That which is gained in height in the bounce.

The power of the impetus lasts throughout the whole reflected motion and ends at the beginning of the natural motion.

The moving body observes as much elevation in its reflected motion as the power of the percussion accompanies it in that motion.

The power of the percussion does not accompany the motion of the moving body except at the summit of the greatest height of its bounce.

The power of the percussion does not accompany the reflected motion except at the summit of its height.

The moving body rises as much in its reflected motion as the power of the percussion accompanies it.

The moving body moves as far from the place it struck as the power of the impetus that accompanies it lasts.

And it rises as much as the percussion with its power accompanies it.

Therefore the whole length of the reflected motion arises from the simple power of the impetus, and all its length from the simple power of the impetus.

Whence one concludes that the power of the impetus will have such a proportion to the power of the percussion as the height of the reflected motion has to its length.

The moving body moves as far from the struck place as the power of the impetus that moves it lasts: the power of the impetus accompanies it, drives it away, leads it.

And it rises from the struck place as much as the percussion with its power thrusts it and leads it.

Therefore the whole length of the reflected motion arises from the simple power of the impetus, and all its height from the simple power of the blow.

Whence we shall say that the proportion the power of the impetus has to the power of the percussion is as the height of the reflected motion has to its length.