The Indus Civilization (Cambridge History of India, Supplementary Volume) c15.20

c15.20

A considerable number of Harappan weights has been examined, and their constant accuracy cited as an illustration of civic discipline. They are uninscribed, but fall into a well-defined system unlike any other in the ancient world. In the lower denominations, the system is binary: 1, 2, 1/3 × 8, 8, 16, 32, etc., to 12,800, with the traditional Indian ratio 16 (cf. 16 annas = 1 rupee) as the probable unit, equivalent to 13.625 g. In the higher weights the system was decimal, with fractional weights in thirds. Seven exceptional weights from Mohenjo-daro seem to conform with a different ratio, though the number is too small to build on:³ otherwise the uniformity is striking and significant.