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The "Jyotish Yantra' (Astrolabe) at the L. D. Institute.
The study of the instruments and technology to any science is one of the essential steps for understanding its evolution. Instruments which have survied from various periods in the past will provide the most concrete evidence of the corresponding stages in the evolution of the particular science to which they relate. The collection and systematic arrangement of scientific instruments to illustrate the evolution of science and technology in India has not been attempted in any of our museuins. This is largely due to the absence of interest in the preservation of objects of historical value, and partly due to the great decline of the scientific spirit in India which resulted from foreign comination.
Various kinds of mechanical devices are mentioned in our sastras and other early literary works in Indian languages, but few of thein exist today. Only some items associated with historical personages or having some sentimental value have been preserved, at times by persons who had no idea of their value.
Though astronomy is one of the oldest among the sciences, and coupled with astrology one of the most widely cultivated, not many early astronomical instruments are found in India today. The well known collection of such instruments at Jaipur owes its origin to Maharaja Sawai Jai Singh II (1686-1743), the famous astronomer prince who built the astronomical observatories (Jantar Mantar) at Jaipur, Delhi, Banaras and Ujjan, which still survive as historical monuments at these places. He has also written a book about the astrolable (Yantra Raja Rachana) The astrolable appears to have played the most important part in Jai Singh's work. Jai Singh himself tells us that he first constructed, 'according to Mussulman books, instruments of brass. His collection of metal instruments which Kaye found at Jaipur included Arabic and Persian astrolabes dating from the time of Shah Jahan.
In the middle ages the astroable was one of the chief astronomical instruments. The Arbas perfected it at a very early date and it remained one of the principal astrnomical instruments until about the 17th century. The Hindu name for the astrolable is Yantra Raja. The carliest Hindu work on this instrument is by Mahendra Suri, written in A.D. 1370. It was usually of brass and varied in diameter from a couple of inches to several feet.