A mechanical watch is a watch that uses a non-electric/electronic mechanism to measure the passage of time. It is driven by a spring which must be wound periodically, and which releases the energy to activate the balance wheel, which oscillates back and forth thanks to the Balance spring at a constant rate, transmitting the impulse through the lever escapement to the gear train, that divides the impulse into hours, minutes and seconds, thus making a 'ticking' sound when operating. Mechanical watches evolved in Europe in the 1600s from spring powered clocks, which appeared in the 1400s.