But if that other equal body be likewise in motion, and moving in the same direction, after contact they will move with reciprocal velocities.
"3.

A body, however great, is moved by a body however small impelled with any velocity whatsoever.
"5.

The quantity of motion of two bodies may be either increased or diminished by their shock; but the same quantity towards the same part remains, after subtracting the quantity of the contrary motion.
"6.

The sum of the products arising from multiplying the mass of any hard body into the squares of its velocity is the same both before and after the stroke.
"7.

A hard body at rest will receive a greater quantity of motion from another hard body, either greater or less than itself, by the interposition of any third body of a mean quantity, than if it was immediately struck by the body itself; and if the interposing body be a mean proportional between the other two, its action upon the quiescent body will be the greatest of all."(10) This was only one of several interesting and important communications sent to the Royal Society during his lifetime.