Anchor Escapement
American Watchmaker and Jeweler (1892)
This form of escapement is mostly used in clocks, although in the older watches a variety of lever escapement was also known as the anchor escapement and was so called because of the resemblance of the earliest forms to a ship's anchor. The variety of forms in this escapement are innumerable, and include both the dead beat and recoil escapements. Like many other inventions in horology, neither the inventor nor the date of this escapement is known with certainty, the two claimants for the honor being Hooke and Clement, the latter a London clockmaker, in the years 1675 to 1680. The imperfect escapement in use at the time of the application of the pendulum to clocks was the source of much annoyance and the clockmaker was constantly on the alert for an escapement which would give to the pendulum a more nearly isochronous vibration, with the result of the invention of the anchor escapement, which remains practically the same at the present day. There are clockmakers who believe that the recoil escapement is preferable to the dead beat escapement, but this is not a fact, if proper care is given to every detail of both the designing and the execution of the work. The recoil escapement was made to overcome inequalities in the motive force, for with this form the pendulum was not so sensitive to a change in the motive power as in the dead-beat escapement. There is a form of clock escapement made which is a combination of the dead-beat and recoil, being dead-beat on one pallet and recoil on the other, and from this circumstance are known as half dead-beat or half recoil escapements. Fig. 6 illustrates a form of anchor escapement which is extensively used in American watches.
What Has Changed in the Last Century
The mechanism itself is exactly as the American Watchmaker and Jeweler described it in 1892: recoil and dead-beat anchor escapements, and the half-dead-beat hybrid, are still what you find inside a pendulum clock today, and the dead-beat form is still credited to George Graham. The attribution question the entry left open has narrowed a little, with most horological writers now giving the anchor to the London clockmaker William Clement around 1670, while Hooke's claim is generally treated as unproven. What has changed is the escapement's standing rather than its design: pendulum clocks reached their limit with the free-pendulum clocks of the 1920s, and precision timekeeping then passed to quartz oscillators and, from the 1950s, caesium atomic clocks, which in 1967 became the basis of the definition of the second. The anchor escapement survives as a craft and heritage mechanism, not as a scientific instrument.
Written for this edition, 2026.