History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c14.s3.18

v1.c14.s3.18

An examination of a large number of coins apparently intended to be round reveals that only a few of them are exactly circular in shape. It appears that the very method of production followed in ancient Indian mints made it impossible for the true circle to be obtained, since there was nothing to stop the flan from spreading irregularly under the blow of the hammer.¹⁵