A Philosophical Essay of Musick

...determined that the pulses at the mouth in such a case will receive no interruption by the trapped air, but may maintain their positions and produce a tone varying in the same proportion from the tone of the pipe.

It may be objected that if this were so, there would be a mixture of sounds; not only would the tone that is in harmony with the tone of the pipe be heard, but also the tone of the pipe itself along with it.

To this it may be answered that the vibration of the trapped air is not significant enough to be heard distinctly, though it may alter a sound. We see this when a pipe produces its true tone: it resonates more deeply in the body original: "speaks more in the belly" than when it breaks into an octave. But to set aside that answer, perhaps when the note breaks, the column of trapped air divides into proportional parts. This happens because the vibrating force at the mouth and the resistance at the opening meet one another in the middle, or at other divisions. This will make the vibrations of the trapped air coincide with every pulse at the mouth of the pipe. This is the more probable because a very small opening in the middle of a pipe will make it break into an eighth an octave above; this seems to happen not by any reduction of the trapped air, but by interrupting the integrity of the air column.

Of the nature of Keys in MUSIC, and

of a single TUNE.

Before any note is struck, the ear is indifferent to all sounds. But when any tone is heard, that indifference is ended, and the mind is occupied with the present sound. If the second note has no relation to the first, the impression made by the first will be completely wiped out and forgotten; the sounds will be disjointed and incoherent. But if the second note has a relation to the first, it is consistent...