The Astronomical Observatories of Jai Singh c15.s2.t1.9

Language: English

c15.s2.t1.9

(6) The instrument of two pillars. At the centre of a bar supported by two pillars a pin was fixed, round which revolved an alhidade, or sighter, 12 feet long. Vertically beneath this pin was another, to which was fastened a graduated bar, 17½ feet long, and along this bar the end of the sighter was free to run. This appears to have been a modification of Ptolemy's parallactic rulers.¹

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