The Astronomical Observatories of Jai Singh c6.s1.1

c6.s1.1

9. Of these metal instruments the astrolabe appears to have played the most important part in Jai Singh's work. Indeed in the middle ages the astrolabe was one of the chief astronomical instruments. The Arabs perfected it at a very early date and it remained one of the principal astronomical instruments until about the 17th century, and is still used in the East for astrological purposes. It was usually of brass¹ and varied in diameter from a couple of inches to several feet. The mariner's astrolabe (as used by Columbus) was adapted from that of the astronomers about A.D. 1480, but was superseded by Hadley's Quadrant of 1731. The famous scholar Gerbet, who afterwards became Pope Sylvester II, had such skill in making astrolabes, etc., that he was supposed to have sold his soul to the devil. There are many references in mediæval literature to the astrolabe. More than three centuries before Jai Singh, Chaucer wrote his Treatise on the Astrolabe. "Trust well," he says, "that alle the conclusions that have be founde, or else possibly might be founde in so noble an instrument as is an Astrolabe been unknowe parfitly to any mortal man in this regioun, as I suppose."