Alter ego (Lat., 'another I'), a second self, one who represents another in every respect. This term was formerly given, in the official style of the Kingdom of the Two Sicilies, to a substitute appointed by the king to manage the affairs of the kingdom, with full royal power.
Alter′nate, in botany, placed on opposite sides of an axis at a different level, as leaves.—Alternate generation, the reproduction of young not resembling their parents, but their grandparents, continuously, as in the jelly-fishes, &c. See Generations, Alternation of.
Alternator. See Electricity.
Althæ′a, a genus of plants. See Hollyhock and Marsh-mallow.
Althorn, one of the instruments of the sax-horn family, the tenor sax-horn. See Sax-horn.
Al′tiscope, an instrument consisting of an arrangement of mirrors in a vertical framework,
by means of which a person is enabled to overlook an object (a parapet, for instance) intervening between himself and any view that he desires to see, the picture of the latter being reflected from a higher to a lower mirror, where it is seen by the observer.
Al′titude, in mathematics, the perpendicular height of the vertex or apex of a plane figure or solid above the base. In astronomy it is the vertical height of any point or body above the horizon. It is measured or estimated by the angle subtended between the object and the plane of the horizon, and may be either true or apparent. The apparent altitude is that which is obtained immediately from observation; the true altitude, that which results from correcting the apparent altitude, by making allowance for parallax, refraction, &c. Altitude is one of the main determining influences of local climate. Its increase has the same effect on temperature as an increase of distance north or south of the equator.
Altitude-and-azimuth Instrument. See Altazimuth.