Planispheric Astrolabes from the National Museum of American History

Abstract

This monograph describes via catalog entries and comparative analysis what has for many years been one of the five largest collections of planispheric astrolabes in the world. Until 1974, when seven instruments that had been on long term loan were returned to their owner, the National Museum of American History of the Smithsonian Institution preserved 48 examples of functioning astrolabes. This is the first detailed discussion of all 48, together referred to as the collection. The majority of the instruments, including the seven no longer on loan to the museum, once were part of the collection of Samuel Verplanck Hoffman of New York City.<br/>An introductory chapter, using words and drawings, describes the basic elements of a planispheric astrolabe, thereby introducing terms that appear frequently in later sections. The section "Historical Perspective" emphasizes the information conveyed by the makers&#39; names and dates inscribed on instruments in the collection. It places this information in the larger context of the history of the development of the astrolabe. Each of the functional elements incorporated into the astrolabes in the collection is discussed in detail in a chapter devoted to comparative analysis. That section illuminates distinctions between European instruments and instruments made in India or in the Muslim world. In each section, the basic features of a functional element are described and any remarkable treatments of these features are noted. In addition, the traditional function of each element is specified, relying on instructions for its use prepared by Masha allah, al-Biruni, or Chaucer. Photographs illustrate each section.<br/>Complementing this comparative analysis is an illustrated catalog of the collection. It includes transcriptions and translations of inscriptions that appear on the instruments. Appended to the catalog are two sections that present and discuss the information conveyed by the gazetteers incorporated into many Muslim astrolabes and the star networks (or retes) included on all complete astrolabes in the collection. Finally, a third appendix describes the process used to prepare the ecliptic circle component of the astrolabe&amp;apos;s star network. In doing so it conveys basic information about the construction of a planispheric astrolabe.