A PORTION of our last chapter dealt of Centrifugal Force. We will now proceed to another well-known power, which seems to be a variation, or perhaps a division, of the same power. I mean the principle of Oscillation, which has done so much for the present state of the world. I mention the connection of the two principles because it is evident that, if Oscillation were continued in one direction, it would be converted into centrifugal force. In fact, it can only be considered as centrifugal force interrupted.

The chief point in this subject is the equal time occupied by the oscillating body, no matter what may be the “arc” distance through which it always, provided that the length of the line remains the same. The discovery of this principle by Galileo in a church at Florence is too well known to need repetition.

This principle may be observed by any one, and at almost any time. The Spider at the end of its line illustrates it, and so does a stone tied to a string, both of which objects are shown in the illustration.

In various departments of Art, Oscillation is absolutely invaluable. We will take, for instance, the best known of these examples, namely, the Pendulum, by which the movements of clocks are regulated. Without some mode of regulation, the works would run down rapidly, and the clock rendered incapable of measuring time.