Magnetic azimuth

Azimuth Az"i*muth, n. [OE. azimut, F. azimut, fr. Ar. as-sum?t, pl. of as-samt a way, or perh., a point of the horizon and a circle extending to it from the zenith, as being the Arabic article: cf. It. azzimutto, Pg. azimuth, and Ar. samt-al-r[=a]'s the vertex of the heaven. Cf. {Zenith}.] (Astron. & Geodesy) (a) The quadrant of an azimuth circle. (b) An arc of the horizon intercepted between the meridian of the place and a vertical circle passing through the center of any object; as, the azimuth of a star; the azimuth or bearing of a line surveying. [1913 Webster]

Note: In trigonometrical surveying, it is customary to reckon the azimuth of a line from the south point of the horizon around by the west from 0[deg] to 360[deg]. [1913 Webster]

{Azimuth circle}, or {Vertical circle}, one of the great circles of the sphere intersecting each other in the zenith and nadir, and cutting the horizon at right angles. --Hutton.

{Azimuth compass}, a compass resembling the mariner's compass, but having the card divided into degrees instead of rhumbs, and having vertical sights; used for taking the magnetic azimuth of a heavenly body, in order to find, by comparison with the true azimuth, the variation of the needle.

{Azimuth dial}, a dial whose stile or gnomon is at right angles to the plane of the horizon. --Hutton.

{Magnetic azimuth}, an arc of the horizon, intercepted between the vertical circle passing through any object and the magnetic meridian. This is found by observing the object with an azimuth compass. [1913 Webster]