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ALGIERS. tacks. At present it is used as barracks for the French soldiers, and many of its historical features have been entirely obliterated. The modern city has several splendid churches, including a Roman Catholic cathedral. Of educational institutions the city has schools of law, medicine, science, and letters, several lyefes for the natives, as well as for Frenchmen, a number of commercial colleges and higher Mussulman schools. There are also a library and niusoum, two theatres, and a number of scientific societies. The harbor is very spacious and well fortified. The commerce of Algiers is very extensive, and its shipping amounts to nearly 7,000,000 tons an- nually. The commerce is chiefly with France; but tiiere is also considerable export trade with Great Britain, Spain, Portugal, and Italy. Al- giers is also one of the most important coaling stations on the Jlediterranean. Owing to its mild climate and the fertile as well as pictur- esque country in which it is situated, Algiers is rapidl}' becoming a favorite health resort, and its transient population is steadily increasing. Algiers is connected by rail with Oran and Constantine, and communicates with France by steamer and cable. Since the French occupation, the growth of Algiers has been quite rapid. In 1838, it had a population of 30,000; 1881, 65,000; 1891, 83,000; ISUU, 00.784, of which over 40 per cent, were French, about 24 per cent. Moors, and a great number Jews. The percentage of natives is steadily declining, while the foreign popuh^tion, especially the French, shows a steady increase. Algiers is the seat of the Governor- General and of the superior civil and mili- tary officials of Algeria and the department and arrondissement of Algiers. The city is supposed to have been founded in the first half of the tenth century, and fell into the hands of France in 1830.

ALGOA BAY, .il-go'a. A large inlet at the southeastern extremity of Cape Colony (Map: Africa, G 8). It has a good harbor, and re- ceives the Sunday and Baasher rivers. The bay is of considerable commercial importance, and is known in history as the landing place of the first Britisli immigrants to South Africa. Port Elizabeth is situated on the w-estern side of the bay.

ALGOL, al'gol (Ar. al-r/hill, the destroyer, demon ). A remarkable variable star in the con- stellation Perseus. Its period is known with very great exactness, and amounts to 2 days, 20 hours, 48 minutes, and 55.4 seconds. This period is maintained with great regularity. Or- dinarily the star is of the second magnitude; but it suffers periods of diminution, lasting four and one half hours, followed by constant minima of twenty minutes, and a return in tliree and one half hours to the original brilliancy. At mini- mum it is of the fourth magnitude, and gives only one-sixth as much light as it does in the maximum phase. Algol is the type of a class of variable stars whose minimum phase is very short. This phenomenon is ascribed to the tem- porary partial interposition of another star be- tween Algol and the earth. There must be a comparatively non-luminous companion-star be- longing to the Algol system; and mutual orbital revolution must bring this in line between Algol and the earth at regularly recurring intervals. That the visible Algol is actually subject to orbital motion, has become certain from the spec- troscopic observations of Vogel (1889), who found that the visible star is receding from the earth about twenty-seven miles per second before the minima, and approaching us at about the same rate after the minima. His approximate estimate of the dimensions of the system assigns to the distance between Algol and the dark com- panion a value of 3,250,000 miles, and makes the diameters of the two bodies 840,000 and 1,060,000 miles. The orbit is supposed to be seen nearly edgewise from the earth. C'liandler's suggestion that there exists still another invisible compo- nent rests upon less reliable evidence, derived from a study of the variations in Algol's position on the sky, as observed with meridian instruments by several successive generations of astronomers.

ALGOM'ETER. See.

ALGO'NA. A city and county seat of Kossuth Co., Iowa, 125 miles north by west of Des Moines, on the east fork of the Des Moines River, and on the Iowa Central, the Chicago and Northwestern, and the Chicago, Milwaukee and St. Paul railroads (Map: Iowa, CI). It is the centre of an agricultural, dairying, and live stock region, and has manufactures of flour, but- ter tubs, foundry and machine shop products, planing mill products, bricks, tile, wagons, etc. The city contains a public library, opera house, and a handsome court house. Pop. 1890, 2068; 1900, 2;tll.

ALGON'KIAN SYS'TEM. In geology, that system, consisting chiefly of higlily metamor- phosed clastic rocks, that lies uncomformably be- tween the Archfean beneath and the Cambrian above, and at the very bottom of the entire series of sedimentary rocks of the earth's crust. The name Algonkian was proposed by Waleott in 1889, and has been quite generally accepted by the more progressive American geologists. The rocks of this system consist of crystalline marbles, slates, schists, quartzites, conglomer- ates, and gneisses, all of which have, through more or less profound regional metamorphism, been derived from original sedimentary rocks, such as limestones, shales, and sandstones. In certain regions, particularly in the vicinity of the great lakes of North America, the Algonkian formations have undergone still further contact metamorphism through the intrusion of great masses of igneous rocks, and in this association occur some of the most important iron and cop- per deposits of the world. The known fossils of Algonkian age are very obscure and few in num- ber. Because of the extensive metamorphism suffered by the rocks of both the Archaean and Algonkian systems, rendering, in many regions, their separation under the two divisions almost impossible, it is thought advisable to consider all rocks formed before the Cambrian period un- der the more comprehensive title Pbe-Cambrian Formations.

ALGON'QUIAN STOCK. The most widely extended and most important Indian linguistic stock of North America, formerly occupying nearly the whole area (with the exception of that occupied by the Iroquoian tribes) stretching from Labrador to the Rocky Mountains in the north, and extending southward to Pamlico Sound on the coast, and to the Cumberland River in the interior. It included several hundred tribes and sub-tribes speaking probably forty