Music, the interval or space of time which the person who beats time takes between the rising and falling of his hand or foot, in order to conduct the movement, sometimes quicker, and sometimes slower, according to the kind of music, or the subject that is sung or played.

The measure is that which regulates the time we are to dwell on each note. See Time.

The ordinary or common measure is one second, or 60th part of a minute, which is nearly the space between the beats of the pulse or heart; the syttole, or contraction of the heart, answering to the elevation of the hand; and its diafhole, or dilatation, to the letting it fall. The measure usually takes up the space that a pendulum of two feet and a half long employs in making a swing or vibration. The measure is regulated according to the different quality or value of the notes in the piece; by which the time that each note is to take up is expressed. The semibreve, for instance, holds one rise and one fall; and this is called the measure or whole measure, sometimes the measure note, or time note; the minim, one rise, or one fall; and the crotchet, half a rise, or half a fall, there being four crotchets in a full measure.

Measure Binary, or Double, is that wherein the rise and fall of the hand are equal.

Measure Ternary, or Triple, is that wherein the fall is double to the rise; or where two minims are played during a fall, and but one in the rise. To this purpose, the number 3 is placed at the beginning of the lines, when the measure is intended to be triple; and a C, when the measure is to be common or double. This rising and falling of the hands was called by the Greeks ἀγρίς and ἑταῖρος. St Augustine calls it plausus, and the Spaniards compas. See ARSIS and THESIS.

Powder Measures in Artillery, are made of copper, and contain from an ounce to 12 pounds; these are very convenient in a siege, when guns or mortars are loaded with loose powder, especially in ricochet firing, Measuring, &c.