Editing Pendulum (section)

=== 1851: Foucault pendulum ===
{{Main|Foucault pendulum}}
In 1851, [[Jean Bernard Léon Foucault]] showed that the plane of oscillation of a pendulum, like a [[gyroscope]], tends to stay constant regardless of the motion of the pivot, and that this could be used to demonstrate the  [[rotation of the Earth]]. He suspended a pendulum free to swing in two dimensions (later named the [[Foucault pendulum]]) from the dome of the [[Panthéon, Paris|Panthéon]] in Paris. The length of the cord was {{convert|67|m|abbr =on}}. Once the pendulum was set in motion, the plane of swing was observed to [[precess]] or rotate 360° clockwise in about 32 hours.<ref>{{cite journal|url=https://www.maa.org/sites/default/files/pdf/upload_library/1/1/Oprea-Ford-1996.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.maa.org/sites/default/files/pdf/upload_library/1/1/Oprea-Ford-1996.pdf |archive-date=2022-10-09 |url-status=live|title=Geometry and the Focault Pendulum|publisher= Mathematical Association of America|first=John|last=Oprea|access-date=13 April 2021|date=1995 |journal= The American Mathematical Monthly|volume=102|issue=6|pages=515–522|doi=10.1080/00029890.1995.12004611}}</ref>
This was the first demonstration of the Earth's rotation that did not depend on celestial observations,<ref>Amir Aczel (2003) Leon Foucault: His life, times and achievements, in {{cite book
  | last = Matthews
  | first = Michael R.
  |author2=Colin F. Gauld |author3=Arthur Stinner
  | title = The Pendulum: Scientific, Historical, Educational, and Philosophical Perspectives
  | publisher = Springer
  | year = 2005
  | page = 177
  | url = https://books.google.com/books?id=3GV2NgDwtjMC&pg=PA177
  | isbn = 978-1-4020-3525-8}}</ref> and a "pendulum mania" broke out, as Foucault pendulums were displayed in many cities and attracted large crowds.<ref>{{cite web
 |last=Giovannangeli 
 |first=Françoise 
 |date=November 1996 
 |url=http://www.paris.org/Kiosque/nov96/foucault.html 
 |title=Spinning Foucault's Pendulum at the Panthéon 
 |publisher=The Paris Pages 
 |access-date=2007-05-25 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20070609102153/http://www.paris.org/Kiosque/nov96/foucault.html 
 |archive-date=2007-06-09 
}}</ref><ref>{{cite book
  | last = Tobin
  | first = William
  | title = The Life and Science of Leon Foucault: The man who proved the Earth rotates
  | publisher = Cambridge University Press
  | year = 2003
  | location = UK
  | pages = 148–149
  | url = https://books.google.com/books?id=UbMRmyxCZmYC&pg=PA148
  | isbn = 978-0-521-80855-2}}</ref>