ब्राह्मस्फुटसिद्धान्त (ब्रह्मगुप्त - शून्य, कुट्टक, बीजगणित एवं सम्पूर्ण २१ अध्याय सान्वय सटीक)

GOLAYANTRA OR ARMILLARY SPHERE 341 equinoctial colure, and adding an inner secondary of the ecliptic, which as well as the meridian, is doubled. According to Lalande, the astrolobe of Ptolemy, from which Tycho Brahe derived his equatorial armillary, consisted only of four circles: two placed at right angles to represent the ecliptic and solstitial colure; a third turning on the poles of the ecliptic and serving to mark longitudes; and a fourth, within the other three, furnished with sights to observe celestial objects and measure their latitudes and longitudes. Whether the ancient Greeks had any more complicated instrument formed on similar principles, and applicable to astro- nomical observations, is perhaps uncertain. We have no detailed description of the instrument which Archimedes is said to have devised to represent the phenomena and motions of the heavenly bodies; nor any sufficient hint of its construction; nor does Cicero’s account of the sphere exhibited by Posidonius suggest a distinct notion of its structure. Among the Arabs, no addition is at present known to have been made to the armillary sphere; between the period when the Almagest was translated and the time of Alhazen, who wrote a treatise of optics, in which a more complicated instrument than that of Ptolemy, is described; Alhazen’s armillary sphere is stated to have been the prototype of Tycho Brahe’s; but neither the original treatise, nor the Latin translation of it, are procurable and one is therefore unable to ascertain whether the sphere, mentioned by the Arabian author, resembled that described by Indian astronomers. At all events, says Colebrooke, he is more modern than the oldest of the Hindu writers. Here we give the literal translation of the passage on armi- llary sphere or Golayantra occurring in the Sūrya-Siddhānta : Let the astronomer frame the surprising structure of the terrestial and celestial spheres. Having caused a wooden globe to be made (of such size) as he pleases; to represent the Earth : with a staff for the axis passing through the centre, and exceeding the globe at both ends; let him place the supporting hooks, as also the equinoctial circle. Three circles must be prepared, (divided for signs and degrees), the radius of which must agree with the