Eduard Selling (5 November 1834 in

Ansbach Ansbach ( , ; ) is a city in the Germany, German state of Bavaria. It is the capital of the Regierungsbezirk, administrative region of Mittelfranken, Middle Franconia. Ansbach is southwest of Nuremberg and north of Munich, on the river Fränk ...

– 31 January 1920 in

Munich Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is no ...

) was a German

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

and inventor of

calculating machine A mechanical calculator, or calculating machine, is a mechanical device used to perform the basic operations of arithmetic automatically, or a simulation like an analog computer or a slide rule. Most mechanical calculators were comparable in s ...

s. Selling studied mathematics at the Universities of

Göttingen Göttingen (, ; ; ) is a college town, university city in Lower Saxony, central Germany, the Capital (political), capital of Göttingen (district), the eponymous district. The River Leine runs through it. According to the 2022 German census, t ...

and

(under

Philipp Ludwig von Seidel Philipp Ludwig von Seidel (; 24 October 1821 in Zweibrücken, Germany – 13 August 1896 in Munich, German Empire) was a German mathematician. He was the son of Julie Reinhold and Justus Christian Felix Seidel. Philosopher & math theorist Imre La ...

). He obtained the

doctorate A doctorate (from Latin ''doctor'', meaning "teacher") or doctoral degree is a postgraduate academic degree awarded by universities and some other educational institutions, derived from the ancient formalism '' licentia docendi'' ("licence to teach ...

in Munich in 1859, under the supervision of

Bernhard Riemann Georg Friedrich Bernhard Riemann (; ; 17September 182620July 1866) was a German mathematician who made profound contributions to analysis, number theory, and differential geometry. In the field of real analysis, he is mostly known for the f ...

.Selling (1859): ''Über Primzahlen und die Zusammensetzung der Zahlen aus ihnen in dem rationellen und in complex-irrationellen Zahlengebieten'' On recommendation of

Leopold Kronecker Leopold Kronecker (; 7 December 1823 – 29 December 1891) was a German mathematician who worked on number theory, abstract algebra and logic, and criticized Georg Cantor's work on set theory. Heinrich Weber quoted Kronecker as having said, ...

he became professor extraordinarius of mathematics at the

University of Würzburg The Julius Maximilian University of Würzburg (also referred to as the University of Würzburg, in German ''Julius-Maximilians-Universität Würzburg'') is a public research university in Würzburg, Germany. Founded in 1402, it is one of the ol ...

in 1860 – against the will of the philosophical faculty and the mathematics professor Aloys Mayr. There, he also taught astronomy and became

conservator-restorer A conservator-restorer is a professional responsible for the Conservation-restoration of cultural heritage, preservation of artistic and cultural artifacts, also known as cultural heritage. Conservators possess the expertise to preserve cultural ...

at the astronomical department in 1879. In 1873 he wrote an important paper on binary and ternary

quadratic forms In mathematics, a quadratic form is a polynomial with terms all of degree two (" form" is another name for a homogeneous polynomial). For example, 4x^2 + 2xy - 3y^2 is a quadratic form in the variables and . The coefficients usually belong to ...

which was also translated into French and cited by

Henri Poincaré Jules Henri Poincaré (, ; ; 29 April 185417 July 1912) was a French mathematician, Theoretical physics, theoretical physicist, engineer, and philosophy of science, philosopher of science. He is often described as a polymath, and in mathemati ...

Émile Picard Charles Émile Picard (; 24 July 1856 – 11 December 1941) was a French mathematician. He was elected the fifteenth member to occupy seat 1 of the Académie française in 1924. Life He was born in Paris on 24 July 1856 and educated there at th ...

and

Paul Gustav Heinrich Bachmann Paul Gustav Heinrich Bachmann (22 June 1837 – 31 March 1920) was a German mathematician. Life Bachmann studied mathematics at the university of his native city of Berlin and received his doctorate in 1862 for his thesis on group theory. He th ...

. Beginning with 1877 he also became concerned with

insurance Insurance is a means of protection from financial loss in which, in exchange for a fee, a party agrees to compensate another party in the event of a certain loss, damage, or injury. It is a form of risk management, primarily used to protect ...

, and participated in the reorganization of the pensions in

Bavaria Bavaria, officially the Free State of Bavaria, is a States of Germany, state in the southeast of Germany. With an area of , it is the list of German states by area, largest German state by land area, comprising approximately 1/5 of the total l ...

on behalf of the Bavarian government. His application for a promotion to professor ordinarius was declined in 1891. In 1906 he became

emeritus ''Emeritus/Emerita'' () is an honorary title granted to someone who retires from a position of distinction, most commonly an academic faculty position, but is allowed to continue using the previous title, as in "professor emeritus". In some c ...

. For his own extensive computations (for instance,

signed-digit representation In mathematical notation for numbers, a signed-digit representation is a positional numeral system with a set of signed digits used to encode the integers. Signed-digit representation can be used to accomplish fast addition of integers becau ...

), he initially used computational machines by

Thomas de Colmar Charles Xavier Thomas de Colmar (May 5, 1785 – March 12, 1870) was a French inventor and entrepreneur best known for designing, patenting, and manufacturing the first commercially successful mechanical calculator, known as the Arithmometer. Add ...

with which he was not satisfied. Therefore, he built multiplication machines after the model of a

Pantograph A pantograph (, from their original use for copying writing) is a Linkage (mechanical), mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a se ...

, for which he got a patent in 1886, and a prize at the Chicago World's Fair in 1893. However, the machine was complicated to use and to produce, so it didn't gain much importance. Some 30 to 40 devices were produced until 1898. He also built a few copies of an improved version and designed a third electrical machine (patent in 1894). The later inventor of computational machines, Christel Hamann, participated in those constructions. Some copies of Selling's machine can be seen, for instance, in the

Deutsches Museum The Deutsches Museum (''German Museum'', officially (English: ''German Museum of Masterpieces of Science and Technology'')) in Munich, Germany, is the world's largest museum of science museum, science and technology museum, technology, with a ...

in Munich.

References

Works

External links

Selling in Rechnerlexikon
an
Stephan Weiss ''Die Multipliziermaschinen von Eduard Selling'', 2004, pdf
{{DEFAULTSORT:Selling, Eduard 1834 births 1920 deaths 19th-century German mathematicians 20th-century German mathematicians University of Göttingen alumni Ludwig Maximilian University of Munich alumni Academic staff of the University of Würzburg