DOPPELMAYER, JOHANN GABRIEL, a German mathematician, born at Nurnberg in 1671, was the son of a trader iu that city, who Lad distinguished himself by his taste for physics, and is said to have made aomo improvements in the air-pump. Johann was sent for instruction to Altorf, and he completed his education at tho University of Halle, where he applied himself to the study of the law ; but, abandoning this pursuit, be cultivated with diligence the different branches of natural philosophy. In 1700 he made a journey to Basel, whence he proceeded to Holland, and he aubaequently visited England. After tin absence of two years he returned to Nurnberg, where in 1704 he was appointed professor of mathematics and astronomy, which post he held during the remainder of his life, In December 1733 he was admitted a fellow of the Royal Society of London, and in 1740 a member of the academies of Sciences at St. Petersburg and Berlin. He died December 1, 1750.
Doppclmayer was acquainted with the French, Italian, and English languages, beaidea Latin and his native tongue. lie had acquired
considerable akill in grinding lenses for object-glasses, and in polishing specula for reflecting telescopes; and in the latter part of his life he distinguished himself by the performance of electrical experiments. He published in German (1714), and also in Latin (1731), nu Intro duction to Geography,' as an accompaniment to the 'Atlas' of Homann; Notices of the Mathematicians and Artists of Niirnberg,' in German (1730); and a 'Celestial Atlas; engraved on thirty plates, with descrip tions in Latin (1742); a translation, in Latin, of Street's 'Astronomical Tables ;' also translations, in German, of Wilkina'a Defence of Coper nicus,' and of Bion's Trait6 de la Construction, etc., des Instruments d'Astronomie;' bat his principal work is one entitled Neu-entdeckte Phmnomena von Bewanderns-wiirdigen Wilrekungen der Natur, wciche bey der fast alien CUrpern zukommenden electrischen Kraft in einem Systerunti vorstellig gemacht; Ito, NUrnberg, 1774.