C. L. Lehmus
Encyclopedia
Daniel Christian Ludolph Lehmus (July 3, 1780 in Soest
– January 18, 1863 in Berlin
) was a German mathematician, who is today best remembered for the Steiner–Lehmus theorem, that was named after him.
Lehmus was the grandson of the German poet Johann Adam Lehmus (1707-1788). His father Christian Balthasar Lehmus was a science teacher and director of a gymnasium
in Soest, as such he took it upon himself to school his son. From 1799 to 1802 Lehmus studied at universities of Erlangen
and Jena
. In 1803 he went to Berlin, where he was giving private lectures in mathematics and pursued further studies at the university, which awarded him a PhD
in 1811. From December 18, 1813 to Easter 1815 Lehmus was employed as a lecturer (Privatdozent
) by the university, but in 1814 he became a teacher for math and science at the Hauptbergwerks-Eleven-Institut (mining school
) in Berlin as well. In 1826 he also assumed a teaching position at the Königlichen Artillerie- und Ingenieurschule (military engineering school) and was granted the title of a professor at that school in 1827. In 1836 he was awarded the Order of the Red Eagle
(4th class). In addition to his two teaching positions Lehmus was giving lectures at the university until 1837 as well.
Lehmus wrote a number of math and science textbooks, best known was probably his Lehrbuch der Geometrie, which saw several editions. He published articles in various math journals, in particular he was a regular contributor to Crelle's Journal
and provided an article for its very first edition in 1826. He published an elegant trigonometric solution of Malfatti's problem in the french math journal Nouvelles Annales de Mathématiques, but due to a copy error the author's name was given as Lechmütz.
In 1840 Lehmus wrote a letter to the French mathematician C. Sturm asking him for an elementary geometric proof of the theorem, that is now named after him. Sturm passed the problem on to other mathematicians and Jakob Steiner
was one of the first who provided a proof. In 1850 Lehmus came up with a different proof on his own. The theorem itself proved to be a rather popular topic in elementary geometry being a subject of somewhat regular publications for over 160 years.
Soest, Germany
Soest is a town in North Rhine-Westphalia, Germany. It is the capital of the Soest district. After Lippstadt, a neighbouring town, Soest is the second biggest town in its district.-Geography:...
– January 18, 1863 in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
) was a German mathematician, who is today best remembered for the Steiner–Lehmus theorem, that was named after him.
Lehmus was the grandson of the German poet Johann Adam Lehmus (1707-1788). His father Christian Balthasar Lehmus was a science teacher and director of a gymnasium
Gymnasium (school)
A gymnasium is a type of school providing secondary education in some parts of Europe, comparable to English grammar schools or sixth form colleges and U.S. college preparatory high schools. The word γυμνάσιον was used in Ancient Greece, meaning a locality for both physical and intellectual...
in Soest, as such he took it upon himself to school his son. From 1799 to 1802 Lehmus studied at universities of Erlangen
Erlangen
Erlangen is a Middle Franconian city in Bavaria, Germany. It is located at the confluence of the river Regnitz and its large tributary, the Untere Schwabach.Erlangen has more than 100,000 inhabitants....
and Jena
Jena
Jena is a university city in central Germany on the river Saale. It has a population of approx. 103,000 and is the second largest city in the federal state of Thuringia, after Erfurt.-History:Jena was first mentioned in an 1182 document...
. In 1803 he went to Berlin, where he was giving private lectures in mathematics and pursued further studies at the university, which awarded him a PhD
PHD
PHD may refer to:*Ph.D., a doctorate of philosophy*Ph.D. , a 1980s British group*PHD finger, a protein sequence*PHD Mountain Software, an outdoor clothing and equipment company*PhD Docbook renderer, an XML renderer...
in 1811. From December 18, 1813 to Easter 1815 Lehmus was employed as a lecturer (Privatdozent
Privatdozent
Privatdozent or Private lecturer is a title conferred in some European university systems, especially in German-speaking countries, for someone who pursues an academic career and holds all formal qualifications to become a tenured university professor...
) by the university, but in 1814 he became a teacher for math and science at the Hauptbergwerks-Eleven-Institut (mining school
School of Mines
A school of mines is a term used for many engineering schools established in the 18th and 19th centuries that originally focused on mining engineering and applied science...
) in Berlin as well. In 1826 he also assumed a teaching position at the Königlichen Artillerie- und Ingenieurschule (military engineering school) and was granted the title of a professor at that school in 1827. In 1836 he was awarded the Order of the Red Eagle
Order of the Red Eagle
The Order of the Red Eagle was an order of chivalry of the Kingdom of Prussia. It was awarded to both military personnel and civilians, to recognize valor in combat, excellence in military leadership, long and faithful service to the kingdom, or other achievements...
(4th class). In addition to his two teaching positions Lehmus was giving lectures at the university until 1837 as well.
Lehmus wrote a number of math and science textbooks, best known was probably his Lehrbuch der Geometrie, which saw several editions. He published articles in various math journals, in particular he was a regular contributor to Crelle's Journal
Crelle's Journal
Crelle's Journal, or just Crelle, is the common name for a mathematics journal, the Journal für die reine und angewandte Mathematik .- History :...
and provided an article for its very first edition in 1826. He published an elegant trigonometric solution of Malfatti's problem in the french math journal Nouvelles Annales de Mathématiques, but due to a copy error the author's name was given as Lechmütz.
In 1840 Lehmus wrote a letter to the French mathematician C. Sturm asking him for an elementary geometric proof of the theorem, that is now named after him. Sturm passed the problem on to other mathematicians and Jakob Steiner
Jakob Steiner
Jakob Steiner was a Swiss mathematician who worked primarily in geometry.-Personal and professional life:...
was one of the first who provided a proof. In 1850 Lehmus came up with a different proof on his own. The theorem itself proved to be a rather popular topic in elementary geometry being a subject of somewhat regular publications for over 160 years.
Works
- Aufgaben aus der Körperlehre. Berlin/Halle 1811
- Lehrbuch der Zahlen-Arithmetik, Buchstaben-Rechenkunst und Algebra. Leipzig 1816
- Lehrbuch der angewandten Mathematik. Volume I-III, Berlin 1818, 1822
- Theorie des Krummzapfens. Berlin 1818
- Die ersten einfachsten Grundbegriffe und Lehren der höheren Analysis und Curvenlehre. Berlin 1819
- Uebungsaufgaben zur Lehre vom Größten und Kleinsten. Berlin 1823
- Lehrbuch der Geometrie. Berlin 1826
- Sammlug von aufgelösten Aufgaben aus dem Gebiet der angewandten Mathematik. Berlin 1828
- Grundlehren der höheren Mathematik und der mechanischen Wissenschaften. Berlin 1831
- Anwendung des höheren Calculs auf geometrische und mechanische, besonders ballistische Aufgaben. Leipzig 1836
- Kurzer Leitfaden für den Vortrag der höheren Analysis, höheren Geometrie und analytischen Mechanik. Duncker und Humblot 1842
- Algebraische Aufgaben aus dem ganzen Gebiet der reinen Mathematik mit Angabe der Resultate. Duncker und Humblot 1846
- Grenz-Bestimmungen bei Vergleichungen von Kreisen, welche von demselben Dreieck abhängig sind, sowohl unter sich als auch mit dem Dreieck selbst. C. Geibel 1851