Devices based on sundials; used to display time with two mechanical arms, one shorter than the other, pointing to the hour and minute, respectively (some had a third hand which tracked the passing seconds); minutes were calculated by multiplying the number closest to the big hand by five. Sometimes required winding. Sometimes read using terms like “quarter” or “half.” Sometimes necessitated doing math by assigning values to letters such as X, V, and I. Conveniently, the hands moved in the direction known as “clockwise.”