaking, it may be said that the aerodrome is now about 
ready for its first trial, with the exception of the engine. The wings 
have been greatly improved since you last visited the work; a full set 
161 
with duplicates has been entirely completed and is ready for use. The 
frame of the aerodrome itself, ready for the reception of the engine, is 
also in a finished state and has been found very satisfactory as regards 
strength. The steering mechanism, with its duplicate, is also complete 
and ready for use. The very extensive launching apparatus, built as a 
superstructure to the house boat was completed this spring and is assem?
bled in its proper position on the house boat. This launching carriage, 
which immediately supports and carries the aerodrome, is also finished 
and very satisfactory, while the propellers and the large number of 
other minor accessories are also ready for use. 
The engine, which was being constructed under contract by Mr. Bal?
zer, has failed to fulfill the required conditions, having developed only 
about two-thirds the power required. A very thorough search both in this 
country and in Europe for a builder of a suitable engine, has failed to 
discover one willing to undertake the contract, or, in fact, to offer any 
assistance whatever. It has therefore become necessary to undertake the 
construction here and this is now going on under Mr. Manly's supervi?
sion. In order to save time and expense, the Balzer engine, the parts of 
which were admirably constructed, has been brought to Washington 
and is now being utilized in this work. 
Mr. Manly states that he expects to get a preliminary test of the en?
gine under the changed conditions by the close of the present week, but 
thinks it unsafe to expect immediate success. 
During the year the one-quarter size working model of the large 
aerodrome has been constructed, and it had been hoped that some tests 
with this would be made before the close of summer, but owing to the 
failure of the small engine which Mr. Balzer was also building for this, 
no tests have yet been possible, though everything with the exception of 
the engine is entirely completed. 
If you can find the opportunity, before finally completing your report, 
to call at the Institution, I feel very certain that you will be able to 
more readily appreciate the very good progress which has been made 
during the year. 
/ January 1901?Manly to Langley both in Washington, D.C. (in part) 
I have the honor to submit for your consideration a report on the 
condition of the aerodromic work at the close of December, 1900, with 
a review of the progress which has been made during the past year, and 
a statement of the work remaining to be done before the large aero?
drome will be ready for its field trials. 
162 
GREAT AERODROME 
Engine 
The rotary cylinder gasoline engine which was intended as the first 
of two similar ones each of which was to be of 12 brake hp and weigh?
ing 100 lbs., and which was contracted for by Mr. Balzer on the 12th of 
December, 1898, to be completed in 10 weeks from that date, was given 
its first Prony brake test on the 9th of May, 1900, and developed un?
steadily for a few minutes, approximately 4 horsepower. After spending 
6 weeks from the 6th of May to the 17th of June in New York City at 
Mr. Balzer's shops in personally looking after the work, though all or?
ders of course still passing through Mr. Balzer's hands, the engine was 
finally made to develop 8 horsepower steadily, this increase in horse?
power however having been accomplished only after a series of the 
most tedious tests and changes. These changes consisted partly in im?
proving the "wiping contact" sparking arrangement, partly in additions 
to the combustion chamber to prevent the leakage of compression, also 
in remodeling and enlarging the rotating inlet sleeve. 
There then being very little reason to believe that Mr. Balzer would 
be successful with this engine, since the past thirteen months had been 
devoted to a most discouraging series of tests and changes, and there 
being no engine builders in this country willing to undertake the con?
struction of such a one, and after having under your orders made a 
brief trip to Europe in June, and there so far as time allowed, made a 
careful search among the principal builders in England, Germany, 
France, and Belgium, for one willing to undertake it, I was unable to 
find anyone who would attempt such a construction. 
I may refer in this same connection to the interview you yourself 
had with Mr. Maxim and also a subsequent one with Comte de Dion, 
the results of which are given in your letters to me of July 11 and July 
30th.77 
Briefly it may be said that both Mr. Maxim and Comte de Dion were 
opposed to the rotary form of engine, and that they also agreed that 
nothing could be done with other forms to procure a suitable engine 
weighing not more than 4 kilos to the horsepower except after long ex?
periment with an indefinite prospect of success. Mr. Maxim thought 
that with an engine of the ordinary form, a cylinder 3 inches in diame?
ter with a 6 inch stroke could be made to develop 3 horsepower at a 
weight of 10 or 12 pounds to the horsepower, and offered you the use of 
"Langley to Manly, 11 July 1900 (page 77); Langley to Manly, 30 July 1900 
(page 80) . See also Langley memorandum, 10 July 1900 (page 77) ; and Langley 
memorandum, 30 July 1900 (page 78) . 
163 
a workshop and skilled workmen to undertake such a construction; but 
his engineer, as I understood you, was not so confident. The results 
which Comte de Dion thought possible are given in detail in your let?
ter to me of July 30th. 
I returned from Europe, reaching New York August 13th, and im?
mediately made an inspection of the changes which Mr. Balzer had been 
making on the engine during my absence. The results of this inspection 
was that I found that whereas the engine had been developing 8 horse?
power when I left it on June 17th, it was now developing only 6 horse?
power. 
Having previously consulted with you and learned your wishes in 
case the Balzer engine should finally fail, and believing it to be for the 
best interest of the work to procure for further experimental purposes 
the parts of this engine which Mr. Balzer had built, the advantage in 
these as mere parts being fully worth the contract price of the engine, I 
accordingly directed Mr. Balzer to ship the engine immediately to 
Washington. On August 15th I returned to Washington, and as soon as 
the engine was received, commenced a series of radical changes in it 
both with respect to the principle and also minor details. The record of 
these changes and the results which I obtained are contained in my let?
ters to you from August 21st to October 9th.78 Regarding these changes 
I may say in brief that using the cylinders, bed-plates, crank and vari?
ous minor parts of the engine which Mr. Balzer had constructed, but 
with radical changes both in the principle and in the mechanical de?
tails, the engine was gradually perfected. The first preliminary run was 
made on September 7th and at a speed of 750 rpm the horsepower as 
shown by the Prony brake varied between 12 and 16, the fluctuations 
being due to the heating and consequent binding of the brake. 
While these changes were in progress you wrote on September 30 
briefly stating the fact that Mr. Maxim had offered to put his shop and 
workmen in England at your disposal, and asking if I would hold 
myself responsible for producing in the Institution shops an engine 
suitable for the aerodrome, with the understanding that nothing short 
of 20 horsepower for a maximum weight of 200 lbs. would answer the 
purpose. In reply to this inquiry I cabled, "Manly will build engine 
here in reasonable time." 
At this time, September 30th, the 5 original cylinders of the engine 
were still being used, and the circular form of mounting was still re-
78
 Manly to Langley, 21 August 1900 (page 80): Manly to Langley. 11 September 
1900 (page 86) ; Manly to Langley, 18 September 1900 (page 87) ; Manly to 
Langley, 9 October 1900 (page 91) . 
164 
tained without revolution. However, many changes had been made 
both in the principle and in the details and the advance from the 8 
horsepower obtained just before I went to Europe to the 20 horsepower 
which was later reached was mainly due to first,?keeping the cylinders 
stationary,?second, to improved valve gear, which made all of the cylin?
ders work alike, third, to the invention of an effective secondary spark?
ing arrangement which insured each spark occuring in the proper cylin?
der at the proper time, and to many other minor changes which in 
themselves appear small, but on which the success of the engine largely 
depended. 
27 September 1901?Langley's Report on Progress of Aerodromic Work 
on Account of the Board of Ordnance and Fortification from 1 January 
1899 to 1 October 1901 
In connection with this present report, I may recall to the Board a 
preliminary report which was made in October, 1899, and which con?
tained a statement of the progress made in the work between January 
1st, 1899 and October 14, 1899. 
As the Board is probably aware through a statement of condition of 
the work on September 6, 1900, which was made during my absence 
from this country, but which was communicated to the Board through 
its Recorder, Captain I. N. Lewis, the great delays which have occured 
in the work and which were not anticipated in the beginning, have 
been occasioned by the failure of the engine builder with whom I had 
closed a contract before engaging on this work for the Board, to build 
an engine of sufficient power and of a weight not prohibitory to the suc?
cess of the work and that after this failure of the engine builder to ful?
fill his contract, and also after a most thorough and complete search 
both in this country and in Europe for a competent builder willing to 
undertake the construction of a suitable engine, I was forced greatly 
against my wish to undertake the construction of the engine with the 
very limited facilities at my disposal in the Institution shops. 
