A Concise History of Science in India c6.s4.t1.4

c6.s4.t1.4

The east-west and the north-south lines are easily determined by observing the points where the shadow of the gnomon touches a circle drawn on the horizontal plane in the forenoon and in the afternoon. The line joining these two points is parallel to the east-west line passing through *O*; the north-south line passing through *O* is perpendicular to the former. All Hindu texts give clear rules for finding these cardinal directions.