ENCKE, Jou. FRANZ, the well-known astronomer, was b. Sept. 23, 1791, at Hamburg, where his father was a clergyman. After studying at GiAtingen, he served, during the campaign of 1813-14, in the artillery of the Hanseatic legion, and in 1815, in the Prus sian army, as lieut. of artillery. On the establishment of peace, he left the service, and became assistant, and afterwards principal astronomer in the observatory of Seeberg, near Gotha. In 1825, chiefly at the instigation of Bessel, he was called to Berlin as suc cessor to Tralles, in the secretaryship of the academy of sciences, and as director of the observatory. While at Gotha, the astronomical prize offered by Cotta was awarded to E. by the judges Gauss and Olbers, for his determination of the orbit of the comet of 1680. This led him to solve another problem, which had been proposed along with the other—viz., the distance of the sun. The solution, by means of the two transits of
Venus in 1761 and 1769, is published in two separate tracts (Die Eny'ernung der ,Bonne, Gotha, 1822-24). In 1819, he proved that the comet discovered by Pons, Nov. 26, 1818, revolved in the hitherto incredibly short period of about 1200 days, and had been already observed in 1786, 1795, and 1805. It has since gone by the name of E.'s comet, and has appeared regularly; the period of its recurrence being 3.29 years, or about years. See COMETS. E:'s researches on this subject are contained in the Transactions of the Berlin Academy. In 1830, he undertook to edit the Berlin Astronomical Almanac, in which he published a number of astronomical treatises. Three volumes have appeared of Astronomical Observations at the Berlin Observatory, begun in 1855. He died 2d Sept., 1865.