The entire frame work adapted for utilizing an engine of the type 
and dimensions originally contracted for, was completed during the 
spring of 1900, as was also the special houseboat with its essential super?
structure carrying its launching apparatus. 
After repeated encouragements from the engine builder who had 
originally contracted for the engine, and a final failure in June, 1900, 
to fulfill the contract, the search both in this country and in Europe 
mentioned above for a competent engine builder was instituted, and 
upon the failure of this search, in August 1900 some of the materials 
165 
382-902 O 71 12 
from the original contractor were purchased and made use of in the ex?
periments which were immediately begun in the Institution shops to?
ward the building of an engine suitable for use in the already com?
pleted frame. Utilizing some of the parts of this condemned engine, an 
engine was constructed which on repeated tests proved itself capable of 
developing horsepower for weight within the limits essential to the suc?
cess of the work, but unfortunately of not quite large enough size to 
furnish the full power which I deemed essential to have at the disposal 
of the aeronaut at the first trials in free flight and until the aeronaut 
had gained some practice in the manipulation of the machine. 
A new larger engine capable of furnishing the full power necessary 
for the first trials in free flight was begun in the early part of the pre?
sent year, but unfortunately owing to the serious delay of several 
months in obtaining the very special materials necessary for the engine, 
and to other unavoidable delays which have since occurred in the course 
of construction, this new and larger engine is not yet quite complete, 
though it is rapidly nearing completion, and will unless some serious 
accident or delay occur, be ready for a trial during the present month 
of October, as will also its necessary accessories adapted to its use in the 
already completed frame. 
Every precaution which it has been possible to foresee has been taken 
to insure a very early trial in free flight upon the completion of the en?
gine, and unless serious delays should occur, which are not expected, but 
which are always possible in such light constructions, upon the intro?
duction of the high-powered engine in its frame, there appears at pre?
sent good reason to expect to be able to make the first trial in free flight 
before the close of the present year. 
If the Board should favor me by a visit to inspect the progress of the 
work, I think that a much more intelligent idea may be formed of its 
present condition and of the work remaining before the first experi?
ment in free flight is made. 
Several months and several letters later the controversy was aired in 
the press as follows: 
25 October 1931?The New York Times 
LANGLEY AIRPLANE IN NEW DISPUTE 
Friends of S. M. Balzer Say He, Not C. M. Manly Invented the Engine. 
SCORE NATIONAL MUSEUM 
Smithsonian Institution Faces a Controversy Similar to That Which 
It Had With Orville Wright. 
166 
The Smithsonian Institution, which several years ago was a party to a 
lively controversy with Orville Wright over whether the "Langley 
Aerodrome" was entitled to be called the first man-carrying, heavier-
than-air flying machine, is likely to become involved in a related dis?
pute. Mr. Wright, after forcing the museum to change the legend on 
the cards on the Langley machine, sent his historic airplane, the first 
ever to fly with a pilot, to the Kensington Museum in Great Britain, 
where it appears likely to stay instead of in the Smithsonian. 
Curiously enough, the Langley Aerodrome, which crashed when 
Charles M. Manly attempted to fly over the Potomac River, is directly 
concerned now. Evidence is being gathered to dispute the long-standing 
claim that Manly designed and built the "Manly-engine," a remarkable 
power plant in which features in use in aircraft engines today were in?
corporated and which developed more than fifty horsepower when it 
was installed in Langley's flying machine. 
Friends Press Balzer's Claim.?Friends of Stephen M. Balzer, head of 
the Balzer Engineering Company of Andover, N. J., and formerly the 
Balzer Motor Company of New York, have come forward and are press?
ing vigorously the claim that Balzer, not Manly, designed and built the 
original engine for which Manly posthumously received the Langley 
Medal a year ago. 
Mr. Balzer himself, however, was reluctant yesterday to talk about 
the matter. He admitted that with the help of John McK. Ballou, an 
aeronautical engineer now working on the Merrill safety plane, and 
others, among them his former employees and his former patent lawyer, 
he is gathering evidence to prove that he and not Manly designed and 
built the famous engine, and that even though Manly did rebuild it in 
the shops of the Smithsonian Institution with larger cylinders, Balzer's 
mechanics, designs, gauges and jigs were sent to Washington from New 
York to help in the work. 
The five-cylinder radial engine now stands in a glass case beneath the 
aerodrome in the National Museum, and the last line on the card de?
scribing the exhibit reads: 
"Built in the shops of the Smithsonian Institution by Charles M. 
Manly, under the direction of S. P. Langley." 
Nearby is an ancient motor vehicle?the first, it is said, ever to run on 
the streets of New York. It was built by Balzer in 1894 and donated to 
the Smithsonian at a later date. 
It is a development of the engine in this automobile which is now 
called the Manly engine and which was used in the attempt to fly the 
Aerodrome. In recalling the history of those early days of the internal 
167 
combustion engine Mr. Balzer says that he experimented from 1894 
until 1898. He could find nothing suitable for spark plugs so he hit 
upon the idea of employing a maker of false teeth to cast porcelain 
cores for his platinum wire electrodes. In 1896 he applied for patents on 
his engines and automobiles which were issued finally in 1903. Long be?
fore he was asked by the Smithsonian to build an engine for a flying 
machine he devised a carburetor that worked successfully as testified by 
Manly in his memoirs which consisted of a sheet metal shell filled with 
small pieces of porous wood saturated with gasoline. The supply was 
kept ample by a feeding valve and the engine sucking air through this 
shell obtained the mixture necessary for combustion. 
For years some of us have been trying to get Mr. Balzer to seek to 
establish the fact that it was his engine in all its essentials and not 
Manly's that stands in the Smithsonian today, Mr. Ballou said yester?
day; but he said that Professor Langley asked him to say nothing about 
his work and after Langley's death he felt that the promise still was sa?
cred. It was not until Mr. Manly died and in spite of patent records 
which can be seen in the bureau today, and after the Smithsonian 
awarded the Langley medal to Mr. Manly's son for his father's achieve?
ments that we persuaded Balzer to let us go ahead and try to establish 
the facts. In his chapter in the Langley memoirs concerning the engine, 
Manly did not mention Balzer except as "a builder" whose engine 
failed, resulting in the transfer of the whole project to Washington. No?
where does he mention that in rebuilding the engine he sought Balzer's 
help, used his measurements and jigs, utilized his methods for shrink?
ing on the new cylinders and even had the aid of Balzer's own mechan?
ics in rebuilding the motor. 
As in the Wright controversy so in this case, Ballou said, the Smith?
sonian has not shown any enthusiasm toward correcting their error nor 
in righting an injury inflicted on a worthy person. Fortunately both Mr. 
Balzer's automobile and his engine are at present in the National Mu?
seum of the Smithsonian Institution and cannot therefore be sent to a 
British museum as in the case of the original Wright brothers' mach?
ine. 
Balzer is today strong and active. He works daily in his laboratory, 
despite his 70 years. He is still confident that if a man with some 
knowledge of the air had been chosen to fly the ill-fated Langley ma?
chine instead of an engineer it might have been the first to fly. 
ORIGINAL PLANS FOR MOTOR 
In discussing his own work on the engine Mr. Balzer said that it 
168 
gave them a lot of trouble. Originally it was the plan to build two 
twelve horsepower engines, but with the increased weight necessary it 
was decided that one motor which would develop twenty-four horse?
power should be sought. While work was progressing on the engine Mr. 
Balzer was called upon by Professor Langley and Manly to fabricate 
various other parts of the flying machine, including the main frame 
supports of the engine, which had at first been built in the shops of the 
Institution, but, owing to faulty design and construction, had failed, ac?
cording to Ballou. 
In connection with the carbureter which is now on the engine, Mr. 
Balzer's friends say that credit should be given to him. 
