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 LEON LEONHARD 353 on the slope of a bill, which is crowned by the cathedral of Santa Maria de Regla, a noble Gothic edifice, originally founded in the 12th century. The town is surrounded by an octag- onal wall, with 11 gates. The streets are gen- erally narrow and irregular, but a few of them are handsome, and there are several public squares ornamented with fountains. Among the noteworthy public buildings are the church of San Isidoro, the convent of San Marcos de Leon, the town house, court house, epis- copal palace, palace of the civil governor, and several hospitals. The manufactures are linen goods, leather, hats, and earthenware. Leon was founded by the Romans, who called it Le- gio, from the seventh legion, quartered there in the time of Augustus. LEON, a city of Mexico, in the state of Gua- najuato, capital of a district of the same name, on the right bank of the Rio Torbio, 100 m. K W. of Mexico ; pop. about 100,000 (second only to that of the capital). It stands in a fertile valley about 6,000 ft. above the sea, has good streets, and is generally well built, fn the principal square, little inferior to any other in the republic, stand the old governor's palace, the handsome parish church, and a picturesque arcade with numerous fine shops. There are several other churches, three convents, a hos- pital, and a Latin and several primary schools. This city, one of the most flourishing and in- dustrious in Mexico, has an extensive commerce in wheat and other grains. Some cotton and woollen stuffs are manufactured, but the chief industry is tanning. Leon was founded in 1576, and made a city in 1836; but its com- mercial importance does not date beyond 1855, about which time it became the chief entrepot of the fertile region of the Bajio. LEON, a city of Nicaragua, in the plain and capital of the department of the same name, 53 m. N". W. of Managua; pop. about 25,000. The streets are good, and some are paved and lighted ; the houses are mostly of one story ; the public edifices are numerous and spacious, but not remarkably handsome. The cathedral, from the tower of which are visible the 13 volcanoes of the Sierra de los Marrabios, though occupying an entire block, is less imposing than the churches of Calvary and La Merced ; be- sides these there are 12 other churches. In the principal square are the old and new epis- copal palaces, the old government house, uni- versity, and barracks. The antique convents of La Merced and La Recoleccion are converted into public offices, and a third into a hospital. A ravine, separating Guadalupe from the city proper, is crossed by a grand bridge, and other bridges were to be completed in 1874. In the surrounding country, which is very picturesque, mineral and thermal springs abound ; and good roads lead from the city in every direction. Some dressed leather and cutlery are manufac- tured, and a few articles are exported through the port of Corinto on the Pacific. Leon was founded in 1523 by Francisco F. de Cordoba, on the W. shore of Lake Managua ; but a series of calamities necessitated its transfer in 1610 to its present site, adjoining the ancient Indian village Subtiaba, which, with 6,000 inhabitants, and forming a distinct municipality, is separated from it by a single street. In 1823, 1,000 houses were burned in one night. The ruins of Old Leon are still visible. LEON, Isla de. See CADIZ. LEON, Ponce de. See PONCE DE LEON. LEONARDO DA PISA, or Leonardo Bonaeci or Bonaecio, an Italian mathematician, born in Pisa about 1170 ; the year of his death is unknown. He is also called FIBONACCI, an abbreviation of Filius Bonaeci. Little is known of him be- yond what can be gathered from his mathe- matical works. His father placed him when very young in charge of a master who taught him the Arabic (or, as he calls it, the Indian) system of arithmetic, and he seems to have devoted the greater part of his life to the study of that science. Though the Arabic system was known in Europe previous to the time of Bonaeci, yet he greatly extended that knowl- edge, and according to some he was the first to introduce algebra into Europe. He travelled in Egypt, Syria, and other countries, for the purpose of learning the different systems of arithmetic in use, and came to the conclusion that the Arabic or Indian method surpassed all others. His principal work is Liber Abaci, the word abacus, the name of a well known instru- ment used in calculation, being employed by him, in accordance with the custom of his time, to denote arithmetic in its most general sense. He was also the author of works on the Dio- phantine analysis and geometry, all of which give evidence of great mathematical genius. A splendid edition of the Liber Abaci was published at Rome in 1857, edited by B. Bon- compagni, to whom the modern world is indebt- ed for its knowledge of the works of Bonaeci. LEONARDO DA VINCI. See VINCI. LEONHARD, Karl C'asar von, a German geolo- gist, born at Rumpelheim, near Hanau, Sept. 12, 1779, died in Heidelberg, Jan. 23,^1862. He was educated at Marburg and Gottingen, was employed in making several scientific jour- neys in different parts of Germany, and until 1814 held important offices in the administra- tion of the principality of Hanau. Retiring from the service of the state to devote himself exclusively to study, he became in 1816 mem- ber of the Bavarian academy of sciences, and in 1818 professor of mineralogy and geology in the university of Heildelberg. His works in this department of science are very numer- ous, the latest being Orundzuge der Minera- logie (2d ed., I860). From 1830 to 1858 he edited, in conjunction with Bronn, the Jahr- luchfur Mineralogie, Geognosie, Geologic und Petrefactenkunde. His son GUSTAV, born in Munich, Nov. 22, 1816, is professor in the university of Heidelberg, and has published several works upon mineralogy and geology, among which are Die Mineralien Badens nach