38 ASTER stem, serrate leaves, purple or blue flowers in panicles, found with the preceding, but taller, 6 to 10 feet; A. l<evis, macrophylhui, specta- lilit, horizontals, Oalifornicus, and mutabilu versicolor, all worth cultivating; the last two change color with age. In England they are all called Christmas or Michaelmas daisies. The Chinese pay special attention to the cultivation of many species of this genus, and the results of their skill have been introduced in America and are favorites with horticulturists. The first China asters were brought to Europe early in the 18th century. Asters require a free, rich soil, and moderate exposure to the sun. The Chinese cultivate them almost exclusively in pots. A. argyrophyllus, a native of New Holland, is a shrubby species, growing to the height of 10 feet; the flowers are very nu- merous in little heads, whitish gray with yel- low disk, and smelling strongly of musk ; this species is half-hardy in southern England. A. calestis, from the Cape of Good Hope, is a hot- house plant, blooming the whole year; the flowers sky-blue, disk yellow. ASTER. I. Ernst Ladwlg von, a German mil- itary engineer, born in Dresden in November, 1T78, died in Berlin, Feb. 10, 1855. In 1794 he entered the corps of engineers in the Saxon army, iii which his father had held high rank. He was made lieutenant in 1800, and captain in 1809. A plan made by him for the fortifica- tion of Torgau attracted the attention of Na- poleon, who adopted it ; the fortress was fin- ished under Aster's superintendence, and after the Russian campaign, in which he took {>art, he was appointed its commander. Soon after this he left the Saxon for the Russian service. He fought at- Bautzen and Leipsic, and distin- guished himself by several expeditions with a detachment of Cossacks which he commanded. In 1813 he reentered the Saxon service, and in 1814 was made colonel. In 1815 he entered the Prussian engineer corps, and took part in the battles of Ligny and "Waterloo and in several sieges. In the same year he was made a gen- eral, and inspector of the Prussian fortifica- tions. He now established his reputation as a master of his art by the construction of the great fortresses of Coblentz and Ehrenbreit- stein. Of these he was appointed commander in 1825, still holding the office of inspector general. He became a lieutenant general in 1827, and in 1842 general of infantry. He was also made a councillor in 1837. He left a collection of essays and volumes, published together after his death, under the title Nach- gelassene Schriften (5 vols., Berlin, 1856-'61). See also the work of Eiler, Betrachtungen und Urtheile E. L. von Aster's uber die politi- schen, kirchlichen -and padagogischen Partei- bewegungen misers Jahrhunderts (2 vols., Saar- brucken, 1858-'9). II. Karl Hclnrlch von, broth- er of the preceding, born in Dresden, Feb. 4, 1782, died there, Dec. 23, 1855. He entered the Saxon artillery corps in 1796, and took part in the battle of Jena. He was soon after- ASTEROIDS ward temporarily assigned to a professorship in the military school at Dresden, and was made lieutenant colonel in 1831. He retired in 1834, and received the honorary rank of colonel in 1844. He wrote many military works, and his Lehre vom Festungskriege (2 vols., Dresden, 1812; 3d ed., 1835) is a text book on the subject of fortifications in the Prussian military schools, and has been trans- lated into several languages. ASTERABAD. See ASTBABAD. ASTEKIAS. See STAB FISH. ASTEROIDS, a ring of small planets travel- ling between the orbits of Mars and Jupiter. It had long been noticed that no empirical law of planetary distances would give an account of the wide disparity between the distance sepa- rating the orbits of the earth and Mars and that which separates the paths of Mars and Jupiter. When Sir W. Herschel's discovery of Uranus in 1781 had confirmed Bode's em- pirical law, astronomers were led to search for a planet travelling in the orbit which, accord- ing to that law, should lie between the paths of Mars and Jupiter. On Jan. 1, 1801, such a planet was discovered by Piazzi, who called it Ceres. In March, 1802, while looking for the new planet, Olbers discovered another, travel- ling at about the same distance from the sun. He called it Pallas. Two others discovered before 1808 were called Juno and Vesta. In 1845 Hencke of Prussia discovered a fifth. Since then the progress of discovery has scarce- ly been interrupted by a single barren year. Luther in Germany, Goldschmidt in France, Watson in America, Hind in England, and De Gasparis in Italy were until 1873 the most suc- cessful asteroid seekers. Recently Prof. Peters of the Litchfield observatory, Clinton, N. Y., has shared their honors, having thus far discovered more asteroids than any other astromomer save Luther. He discovered three new asteroids in July and August, 1872, and two more in Feb- ruary, 1873, raising the known number to 130. Olbers endeavored to explain the existence of the zone of asteroids by the theory that a planet which had once travelled between the paths of Mars and Jupiter had exploded, and that the as- teroids are its fragments. But Prof. Newcomb has shown, by an elaborate investigation of the asteroidal motions, that " although there are some peculiarities which might favor Olbers's hypothesis, there are a far greater number of cases which undoubtedly negative the assump- tion." Prof. Kirkwood has shown that when the mean distances of the asteroids are arranged in order, certain gaps can be recognized ; that in fact "there are no asteroids having mean distances lying near certain definite values." He shows how these gaps by their position in- dicate the probability that the asteroidal zone was formed from scattered cosmical matter travelling around the sun under the perturb- ing influence of the planet Jupiter. Leverrier, from an analysis of the motions of Mars, has shown that the combined mass of all the aste-