When the engine was delivered to the Smithsonian, according to Bal?
lou, it was equipped with a carbureter, if not the one on exhibit, it was 
certainly a copy of it in every detail, yet the card on it makes no men?
tion of Balzer as its inventor. 
The card reads: 
"Carbureter of Manly Engine?This is the surface type carbureter 
consisting of a tank filled with porous wood. . . . This type of Carburet?
er was selected by Manly after tests of many other types. It kept the 
engine running even after the Aerodrome turned over on its back." 
Nowhere in Manly's writing is Balzer mentioned by name. The 
motor, according to Manly, failed even after changes, to develop more 
than four horsepower continuously, so he decided to give up working 
further on the motor and seek another one elsewhere. He went to Eu?
rope but could not find a motor or a motor manufacturer who would 
build an engine for the Institution so he returned to New York and the 
"engine builder" again. Here, according to his chapter in the Langley 
memoirs, Manly found no progress so he promptly condemned the en?
gine and a smaller motor Balzer was building for a model. Manly says 
that he took the parts of the two engines to Washington as it was hoped 
that some of the parts of the engines might prove of use in experimen?
tal work. 
It is the contention of Balzer's friends that instead of using a few 
parts in experimental work the so-called new engine was built up en?
tirely of these parts or parts modeled exactly on them and for these rea?
sons alone they believe Balzer instead of Manly should be recognized as 
the designer and creator of the Manly engine.79 
79
 On 4 April 1932, Dr. Abbot. Secretary of the Institution, took a constructive 
step by asking one of the six mechanics who had worked for Balzer and Manly 
to evaluate their contributions to the engine project. 
169 
4 April 1932?C G. Abbot in Washington, D.C, to George D. Mac Don?
ald, 149 Blue Hill Avenue, Milton, Massachusetts 
Mr. Stephen Balzer and his friends feel aggrieved by the award re?
cently made to Charles M. Manly, posthumously, by the Smithsonian 
Institution of the Langley Gold Medal for Aerodromics. This award 
was made largely on account of the high praise given Manly in an in?
ternational address by Mr. Charles Lawrence, then President of the 
Wright Corporation. 
Mr. Balzer claims as his achievement the building of the large en?
gine, and desires the Smithsonian to publish the statement I enclose as 
a measure of justice to him. Of course the Institution intends to be 
strictly just in the matter, and I realize that from your close connection 
with the work you know all the circumstances well enough to check Mr. 
Balzer's claims. 
I am therefore venturing to ask you, who were Manly's associate dur?
ing many years, for the sake of securing exact justice to his memory, to 
carefully consider all the statements of Mr. Balzer's memorandum, and 
comment on all that seem to you inexact. For instance he gives the im?
pression that you and Newham and Hewitt were given by him to 
Manly as an act of grace and assistance on Balzer's part. Hewitt, how?
ever, has told me that he had left Balzer, was working in Connecticut, 
and applied to Manly for a job. Possibly you and Newham may have 
found Balzer slow pay and preferred to come to Manly on your own 
motion. 
But the really grave question is whether Balzer is deserving so much 
and Manly so little credit for the large engine as Balzer claims in the 
latter part of his memorandum. To this I hope you will give particular 
attention and make careful comments. I shall understand that wher?
ever you make no comment you accept the statement of the memoran?
dum. 
I feel that, recalling your long association with Manly, you will be 
willing to perform this service now that he is dead, but I shall be glad 
to give you an honorarium of $50 from the Institution to reimburse 
you for the time you will have to give if you will kindly assist me as I 
have indicated. I am sending a copy of the Manly Memoir in case you 
should need to refresh your recollection, and you will please return it 
when finished. 
21 April 1932?MacDonald in Milton, Massachusetts, to Abbot in 
Washington, D.C. 
I am extremely sorry to keep you waiting so long for this statement of 
170 
my experience while at the Smithsonian Institution and particularly 
while working on the Balzer-Manly motors. 
Regarding Mr. Stephen Balzer and his friends feeling aggrieved by 
the recent award to Charles M. Manly, I do not know of any reason 
why they should feel grieved. In my opinion they are not entitled to 
any consideration. 
Concerning Mr. Manly's associates during the many years I was with 
him, I can say that I saw very few of them as I don't think there were 
many. One was Dr. Stratton, who is now dead, and another was Wil?
liam McKay Smith, who has been in charge of the switchboard depart?
ment of the Western Electric Company on West Street, New York City. 
I should think that Mr. Smith could give you quite a good deal of in?
formation as he had charge of Mr. Manly's laboratory while Mr. Manly 
was in Buffalo with the Curtiss Company. 
In regards to Mr. Balzer giving the impression that he gave us to Mr. 
Manly, it came about this way:? 
Mr. Manly came to us and asked us if we would go down to Wash?
ington and work for him at the Smithsonian Institution. Mr. Balzer 
was willing for us to go inasmuch as he had no more work for us. 
In making his engine Mr. Manly had to use some of Mr. Balzer's 
ideas but he used so few of them that they only have a minor impor?
tance. For example, the five cylinder radial disposition about the crank. 
I was looking at a three cylinder radial steam engine today that was 
made 45 years ago with the same crank mounting and exactly the same 
design as the Balzer crank.80 
You will see by the new parts as shown in my report that there were 
only about three old parts used in making the new engine. 
You can judge for yourself how much credit is due to Mr. Balzer but 
my firm belief is that Mr. Manly is deserving of every bit of reward 
which has been given to him. 
RE:?STEPHEN M. BALZER CLAIMS & ACHIEVEMENTS 
While I was working at the Balzer shop in New York I saw the auto?
mobile and engine that is now in the United States National Museum 
in Washington, D.C, but I have never seen it running. However, I 
think it was nearly as good as the last one he made. I saw it and it acted 
the same as the one he made for the Smithsonian Institution. 
In regards to the Gnome, the LeRhone and the Crossley motors, their 
mechanism is altogether different from the Balzer motor. They have a 
"MacDonald wrote Abbot on 19 May 1932 to say that this steam engine was 
actually only 34 years old. 
171 
closed in crank chamber and take the gas in through the crank cham?
ber and up through the piston head. 
The carbureter used on the 52 hp engine was entirely different from 
the carbureter used on the original Balzer motor as is fully explained 
on pages 224 and 225 of the Langley "Memoir on Mechanical Flight." 
Water Jackets on Cylinders 
I can say that I never saw any drawings or any letters from Mr. Bal?
zer where he made any mention of water jacketing the cylinders. That 
was all planned after the cylinders were held stationary by Mr. Manly. 
At the first test after holding the cylinders stationary the engine came 
right up to speed but got terribly hot. We then put a large fan blowing 
the hot air off. That made a good showing. Then, the next thing was to 
wet cloths. We kept running cold water on each cylinder. 
By this method the first brake test was made. After making several 
brake tests Mr. Manly decided to stop and put water jackets on the cyl?
inders. 
I can't see how Mr. Balzer can make any claim on the water jackets 
because the engine was made into a stationary cylinder and is no longer 
a rotary engine. 
Ignition 
The platinum pointed spark plugs were redesigned by Mr. Manly 
from one spark plug that came with the Comte de Dion small engine 
which Professor Langley sent over from France. Comte de Dion single 
jump spark coil was used on all tests. 
Timing Gears and Distributor Advance and Retard Mechanism 
The Comte de Dion timing gears and distributor advance and retard 
mechanism were redesigned by Mr. Manly and made at the Smith?
sonian Institution. 
Utilizing Flywheel and Crankshaft 
I saw it and it was nothing more than a friction disc. If you moved 
out of center one way the car would go ahead. If you moved the other 
way the car went backwards. 
Building the New Engine 
When Mr. Manly was building the new engine I don't think he 
asked help from anyone, and as far as Mr. Balzer having anything to do 
with it I can't see that he did. Mr. Manly got some tools from Mr. Bal?
zer but I don't think we used them because the small tools would not 
work on the large motor. Mr. Balzer was never at the Smithsonian In?
stitution in my time. Of course he would have been glad to help out if 
172 
he had been asked to but there was never a time when we were in trou?
ble. The work always went right along. 
