The Astronomical Observatories of Jai Singh c6.s1.t1.11

c6.s1.t1.11

³ To draw the temporary hour circles, divide the day portion (that is the portion below the horizon in the diagram) of each of the three circles—the tropic of Capricorn, the equator, and the tropic of Cancer—into twelve equal parts and draw circles *t*₁, *t*₂, etc., through each trio of corresponding parts. For the equal hours draw through *X*, the centre of the circle of the horizon, a circle concentric with the equator and tropics. Graduate this circle at intervals of 15 degrees starting from the south point and proceeding westwards. With the south point and in succession the other points of graduation as centres, and radius equal to the radius (*XH*) of the horizon draw arcs *e*₁, *e*₂, etc., from the circle of Capricorn to that of Cancer. (These arcs will pass through the equal divisions of the equator, already marked for temporal hours.) The result of this construction is that any point on the ecliptic, as the ‘ankabūt is rotated, passes from one equal hour line to another in one twenty-fourth of a revolution.