ALT 55 



are called alternate quarters. 3. In 



geometry, applied to the internal angles 

 made by a line cutting two parallels, and 

 lying on opposite sides of the bisecting 

 line. Thus, 



AL C 



a and ' are alternate angles, and if the 

 two straight lines be parallel they are 

 equal. The alternate terms of a propor- 

 tion are the first and third, and the second 

 and fourth ; and the terms of the propor- 

 tion are said to be taken alternately or 

 by alternation, when the second and third 

 are made to change places ; thus, 

 a : b :: c : d, by alternation, becomes 

 a : c : : b : d. 



ALTERNATION, Lat. alternatio. In arith- 

 metic, the alternation of numbers is called 

 permutation. See ALTERNATE. 



ALTH.S:'A, the generic name of the marsh- 

 mallow, of which there are 12 species, two 

 of which are British. Class monadelphia, 

 order polyandria. Name from othda, to 

 cure, in reference to its supposed healing 

 virtues. 



AL'TICA, a genus of tetramerous cole- 

 optera, of the family cyclica. Name from 

 et^nxo;, a leaper, in reference to their 

 lively movements. The insect is known 

 familiarly by the name of the garden flea. 



ALTIM'ETER, from Lat. altus, high, and 

 (JUT^OV, measure. An instrument for 

 measuring altitudes on geometrical prin- 

 ciples ; e. g. a quadrant. 



AI/TIN, a money of account in Russia, 

 value three copecks. 



ALTIN'CAR, a species of factitious salt 

 used in the fusion and purification of 

 metals : it is crude borax, and now 

 usually called tincal. 



ALTIS'SIMO, Italian, highest: applied in 

 music. 



AL'TITCDE, Lat. altitudo, of altus, high. 

 1. Height : the elevation of the vertex of 

 an object above its foundation, as the 

 elevation of a column : the elevation of an 

 object above the surface on which we 

 stand, or other surface to which we refer 



it, as the elevation of a meteor. 2. In 



tnenutrntion, altitudes are divided into 

 accessible and inaccessible, according as the 

 base is approachable or inapproachable. 

 3. In astronomy, the elevation of the 

 sun, a star, or other object above the 

 horizon, is called its altitude ; and this is 

 true or apparent altitude, according as it 

 is taken from the true or apparent hori- 

 zon. See HORIZON. -4. The altitude of 



the eye, in perspective, is its perpendicular 



height above the geometrical plane. 



5. Meridian altitude, in astronomy, is an 

 arc of the roeridian, between the horizon 



and any star or point on the meridian. 

 The difference between the true and 

 apparent place of the star, caused by re- 

 fraction, is called the parallax of altitude. 



6. Altitude of motion is its measure 



estimated in the line of direction of the 

 moving force. Dr. Wallis. 7. Deter- 

 minative altitude is that whence a heavy 

 body falling acquires a certain velocity, 

 by its natural accelerations. 



AL'TO (Ital. from Lat. altus}, high. In 

 music, the counter and tenor part ; the 

 part immediately below the treble or 

 highest. The term is also used to denote 

 the tenor violin. 



ALTO AND BASSO (high and low), in ol.i 

 law, signified a submission of all differ- 

 ences of every kind to arbitration. 



ALTO-OCTAVO (Ital.), an octayt higher. 



AL'TO-RELIE'VO (Ital. for hi^h relief). 

 The name given to that spcf-;^ of sculp- 

 ture in which the figures vject half or 

 more, without being wholly detached 

 from the ground. See RKUBVO. 



ALTO-BIPIEN'O (Ital.). in music, a name 

 given to the tenor of the great chorus, 

 which sings or plays only in panic alia 

 places. 



ALTO-TENOEE (Ital.), that part of the 

 great vocal scale between the mezzo 

 soprano and the tenor. 



ALTO-VIOLA, j (Ital.), a small tenor 



ALTO-VIOLINO, ) violin. Alto is guiud- 

 times used in the same sense. 



ALU'DEL, Lat. a, and lutum, lute. A 

 spear-shaped vessel open at both ends, 

 used in sublimation. A series of them aj^ 

 placed above one another, and fitted ex- 

 actly together, with a pot at the bottom, 

 containing the matter to be sublimed, and 

 a receiver at the top to collect the volatr.a 

 matter. They are now rarely used except 

 in Spain for distilling mercury. 



ALU'LA, Lat. ala, a wing. In ornitho- 

 logy, the group of ill- feathers attached to 

 the carpus, and sometimes called the 

 bastard wings (ala spuria). 



ALUM, Lat. alnmen, Germ, alaum. A 

 triple sulphate of alumina and potash, or 

 ammonia : it is both native and factitious. 

 It is usually obtained by roasting and 

 lixiviating certain clays containing 

 pyrites, and to the leys adding a certain 

 quantity of potash ; the salt is then ob- 

 tained by crystallization. In medicine it 

 is used as an astringent; in dyeing, to fix 

 colours ; in tanning, to restore the cohe- 

 sion of skins ; in candle-making, to harden 

 the tallow. The crystals are octahe- 

 drons ; the taste acerb and subacid : the 

 solution reddens the vegetable blues. It 

 dissolves in about five parts of water at 

 60 Fah. 



ALCM-EARTH, a massive mineral of a 

 blackish-brown colour. It is nearly 

 allied to the clay-slate, but contains a con- 

 siderable quantity of bituminous matte/ 



