Mechanical watch is a watch that uses a non-electric mechanism to measure the passage of time. They are driven by a spring (called a mainspring) which must be wound periodically, and releases the energy to turn the watch's wheels as it unwinds. They keep time with a balance wheel, which oscillates back and forth at a constant rate, and make a 'ticking' sound when operating. Mechanical watches evolved in Europe in the 1600s from spring powered clocks, which appeared in the 1400s.Mechanical watches are not as accurate as modern quartz watches and are generally more expensive. They are now worn more for their aesthetic qualities and as jewelry than for their timekeeping ability.
The first spring-powered pocket watch was created by Peter Henlein in 1524. In 1556, Taqi al-Din may have created a spring-powered pocket watch that could measure time in minutes, by having three dials for the hours, degrees and minutes.Until the quartz revolution of the 1960s, all watches were mechanical. Early watches were terribly imprecise; a good one could vary as much as 15 minutes in a day. Modern precision (a few seconds per day) was not attained by any watch until 1760, when John Harrison created his marine chronometer.
Mechanical watches are powered by a mainspring. Because the mainspring provides an uneven source of power (its torque steadily decreases as the spring unwinds), watches from the early 1500s to the early 1800s featured a chain-driven fusee which served to regulate the torque output of the mainspring throughout its winding. Unfortunately, the fusees were very brittle, were very easy to break, and were the source many problems, especially inaccuracy of timekeeping when the fusee chain became loose or lost its velocity after the lack of maintenance.
