accessible, and inaccessible. See PRACTICAL GEOMETRY.

Altitude, of a figure, is the nearest distance of its vertex from its base, or the length of a perpendicular let fall from the vertex to the base.

Altitude in optics, is the height of an object above a line, drawn parallel to the horizon from the eye of the observer.

Altitude of the eye, in perspective, is its perpendicular height above the geometrical plane.

Altitude of a star, &c. in astronomy, is an arch of a vertical circle, intercepted between the star and the horizon. See ASTRONOMY.

Altitude of motion, according to Dr Wallis, is its measure estimated in the line of direction of the moving force.

Altitude, in astrology. See EXALTATION.

Altitude of fluids, is more usually expressed by the term depth. See DEPTH.

Determinative Altitude, that from whence a heavy body falling, acquires a certain velocity by its natural acceleration.