Types of Mechanical Clocks

History

• Historians have not ascertained the origin of the mechanical clock but do know that the mechanical clock was invented in monasteries. A mechanical device was devised to toll the bell that brought monks to prayer services. The oldest surviving clock is located in England at the Salisbury Cathedral and dates back to 1386.

Tower Clock

• The original mechanized clock was the tower clock, which was derivative of the clocks made in the monasteries. These clocks were quite large, often made from iron structures. Falling weights drove this clock. These weights were attached to a long cord or rope that was coiled around a drum or the main shaft of the clock. The "verge" regulated the falling and lifting of the weight. A verge was a large wheel with teeth that transferred energy from the falling weight and the turning of the clock hands.

Coiled Spring Clock

• During the early 15th century, inentorss introduced the spring-driven clock. These clocks became small and portable because they no longer required large weights. People began using these mechanical clocks in their homes. Like the tower clocks, they tended to be inaccurate by about a half hour each day. These clocks were wound, literally loosening the coiled spring inside the watch that would slowly ravel and turn the wheels, regulating the hands of the clock.

Pendulum Clock

• Shortly after the spring mechanism, in the late 16th century, Galileo began using a pendulum to regulate the mechanical clock time. Similar to the weight mechanism, the pendulum's own weight causes it to swing back and forth, gaining momentum and energy upon each swing. The pendulum arc corresponds to the second hand of the clock and, depending on its arc, relates to about one second in time. The pendulum may swing more frequently given the size of the clock, increasing as the clock becomes smaller.

Drawbacks

• The mechanical clock has since been replaced with electrical, quartz and atomic clocks to maintain more accurate time. The most notable drawback of the mechanical clock is that it relies on gravity, but it cannot use gravity with perfect efficiency, so the mechanism begins to slow and causes inaccurate time keeping.