All of the characteristics of a sound wave may be graphically represented by curves.
Even the sound wave, or wave of concussion, had a mind to distinguish itself.
Surely, if a condensation is not produced, there can be no sound wave!
According to the wave theory, a condensation and rarefaction are necessary to constitute a sound wave.
These terms must not be confounded with the term "sound wave" or "vibrations" so often used in discussions on the theory of sound.
If the air is removed from around the apparatus no sound wave can go forth.
The sound wave appears in the first dozen pictures as a hazy ring of light, opening out from the center of explosion.
The form of the reflected light wave will be identical with that of a sound wave reflected under similar conditions.
In the first picture the sound wave C appears as a circle of light and shade, and has just intersected the plate.
We will now consider a case of refraction, and show the slower velocity of the sound wave in carbonic acid.