This is like a simple clock escapement, and prevents repeated typing.

Although no other example is known, it is possible that this was the first clock escapement design.

They used a motor with its speed regulated by a clock escapement, cam-operated contacts, and a jeweled-bearing spur-gear differential.

The weight of the balls on the descending chain drives a conventional pendulum clock escapement, geared to the hands on the four faces.

Finally, the "circular error" of a pendulum decreases as length of the swing decreases, so better clock escapements could greatly reduce this source of inaccuracy.

However, indirect evidence, such as a sudden increase in cost and construction of clocks, points to the late 13th century as the most likely date for the development of the modern clock escapement.

There is a "Learning Center" introducing some of the basic technologies of the mechanical timekeeper, such as the pendulum, and a large and varied exhibit on many types of clock escapement.

Towneley designed a novel clock escapement for this purpose and two astronomical clocks were commissioned to his design from the clockmaker Thomas Tompion and installed at the Greenwich Observatory.

Encouraged by the possibilities of commerce or trade, these extraordinarily sophisticated modifications of the world come into being, sometimes anonymously (as with the invention of the clock escapement or eyeglasses), sometimes under the guidance of an inventor.

Elected a Fellow of the Royal Society in 1821 for mathematical achievements, he had by that time invented a logometer (an early slide rule), and went on to design and patent a friction wheel and a clock escapement.

But when his brother Kerin, youngest son of Evor the Clockmaker, commits an indescretion with Adeliza, a neighbor's daughter, he is packed off on a hasty quest to uncover the secret of an advanced clock escapement for the family firm.

Other Chinese discoveries and inventions from the Medieval period,include: block printing, movable type printing, phosphorescent paint, endless power chain drive and the clock escapement mechanism.The solid-fuel rocket was invented in China about 1150, nearly 200 years after the invention of gunpowder (which acted as the rocket's fuel).

This great astronomical hydromechanical clock tower was about ten meters high (about 30 feet) and featured a clock escapement and was indirectly powered by rotating wheel either with falling water and liquid mercury, which freezes at a much lower temperature than water, allowing operation of the clock during colder weather.