Fig. 46.—BAT AND BALL.

867. What principles of natural philosophy are illustrated by the results of bat and ball?

Percussion, when the bat strikes the ball; rotatory motion, when the ball is sent whirling away; momentum, which it acquires by velocity; elasticity, when it rebounds from an object against which it strikes; reflected motion, when it is turned by a body upon which it impinges; friction, as it rolls along the ground; the communication of force, when it sets another body in motion against which it strikes; gravitation, when it falls to the earth; and inertia, when it lies in a state of rest.


"A wise son makes a glad father: but a foolish son is the heaviness of his mother."—Proverbs x.


868. Why do pith-tumblers always pitch upon one end?