Johann Heinrich Rahn (mathematician)

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Johann Heinrich Rahn , also Hans Heinrich Rahn, Latinized Rhonius, (born March 10, 1622 in Töss (today Winterthur ), † May 25, 1676 in Zurich ) was a Swiss mathematician. He is known for his Teutsche Algebra , in which the divided sign appears in printed form for the first time .

Life

He was the son of Hans Heinrich Rahn (1593–1669), then bailiff in Töss, later (1655–1669) mayor of Zurich, and Ursula Escher vom Glas (1591–1663). His uncle Hans Rudolf Rahn (1595–1655) was also mayor of Zurich (1644–1655). From 1642 Rahn was a representative of the Aries Guild in the Grand Council of the City of Zurich and from 1669 was also in the more exclusive Small Council of Zurich. In 1651 he became subordinate and under his direction used Swedish artillery (Bernfeld artillery) were purchased during this time. In 1658 he became Vogt of the Landvogtei Kyburg , which he stayed until 1664 when he opened a silk manufacture in Zurich on Neumarkt. In 1670 he became Obervogt von Küsnacht , 1672 Oberzeugherr and 1674 Säckelmeister .

In 1642 he married the pastor's daughter Elisabeth Holzhalb (born 1626) and had three sons with her: Hans Heinrich (born 1646), Hans Conrad (born 1664) and Hans Rudolf (born 1669).

Rahn's interest in mathematics was probably stimulated by his uncle Hans Georg Werdmüller (1616–1678), a military engineer who led the construction of the fortifications of Zurich from 1642 to 1675. It was introduced into algebra from 1654 by John Pell , who was Oliver Cromwell's representative for the Protestant cantons of Switzerland from 1654 to 1658 , with the task of splitting them off from the association with the Catholic cantons. He had an exchange of letters with Pell, some of which has been preserved (with a first letter from November 1654). He received regular lessons from Pell probably from 1657 - according to John Aubrey's biography of Pell, Rahn came to lessons in Zurich every Friday evening - and ended in early 1658 when Rahn became bailiff in Kyburg.

In 1659 Rahn published his Teutsche Algebra , in which the algebraic methods of François Viète and René Descartes were first presented in German. He found further problems in the works of Frans van Schooten , Diophant and Christophorus Clavius . The book was also influenced by the lessons of Rahn's teacher John Pell - thanks to Pell (without naming the name because he did not want it) can be found in the foreword. The book also features the divided sign (÷) for the first time in printed form. In addition to elementary arithmetic, the solution of equations and analytical geometry are dealt with. It also contains a form of Pell's equation .

The book found further dissemination through the English translation by Thomas Brancker, published in 1668 with the assistance of John Pell (who contributed considerable parts to about half of the book, but did not want to be named as co-author). Pell suggested the translation after receiving the book in 1660 - he saw in it a more modern algebra text than the standard English work by William Oughtred at the time (Clavis Mathematicae, 1631). Through the translation, the divided sign was also spread in the English-speaking world. The translator Brancker had originally replaced it with a different symbol, but at Pell's insistence he used the original symbol again.

There is also an extended Latin version of the Algebra from 1667 ( Algebra Speciosa seu Introductio in Geometriam Universalem ), which he did not publish after the publication of the English translation, but deposited it in the Zurich City Library.

He also dealt with astronomy (forecasting eclipses and comets) and designed a perpetual calendar. He was an opponent of astrology. Rahn also wrote a book (in Latin) on Diophant's problems (intended to complement the Latin edition of his algebra) and a book on optics; but both are not preserved.

Fonts

literature

  • R. Acampora Johann Heinrich Rahn and his Teutsche Algebra , in R. Gebhardt (editor) visor and arithmetic books of the early modern times , writings of the Adam-Ries-Bund Annaberg-Buchholz 19, 2008, pp. 163–178
  • Moritz Cantor :  Rahn, Johann Heinrich . In: Allgemeine Deutsche Biographie (ADB). Volume 27, Duncker & Humblot, Leipzig 1888, p. 174 f.
  • Noel Malcolm, Jacqueline Stedall John Pell (1611–1685) and His Correspondence with Sir Charles Cavendish: The Mental World of an Early Modern Mathematician , Oxford University Press, Oxford, 2005
  • Christoph Scriba John Pell's English Edition of JH Rahn's Teutsche Algebra , in: RS Cohen (editor) For Dirk Struik , Reidel: Dordrecht 1974, pp. 261-274
  • Jacqueline Stedall A Discourse Concerning Algebra: English Algebra to 1685 , Oxford University Press, Oxford, 2002

Web links

personal data
SURNAME Rahn, Johann Heinrich
ALTERNATIVE NAMES Rahn, Hans Heinrich
BRIEF DESCRIPTION Swiss mathematician
DATE OF BIRTH March 10, 1622
PLACE OF BIRTH Töss (Winterthur)
DATE OF DEATH May 25, 1676
Place of death Zurich