The Operation of Sand Clocks and Their Medieval Development

Abstract

The sand clock1 is one of those technological enigmas whose development seems to have been dependent as much on concurrent human values as on the logical course of technological advancement. Technologically speaking, this device could have been developed at any time after the successful introduction of the water clock (clepsydra) sometime before 1500 B.c.,2 since both devices operate on the same fundamental principles with a liquid being used as the flowing substance in one case and a powdered granular material in the other. Yet all artifactual evidence to date indicates that the sand clock did not