Anchor escapement the anchor is aligned with the bending point of the spring. This arrangement results in a more stable pendulum support than simply suspending the pendulum directly from the anchor. The anchor is very tolerant of variations in its geometry, so its shape varied widely. In late 19th century, in Britain, the usual design was a 90° angle between the pallets, which meant locating the anchor pivot a distance of ≈ 1.4 times the escape wheel radius from the escape wheel pivot. In a grandfather clock, which had a pendulum which swung once per second, the escape wheel often had 30
Anchor escapement is still a frictional rest escapement because the sliding of the escape tooth on the dead face adds friction to the pendulum's swing, but it has less friction than the recoil escapement because there is no recoil force. In contrast to the backward slant of the anchor escape wheel teeth, the deadbeat escape wheel teeth are radial or slant forward to ensure that the tooth makes contact with the 'dead' face of the pallet, preventing recoil. In 1826 British astronomer George Airy proved that a pendulum that is driven by a drive impulse that is symmetrical about its bottom equilibrium