Is another contrivance for registering
or counting revolutions. A tappet, B, supported
on the fixed pivot, C, is struck at
every revolution of the large wheel (partly
represented) by a stud, D, attached to the
said wheel. This causes the end of the tappet
next the ratchet-wheel, A, to be lifted,
and to turn the wheel the distance of one
tooth. The tappet returns by its own weight
to its original position after the stud, D, has
passed, the end. being jointed to permit it
to pass the teeth of the ratchet-wheel.