NEW PARTS MADE AND REDESIGNED ON MANLY ENGINE 
1. Five new cylinders. 
Five inch bore with large valve chambers, cylinders and valve 
chambers water jacketed with V32 bright metal sheet steel. 
2. Five new large intake valves also five new valve cages. 
3. Five new exhaust valves. 
4. Five new pistons of special design. 
5. Five spark plugs designed and made at the Smithsonian Institu?
tion, designed by Manly. First five made by R. S. Newham. 
6. Circular intake manifold fitting over five intake valves and fas?
tened air tight by flange nuts. 
7. Water jacket fittings?two circular manifolds fitted to cylinders with 
flange nuts. 
8. One new crankshaft hammer forged of Krupp steel EF 60.0. 
9. One exhaust valve timing cam and timing gear mechanism. 
10. One supporting bed plate drum. 
11. One worm gear and one worm for motor starting crank. 
12. One water pump driving gear and one shaft and pinion. 
13. Two flange couplings for crankshaft. 
14. Engine supporting bed plate square tubing on sides. 
15. Ignition system distributor and timing gears and advance and re?
tard control 
16. Two special design flywheels. 
17. Two crank pin balancing arms. 
18. Crank pin lubricating system. 
19. Valve springs. 
20. Five punch rods for exhaust valves. 
21. Studs and screws. 
22. Four connecting rods wrist pin type. 
23. Four connecting rod shoes special metal. 
24. Two shoe retaining cones. 
25. Two jam nuts. 
26. One special connecting rod with a full bearing at all angles. 
BALZER?"SLIPPER TYPE CRANK AND CONNECTING ROD BEARINGS, 
PERMITTING ALL FIVE CONNECTING ROD AXES TO LIE IN 
THE SAME PLANE WHILE OPERATING A SINGLE THROW CRANK." 
Slipper type connecting rods will not work having five connecting 
rod shoes fastened directly to the crank. In the first place you can't oil 
173 
the connecting rod shoes because there will be much more oil coming 
out between the shoes than the shoes are getting. I saw the old Balzer 
motor crankshaft getting so hot that the sparks were flying from it. 
That was after the cylinders were water jacketted on the long tests. We 
used to squirt oil from the outside on to the crank but it would come 
off faster than it went on to the crank pin. The connecting rod shoes 
have no bearing?about 314 square inches to start with and when the 
pressure comes on I doubt if there is 2y2 square inches. When the pres?
sure came down on the center of the shoe the ends had a tendency to 
come up. You can readily see that 2i/2 inch bearing surface is nothing 
for a five inch piston having seventy-five to eighty pounds compres?
sion to the square inch. 
It was thought that by using some different kind of metal in the con?
necting rod shoes this might remedy the trouble so a new crankshaft 
was made in the same way. You can see the threads on the crank pin 
where the cone bearings were screwed on the crank pin. 
The engine was finished, assembled, and set up in the testing stand 
and all adjustments made. The engine started right off and ran like a 
clock so it was decided to run lightly and let everything wear in. In the 
meantime we got the dynamometers set and lined up for the brake tests. 
The dynamometers were coupled up. We started up the engine and ran 
with part load for about i/2 hour. Stopped and found the crank pin hot 
but not cutting. Cooled off and started again, running with a little 
more load for about the same length of time. Stopped and found it was 
still hotter. The next test was more load and longer run until the 
smoke was coming off the crank pin. Stopped and found the pin start?
ing to cut. The test was stopped and it was decided to try Parson's 
White Bronze in the connecting rod shoes. Had a pattern made and fin?
ished up a set of shoes. Tried them out and found a little improvement 
but nothing like what was wanted. Just the minute the load was put on 
it started to heat up and the heavier the load the worse it got. That was 
when everything looked like complete failure. No bearing surface and 
no way to oil. What could be done. 
After a lot of deep thinking Mr. Manly struck on #1 connecting rod. 
Would it work? It was made up and tried out and it workedl It not 
only oiled the crank pin but it also gave the other four connecting rods 
a full bearing. By #1 connecting rod having a full complete bearing 
around the crank pin the oil was trapped and wasn't thrown off. The 
other four connecting rods were mounted around the outside #1 
connecting rod and needed very little oil. 
This achievement was the key of success for the Manly engine. Take 
174 
the Manly connecting rods out and put the old ones in and you have 
complete failure. The engine will burn up in one hour's run?that is 
with a load. 
10 September 1932-C G. Abbot in Washington, D.C, to Mr. Lloyd N. 
Scott, 535 Fifth Avenue, New York City 
Your letter of August 26 reaches me after my return from New Eng?
land where I had a very fine view of the eclipse and also visited my rela?
tives. 
Mr. Edgar Moore asked me to recommend someone competent to ad?
vise him in his legal matters and I could think of no one so likely to be 
satisfactory as yourself. 
The Balzer matter was referred to Basil Manly. He took it up with 
his brother Prof. John Manly and we received on August 31a letter, a 
copy of which I enclose. This letter makes it look as if whatever we 
might do for Balzer would merely get us into hot water with Manly. 
Would you advise a conference with Manly to see whether we may get 
by with the proposed sop to Balzer without objections on the part of 
the Manly's? 
P.S. Do you really think that, in view of Mac Donald's statement, 
Balzer can do us any harm if we should now inform him that in view of 
our researches we find the record sufficiently correct and then sit tight? 
1 June 1933?Ballou in Andover, New Jersey, to Scott in New York City 
Enclosed you will find blue printed copies of three affidavits, in du?
plicate, one from Mr. Balzer's bookkeeper and secretary at the time of 
the building of the "Manly Engine," and other two from mechanics 
who worked first for Mr. Balzer and later for Mr. Manly on the engine. 
You have also a letter from Mr. George D. Mac Donald, intended, evi?
dently at the request of Mr. Basil Manly, to discredit Mr. Balzer, but 
definitely substantiating my claims for Mr. Balzer instead. I have a very 
similar letter from him. You have seen most of the pertinent correspon?
dence in the case, wherein Mr. Charles M. Manly discredits himself by 
expressing a gross ignorance of the simplest ideas in elementary physics; 
and again wherein he is requesting advice from Balzer; and still further 
wherein he is requesting tools and other equipment for the reconstruc?
tion of the engine. 
I am here with Mr. Balzer for a couple of days while enroute for 
California. I have discussed the controversy with him again in the 
light of the three new pieces of evidence, namely, these affidavits, 
and he is unwilling to submit the matter to settlement, as you sug-
175 
gested, by a committee to be chosen. It is perfectly clear now, that 
the engine on exhibition in the Smithsonian IS the Balzer engine, 
reconstructed by Manly. You now know the facts, and in fairness to 
your client as well as to Mr. Balzer, your true duty in representing 
your client is to find a graceful means of relabelling the engines and 
publishing the facts. We will not try to dictate the title, but suggest 
t h a t THE BALZER ENGINE RECONSTRUCTED BY MANLY, Or THE ENGINE USED 
IN THE LANGLEY AERODROME BUILT IN NEW YORK CITY BY STEPHEN M. 
BALZER UNDER HIS UNITED STATES PATENTS AND RECONSTRUCTED BY 
CHARLES M. MANLY IN THE SHOP OF THE SMITHSONIAN INSTITUTION, Or 
THE BALZER-MANLY ENGINE, would be truthful and entirely satisfactory 
to us. 
Just because a fraudulent label has been posted on the engine and a 
medal awarded, perhaps inadvertently, is no reason for those who now 
know the truth to perpetuate the fraud. Last Fall, you wrote me sug?
gesting that we submit our proofs, altho we had already furnished more 
than sufficient evidence to establish the facts, including the patent cop?
ies. You have now in your hands unrefutable proofs from the pens of an 
antagonistic witness, a favorable witness, and two impartial but fair 
minded witnessess, in addition to the letters, pictures (in the files of 
the Institution) contracts, and verbal opinions. 
