Rotary querns

Rotary querns also called rotary grinding stone, hand mills etc., consists of two circular stones of varying diameters that fit together: an upper, mobile stone and a lower, stationary stone.  The upper mobile stone is called the hand stone. The lower one is the stationary stone. There the upper stone rotates over the bottom stationary stone by means of a projecting handle. Grain, pulses and other foods and materials are fed through a central hopper and ground between the faces of the two stones.

An Indian women using Rotary quern (courtesy:millsarchive.org)