Part 706

4. An instrument for measuring altitudes, variously constructed and mounted for different specific uses in astronomy, surveying, gunnery, etc., consisting commonly of a graduated arc of 90∞, with an index or vernier, and either plain or telescopic sights, and usually having a plumb line or spirit level for fixing the vertical or horizontal direction.

Gunner's quadrant, an instrument consisting of a graduated limb, with a plumb line or spirit level, and an arm by which it is applied to a cannon or mortar in adjusting it to the elevation required for attaining the desired range. -- Gunter's quadrant. See Gunter's quadrant, in the Vocabulary. -- Hadley's quadrant, a hand instrument used chiefly at sea to measure the altitude of the sun or other celestial body in ascertaining the vessel's position. It consists of a frame in the form of an octant having a graduated scale upon its arc, and an index arm, or alidade pivoted at its apex. Mirrors, called the index glass and the horizon glass, are fixed one upon the index arm and the other upon one side of the frame, respectively. When the instrument is held upright, the index arm may be swung so that the index glass will reflect an image of the sun upon the horizon glass, and when the reflected image of the sun coincides, to the observer's eye, with the horizon as seen directly through an opening at the side of the horizon glass, the index shows the sun's altitude upon the scale; -- more properly, but less commonly, called an octant. -- Quadrant of altitude, an appendage of the artificial globe, consisting of a slip of brass of the length of a quadrant of one of the great circles of the globe, and graduated. It may be fitted to the meridian, and being movable round to all points of the horizon, serves as a scale in measuring altitudes, azimuths, etc.

Quad*ran"tal (?), a. [L. quadrantalis containing the fourth fourth part of a measure.] (Geom.) Of or pertaining to a quadrant; also, included in the fourth part of a circle; as, quadrantal space.

Quadrantal triangle, a spherical triangle having one side equal to a quadrant or arc of 90∞. -- Quadrantal versor, a versor that expresses rotation through one right angle.

Quad*ran"tal, n. [L.] 1. (Rom. Antiq.) A cubical vessel containing a Roman cubic foot, each side being a Roman square foot; -- used as a measure.

2. A cube. [R.]

Quad"rat (?), n. [F. quadrat, cadrat. See Quadrate.] 1. (Print.) A block of type metal lower than the letters, -- used in spacing and in blank lines. [Abbrev. quad.]

2. An old instrument used for taking altitudes; -- called also geometrical square, and line of shadows.

Quad"rate (?), a. [L. quadratus squared, p. p. of quadrare to make four-cornered, to make square, to square, to fit, suit, from quadrus square, quattuor four. See Quadrant, and cf. Quadrat, Quarry an arrow, Square.] 1. Having four equal sides, the opposite sides parallel, and four right angles; square.

Figures, some round, some triangle, some quadrate.

Foxe.

2. Produced by multiplying a number by itself; square. " Quadrate and cubical numbers." Sir T. Browne.

3. Square; even; balanced; equal; exact. [Archaic] " A quadrate, solid, wise man." Howell.

4. Squared; suited; correspondent. [Archaic] " A generical description quadrate to both." Harvey.

Quadrate bone (Anat.), a bone between the base of the lower jaw and the skull in most vertebrates below the mammals. In reptiles and birds it articulates the lower jaw with the skull; in mammals it is represented by the malleus or incus.

Quad"rate (?), n. [L. quadratum. See Quadrate, a.] 1. (Geom.) A plane surface with four equal sides and four right angles; a square; hence, figuratively, anything having the outline of a square.

At which command, the powers militant That stood for heaven, in mighty quadrate joined.

Milton.

2. (Astrol.) An aspect of the heavenly bodies in which they are distant from each other 90∞, or the quarter of a circle; quartile. See the Note under Aspect, 6.

3. (Anat.) The quadrate bone.

Quad"rate (?), v. i. [imp. & p. p. Quadrated (?); p. pr. & vb. n. Quadrating.] [See Quadrate, a.] To square; to agree; to suit; to correspond; -- followed by with. [Archaic]

The objections of these speculatists of its forms do not quadrate with their theories.

Burke.

Quad"rate, v. t. To adjust (a gun) on its carriage; also, to train (a gun) for horizontal firing.

Quad*rat"ic (?), a. [Cf. F. quadratique.]

1. Of or pertaining to a square, or to squares; resembling a quadrate, or square; square.

2. (Crystallog.) Tetragonal.

3. (Alg.) Pertaining to terms of the second degree; as, a quadratic equation, in which the highest power of the unknown quantity is a square.