What Makes the Works of a Watch Go?
A watch like any other machine which we have, only goes when power is applied in some form or another. In the case of a watch it is a spring. A spring is an elastic body, such as a strip of steel, as in the case of the watch, coiled spirally which, when bent or forced out of its natural state, has the power of recovering its shape again by virtue of its elastic power. The natural state of a watch spring is to be open flat and spread out to its full length. When you wind a watch you coil this spring, i.e., you bend it out of its natural shape. As soon as you stop winding the spring begins to uncoil itself, trying to get back to its natural shape, and in doing so makes the wheels of the watch which operate the hands go round. The spring then, or rather its elasticity, which always makes an effort to get back to its natural state, is the power which makes the watch go. Men who make watches arrange the spring and the other machinery in the watch in such a way that it will uncoil itself only at a certain rate of speed. Sooner or later the spring loses its elasticity and then its power to make the watch go.