Please do not make it incumbent upon us to take other steps to rec?
tify this false history. Your efforts at this time can avert much expense 
to your client and ourselves, and can prevent the publication of much 
truthful but disagreeable matter against Mi. Charles M. Manly that 
would certainly come to light if we were forced to go elsewhere for jus?
tice and fair play. 
14 March 1932?Affidavit sworn by Berthold D. Willenbrock before 
George H. Hill, Notary Public, New York City 
I am a citizen of the United States having a place of business located 
at 100 East 86th Street, in the City, County and State of New York. I 
was employed by Mr. Stephen M. Balzer under the title of bookkeeper 
from September, 1899 until September 1900. My duties in the Balzer 
shops comprised keeping all of the accounts and records, handling all 
the correspondence and acting as secretary to Mr. Balzer, determining in 
the shops the time that the various men devoted to the various jobs in 
progress, preparing the payroll, receiving the incoming money and dis?
bursing the money to cover accounts payable and the payroll to the 
men. During said time period of my employ in the Balzer shops in New 
York City I was in intimate contact with and familiar with all of the 
176 
work being executed therein, including a large radial gasoline engine 
and a small radial gasoline engine for the Smithsonian Institution, and 
with all of the business transactions pertaining to the work of the Balzer 
shops. 
I have read Chapter VIII of the Langley Memoir on Mechanical 
Flight, and find it to be a combination of statements of facts, of 
shrewdly stated half-truths, and of direct falsehoods, all carefully ar?
ranged with the evident intention of throwing discredit on Mr. Balzer, 
and leading the reader of said chapter to the false conclusion that Mr. 
Charles M. Manly and not Mr. Stephen M. Balzer was the originator 
and constructor of the engine used in Professor Langley's full scale ex?
periments on Mechanical Flight. 
Referring to the second paragraph on Page 218 of said Chapter VIII, 
the statement: "After remaining in New York for several weeks, during 
which time many changes were made in the engine, he finally got it to 
the point where it would develop four horsepower continuously; but it 
seemed impossible to get any better results without an indefinite 
amount of experiment, it was decided that all hope of making this en?
gine an immediate success would have to be abandoned" is entirely 
misleading and false. I was present at the Balzer shops every working 
day from May 6, 1900 until July 1, 1900 and I know that Mr. Manly 
was not in the Balzer shops for more than two consecutive days sepa?
rated by an interval of at least two weeks. I do not know where he was, 
but I do know that he was not at the Balzer shops during the remainder 
of this time. The engine was developing eight horsepower continuously 
instead of four. 
Referring to the first paragraph on Page 219,?Mr. Manly did not go 
to Europe about the middle of June, 1900. He was present at a confer?
ence in the Balzer shops with Mr. Balzer on June 26, 1900. 
Referring to the third paragraph on Page 219,?Mr. Manly did not 
condemn either the large or the small engine. He accepted both, altho 
the small one was not complete, and in consideration of its being in?
complete Mr. Balzer allowed $100.00 on it, accepting $700 instead of 
the agreed $800 for it, with the understanding that Messrs. Newham 
and MacDonald would complete it in the shops of the Smithsonian In?
stitution. These gentlemen were skilled mechanics who had been up to 
this time in the employ of Mr. Balzer and had become expert in execut?
ing the work on the Balzer engines. The statement that Mr. Balzer had 
practically bankrupted himself in his attempts to build these two en?
gines and had spent $8,000 or $10,000 in actual wages over and above 
the contract prices, constitutes a direct falsehood. He did not spend any 
177 
considerable sum over and above the contract prices and the work on 
these two engines was only a small part of the total work in the Balzer 
shops. 
The first paragraph of Page 220 is a combination of direct falsehoods 
and shrewd half truths. Preparatory to the acceptance of the two Balzer 
engines by Mr. Manly, Messrs. Balzer and Manly held a conference at 
which I was present wherein Mr. Balzer agreed to let his two most 
skilled mechanics be taken over by the Smithsonian Institution to con?
tinue work on the small engine and to make certain alterations in the 
large engine that Mr. Balzer laid out in detail. These alterations in?
cluded the substitution of a jump-spark ignition system for the primary 
electric ignition system at that time on the engine. This jump-spark sys?
tem was similar to the system used at that time on the Balzer automo?
bile engine, and employed a single buzzing spark coil and a single set of 
electric batteries with a distributor to lead the spark to the proper cyl?
inder at the proper time. Spark plugs were used in the cylinders. Mr. 
Balzer showed Mr. Manly one of the Balzer engines embodying this ig?
nition system, and gave him detailed instructions as to its working and 
construction. These improvements or alterations included also water 
jackets for the cylinders, brazed up out of sheet steel, to simulate the 
water jackets cast in the heads of the Balzer automobile engines. 
The last two sentences of Page 224 and all of Page 225 of said Chap?
ter VIII is a fairly accurate description of the carbureter that was de?
livered in August 1900 as part of the equipment of the Balzer engine 
for use in the Langley Aerodrome from the Balzer shops in New York. 
I distinctly remember having myself obtained the Tupelo wood and 
brought it to the Balzer shops for the making there of this carbureter. 
I have been in Washington and have seen an engine in a glass case in 
the National Museum of the Smithsonian Institution that was desig?
nated as the Manly engine. I can identify this engine as the Balzer en?
gine, reconstructed with larger cylinders and embodying the improve?
ments suggested by Mr. Balzer to Mr. Manly in August 1900 as 
hereinbefore described. 
I was present at various conferences between Messrs. Balzer and 
Manly at the Balzer shops, between September 1899 and August 1900. 
On various occasions at these conferences I was astonished at Mr. Man?
ly's display of ignorance not only of gasoline engines, but of shop prac?
tice in general and of even elementary physical science. I have read a 
letter from Mr. Manly to Mr. Balzer dated September 28, 1900 and find 
the misconception by Mr. Manly of the simple laws of nature as ex?
pressed in said conferences. 
178 
The aforesaid engine that I saw in Washington retains the following 
features from the Balzer engine from which it was reconstructed:? 
(1) 5 cylinder radial disposition. 
(2) Cylinder mounting of two rings that carry also the main bearings. 
(3) Steel cylinders shrunk over cast iron liners. 
(4) Slipper type connecting rod bearings on a single throw crank. 
(5) Hollow crankshaft. 
(6) Elongated diamond shape steel tubing engine bearers with sheet 
steel web brazed to the tubes. 
(7) Four cycle timed 1 -3 -5 -2 -4 . 
(8) A two lobed cam for operating the valves. 
(9) Tupelo wood filled carbureter. 
22 May 1933?Affidavit sworn by Fred Hewitt before Robert T. High-
field, Notary Public, Washington, D.C. 
I am a citizen of the United States residing in Washington, District 
of Columbia, where I am editor and manager of the Machinists Jour?
nal.81 I was formerly a resident of New York City where I was graduated 
from the Technical School of Cooper Union, and where I was working 
as an expert mechanic. In March of 1900 my friend Richard S. New?
ham informed me that he was being released from employment in 
New York City to enter the employ of the Smithsonian Institution in 
Washington, and that there would be a vacancy for a competent me?
chanic. I therefore replaced Mr. Newham in the shop of Mr. Stephen 
M. Balzer in March, 1900 in the section of New York known as Mott 
Haven. 
While in the employ of said Balzer, I was at times detailed to work 
on a radial five cylinder gasoline engine that said Balzer had invented 
and patented and was building on contract for Professor Langley's 
Aerodrome. I remember that I considered this the most remarkable in?
vention in the way of engines that I had ever seen. While engaged in 
working on said engine, I became thoroughly familiar with its con?
struction and with the unique features that characterized it. I also be?
came familiar with a small scale replica of said engine, that said Balzer 
was constructing on contract to the Smithsonian Institution. 
About the middle of August, 1900 Mr. Manly of the Smithsonian In?
stitution came to New York and accepted delivery on both engines, 
altho the smaller one still lacked cooling fins on the cylinders, and the 
full size one had tested somewhat short of its guaranteed power output. 
81
 Machinists Monthly lournal, was the official organ of the International Associ?
ation of Machinists, Washington, D. C. 
