XVI. On a mechanical theorem applicable to heat

The following theorem (virial theorem) is proved: let there be any system of material points in stationary motion. (Stationary motion means that the points are constrained to move in a limited region of space, and the velocities only fluctuate within certain limits, with no preferential direction.) Denote by X, Y, Z the components of the force acting on a particle at position x, y, z in space, and form the quantity