Essay on the Architecture of the Hindus c4.57

c4.57

"Having marked," says the commentary, "a point in the middle of a level piece of ground, from that point, and with a radius equal to the length of the shadow projected at the third *ghatica* after the sun's rise, plus half of the diameter of the gnomon (because the shadow is measured from the circumference of the gnomon), let a circle be described, and in the centre of it let a *sanc'hu* be erected, of twelve *angulas* in height and of the same diameter: mark points where the shadow falls before and after noon on the east and west of the circumference; then having computed the sines of the declination three *ghaticas* after sun-rise, and three *ghaticas* before sun-set, multiply the difference between these two sines by the hypothenuse of the shadow at the third *ghatica* after sun-rise, and the product being divided by the cosine of the latitude of the place, the quotient will give the *angulas* or their integral parts. Then remove the eastern point so many *angulas*, &c. according as the sun is in the south or north latitude; by this means all the points of the compass may be rectified.”