Escapement which slowly replaced the anchor in precision clocks. The Graham or deadbeat escapement was an improvement of the anchor escapement first made by Thomas Tompion to a design by Richard Towneley in 1675 although it is often credited to Tompion's successor George Graham who popularized it in 1715. In the anchor escapement the swing of the pendulum pushes the escape wheel backward during part of its cycle. This 'recoil' disturbs the motion of the pendulum, causing inaccuracy, and reverses the direction of the gear train, causing backlash and introducing high loads into the system, leading to friction and wear. The
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