This want undoubtedly led to the
invention of the detent escapement. The early escapements were all
frictional escapements, i.e., the balance staff was never free from
the influence of the train. The verge escapement, which was undoubtedly
the first employed, was constantly in contact with the escape wheel, and
was what is known as a "recoiling beat," that is, the contact of the
pallets actually caused the escape wheel to recoil or turn back. Such
escapements were too much influenced by the train, and any increase in
power caused the timepiece to gain. The first attempt to correct this
imperfection led to the invention and introduction of the fusee, which
enabled the watchmaker to obtain from a coiled spring nearly equal power
during the entire period of action. The next step in advance was the
"dead-beat escapement," which included the cylinder and duplex. In these
frictional escapements the balance staff locked the train while the
balance performed its arc of vibration.
FRICTIONAL ESCAPEMENTS IN HIGH FAVOR.
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