179 
I remained in the employ of the Balzer shop until November, 1900 
when I went to work in Norwalk, Connecticut. In January, 1901 I ac?
cepted an offer of employment from Mr. Manly in the shop of the said 
Institution in Washington, and went to work there, where I remained 
until January, 1904. 
Upon my assuming my duties as an expert mechanic in said shop in 
Washington, I was detailed to construct various parts for the engine 
that was used in the Langley Aerodrome, and which is at present on 
exhibit in the National Museum of the Smithsonian Institution, desig?
nated as the Manly engine. This engine is a reconstruction of the large 
Balzer engine hereinbefore referred to, but with larger cylinders substi?
tuted for the original ones, with the cylinders held stationary, whereas 
in the original engine they revolved and the crankshaft was stationary, 
and with a De Dion design of electric ignition substituted for the make 
and break electric ignition supplied by Balzer. I constructed new pis?
tons and rings, as the enlarged bore required them, altho the stroke was 
not changed, and these new pistons were lighter in weight than the 
original pistons. I also constructed the new combustion chambers for 
the larger cylinders. The nucleus of this new engine was the two side 
rings and the knee brackets with the main bearings, the front engine 
bearer, the cam and timing gear assembly and the valve lifter guides 
from the original Balzer engine. Mr. Manly secured the drilling jig 
from Mr. Balzer wherewith to drill the flanges on the new cylinders, to 
assure their fitting the original Balzer main frame described above. The 
new, larger cylinders were constructed according to Balzer's method as 
used on the original cylinders, namely, shrinking the steel tubing cylin?
ders over cast iron liners, and boring in the assembly. The method of 
construction enabled us to gain sufficient strength, with remarkable 
lightness as well as excellent resistance to wear, for which the engine is 
famous. The combustion chambers were brazed to the steel cylinders, 
and brazed-up water jackets were secured to the cylinders and combus?
tion chambers for cooling. The Balzer construction of the crank pin 
bearing was improved by using a master rod with a bronze crankpin 
bushing, upon which the other four connecting rod segments bore, and 
about which they were retained by end rings similar to Balzer's end 
rings. 
I distinctly recollect how, when it was decided to braze cooling fins on 
the cylinders of the small replica of the Balzer engine in the shop in 
Washington, Professor Langley remarked that it seemed a shame to 
spoil the excellent appearance of the finish by heating them. This small 
engine, with slight modification was used successfully for flights of a 
180 
small model of the man-carrying sized Aerodrome. This model, with the 
modified Balzer engine is on exhibit in the National museum of the 
Smithsonian Institution. 
The Balzer engine, as originally built in New York was equipped 
with a carbureter comprising a sheet metal envelope containing Tupelo 
wood fragments into which gasoline was fed. After considerable work 
had been done at the shop of the Smithsonian Institution in an en?
deavor to find a substitute for this carbureter, which led Mr. Manly to 
the conclusion that nothing else was as satisfactory, a larger copy was 
constructed which was used with the engine in the Aerodrome. 
I always had and still have the highest regard for Mr. Manly and for 
his ability as an engineer as well as for his moral courage that led him 
to persist in the development of the flying machine in the face of heart?
breaking ridicule, and for his physical courage, that led him to risk his 
life in his attempt to pilot it. 
In my estimation, the Manly engine is an enlarged reconstruction of 
the Balzer engine, and it is reasonable to assume that Manly would 
never have thought of using a radial engine had he not had Balzer's 
patented engine as a nucleus for its construction. The success of this en?
gine is due to the combined efforts of Balzer and Manly. 
23 May 1933?Affidavit sworn by Richard S. Newham before Robert T. 
Highfield, Notary Public, Washington, D.C. 
I am a citizen of the United States and reside in the City of Washing?
ton, District of Columbia. I was educated at Cooper Union in the City 
of New York and in 1899 I was a resident of the City of New York, 
where I was working as an expert mechanic. I was employed in 
October 1899 by Mr. Stephen M. Balzer of the City of New York 
to work in his shop on the construction of certain working models 
of pneumatic tools and equipment that were exhibited in the Paris Ex?
position. While I was in the employ of said Balzer, Mr. Manly from the 
Smithsonian Institution at Washington, D.C. called upon Mr. Balzer to 
find out how work was progressing on an engine invented and designed 
by said Balzer which was under construction in the Balzer shop, on con?
tract to said Institution, and a smaller replica of said engine, also for 
said Institution. Manly expressed himself as desirous of securing the 
services of competent mechanics to work on the construction of Profes?
sor Langley's Aerodrome in Washington; and he asked Mr. Balzer's as?
sistance in securing such men. Early in 1900 Mr. Balzer sent two expert 
men, Messrs Philbrook and Wright, releasing them from employment 
in his shop to enter the employ of said Institution. 
181 
382-902 O - 71 13 
In the course of my work in Mr. Balzer's shop, I was called upon to 
assist in the testing of said large engine, in which capacity I became 
thoroughly familiar with its design and construction. While I was in 
the employ of said Balzer, I found him to be a mechanic of exceptional 
skill and a designer of unusual originality. I admired his ingenuity in 
the invention and reduction to practice of the radial four cycle internal 
combustion engine, as evidenced by the two said engines and a certain 
automobile he had constructed employing an engine of similar type, 
but water cooled. I have seen another of his automobiles of cruder con?
struction along the same lines on exhibit in the museum of the said In?
stitution, designated as a donation by said Balzer, and built in 1894. 
In March, 1900 said Balzer released me from employment in his shop 
in order that I might enter the employ of the said Institution under the 
supervision of said Manly, who had been graduated as an engineer, but 
who was not a mechanic. Accordingly, I went to Washington in March 
1900 to enter the employ of said Institution, and I remained there until 
May, 1904. In the shop of said Institution I worked on the construction 
of the Langley Aerodrome and on a small scale replica thereof. 
About the middle of August, 1900 both of said engines were accepted 
and brought to Washington. The large engine had fallen somewhat 
short of its contracted 12 horsepower, and the small engine was incom?
plete to the extent that radiating fins had not been secured to the cylin?
ders. 
In Washington, slight modifications were made in the large Balzer 
engine in which work, I took an active part. This work, together with 
testing, occupied about a month in all, and consisted principally in 
holding the cylinder assembly stationary and rotating the crankshaft, 
whereas the engine had been originally designed for a stationary crank?
shaft with the radial cylinder assembly rotating as in the Gnome, Le-
Rhone, Crossley, and other engines that became very popular during the 
World War. In the said testing in Washington, the said Balzer engine 
developed far in excess of its contracted power, but Mr. Manly decided 
that even more power would be required to fly the Aerodrome. 
Accordingly Mr. Manly started work on a reconstruction of the large 
Balzer engine. I was detailed to construct various parts of this new 
engine. Balzer's main frame was used as a nucleus in this reconstructed 
engine, which had the same stroke but an enlarged bore,?the original 
Balzer engine having a four and three sixteenth inch bore and a five 
and a half inch stroke, while the engine as finally used in the Aero?
drome has a five inch bore and a five and one half inch stroke. In this 
reconstruction, Balzer's radial disposition was used, and he shipped his 
182 
special tools to said Institution to enable us to drill the new cylinder 
flanges to fit the original Balzer frame upon which the new engine was 
based. One of Balzer's supporting trusses was retained, and the other 
was replaced by a stouter copy of the original. Balzer's original cam and 
actuating mechanism and his original cam followers and cam follower 
supports were used. The reconstructed cylinders were built according to 
Balzer's unique method of shrinking steel sleeves over cast iron liners 
and then boring and finishing the assembled cylinders. The original 
Balzer engine was equipped when delivered by him with his unique 
carbureter comprising a sheet metal shell enclosing a mass of fragments 
of Tupelo wood into which the gasoline was fed. The engine as recon?
structed under Manly's supervision, which was used in the Langley 
Aerodrome, was equipped with a copy of this carbureter built to a 
somewhat larger scale. The crank pin bearing on the original Balzer en?
gine was found inadequate to handle the increased output of the recon?
structed engine. This bearing comprised a segmental terminal on each 
connecting rod, each of which was retained by end rings, one on either 
end, which engaged all five of the segments. This bearing system was 
improved at the Smithsonian shop under Manly's supervision, by equip?
ping one master rod with a bronze liner or bushing that bore directly 
on the crank pin, and upon the exterior of which the segments of each 
of the remaining four rods bore, the assembly being retained by the end 
rings. This bearing was found satisfactory. The make and break igni?
tion system with which said original engine had been equipped by Bal?
zer was not satisfactory, and Mr. Manly instructed us to make a copy of 
the De Dion jump-spark system that was installed on an engine he had 
purchased in France from Comte de Dion. This ignition system was 
successful. 
