ALTITUDE (Lat. altitude, height, from aft us, high, lofty). In astronomy, the elevation of a heavenly body above the horizon. It is m•as ured not as a linear distance, but by the angle which a line drawn from the eye to the heavenly body makes with the horizontal line, in by the are of a vertical circle intercepted between the body and the horizon. Altitudes are measured by means of a t(descope attached to a graduated cir cle. (See Cinel.E.) The telescope being di reeled toward the body to be observed, the angle which it makes with the horizon is measured on the graduated circle. The altitude thus observed must receive various corrections—the chief being the parallax (q.v.) and refraction (q.v.)—in order to get the true altitude. At sea, the alti tude is taken by means of a sextant (q.v.), and then it has further to lie corrected for the (Hu of the visible horizon below the true horizon. (See HomzoN.) The correct determination of alti tudes is of vital importance in the problem of navigation. The sextant is the only astronomi cal instrument of precision that can be used without a fixed support on the Meek of a rolling ship, and it is essentially an instrument for measuring altitudes. See SEXTANT; AtrAzt AlUTI1; LATITUDE.
ALT3IttIlL, iilt/mol (Ger., old mill). A tributary of the Danube, rising at the western border of Bavaria, flowing northeast through the Swabian .lura, and joining the Danube at Kel beim (Slap: Bavaria, I) 4). It is 100 miles long, and connected with an affluent, the Slain, by the Ludwig's Canal.
AUTO (Ital., high). The deepest or lowest species of voice met with in boys or castrates, the voice of women being more properly called contralto. In England the alto voice is often found in adults, especially among the ballad sintwrs: the head notes are carefully developed to abnormal volume and power at the expense of the lower notes, which gradually become atro phied and assume the same timbre as the upper register. It is curious that the original name tants meant the highest voice in ecclesiastical music. It represented the changing, undulating melody sung over the ran t us firm us (q.v.), but owing to its difficulty, it could not be learned by boys, and thus to men with the highest voices was assigned the part, as women were excluded from church choirs—in (slier to-cot in eeelesiu i.e., let women lie silent ill the •hurch.