The American Cyclopædia (1879)/Mädler, Johann Heinrich

MÄDLER, Johann Heinrich, a German astronomer, born in Berlin, May 29, 1794, died in Hanover, March 14, 1874. He gained a high reputation as teacher in the principal normal schools in Berlin. In 1829, in company with his pupil Wilhelm Beer, the brother of Meyerbeer, he commenced the construction of the great map of the moon afterward published at Berlin (1834-'6). This was followed by his Allgemeine Selenographie (2 vols., 1837). In 1833 he made chronometrical observations for the Russian government on the island of Rügen. In 1836 he was appointed director of the Berlin observatory, and in 1840 of that of Dorpat. In 1865 he returned to Germany on account of a disease of the eyes. In his work Die Centralsonne (Dorpat, 1846) he advanced the hypothesis of the existence of a central body, preponderating in mass, as the universal centre of gravity about which the whole stellar universe revolves, designating the bright star &eta; Tauri (Alcyone) in the Pleiades as such centre. This latter assumption is now very generally rejected by astronomers. He made a great number of important observations upon the physical aspects of Mars and Jupiter, upon double stars, the determined periods of variable stars, and the centre of gravity of the solar system. Among his works are: Untersuchungen über die Fixsternsysteme (Mitau, 1847-'8); Populäre Astronomie (Berlin, 1841; 6th ed., 1866); and Geschichte der Himmelskunde nach ihrem gesammten Umfange (Brunswick, 1872-'3).