Editing Pendulum (section)

=== Early proposals ===
One of the first to suggest defining length with a pendulum was Flemish scientist [[Isaac Beeckman]]<ref name="Alder">{{cite book
  | last = Alder
  | first = Ken
  | title = The measure of all things: The seven-year odyssey and hidden error that transformed the world
  | publisher = Simon and Schuster
  | year = 2003
  | location = US
  | page = 88
  | url = https://books.google.com/books?id=jwsDERPMPhsC&q=marin+mersenne+second+pendulum&pg=RA1-PT27
  | isbn = 978-0-7432-1676-0}}</ref> who in 1631 recommended making the seconds pendulum "the invariable measure for all people at all times in all places".<ref>cited in {{cite mailing list
  | last = Jourdan
  | first = Louis
  | title = Re: SI and dictionaries
  | mailing-list = USMA
  | date = 22 October 2001 <!-- 06:59:02
 --> 
  | url = http://www.mail-archive.com/usma@colostate.edu/msg07023.html
  | access-date = 2009-01-27}}</ref>  [[Marin Mersenne]], who first measured the seconds pendulum in 1644, also suggested it. The first official proposal for a pendulum standard was made by the British [[Royal Society]] in 1660, advocated by [[Christiaan Huygens]] and [[Ole Rømer]], basing it on Mersenne's work,<ref>{{cite arXiv
  | last = Agnoli
  | first = Paolo
  |author2=Giulio D'Agostini
  | title = Why does the meter beat the second?
  | date = December 2004
 | eprint=physics/0412078}}</ref> and Huygens in ''[[Horologium Oscillatorium]]'' proposed a "horary foot" defined as 1/3 of the seconds pendulum.  [[Christopher Wren]] was another early supporter. The idea of a pendulum standard of length must have been familiar to people as early as 1663, because [[Samuel Butler (poet)|Samuel Butler]] satirizes it in ''[[Hudibras]]'':<ref>quoted in {{cite journal
  | last = LeConte
  | first = John
  | title = The Metric System
  | journal = The Overland Monthly
  | volume = 6
  | issue = 2
  | page = 178
  | date = August 1885
  | url = https://books.google.com/books?id=sFQ4AAAAIAAJ&pg=PA178
  | access-date = 2009-03-04}}</ref>
:Upon the bench I will so handle ‘em
:That the vibration of this pendulum
:Shall make all taylors’ yards of one
:Unanimous opinion
In 1671 [[Jean Picard]] proposed a pendulum-defined 'universal foot' in his influential ''Mesure de la Terre''.<ref>[https://archive.org/details/bub_gb_uYCNFkRgXCoC/page/n143 <!-- pg=131 --> Zupko, 1990, p.131]</ref>  [[Gabriel Mouton]] around 1670 suggested defining the ''[[toise]]'' either by a seconds pendulum or a minute of terrestrial degree. A plan for a complete system of units based on the pendulum was advanced in 1675 by Italian polymath Tito Livio Burratini. In France in 1747, geographer [[Charles Marie de la Condamine]] proposed defining length by a seconds pendulum at the equator; since at this location a pendulum's swing wouldn't be distorted by the Earth's rotation. [[James Steuart (economist)|James Steuart]] (1780) and [[George Skene Keith]] were also supporters.

By the end of the 18th century, when many nations were reforming their [[Weights and measures|weight and measure systems]], the [[seconds pendulum]] was the leading choice for a new definition of length, advocated by prominent scientists in several major nations. In 1790, then US Secretary of State [[Thomas Jefferson]] proposed to Congress a comprehensive decimalized US 'metric system' based on the seconds pendulum at 38° North latitude, the mean latitude of the United States.<ref>[https://archive.org/details/bub_gb_uYCNFkRgXCoC/page/n143 <!-- pg=131 --> Zupko, 1990, p.140-141]</ref>  No action was taken on this proposal. In Britain the leading advocate of the pendulum was politician [[John Riggs Miller]].<ref>[https://archive.org/details/bub_gb_uYCNFkRgXCoC/page/n143 <!-- pg=131 --> Zupko, 1990, p.93]</ref>  When his efforts to promote a joint British–French–American metric system fell through in 1790, he proposed a British system based on the length of the seconds pendulum at London. This standard was adopted in 1824 (below).