in Dialling, the style, pin, or cock of a dial, which by its shadow shows the hour of the day. The gnomon of every dial represents the axis of the earth: (See Dial and Dialling.)—The word is Greek, γνώμων, which literally implies something that makes a thing known; by reason that the style or pin indicates or makes the hour known.

in Astronomy, a style erected perpendicular to the horizon, in order to find the altitude of the sun. See Astronomy.

By means of a gnomon, the sun's meridian altitude, and consequently the latitude of the place, may be found more exactly than with the smaller quadrants. See Quadrant.

By the same instrument the height of any object may be found: for as the distance of the observer's eye from the gnomon, is to the height of the style; so is the distance of the observer's eye from the object, to its height.

For the uses and application of gnomons, see Geography.

GNOMON of a Globe; the index of the hour circle.