A Philosophical Essay of Musick

by attempting to find the cause of the tone of a pipe, and the pulse that gives the sound.

There is in any pipe a cavity of a certain gauge or size which is exposed to the outward air, though only in some parts of it; and according to the size of that cavity is the tone of the pipe.

The air in any cavity is capable of being compressed by outward force. If the cavity is large, the air easily yields to compression; but if it is small, it is more difficult to compress. When the compressing force ceases, the body of air that was compressed with difficulty flies out with sudden violence; that which is more easily compressed restores itself less quickly. Because of this, every cavity has a certain tone according to the measure of the vibrations of the air within it, which it will maintain regardless of how the force is applied to it. This is similar to how water in a shallow area or creek, when moved by the large waves of the sea, does not maintain the motion of those huge waves, but instead moves in waves proportional to its own size and depth.

Based on this, I conclude that any pipe—whether made of wood, stone, glass, or metal—has a certain and fixed tone according to its gauge and cavity. This is the natural tone which will be produced by blowing into it. If the cavity is small, the sound will be acute original: "acute"; meaning high-pitched, and it may be made even higher in pitch by apertures original: "apertures"; holes or openings, by which the cavity is diminished and the enclosed air is exposed to the outward air to a greater degree.

When I say the tone depends on the proportion of the cavity regardless of what the pipe is made of, I do not deny that if the materials of the pipe are soft and yielding, it may cause some small alteration to the tone compared to what it would be if the materials were of a hard and firm substance, where the impelling air would find a more brisk resistance. However, the difference is insignificant; and since the "spring" The elastic property of air that allows it to bounce back after compression. of the air depends mainly upon the size of the cavity, I take no notice of it.

To show how the pulses are caused, by which the included air is put into this motion, it is necessary to observe the