Editing Pantograph (section)

== History ==
[[File:Eidographe2.svg|thumb|left|Diagram illustrating the principles used by William Wallace's eidograph]]

The ancient Greek engineer [[Hero of Alexandria]] described pantographs in his work ''Mechanics''.<ref>{{cite book| last = Ceccarelli| first = Marco | title = Distinguished Figures in Mechanism and Machine Science: Their Contributions and Legacies| url = https://books.google.com/books?id=UmBnVMA5ri4C| publisher = [[Springer Science+Business Media|Springer]]|date=2007| page = 230| isbn = 978-1-4020-6366-4}}</ref>

In 1603,<ref name=GPscheiner>{{Cite web|url=http://galileo.rice.edu/Catalog/NewFiles/scheiner.html|title=The Galileo Project — Scheiner, Christoph" (history)|first=Albert|last=Van Helden|publisher=Galileo Project, [[Rice University]]|date=1995|access-date=24 March 2020|url-status=live|archive-url=https://web.archive.org/web/20040709143818/http://galileo.rice.edu/Catalog/NewFiles/scheiner.html|archive-date=9 July 2004}}</ref> [[Christoph Scheiner]] used a pantograph to copy and scale diagrams, and wrote about the invention over 27 years later, in ''"Pantographice seu Ars delineandi res quaslibet per parallelogrammum lineare seu cavum"'' (Rome 1631). One arm of the pantograph contained a small pointer, while the other held a drawing implement, and by moving the pointer over a diagram, a copy of the diagram was drawn on another piece of paper. By changing the positions of the arms in the linkage between the pointer arm and drawing arm, the scale of the image produced can be changed.

In 1821, Professor [[William Wallace (mathematician)|William Wallace]] (1768–1843) invented the eidograph to improve upon the practical utility of the pantograph.<ref>{{cite journal|title=Transactions of the Royal Society of Edinburgh. - Edinburgh, Dickson 1788-1905|journal=Transactions of the Royal Society of Edinburgh|date=1836|volume=13|pages=418–439, 637|url=https://books.google.com/books?id=paBbAAAAcAAJ&q=Account%20of%20the%20Invention%20of%20the%20pantograph%20and%20a%20description%20of%20the%20eidograph%2C%20a%20copying%20instrument%20invented%20by%20William%20Wallace&pg=PA418|publisher=Dickson}}</ref> The eidograph relocates the fixed point to the center of the parallelogram and uses a narrow parallelogram to provide improved mechanical advantages.