1. On the Connection between Cohesion, Elasticity, Dilatation, and Temperature

At various times there have arisen supporters of one or other of two extreme hypothesis concerning the nature of what we define as force. These are the hypothesis of “action at a distance” and of “no action at a distance.”According to the latter hypothesis, the centre of gravity of no body, however large or however small, can be moved from a position of rest, nor can its motion be altered in direction or amount, except by direct collision with another portion of matter.