Johann Gabriel Doppelmayr (1677 - 1750)
Johann Gabriel Doppelmayr (also spelled Doppelmaier or Doppelmair) was the son of the Nuremberg merchant Johann Siegmund Doppelmayr (1641-1686) and was born on 27 September 1677 (many early sources incorrectly give his year of birth as 1671). His father had an interest in applied physics and was one of the first to design a vertical vacuum air pump in Nuremberg. Doppelmayr enrolled at the Ägidiengymnasium in 1689 and after completing his studies in 1696 enrolled at the nearby university of Altdorf to study law which he completed in 1698 with a dissertation on the Sun. He then attended lectures on mathematics and natural philosophy by Johann Christoph Sturm (1635-1703) which he completed in 1699 with his dissertation De visionis sensu nobilissimo, ex camerae obscurae tenebris illustrato. He continued his studies on physics and mathematics at the university of Halle where he also learned French and Italian.
In September 1700, Doppelmayr traveled to Berlin and from there, through Lower Saxony, to Holland where he visited Franeker and Amsterdam on his way to Utrecht where he stayed for a couple of months to continue his studies on physics and mathematics and to master the English language. In April 1701, Doppelmayr went to Leiden where he stayed in the house of the astronomy professor Lothar Zumbach von Koesfeld and learned (probably in the Musschenbroek workshop) how to grind and figure telescope lenses. He then traveled to Rotterdam and in May to England where he visited Oxford and London.
After returning to Holland in the end of 1701, Doppelmayr spent another five months in Leiden, where he followed astronomy lessons from Lothar Zumbach von Koesfeld. After visiting Utrecht, Deventer, Osnabrück, Hannover, Kassel, Marburg, Gießen, Wetzlar and Frankfurt, Doppelmayr returned to Nuremberg in August 1702 and was appointed professor of mathematics at the Ägidiengymnasium in 1704, a position that he would hold until his death. In 1723, he received an invitation to become the professor of mechanics at the Academy of St. Petersburg, but Doppelmayr declined and suggested that they should ask the Swiss mathematician Nikolaus Bernouilli for this position.
Doppelmayr wrote on astronomy, geography, cartography, spherical trigonometry, sundials and mathematical instruments. He often collaborated with the cartographer Johann Baptista Homann (1664-1724), a former Dominican monk from Oberkammlach in Schwabia who in 1688 had settled in Nuremberg and became a map engraver for the publishing firms of Jacob von Sandrart and David Funck. In 1702, Homann founded an influential cartographic publishing firm that after his death was continued by his son Johann Christoph Homann (1703-1730) and after the latter’s death by his friend Johann Michael Franz (1700-1761) and his stepsister’s husband Johann Georg Ebersberger (1695-1760) under the name “Homännische Erben”. The publishing firm remained in business under different names until 1848.
Doppelmayr died on 1 December 1750 in Nuremberg, and many believed that this was caused by the fatal effects of a powerful electrical shock which he had received shortly before while experimenting with a battery of electric capacitors. Other sources, however, suggest that Doppelmayr’s electrical experiments were performed several years earlier and were not the cause of his death.