Anchor escapement clockmaker George Graham around 1715. This gradually superseded the recoil escapement and is used in virtually all modern pendulum clocks with anchor escapements. The anchor escapement consists of two parts: the "escape wheel", which is a vertical wheel with pointed teeth on it rather like saw teeth, and the "anchor", shaped vaguely like a ship's anchor, which swings back and forth on a pivot just above the escape wheel. On the two arms of the anchor are curved and flat faces which the teeth of the escape wheel push against, called "pallets". The central shaft of the anchor is attached
Mechanical energy nonconservative forces, like frictional forces, will be present, but often they are of negligible values and the mechanical energy's being constant can therefore be a useful approximation. In elastic collisions, the mechanical energy is conserved but in inelastic collisions, some mechanical energy is converted into heat. The equivalence between lost mechanical energy (dissipation) and an increase in temperature was discovered by James Prescott Joule. Many devices are used to convert mechanical energy to or from other forms of energy, e.g. an electric motor converts electrical energy to mechanical energy, an electric generator converts mechanical energy into electrical energy and a