JOHANN

FRANZ

See also:

• JOHANN FRANZ ENCKE (1791–1865)

ENCKE (1791–1865)  , German astronomer, was born at Hamburg on the 23rd of September 1791 . Matriculating at the university of Gottingen in 1811, he began by devoting himself to astronomy under Carl Friedrich Gauss; but he enlisted in the Hanseatic Legion for the campaign of 1813-14, and became lieutenant of artillery in the Prussian service in 1815 . Having returned to Gottingen in 1816, he was at once appointed by Benhardt von Lindenau his assistant in the observatory of Seeberg near Gotha . There he completed his investigation of the comet of 168o, for which the Cotta prize was awarded to him in 1817; he correctly assigned a period of 71 years to the comet of 1812 ; and discovered the swift circulation of the remarkable comet which bears his name (see COMET) . Eight masterly treatises on its movements were published by him in the Berlin Abhandlungen (1829-1859) . From a fresh discussion of the transits of Venus in 1761 and 1769 he deduced (1822–1824) a solar parallax of 8" • 57, long accepted as authoritative . In 1822 he became director of the Seeberg observatory, and in 1825 was promoted to a corresponding position at Berlin, where a new observatory, built under his superintendence, was inaugurated in 1835 . He directed the preparation of the star-maps of the Berlin academy 183o-18J9, edited from 1830 and greatly improved the Astronemisches Jahrbuch, and issued four volumes of the Astronomische Beobachtungen of the Berlin observatory (1840-1857) . Much labour was bestowed by him upon facilitating the computation of the movements of the asteroids . With this end in view he expounded to the Berlin academy in 1849 a mode of determining an elliptic orbit from three observations, and communicated to that body in 1851 a new method of calculating planetary perturbations by means of rectangular co-ordinates (republished in W . Ostwald's Klassiker der exacten Wissenschaften, No . 141, 1903) .

Encke visited England in 1840 . Incipient brain-disease compelled him to withdraw from official life in November 1863, and he died at Spandau on the 26th of August 1865 . He contributed extensively to the periodical literature of astronomy, and was twice, in 1823 and 183o, the recipient of the Royal Astronomical Society's gold medal . See Johann Franz Encke, sein Leben and Wirken, von Dr C . Bruhns (Leipzig, 1869), to which a list of his writings is appended . Also, Month . Notices Roy . Astr . Society, xxvi . 129; V.J.S . Astr . Gesellschaft, iv .

227; Berlin . Abkandlungen (1866), i., G .

Hagen; Sitzungsberichte, Munich Acad . (1866), i. p . 395, &c . (A . M .