Altitude

(al't -tād.) [From L. altitudo, height.] (Math.) The A. ofa figure is the perpendicular or nearest distance of its vertex from the base of an object, the elevation of such object above the horizontal plane; or it is the length of a perpendicular let fall to that plane. Acce ible A. of an object, is that to whose base there is no acce , to measure the nearest distance to it on the ground from any place; the converso is called inacce ible A.-The instruments most generally used in measuring A. are the quadrant, sextant, theodolite, . -A. of the Eyc. (Persp.) The perpendicular height of the eye above the geometrical plane.-A. of a Star, dc. (Astron.) The elevation of any star or other heavenly body above the horizon, or an arc of a vertical circle, intercepted between the star and the horizon. This A. is ci ther true or apparent, according as it is calculated from the rational or sensible horizon: the difference between these two is called by astronomers the parallax ofA.-A. of Mountains. See HYPSOMETRY. [s. 24]