Editing Franz Reuleaux (section)

==Biography==

===Early life===
Reuleaux was born in [[Eschweiler]] in [[Germany]] (at the time part of [[Prussia]]). His father and grandfather were both mechanical engineers. His technical training was at the [[University of Karlsruhe|Karlsruhe Polytechnic School]]. He then studied at universities in Berlin and Bonn.

===Middle years===
After a time spent in the family business he became a professor at the [[ETH Zurich|Swiss Federal Institute]] in [[Zürich]]. Eventually, in 1879 he became Rector at the Königs Technischen Hochschule Berlin – Charlottenburg. This was a major technical institute, with about 300 professors. He became widely known as an engineer-scientist — a professor and industrial consultant, education reformer and leader of the technical elite of Germany.

Reuleaux was the appointed chairman of the German panel of judges for the Sixth World Industrial Fair opened in [[Philadelphia]] on 10 May 1876. He admitted that German-made goods were far inferior to those of other countries and that German industry's guiding principle was “billig und schlecht” ([[English language|English]]: cheap and shoddy).<ref>{{cite journal | title = 'Cheap and Nasty': German Goods, Socialism, and the 1876 Philadelphia World Fair | author = Andrew Bonnell | journal = International Review of Social History | volume = 46 | date = August 2001 | number = 2 | pages = 207–226| doi = 10.1017/S002085900100013X | pmid = 18574918 }}</ref> This shook business and evoked wide comment in the press.

Reuleaux was a consultant to the development of the [[Otto engine|Otto-Langen]] internal combustion engine, winner of the 1867 World's Fair in Paris, France, based on efficiency.<ref>{{Cite book|title=Franz Reuleaux: Contributions to 19th Century Kinematics and Theory of Machines|author1-link=Francis C. Moon|last=Moon|first=Francis|publisher=Cornell University|pages=7}}</ref>

Reuleaux served on several international juries and commissions and considerably involved in formation of a [[patent]] system, as he was active in German politics.

In 1877, he was elected as a member of the [[American Philosophical Society]].<ref>{{Cite web|title=APS Member History|url=https://search.amphilsoc.org/memhist/search?year=1877;smode=advanced;startDoc=21|access-date=2021-05-10|website=search.amphilsoc.org}}</ref>

He was a member of the [[Royal Swedish Academy of Sciences]] from 1882.

===Kinematics===
Reuleaux believed that machines could be abstracted into chains of elementary links called [[kinematic pair]]s. Constraints on the machine are described by constraints on each kinematic pair, and the sequence of movements of pairs produces a [[kinematic chain]].

He developed a compact symbolic notation to describe the topology of a very wide variety of mechanisms, and showed how it could be used to classify them and even lead to the invention of new useful mechanisms. At the expense of the German government, he directed the design and manufacture of over 300 beautiful models of simple mechanisms, such as the [[four-bar linkage]] and the [[Crank (mechanism)|crank]]. These were sold to universities for pedagogical purposes. Today, the most complete set are at [[Cornell University]] College of Engineering.<ref>[http://kmoddl.library.cornell.edu/ The kinematic models for design digital library]</ref>

Using his notation and methods for systematically varying the elements (e.g. inversions, changing relative sizes of the links, etc.) he showed how the four-bar linkage could be mutated into 54 mechanisms, which fall within 12 classes.