76. 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.