CLOCK

differs from a watch mainly in having its machinery moved by a pendulum. The use of a horologium, or hour-teller, was common among the ancients, and Charlemagne had a clock given to him in 807. In the 12th century clocks were used in monasteries. Richard, abbot of St. Albans, made a clock (somewhat like those now used) in 1326. It indicated the ebb and flood tide. In 1657 Huyghens applied the pendulum to clock-work.