Graham Escapement
An escapement invented by George Graham, in which the locking faces of the pallets are arcs of a circle concentric with the axis of the anchor, from which it gets the name dead-beat escapement, that is, the escape wheel tooth lies dead upon the locking face of the anchor and has no recoil or circular motion, except at the time it delivers an impulse. This form requires more care in making than the recoil. When applied to a seconds pendulum the escape wheel is made with thirty teeth, if a second hand is mounted. The anchor is made to cover from eight to ten teeth of the escape wheel. As the number of teeth covered by the anchor is decreased, correspondingly greater care is necessary in the making. Saunier says, "if this amount is exceeded the thickening of the oil has an appreciable influence, and, with a less amount, very accurate workmanship is necessary.