I was well satisfied with my relations with Mr. Balzer while in his 
shop, and I was also well satisfied with my treatment under Mr. Manly, 
for whom I had a high regard. I consider the successful engine in the 
form in which it was finally used in the Aerodrome as the joint work of 
Balzer, who originated it and laid the foundations for it, and of Manly, 
who reconstructed and refined it. 
183 
Summary 
Although neither Balzer nor Manly invented any of the engine's fea?
tures, they were solely responsible for incorporating them in the design. 
The two most important of these were the radial disposition of an un?
even number of cylinders (patented by Felix T. Millet of Beaumont, 
France?British patent number 5199 of 1889) and the master and link 
rod system (patented by George H. Corliss of Providence, Rhode Island 
?American patent number 17,423 of 1857). 
A list of the important features, their advantages, and credit for their 
incorporation in the design follows: 
1. Radial Configuration?This design was contributed by Balzer, 
and was the principal reason for the engine's light weight. The saving 
in weight was due to the short crankshaft and small "crankcase." 
2. Odd Number of Cylinders?This was also contributed by Balzer. 
The odd number of cylinders permitted their firing in sequence for 
smoother engine operation. 
3. Change for Aircooled Rotary Radial to Watercooled Static Ra?
dial?This modification was contributed by Manly with Balzer's approv?
al. It was completed within a month and doubled the engine's horse?
power. Manly made the change because of his mistaken theory that the 
rotary was only one half as efficient as the radial due to differences in 
their crank angles. The decision was fortuitous, however, because the 
valves, being freed of the centrifugal and inertial forces induced when 
the engine was run as a rotary, worked properly for the first time, and 
permitted the engine to develop its designed power. It was a mixed 
blessing, however, because a water cooling system had to be incorporat?
ed in the design which added to the engine's weight, bulk and com?
plexity. Also the engine vibrated noticeably as a radial (rotaries have 
no absolute reciprocation and are therefore smoother) so flywheels had 
to be added with their weight penalty. 
4. Master and Link Rod System?The Balzer-Manly rotary engine 
(first stage of development) was designed to develop 12 horsepower; 
however, soon after it was converted to a radial by Manly it produced 
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twice this power at which point the Balzer type of slipper bearings 
(connecting rods to crankshaft) proved inadequate. Manly solved the 
problem?lack of proper lubrication and sufficient bearing area?by de?
vising a master and link rod system, and retaining the Balzer type of 
slipper bearings for the link rods. It is interesting to note that Manly's 
particular system was used in the Brownback "Tiger" engines as late 
as the 1930s. Almost all radial engines have had a form of the master 
and link rod system. 
5. Ignition System?Balzer had originally decided to use the modern 
type of high tension or spark plug ignition system but changed his 
mind with Manly's approval, and produced instead the conventional 
(for the time) low tension or make and break ignition system. Later 
Manly changed this to the high tension system along the lines em?
ployed by the Museum's De Dion-Bouton engine. 
In addition Manly placed the spark plug in the cylinder head which 
is a much more efficient arrangement than having the spark originate 
in a combustion chamber on the side of the cylinder as was the case in 
stage one of the engine's development. 
6. Carbureter?This was the Balzer type consisting of a tank contain?
ing porous wooden balls into which fuel flowed and out of which va?
pors passed into the engine's induction system. It was superior to the 
automobile carbureters of the time for this special purpose because it 
was floatless and therefore was not affected by vibration or flight atti?
tudes. 
7. Cylinder Construction?Balzer's double-walled type of cylinder was 
used consisting of an outer seamless stell shell yi6 inch thick to pro?
vide strength, and an inner cast-iron liner also l/16 inch thick to provide 
a properly oiled bearing surface for the piston. This type of construc?
tion was much lighter than the single-walled cast-iron cylinder then in 
common use. 
8. Piston Construction?Manly's design was based on the type of pis?
ton used in the Museum's De Dion-Bouton engine. It had thin walls 
and used a piston pin for the connecting rod bearing. Much weight was 
saved over the original Balzer type of pistons which had thick walls and 
a ball and socket bearing for the connecting rod. 
9. Valve System Construction?Manly simplified and improved Bal?
zer's valve system. Originally each cylinder had two automatic and one 
mechanical valve. The final arrangement consisted of one automatic 
and one mechanical valve. Much of Balzer's original actuating mecha?
nism was retained, namely the two lobed cam together with cam follow?
ers and their supports. 
186 
Before Balzer started his controversy with the Smithsonian, he was 
not given official recognition on the exhibit's plaque. With the culmi?
nation of the controversy in 1933, the present exhibit label exemplifies 
this long overdue credit, which reads as follows: 
BALZER-MANLY ENGINE 
1901 
The Langley Aerodrome of 1903 was powered by this engine, 
which developed 52.4 horsepower at 950 revolutions per minute. 
With 20 pounds of cooling water, batteries and accessories, it 
weighed 207.5 pounds, or 3.96 pounds per horsepower. 
Constructed in the shops of the Smithsonian Institution by 
Charles M. Manly under the direction of Samuel P. Langley, it 
incorporates certain features of design from a rotary engine 
developed by Stephen M. Balzer. When bench-tested in 1902, the 
engine ran continuously for three 10-hour periods. 
187 
Epilogue 
It has been the primary concern of this study to put in perspective 
the contributions of Stephen M. Balzer and Charles W. Manly in the 
development of Langley's aero engine, the most advanced of its kind 
in the world at the turn of the century. In the course of this survey, we 
have been able to answer some of the questions posed at the outset and 
to recognize that it was the combined genius of both men that made 
possible the creation of this engine. 
It was in the attempt to recognize their contributions individually 
rather than jointly, that the inequities to their reputations were perpe?
trated. When the aviation industry finally grasped the significance of 
this engine's development and began copying the basic design on a 
large scale, it felt called upon to recognize the genius of at least one of 
the men responsible for its development. The engine had been so far in 
advance of the times that it had taken twenty years for it to be fully 
appreciated. Thus, it is greatly hoped that after 40 more years of contro?
versy, this account has contributed in part to the full recognition of 
both Balzer's and Manly's participation in this pioneering project. 
188 
List of Names 
ABBOT, CHARLES G., of Washington, D.C. At the turn of the century 
he was, "Aid Acting in Charge, Astrophysical Observatory" of the 
Smithsonian Institution. A prominent astrophysicist, he became the 
fifth Secretary of the Smithsonian Institution. Abbot, having worked 
under Langley, carried on his tradition as an astronomer, and has 
written several books on solar radiation. 
AMES, JOSEPH S., of Baltimore, Maryland was a member of the Na?
tional Advisory Committee for Aeronautics at its inception and rose 
to become its chairman. He wrote several books on aerodynamics, and 
became President of Johns Hopkins University. 
BALLOU, J O H N M C K . , of Long Beach, California, is a consulting 
engineer. He was closely associated with Stephen M. Balzer for many 
years. 
BALZER, STEPHEN M., of New York City was a master mechanic. He 
designed, built, and ran Langley's aero engine in its original configu?
ration as an aircooled rotary radial. 
BELL, ALEXANDER GRAHAM, of Washington, D. C , was a regent of the 
Smithsonian Institution. He is well known for his telephonic and 
phonographic apparatus inventions, and less well known for his 
experiments in heavier-than-air craft. 
BOUTON, M. GEORGE, of Paris France, was the chief engineer of the 
De Dion-Bouton firm. 
