Fig. 23.
If we divide our lever and attach the long end to one portion of an axle, as at A, [Fig. 23], and the short end to another part of it at B, the result will be the same as long as the proportions of the lever are not changed. It will still transmit power or impart motion according to the relative lengths of the two parts of the lever. The capacity of our levers, [Fig. 22], will be limited by that point at which the ends of the levers will separate, because they are held at the points of the fulcrums and constrained to move in circles by the fulcrums. If we put more levers on the same axles, so spaced that another set will come into action as the first pair are disengaged, we can continue our transmission of power, [Fig. 24]; and if we follow this with still others until we can add no more for want of room we shall have wheels and pinions, the collection of short levers forming the pinion and the group of long levers forming the wheel, [Fig. 25]. Thus every wheel and pinion mounted together on an arbor are simply a collection of levers, each wheel tooth and its corresponding pinion leaf forming one lever. This explains why the force decreases and the motion increases in proportion to the relative lengths of the radii of the wheels and pinions, so that eight or ten turns of the barrel of a clock will run the escape wheel all day.
Fig. 24.
We now come to the verge or anchor, and here we have the same sort of lever in a different form; the verge wire, which presses on the pendulum rod and keeps it going is the long arm of our lever, but instead of many there is only one. The short arm of our lever is the pallet, and there are two of these. Therefore we have a form of lever in which there is one long arm and two short ones; but as the two are never acting at the same time they do not interfere with each other.
