AZIMUTH

(From the Arabic.) A term used in as tronomy, to denote the arc of the horizon intercepted between the meridian and the vertical circle pa ing through a star or other celestial body; or the angle made at the zenith by the meridian and the vertical circle in which the body is situated. The azimuth may be counted either from the north or the south point of the horizon: modern astronomers seem to prefer beginning at the north point, and counting eastward and westward to 180°; but it is not one of those elements usually observed in astronomy, being easily deduced from the declination, which can be measured much more conveniently and accurately. In trigonometrical surveys, however, on the earth's surface, the accurate determination of the azimuth of an object is an operation of very great importance. It is usually made with the theodolite. AZIMUTH CIRCLES, or VERTICAL CHICLES, are great circles of the sphere pa ing through the zenith, and intersecting the horizon at right angles. [s. 126]