Book: #2

THE PROCEDURE: 

Attach a vertical rod or stand to the bench. Clamp the apparatus to the rod with the apparatus extending over the edge of the bench so that when the gun is fired the two balls will miss the bench and hit the floor at the same time. Cock the apparatus and place the ball with the whole through it on the shaft of the cocked gun. So that when the gun is fired the shaft is drown out of the ball and the ball drops vertically to the floor. Place the other ball in the dimple on the other side of the apparatus. So that when the gun is fired the shaft hits the side of the ball and sends this ball fling in the horizontal direction. Both balls are set into motion at the same time when the gun is fired and shows that the two balls will strike the floor at the same time despite the difference in the ball's trajectories. The two balls striking the floor can be observed by the simultaneous sounds at the point of impact.