BRASHER, Dr. J O H N A., of Pittsburgh, Pennsylvania, designed and 
built telescopes. He worked with Langley at the Allegheny Observa?
tory, and became its Acting Director. He then became Acting Chan?
cellor of Western University. 
VON BRAUN, WERNHER, of Washington, D. C , is a pioneer rocket 
expert. He was responsible for the development of the German V-2 
long range missile of World War II. Shortly after the war he was 
189 
invited to the United States to participate in its rocket development 
programs, and for several years was head of the George C. Marshall 
Space Flight Center, Huntsville, Alabama. He is presently Deputy 
Administrator for Planning, National Aeronautics and Space Admin?
istration. His abilities as a scientist, leader, and author have made 
him the world's most renowned living rocket and aerospace scientist. 
BYRD, RICHARD E., of Winchester, Virginia, was a pioneer aviator, 
navigator, polar explorer, and author. He was the first to command 
and navigate flights over the north and south poles. 
CORLISS, GEORGE H., of Providence, Rhode Island, patented the mas?
ter and link rod design in 1857 (American patent number 17,423). 
This has been a feature of almost every successful radial engine built 
since the turn of the century. 
CURTISS, GLENN H., of Hammondsport , New York. T h e most promi?
nent pioneering American aviator after the Wright brothers. l i k e 
them he designed, built, and flew his own airplanes and engines. 
DARCY. A Smithsonian carpenter. 
DAVIS, Captain. A member of the Board of Ordnance and Fortifica?
tion, Office of Secretary of War. 
DE DION, COUNT ALBERT, of Paris, France. He was the administrator 
of the DeDion-Bouton firm. 
DICKSON, T . C. Recorder for the Board of Ordnance and Fortification, 
Office of the Secretary of War; replaced Captain I. N. Lewis. 
DRYDEN, Dr. H U G H L., of Washington, D. C. He was Director of the 
National Advisory Committee for Aeronautics and then became 
Deputy Director of the National Aeronautics and Space Administra?
tion, a position he held until his death. 
EIFFEL, A. GUSTAVE, of Paris, France. Best known as the designer and 
builder of the Eiffel Tower and numerous bridges, he nevertheless 
spent more than a decade studying aerodynamics. 
GREELY, Major General ADOLPHUS W., was Chief Signal Officer of tne 
United States of America. 
GODDARD, ROBERT H., of Worcester, Massachusetts, is known as the 
father of United States Rocketry. He built the first successful liquid-
fueled rocket, and continued his developments to the extent that the 
Nazi government used his patents in its V-2 program, dur ing World 
War II . 
190 
HADLEY, F. W. A clerk in Langley's office. 
H E W I T T , FRED. A machinist employed by Balzer to work on the Bal?
zer-Manly engine, and then by Manly for the same purpose. 
HODGES, F. W. A clerk in Langley's office. 
HUNSAKER, Dr. JEROME C , of Boston, Massachusetts, is Professor 
Emeritus of Aeronautical Engineering, Massachusetts Institute of 
Technology. He was responsible for the design of various aircraft 
including the NC-4 , first to cross the Atlantic Ocean. 
KARR, W. W. Accountant of the Smithsonian Institution. During June 
1905 it was ascertained that he had stolen $68,558.61 from the Insti?
tution over a 14-year period. 
LANGLEY, SAMUEL P., of Washington, D. C , was the third Secretary 
of the Smithsonian Institution. Although a foremost astrophysicist 
and inventor of the balometer (a sensitive instrument for measuring 
the temperature of celestial bodies) he is best known for his experi?
ments with heavier-than-air craft. 
LAWRANCE, CHARLES L., of Long Island, New York. He was President 
of the Wright Aeronautical Corporation, manufacturers of the famous 
Wright J -5 "Whir lwind" which powered Lindbergh's "Spirit of St. 
Louis." 
LECOEUR, of Paris, France. An engineer who was employed by the 
DeDion-Bouton Company. 
LEWIS, I. N. Recorder for the Board of Ordnance and Fortification, 
Office of the Secretary of War. 
LINDBERGH,, CHARLES A., of Darien, Connecticut. Best known for his 
famous solo flight from New York to Paris in 1927, he is also well 
known as an author, aviation consultant, and conservationist. 
LUDEWIG. A machinist who worked for Manly. 
MACDONALD, GEORGE D. A machinist employed by Balzer to work 
on the Balzer-Manly engine, and then by Manly for the same purpose. 
T h e Wells diary entries misspell the name as "McDonald." 
MANLY, BASIL, was a brother of Charles M. Manly. 
MANLY, CHARLES M., of Washington, D. C , was Professor Langley's 
"Aide in Aerodromics." He built both of Langley's gasoline powered 
Aerodromes, and developed both of their engines. 
MANLY, J O H N , was a brother of Charles M. Manly. 
191 
MAXIM, Sir H I R A M S., of London, England, was a famous expatriate 
American inventor. In 1894 his 3i/2 ton "lift test r ig" flying machine 
"rose" from the ground. 
MAYNARD, GEORGE C , of Washington, D. C , was Curator of the De?
partment of Mechanical Technology, Uni ted States National Museum, 
Smithsonian Institution. 
MILLET, FELIX T., of Beaumont, Texas, patented the radial disposi?
tion of an uneven number of cylinders in 1889 (British patent num?
ber 5199). This has been an important type of aero engine for more 
than 70 years. 
MOLSON, E., was an entrepreneur interested in promoting Balzer's 
automobile business. 
MOORE, EDGAR, was a friend of Dr. C. G. Abbot. 
NEWHAM, RICHARD S. A machinist employed by Balzer to work on 
the Balzer-Manly engine, and then by Manly for the same purpose. 
PHILBROOK, AUSTIN H. A machinist employed by Balzer to work on 
the Balzer-Manly engine, and then by Manly for the same purpose. 
PIERCE. A machinist employed by the Smithsonian Insti tution. 
PUGSLEY. Agent for Franklin Stock Cylinder Oil Company. 
RATHBUN, R. Assistant Secretary of the Smithsonian Insti tution in 
charge of Office and Exchanges. He ran the Aerodromic projects 
whenever Langley was away. 
REED, R. L., Foreman of Aerodromic Work. Worked on all of the 
Aerodromic projects. His specialty was carpentry. 
RUSSELL. A machinist employed by Manly to work on the Balzer-
Manly engine. 
SCOTT, LLOYD N. Lawyer hired by Abbot, fifth Secretary of the Smith?
sonian Institution, to assist in settling the dispute between the Balzer 
and Manly partisans. 
SHEPARD, ALAN B., JR. , of Houston, Texas. First American astronaut 
in space. 
SMITH, W I L L I A M M C K A Y , was an associate of Manly. Later he was 
placed in charge of the Switchboard Department of the Western Electric 
Company of New York City. 
SPEIDEN, W. L. An independently employed draftsman who often did 
Aerodromic work for Langley and Manly. 
192 
STOUT, J O H N F. Balzer's Sales Agent. 
STRATTON. [Not identified.] 
THURSTON, R. H. Director of the Schools of Mechanical Engineering 
and of the Mechanic Arts, Sibley College, Cornell University. He had 
been a good friend of Langley for many years. 
WALCOTT, CHARLES D. T h e fourth Secretary of the Smithsonian Insti?
tution, succeeding Langley. 
WALTERS. An employee of Sir Hiram Maxim. 
WATKINS, J. E. Curator of Minerals and Technology, Smithsonian 
Institution. 
WEED, J O H N W. Balzer's bondsman. 
WELLS, GEORGE B. Assistant to Manly for the Aerodromic projects. At 
Langley's request he kept a diary which is one of the most important 
sources of information about the Balzer-Manly engine. 
WHEELER, CAPTAIN. A member of the Board of Ordnance and Fortifi?
cation. 
WILLENBROCK, BERTHOLD D. A bookkeeper of Balzer's. 
WRIGHT, F. F. A machinist employed by Balzer to work on the Balzer-
Manly engine, and then by Manly for the same purpose. 
WRIGHT, WILBUR and ORVILLE, of Dayton, Ohio, were the first men to 
make powered, sustained, and controlled flights in an airplane, and 
land on ground as high as that from which they took off. 
193 
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