HANDBOOK OF ACOUSTICS - online book

A complete view of Acoustical Science & its bearings on music, for musicians & music students.

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THE TRANSMISSION OF SOUND.                  13
17 equidistant particles of water at rest, and the circles in which they are about to move, in the same direction as the hands of a clock. In (0), the position of each of these particles is given at the moment when they form parts of the two complete waves A and B, which are supposed to be passing from left to right; the 8th particle from the left has just passed through of its journey,
that isof the whole circumference ; the 7th particle has passed through the 6th through the 5th has just performed
its journey; the 4th, the 3rd, the 2nd, and the first has just completed its course and regained its original position. In (1) each particle has moved throughmore of its curve, and the wave has passed through a space equal to of its length. In (2) each particle has moved through more, and the wave has again advanced as before; and so on, in (3), (4), (5), (6), (7), and (8). Each particle in (8) has the same position as in (0), having made one complete journey ; and the wave has advanced one wave length. Thus we see, as in the experiment with the trough, that each particle makes one complete journey in the same time as the wave takes to travel its own length.
Another variety of wave motion may be studied thus: Fill an india-rubber tube, about 12 feet long and J inch in diameter, with sand, and fasten one end to the ceiling of a room. Hold the other end in-the hand, and jerk it sharply on one side. Notice the wave motion thus communicated to the tube, the wave consisting of two protuberances, one on each side of the position of the tube at rest; the one corresponding to the crest of the water wave, and the other to its trough. Let the uppermost row of dots in fig. 11, represent