Horology (lit. 'the study of time'; related to Latin horologium; from Ancient Greek ὡρολόγιον (hōrológion) 'instrument for telling the hour'; from ὥρα (hṓra) 'hour, time', interfix -o-, and suffix -logy) is the study of the measurement of time. Clocks, watches, clockwork, sundials, hourglasses, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of instruments used to measure time. In current usage, horology refers mainly to the study of mechanical time-keeping devices, while chronometry more broadly includes electronic devices that have largely supplanted mechanical clocks for the best accuracy and precision in time-keeping. People interested in horology are called horologists. That term is used both by...