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away, and the closing of the switch lowers it again. Drawbridges are usually protected by such signals. Electricity is used in some cases to set the levers in motion, particularly in the block-system of operating trains. Automatons. Beings supposed to be without freedom, all their actions being spontaneous and without conscious purpose.—Mechanical toys imitating men or animals have been made from the earliest times. Vaucanson's flute-player 1738, flageolet-player 1741, and duck, very lifelike, even digesting food, are well authenticated. Maelzel exhibited a trumpeter 1809, also a rope-dancer and a chess-player. Song-birds and other toys of quite perfect construction are now produced.

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Autotype. Picture produced by means of a photographic negative, acting upon a carbon film. The film is made by coating paper with a mixture of gelatin, sugar, and coloring matter, which is rendered sensitive to the action of light by bichromate of potash or ammonia. The bichromated gelatin is rendered insoluble proportionately to the light transmitted by the negative. After exposure the film is placed on an indiarubber slab, and made to adhere to it by means of a “squeegee.” When the contact is perfect, the whole is immersed in hot water, which soon softens the paper to a degree that it can be peeled off, leaving behind it the gelatin film. This is allowed to remain in tepid water until the soluble portion, unacted upon by light, is dissolved and washed away. After thoroughly dry, the film is transferred to a waxed or gelatinous paper, to which it fastens itself, and the tones of the print are produced by the varying thickness of the remaining film. As the pigments used as coloring matter are as permanent as ink, they have all the lasting qualities of type-printed impressions from ink on paper. As any coloring matter can be added to the composition, from the deepest blacks to the highest blues, this process is very valuable in the reproduction of old drawings, and other works of art in wash or colored chalks.

Of late years a process invented by Johnson, which has a heavily sized paper for the developing base, making it a flexible support, has added materially to the average result. All the well-known Braun prints are produced by this method.

Autozoöids. True or complete polyps of a differentiated (dimorphic) Alcyonarian colony. Autumn. Season of harvest, lasting from the Autumnal Equinox to the Winter Solstice. Auvergne. Ancient French province, in a mountainous region, long defended by Arverni against Romans. Auxanometer... Instrument or piece of apparatus for registering the rapidity of plant-growth. Auxiliary Capital. Raw material, factories, and similar means of production, as distinguished from capital which maintains the life and efficiency of industrial workers. Auxospore. Body produced by the conjugation of two diatom frustules, the protoplasmic contents uniting to form a body which is at first gelatinous throughout, but ultimately becomes covered by a cell-wall. Auxotonic. Movements of growing vegetable organs. Auzout, ADRIEN, 1630–1691. French mathematician and astronomer; one of the first members of the Academy, 1666. Micrometer, 1667. Ava. Macropiper Methysticum. Plant of natural order Piperaceae, native of South Sea Islands, from the root of which the natives prepare a fermented liquor having an effect like opium. Ava. City on Irawaddy River. Burmah, formerly the capital; nearly destroyed by earthquake 1839. Pop. ab. 7,500. Avalanche. Snow-slide.

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The expense of protecting rail

ways in mountainous countries from these is often great, sheds being required to cover the track and deflect the avalanche.

Entrance to Sãow-shed; Canadian Pacific Ry.

The Canadian Pacific Railway has expended over $3,000,000 for this item.

Avalon. Fabulous island where King Arthur was buried.

Avaricum. Ancient fortified town in Gaul, taken by Caesar; now Bourges.

Avars. Asiatic tribe who troubled the Eastern Empire from ab. 555 till subdued by Charlemagne 769; probably akin to the Huns. Avebury, or ABURY. Village in Wiltshire, Eng., having the largest prehistoric megalithic structure in Britain. Avellaneda, GERTRUDE GOMEs D', b. in Cuba 1816. Spanish poet, dramatist, and novelist; wife of Don Pedro Sabator, 1846. Ave Maria. Prayer in R. C. Ch. , called the Angelic Salutation; used to invoke the Virgin's aid. Ave Maris Stella. A hymn of the R. C. Ch. in praise of the Virgin, supposed to have been written in the 7th or 8th century. Avens. ories of the genus Geum, insignificant herbs of the Rose family. Aventine Hill. One of the seven hills of Rome, on its extreme s. border, between the Palatine and the Porta San Paolo.

Aventinus, or Thurmayer, JoHANNES, 1466–1534. Historian of Bavaria. His work appeared 1534 in an expurgated form, and complete 1580.

Aventurine. Quartz or feldspar in which small scales or spangles of other minerals are disseminated.

Aventurine Glass. Brown, containing particles of metallic copper, called gold stone; used in jewelry. Average. In law, injury not amounting to a total loss. Particular average is the damage falling directly upon an article. General average is the contribution by all the parties to an adventure toward an extraordinary loss sustained by some for the common benefit. Avernus. Lake near Cumae, Italy, in the crater of an extinct volcano, from which arose mephitic vapors, said to kill birds which came near; supposed to be connected with the lower world. Averrhoes, 1126–1198. Arabian philosopher, b. at Cordova. He wrote works on medicine, law, and astronomy, but is best known as a commentator on Aristotle. In this capacity he exerted great influence on the development of scholastic philosophy. It is said that 100 editions of his works were printed in the century following 1472. Averysboro. Village in N.C., scene of a battle between Sherman's and Johnston's forces, March 16, 1865.

