_Trap and Ball.--Gifts from the Vicar.--An Antiquarian History of the Ball.--The See-saw.--The Mechanical Powers.--The Swing.--The Doctrine of Oscillation.--Galileo’s Discovery.--The Pendulum.--An interesting letter.--Mr. Seymour and the Vicar visit Major Snapwell._ Mr. Seymour, having observed his children busily engaged at the game of Trap and Ball, determined, as usual, to make it subservient to scientific instruction. With this view he hastily sketched a diagram, and proceeded with it to the scene of sport. “Now, Tom, let me see how far you have profited by our late conversation. I have some questions to ask you about the action of your Trap and Ball,” said his father. “I do not suppose there is much philosophy in the game,” observed Tom. “Of that we shall judge presently.--Can you tell me the direction which the ball takes after it flies from the spoon of the Trap, in consequence of the blow of the bat upon the trigger?” “It flies upwards, to be sure, and allows me to strike it with my bat,” answered the boy. “Very true; but at what angle?--I see you hesitate, look therefore at the diagram I have prepared, and attend to my explanation of it.” Mr. Seymour produced the sketch which we here present to our readers. [Illustration: Sketch of Trap.] “A B represent the spoon and trigger in their quiescent position. Upon striking the end B with the bat, they are brought into the position C D. The spoon will thus have described the small arc A C, when it will be suddenly stopped by the end of the trigger D coming into contact with the shoe. The motion of the ball, however, will not be arrested, and it will consequently be projected forward out of the spoon.” “Exactly,” exclaimed Louisa, “in the same manner as the shilling flew off the wine glass, or a person on a galloping horse would be thrown over the head by its suddenly stopping.” “I thank you, Louisa; your memory, I perceive, has not suffered from the drenching you received from the water-cart;[25]--but can you tell me,” continued Mr. Seymour, “the direction which the ball will take _after_ its release from the spoon?” This was a step beyond Louisa’s knowledge, and her father, in order to assist her, begged her to consider in what direction it was moving _before_ it left the spoon. “You have just told us,” said Tom, “that it described an arc, or portion of a circle.” “Very well,” said Mr. Seymour; “and did not the philosophy of your sling teach you that, when a body revolving in a circle is suddenly disengaged, it will fly off in a right line in the direction in which it was moving at the instant of its release?--the ball therefore will describe the tangent C E.” “It is all clear enough to me now,” said Tom, evidently vexed that he had overlooked a principle which had been so lately explained to him by the action of his sling. “I now see, too,” added Tom, “why the ball seldom flies off at the same angle in every trap.”