ENCKE, JOHANN FRANZ (1791-1865), German astron omer, was born at Hamburg on Sept. 23, 1791. Matriculating at the University of Gottingen in 1811, he began to devote himself to astronomy under Carl Friedrich Gauss. In 1816, he was appointed 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 (1829-59). From a discussion of the transits of Venus in 1761 and 1769 he deduced (1822-24) a solar parallax of 8".57, long accepted as authoritative. In 1822 he became director of the Seeberg observa tory, and in 1825 was promoted to a corresponding position at Berlin. He died at Spandau on Aug. 26, 1865.