INTERVAL

, in Musie, the difference between two sounds, in respect of acute and grave. Authors distinguish several divisions of an Interval, as first into Simple and Compound. The

Simple Interval is that without parts, or division; such are the octave, and all that are within it; as the 2d, 3d, 4th, 5th, 6th, and 7th, with their varieties.

Compound Interval consists of several lesser Intervals; as the 9th, 10th, 11th, 12th, &c, with their varieties.

This Simple Interval was by the ancients called a Diastem, and the Compound they called a System.

An Interval is also divided into Just or True, and into False. The

Just or True Intervals, are such as all those above mentioned, with their varieties, whether major or minor. And the

False Intervals, are the diminutive or superfluous ones.

An Interval is also divided into the Consonance and Dissonance; which see.

INTESTINE Motion of the parts of fluids, that which is among its corpuscles or component parts.

When the attracting corpuscles of any fluid are elastic, they must necessarily produce an intestine motion; and that, greater or less, according to the degrees of their elasticity and attractive force. For, two <*>lastic particles, after meeting, will fly from each other, with the same degree of velocity with which they met; abstracting from the resistance of the medium. But when, in leaping back from each other, they approach other particles, their velocity will be increased.