Georg Mohr
Encyclopedia
Jørgen Mohr (April 1, 1640 – January 26, 1697) was a Danish
mathematician
. He travelled in the Netherlands
, France, and England.
Mohr was born in Copenhagen
. His only original contribution to geometry
was the proof that any geometric construction which can be done with compass and straightedge
can also be done with compasses alone, a result now known as the Mohr–Mascheroni theorem
. He published his proof in the book Euclides Danicus, Amsterdam
, 1672.
Although the book was included in bibliographies of mathematics, nobody troubled to examine it, and it was totally overlooked for 250 years. The result was instead credited to the Italian Lorenzo Mascheroni
, who independently delivered a proof a hundred years later (1797). Only in 1928, when a young student of mathematics found a copy in a second-hand bookshop in Copenhagen, did Mohr's achievement gain recognition. The book was reprinted in facsimile that year.
Mohr published his Euclides Danicus simultaneously in a Danish and a Dutch edition (each with a long sub-title in the respective language). One would have expected that a scientific work at the time would have been in Latin
- in which case it would have been accessible to a wider circle of readers (for a similar case, see: Caspar Wessel
). However, since he spent much time in the Netherlands, his choice of the national languages rather than Latin may have been inspired by the tradition started by the Dutch mathematician Simon Stevin
.
Mohr was a friend of Tschirnhaus
, and he spent his last few years as a guest in his house. He died in Kieslingswalde near Görlitz
, Germany.
The Danish Mathematics competition is named in honour of Georg Mohr.
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
. He travelled in the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
, France, and England.
Mohr was born in Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...
. His only original contribution to geometry
Geometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....
was the proof that any geometric construction which can be done with compass and straightedge
Compass and straightedge
Compass-and-straightedge or ruler-and-compass construction is the construction of lengths, angles, and other geometric figures using only an idealized ruler and compass....
can also be done with compasses alone, a result now known as the Mohr–Mascheroni theorem
Mohr–Mascheroni theorem
In mathematics, the Mohr–Mascheroni theorem states that any geometric construction that can be performed by a compass and straightedge can be performed by a compass alone. The result was originally published by Georg Mohr in 1672, but his proof languished in obscurity until 1928. The theorem was...
. He published his proof in the book Euclides Danicus, Amsterdam
Amsterdam
Amsterdam is the largest city and the capital of the Netherlands. The current position of Amsterdam as capital city of the Kingdom of the Netherlands is governed by the constitution of August 24, 1815 and its successors. Amsterdam has a population of 783,364 within city limits, an urban population...
, 1672.
Although the book was included in bibliographies of mathematics, nobody troubled to examine it, and it was totally overlooked for 250 years. The result was instead credited to the Italian Lorenzo Mascheroni
Lorenzo Mascheroni
Lorenzo Mascheroni was an Italian mathematician.He was born near Bergamo, Lombardy. At first mainly interested in the humanities , he eventually became professor of mathematics at Pavia....
, who independently delivered a proof a hundred years later (1797). Only in 1928, when a young student of mathematics found a copy in a second-hand bookshop in Copenhagen, did Mohr's achievement gain recognition. The book was reprinted in facsimile that year.
Mohr published his Euclides Danicus simultaneously in a Danish and a Dutch edition (each with a long sub-title in the respective language). One would have expected that a scientific work at the time would have been in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
- in which case it would have been accessible to a wider circle of readers (for a similar case, see: Caspar Wessel
Caspar Wessel
Caspar Wessel was a Norwegian-Danish mathematician and cartographer. In 1799, Wessel was the first person to describe the complex numbers. He was the younger brother of poet and playwright Johan Herman Wessel....
). However, since he spent much time in the Netherlands, his choice of the national languages rather than Latin may have been inspired by the tradition started by the Dutch mathematician Simon Stevin
Simon Stevin
Simon Stevin was a Flemish mathematician and military engineer. He was active in a great many areas of science and engineering, both theoretical and practical...
.
Mohr was a friend of Tschirnhaus
Ehrenfried Walther von Tschirnhaus
Ehrenfried Walther von Tschirnhaus was a German mathematician, physicist, physician, and philosopher...
, and he spent his last few years as a guest in his house. He died in Kieslingswalde near Görlitz
Görlitz
Görlitz is a town in Germany. It is the easternmost town in the country, located on the Lusatian Neisse River in the Bundesland of Saxony. It is opposite the Polish town of Zgorzelec, which was a part of Görlitz until 1945. Historically, Görlitz was in the region of Upper Lusatia...
, Germany.
The Danish Mathematics competition is named in honour of Georg Mohr.
External links
- The Galileo Project
- Official website for the Georg Mohr-Competition