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 This gradually superseded the recoil escapement and is used in virtually all modern pendulum clocks with anchor escapements.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
Escapement was unworkable. Arnold also designed a spring detent escapement but, with improved design, Earnshaw's version eventually prevailed as the basic idea underwent several minor modifications during the last decade of the 18th century. The final form appeared around 1800, and this design was used until mechanical chronometers became obsolete in the 1970s. The detent is a detached escapement; it allows the balance wheel to swing undisturbed during most of its cycle, except the brief impulse period, which is only given once per cycle (every other swing). Because the driving escape wheel tooth moves almost parallel to the pallet, the escapement