Aves. Class of Vertebrates, including animals that are warm-blooded, oviparous. and feathered; with four chambers to the heart, the systemic and pulmonary circulations being completely separated. The right aortic arch persists. There is one occipital condyle. The jaw has no teeth in living birds, but bears horny sheaths, constituting a beak. The neck is long, having 9 to 23 vertebrae that bear short ribs which unite with the transverse processes. The dorsal vertebrae are few; the sternum or breast-bone is well developed. The pelvis consists of two sacral vertebrae and many praesacral (lumbar) vertebrae, some of which bear ribs, united with the elongated ilium. The pubic and ischial bones extend backward, and usuall form no symphysis. The anterior limbs are wings in W.; 124

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the manus develops only the thumb (alula) and first two fingers. The legs have the knee concealed and a prominent intertarsal joint between the tibiotarsus and the tarso-metatarsus. The outer or fifth toe is always absent, and sometimes one or two others from the internal side. Most birds have special air cavities connected with the lungs and air instead of marrow in the bones. The ovary and oviduct of the left side only is developed. The egg has much yolk and is fertilized before it enters the duct where the white and shell are added. Most are monogamous, but migratory in flocks. The class contains four sub-classes, Carinatoe, Ratitae, Saurornithes, and Odomtornithes. This classification is likely to give way before the following: Saururae, Odontormae, Odontolcae, and Eurhipidurae; the last with the superorders: Dromaeognathae, Impemmes, and Euornithes. See these terms. About 10,000 species of birds are known, which have been referred to 2,000 or 3,000 different genera. Avesta, or ZEND-AvestA. Collection of the sacred books of the Parsees containing the religion of Zoroaster. In its present form it does not go back of the Sassanian kings of Persia. under whom it was revised, but it may antedate Cyrus, 558–529 B.C. The books now existing are said to be only fragments of the original collection in Old Persian. They are four: the Yasma, consisting of hymns and other liturgical sections; this is the most ancient part, and contains portions attributed to Zoroaster; the Visparad, likewise liturgical; the Vendidad, which explains the dualistic doctrines and the priestly rules; and the Khordah Avesta, which, unlike the other three, was designed for the laity as well as the priests, being a species of book of devotion. Alexander the Great is said to have burned the complete collection in 21 books from which these were taken.

Avesta Language. Zend, the ancient East Iranian tongue; closely related to Vedic Sanskrit and Old Persian of the Persepolis inscriptions.

Avianus, FLAVIUS, ab. 400. Author of Latin fables.

Avicenna, 980–1037. Arabian philosopher and physician of Bokhara, famous in the Middle Ages. He served in the courts of different Emirs, and was at one time Vizier. Aristotle and Galen were largely introduced to the scholastic philosophy and early Italian schools of medicine through him. Many editions of his works, especially of his Canon of Medicine, have been published.

Avicularia. Small prehensile processes on the theeae of some Polyzoa, which are shaped like a bird's head; used for seizing food. A snapping beak, worked by special muscles, has been developed on this curious organ. Some authors think them modified polyps.

Aviculidae (PEARL MUSSELS or PEARL OYSTERs). Lamellibranchs without siphons, with unequivalved, oblique shell, having a fine inner layer of mother-of-pearl. The anterior adductor muscle is small; the foot is small and secretes a byssus. , Meleagrina is the pearl-mussel especially, and inhabits the gulfs of the Indian Ocean and the Gulf of Mexico.

Inside. Shell. Pearl Oyster, showing Pearl.

The most famous pearl-fishery is located on the n. shore of

Outside of Shell.

Ceylon. The oysters are taken in the spring by divers, in ten fathoms of water. The largest pearls approach two inches in length, but the best average the size of peas. Besides the loose pearls, which are formed around a foreign *i. as grains of sand, dead oyster-eggs, etc., the pearly layer all over the inside of the shell has commercial value. Great Britain uses $500,000 worth each year, ab. 3,000 tons. Avienus, RUFUs FESTUs, ab. 380. Roman author of poems on geographical subjects. Avignon. Ancient town of Provence, on left bank of the Rhone; incorporated into the kingdom of Burgundy; afterward a free republic; held for a time by the Albigenses, and taken by Crusaders 1226. It passed by inheritance to Charles of Anjou and to Joan of Naples; was purchased of her by Clement VI. 1348; became the seat of the Jo court 1309–77, and of the anti-popes 1378–1418; was united to France 1791. It has interesting architectural monuments. Pop., 1891, 43,453.

