This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 Excerpt: ...thrown into water, we see a number of circular waves formed around the place where the stone strikes the surface. Where the stone strikes the water, a depression is made and the water is piled up around it. The water in the depression, however, quickly rises, and even mounts above its ordinary level. The motion is soon ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 Excerpt: ...thrown into water, we see a number of circular waves formed around the place where the stone strikes the surface. Where the stone strikes the water, a depression is made and the water is piled up around it. The water in the depression, however, quickly rises, and even mounts above its ordinary level. The motion is soon communicated to the rest of the water, and around the point where the stone entered the surface a series of circular waves is formed, in which the water is alternately above and below its level when at rest. Experiment (54).--Tie a ball to a string formed of elastic gum, as in the common return-ball. Holding the end of the string in the hand, allow the ball to drop. Observe that it falls for a certain distance, stretching the gum, when the elasticity of the gum causes it to rise until its weight again causes it to fall. Observe, too, that these motions continue for some little time, the ball alternately falling and rising in a nearly vertical direction. When the ball falls, the string lengthens; when the ball rises, the string shortens. It is the elasticity produced by these lengthenings and shortenings, that causes the ball to move down and up. If any part of the air is suddenly disturbed; for example, if it be compressed, it will, on expanding, move to and fro, like the string holding the return-ball, and the compressed part will become alternately less dense, and more dense, than the surrounding air. But these motions are not confined to the air first acted on; they spread in all directions around the point where the air was disturbed and cause spherical waves, in which the air is alternately more and less dense than the surrounding air. 126. The Cause of Sound.--When a bell is struck so as to sound, its sides shake to and fro. These shak ...
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