AZIMUTH
, of the sun, or star, &c, is an arch of the horizon, intercepted between the meridian of the place, and the azimuth or vertical circle passing through the sun or star; and is equal to the angle at the zenith formed by the said meridian and vertical circle. Or it is the complement to the eastern or western amplitude.—The azimuth is thus found by trigonometry; As radius is to the tangent of the latitude, So is the tangent of the altitude of the sun or star, To the cosine of the azimuth from the south, at the time of the equinox.
Azimuth, magnetical, an arch of the horizon contained between the magnetical meridian, and the azimuth or vertical circle of the object; or its apparent distance from the north or south point of the compass. This is found by observing the sun, or star, &c, with an azimuth compass, when it is 10 or 15 degrees high, either before or after noon.
Azimuth Compass, an instrument for finding either the magnetical azimuth or amplitude of a celestial object. The description and use of this instrument, see under the article Compass.
Azimuth Dial, a dial whose stile or gnomon is perpendicular to the plane of the horizon.
Azimuths, or Vertical Circles, are great circles of the sphere intersecting each other in the zenith and nadir, and cutting the horizon at right angles.—These azimuths are represented by the rhumbs on common sea charts; and on the globe by the quadrant of altitude, when screwed in the zenith. On these azimuths is counted the height of the sun or stars, &c, when out of the meridian. |
