## Exhibit of the Month November 2016

### Leibniz Calculating Machine, 1695 (1992 reproduction)

November 14th is the 300th anniversary of the death of Gottfried Wilhelm Leibniz (1646-1716). Leibniz is mainly known as a philosopher but he had in fact many talents, including being an excellent mathematician.

Historic milestone: Leibniz’s "four-species calculator" (replica) © SDTB / Photo: C. Kirchner

Along with theoretical disquisitions he also applied himself to very practical mathematical questions: He sought to construct a calculating machine that would perform the basic arithmetical operations of addition, subtraction, multiplication and division. This automation was Leibniz’s attempt to free his contemporaries from the "menial work of calculation".

### A calculating machine, with which "numbers reckon themselves"

From 1670 on, Leibniz developed one such "four-species calculator", with which "numbers should reckon themselves".

This inferred that no manual transfer of intermediate results would be necessary. In 1673 he completed a wooden model of his machine and demonstrated it for the Royal Society in London. However, on this occasion it failed to function adequately - as it did most of the time. The main problem was that precision engineering in the 17th century had not yet advanced enough to build such a machine.

Leibniz, however, was not deterred and continued to build a number of improved versions during his lifetime. Starting in 1682, he consequently developed a new process for entering numbers by means of a so-called "Staffelwalze" - a stepped cylinder upon which nine teeth with differing lengths are attached. Calculators were still employing this principle in their construction as late as the 20th century.

The machine on display here is also based on a stepped cylinder. It is a reproduction of the only remaining Leibniz calculating machine that was built from 1695 on. The original is now housed in the Gottfried Wilhelm Leibniz Bibliothek Hannover.

### In addition

- Section "Mathematics and Computer Science" in the Deutsches Technikmuseum
- Exhibition "The Network People, Cables, Data Streams" in the Deutsches Technikmuseum
- Braille Typewriter from 1958 and Adding Machine "Hamann Selecta" from 1931
- GDR Self-Assembly Computer Z 1013 from 1987
- Article Gottfried Wilhelm Leibniz - Wikipedia