The Astronomical Observatories of Jai Singh c9.8

c9.8

In figures 34 and 35, AB is one edge of the gnomon, the angle ABC is equal to the latitude of the place, EF and GH are at right angles to AB, as also are DF, MH. If KL is the direction of the sun, then the arc KG indicates the time before noon, and the angle HGL the declination, or sun’s angular distance from the equator. In the actual structure, the considerable width of AA¹ and GE (each being over 9 feet at Jaipur) practically duplicates the instruments. Each edge of the quadrants is graduated in hours and minutes,² as well as in degrees, and each edge of the gnomon has two scales of tangents, one from H to B, and the other from F to A. In the figure tan HGL = HL/GH, and GH is the radius of the quadrant MKG.