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
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