Granting any two sounds are drawn from two instruments at the same time,
there will be heard a third sound, the more perceptible as the listener
is near the middle of the distance between them.
If the two sounds are succeeding ones in the order of consonance, as,
for instance, the octave and the twelfth, the double octave and the
seventeenth major, &c., the sound resulting will be the octave of its
principal.