The Astronomical Observatories of Jai Singh c11.s2.t1.2

c11.s2.t1.2

47. Samrāṭ Yantra.—The large Samrāṭ Yantra is situated at the south-east corner of the observatory enclosure. It is the largest of all of Jai Singh's instruments, being nearly 90 feet high and 147 feet long, the radius of each quadrant being 49 feet 10 inches. It is graduated to read to seconds, but this is impossible in practice, owing to the ill-defined shadow (i.e., due to the size of penumbra). The tangent scales on the edge of the gnomon (see p. 36) cannot now be used, owing to the instrument overlooking the palace zenana enclosure. The readings of the quadrants appear to be slightly inconsistent, the eastern quadrant giving readings that are about two minutes out, as compared with the time registered on the western quadrant.