(Lat.), equipoise, equality of weight, balance; as when the two ends of a lever or a balance, Equimultiples, in Arithmetic and Geometry, a number or quantity multiplied by the same number or quantity. Hence equimultiples are always in the same ratio to each other as the simple quantities before multiplication. Thus, if 6 and 8 are multiplied by 4, the equimultiples 24 and 32 will be to each other as 6 to 8.

Equinoctial (aequus, equal, and noct, night), in Astronomy, a great circle of the sphere, under which the equator moves in its diurnal motion.

The equinoctial, or equinoctial line, is ordinarily confounded with the equator; but there is a difference, the equator being moveable, and the equinoctial immoveable; the equator being drawn about the convex surface of the sphere, and the equinoctial on the concave surface of the magnus orbis.

When the sun, in its progress through the ecliptic, comes to this circle, the days and nights are equal all over the globe. The equinoctial, then, is the circle which the sun describes, or appears to describe, at the time of the equinoxes; that is, when the length of the day is everywhere equal to that of the night, which happens twice a-year, viz., about the 21st of March and the 23rd of September.

Equinoctial Points, the two points in which the equator and ecliptic intersect each other. The one, being in the first point of Aries, is called the vernal point or equinox; the other, in the first point of Libra, is denominated the autumnal point or equinox. See Astronomy, vol. iv., p. 12.

Equinoctial Dial, a dial of which the plane is parallel to that of the equinoctial.