Model: X01 Verge and Foliot Escapement
Escapements convert static energy, as in the form of a falling weight, into periodic oscillations which can then be used to measure the passage of time. As such escapements are dynamic mechanisms as opposed to kinematic devices.
This model has its origins around the first millennium according to Reuleaux and certainly by the middle ages c 1300, according to other references. This model has a balance wheel with elastic spring. The original verge and foliot did not have a harmonic oscillator until Huygens(1629-1695) added the pendulum to control the period of the oscillation. Later the balance wheel was used to replace the pendulum as in the sea going chronometers developed by John Harrison in the 18th century.
A verge and foliot escapement was used in many cathedral tower clocks as in Salisbury Cathedral (1386) in England.
Many clock escapement models may be seen in the National Clock and Watch Museum in Columbia Pennsylvania.

Francis Moon 2001-00-00