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Avila y Zuniga, LUIs D', ab. 1490–ab. 1562. Spanish historian of the German war of 1546–47. Aviler, AUGUSTIN CHARLEs, 1653–1700. French associate of Mansard, and writer on architecture. Avitus, ALCIMUs ECDICIUs, ab. 450–ab. 525. Bp. of Vienne in Gaul ab. 490; author of a Latin epic on the Creation, the }.} the Flood, etc., notable for its resemblance to Paradise Sl. Avitus, MARCUS MAECILIUS, ab. 400–457. Prefect of Gaul 439; emperor 455–56. Avocet. Wading bird with palmated feet, of the genus

The Common Avocet (Recurvirostra avocetta).

soirotra. Bill is slender, flexible, and bent upward toward the tip. Avogadro, AMADEo, 1776–1856. Prof. of physics at Turin 1820. He announced 1811 the law that equal volumes of different gases under the same conditions of temperature and pressure contain the same number of molecules. Avoirdupois. English standard weights for everything except medicines, precious metals, and gems, for which apothecaries' and troy weights are used:

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4 quarters = hundredweight (cwt.). 20 hundredweight ton (ton). In U.S. for some commodities the quarter weighs 100 lbs., and ton of 2,000 lbs. is used. Award. The decision by arbitrators of a controversy submitted to them by the parties; it may be oral, unless the submission or a statute requires a writing; it must dispose of all o included in the submission and must be certain; it may e set aside for willful misconduct of the arbitrator, or for a violation of statutory requirement. Awlwort. Subularia aquatica. Minute aquatic plant of the natural family Cruciferae, found in N. America and Europe. Axes of Reference. Fixed lines from which as data positions are determined. Axil. Point above the insertion of a leaf on a stem. Lateral buds appear in this position and are said to be axillary. Axile. Placentae in the ovary of a flower, when placed along the sides of a central axis, formed by the adhesion of two or more carpellary leaves. Axilla. Armpit, or o: under the shoulder joint, bounded in front and behind by folds of muscle, outwardly and inwardly by the arm and chest, containing the large vessels and nerves of the arm and a number of lymphatic glands, which render injuries and operations in their vicinity dangerous. Axioms. Self-evident truths, assumed at the basis of the several sciences. It is common in mathematics to formulate them as fundamental conditions of proof. Axis. Line about which a body (e.g., the earth) revolves.— Next to the uppermost of the vertebrae, jointed to the atlas and skull in such manner as to allow of rotation of the head.—Middle of the back of Trilobites.—Line around which the whorls of a snail's shell are turned.—In architecture, central line of a plan. Axis. Spotted hog deer, found in India; similar to European fallow deer. Axis of Structure. a locus, as of an ellipse. Axis of symmetry. Line to which corresponding parts of a locus, or corresponding elements in a group of quantities, bear the same relation. Axolotl. Amblystoma (Siredom) maculatum of Mexico; a

Line fixed as an element in forming

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Axum. City of Abyssinia, once capital of Ethiopia, now mainly in ruins; celebrated for its peculiar round-topped and slab-shaped obelisks, and for its ancient Arabic inscriptions. Ayacucho. Town of Peru, scene of a battle, Dec. 9, 1824, between the Spaniards and S. Americans. The former, though superior in numbers, were totally routed, with a loss of 2,600, and surrendered the next day. The result was the virtual independence of the Spanish settlements in S. America. Ayala, PEDRO LOPEz D’, 1832–1407. Spanish poet, historian, and statesman. Chronicles of the Kings of Castile. His Rhymes of the Palace were written while a prisoner of war in England, and have but lately come to light. Aye-Aye. Cheiromys Madagascariensis. Quadruped as large as a hare; formerly classed as a rodent, now regarded as a lemur. Inhabits Madagascar. Ayesha, ab. 610—677. Daughter of Abu-Bekr and favorite wife of Mohammed. Aylesford. Village in Kent where the Britons were victorious over the Saxons and Horsa was slain, 455. Ayrer, JACOB, d. 1605. German dramatist. Sixty-six of his lays, resembling those of Hans Sachs, were pub. at Nuremerg 1618. Ayrshire. See CATTLE. Ayton, SIR RoBERT, 1570–1638. Scottish poet. Aytoun, WILLIAM EDMONDstounE. 1813–1865. Scottish poet and critic; prof. Univ. Edinburgh 1845. Lays of the Scottish Cavaliers, 1848; Bothwell, 1856. Azalea. Genus of showy-flowered shrubs, of the Heath family, natives of both the Old World and the New. By some

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one of its extremities. It is to be observed that, owing to the convergence of the meridians, the azimuths measured at the extremities will in general not be equal.

Azimuth Compass. Compass having the needle attached to a circular graduated disk and furnished with a prism, so that the eye can read bearings or azimuths of a point in the line of sight; used for rough work in reconnaissance surveying.

A Z in e s . Compounds in which two aromatic nuclei are united by two nitrogen a to m s. Thus the phenylene azine is

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Containing See Azo

Azimuth Compass.

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