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o which a plane is divided by the coördinate axes. The upper right-hand part is the first quadrant; the upper left-hand part the second; the lower left-hand part the third; and the lower right-hand part the fourth quadrant.

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 90º. -- Quadrantal versor, a versor that expresses rotation through one right angle.

A thin quadrant, made of brass, wood, etc., showing a stereographic projection on the plane of the equator. By it are found the hour of the day, the sun's azimuth, the altitude of objects in degrees, etc. See Gunter's scale.

Having three quadrants; thus, a triquadrantal triangle is one whose three sides are quadrants, and whose three angles are consequently right angles.

as, an adroit mechanic, an adroit reply. "Adroit in the application of the telescope and quadrant." Horsley. "He was adroit in intrigue." Macaulay.

The portion of a graduated instrument, as a quadrant or astrolabe, carrying the sights or telescope, and showing the degrees cut off on the arc of the instrument Whewell.

An instrument for taking altitudes, as a quadrant, sextant, etc. Knight.

A modification of the quadrant, for measuring small angles. [Obs.]

hape of a circular arc or an arch; as, the colored arc (the rainbow); the arc of Hadley's quadrant.

The quadrant of an azimuth circle.

t formerly used for taking the altitude of the heavenly bodies, but now superseded by the quadrant and sextant; -- so called because the observer turned his back to the body observed.

A rude sort of quadrant formerly used for taking the sun's altitude at sea.

ing are of the circle. Let AB be an arc in a circle, whose radius OA is unity let AC be a quadrant, and let OC, DB, and AF be drawnpependicular to OA, and EB and CG parallel to OA, and let OB be produced to G and F. E Then BD is the sine of the arc AB; OD or EB is the cosine, AF is the tangent, CG is the cotangent, OF…

r of astronomy at Gresham College, London, who invented also Gunter's chain, and Gunter's quadrant.

of a hollow ball of ivory or metal suspended by a treated from the center of a graduated quadrant, and held in a stream to measure the velocity of the water by the inclination given to the thread; a kind of current gauge.

us (below). -- Index finger. See Index, 5. -- Index glass, the mirror on the index of a quadrant, sextant, etc. -- Index hand, the pointer or hand of a clock, watch, or other registering machine; a hand that points to something. -- Index of a logarithm (Math.), the integral part of the logarithm, and always one les…

A thin, flat piece of board in the form of a quadrant of a circle attached to the log line; -- called also log-ship. See 2d Log, n., 2.

ertaining to a wall; being on, or in, a wall; growing on, or against, a wall; as, a mural quadrant. "Mural breach." Milton. "Mural fruit." Evelyn.

An instrument for measuring angles (generally called a quadrant), having an arc which measures up to 9Oº, but being itself the eighth part of a circle. Cf. Sextant.

A figure, somewhat hatched-shaped, bounded by a semicircle and two inverted quadrants, and equal in area to the square ABCD inclosed by the chords of the four quadrants. [Written also pelicoid.] Math. Dict.