[Illustration: FIG. 172.--The pitch given out by a fork depends upon
its shape.]
The disturbance created by a vibrating body is called a wave.
256. Waves. While the disturbance which travels out from a sounding
body is commonly called a wave, it is by no means like the type of
wave best known to us, namely, the water wave.
If a closely coiled heavy wire is suspended as in Figure 173 and the
weight is drawn down and then released, the coil will assume the
appearance shown; there is clearly an overcrowding or condensation in
some places, and a spreading out or rarefaction in other places. The
pulse of condensation and rarefaction which travels the length of the
wire is called a wave, although it bears little or no resemblance to
the familiar water wave. Sound waves are similar to the waves formed
in the stretched coil.
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