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.
Examine the second photograph, which shows a spherical, sound wave starting at the focus of a parabolic mirror.
Surely, if a condensation is not produced, there can be no sound wave!
The sound wave starts in one focus and the reflected wave, of spherical form also, shrinks to a point at the other focus.
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.
These terms must not be confounded with the term "sound wave" or "vibrations" so often used in discussions on the theory of sound.
This is followed almost immediately by the sound wave through the sea.