**Johann Doppelmayr** was a German mathematician who wrote on astronomy, spherical trigonometry, sundials and mathematical instruments.

- Johann Doppelmayr entered the Aegidien Gymnasium in Nuremberg in 1689.
- Doppelmayr was to return to this Gymnasium as a professor later in his career.
- From Nuremberg, Doppelmayr went to the University of Altdorf in 1696 where he studied law, mathematics and natural philosophy.
- In 1698 he completed a dissertation on the sun, then went on to attend lectures on mathematics and natural philosophy by Johann Christoph Sturm who was considered the leading experimental physicist in Germany at the time.
- Doppelmayr submitted his dissertation De visionis sensu nobilissimo, ex camerae obscurae tenebris illustrato Ⓣ(On the most noble visions illustrated with the 'camera obscura') in 1699.
- First Doppelmayr went to Berlin in September 1700 from where he moved on to Franeker and Amsterdam in Holland before arriving in Utrecht.
- Doppelmayr made good use of his time, as he did in every place he visited, learning instrument making skills in Leiden such as how to make telescopes and how to grind lenses.
- Doppelmayr was appointed professor of mathematics at the Aegidien Gymnasium in Nuremberg in 1704 and he remained there for the rest of his life.
- Although Doppelmayr was to remain at the Aegidien Gymnasium in Nuremberg for the rest of his life, this was very much his choice since he had opportunities to move to much more prestigious positions.
- Doppelmayr wrote on astronomy, spherical trigonometry, sundials and mathematical instruments.
- The French mathematics text Traité de la construction et des principaux usages des instrumens de mathématiques Ⓣ(Treatise on the making and the main uses of mathematical instruments) by Nicolas Bion, published in Paris in 1709, was translated in German by Doppelmayr in 1712 as Neu-eröffnete mathematische Werck-Schule Nicolai Bion Ⓣ(New mathematical works of Nicolai Bion.).
- As a final example, Doppelmayr translated the English text Discovery of a new World in the Moon by John Wilkins (which had been published in London in 1638 and was a vigorous defence of the ideas of Copernicus) into German publishing it as Johannes Wilkins, des fürtrefflichen Englischen Bischoffs zu Chester Vertheidigter Copernicus, oder Curioser und gründlicher Beweiss der Copernicanischen Grundsätze Ⓣ(A German translation of the Discovery of a new Worlde in the Moone by John Wilkins.) in 1713.
- Doppelmayr also wrote a book of tremendous value giving biographical details of 360 mathematicians and instrument makers of Nuremberg from the 15th to the 18th century.
- Perhaps the most famous of all of the works by Doppelmayr is the Atlas Coelestis Ⓣ(Atlas of the heavens) which he published in Nuremberg in 1742.
- We mentioned above Doppelmayr's translation of a mathematics text.
- He was an enthusiastic experimental physicist and he published Physica experimentis illustrata Ⓣ(Illustrated physics experiments) in 1731 which describes 700 experiments which Doppelmayr had carried out himself.
- However this cause of death is not universally accepted by historians and more recent research has led to several making the claim that Doppelmayr's electrical experiments were completed several years before his death so, these sources claim, could not have been the cause of his death.

Born 27 September 1677, Nuremberg, Germany. Died 1 December 1750, Nuremberg, Germany.

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Astronomy, Origin Germany

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive