Oxford Electric Bell: Difference between revisions
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[[Image:Oxford-electric-bell.svg|thumb|upright|Charged by the two piles, the clapper moves back and forth between the two bells.]] |
[[Image:Oxford-electric-bell.svg|thumb|upright|Charged by the two piles, the clapper moves back and forth between the two bells.]] |
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The '''Oxford Electric Bell''' or '''Clarendon Dry Pile''' is an [[experiment]]al [[electric bell]] that was set up in 1840 and which has rung almost{{Clarify|date=August 2012}} continuously ever since |
The '''Oxford Electric Bell''' or '''Clarendon Dry Pile''' is an [[experiment]]al [[electric bell]] that was set up in 1840 and which has rung almost{{Clarify|date=August 2012}} continuously ever since. It was "one of the first pieces" purchased for a collection of apparatus by clergyman and physicist Robert Walker.<ref>{{ODNBweb|id=38098|title=Walker, Robert}}</ref><ref>{{cite web|title=Exhibit 1 - The Clarendon Dry Pile|url=http://www.physics.ox.ac.uk/history.asp?page=exhibit1|work=Department of Physics|publisher=Oxford University|accessdate=8 January 2012}}</ref> It is usually located in the foyer of the [[Clarendon Laboratory]] at the [[University of Oxford]], [[England]], but {{As of|December 2009|lc=y}} it has been moved into an adjacent corridor due to construction work, and is still ringing, though inaudibly, because it is behind two layers of glass. |
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== Design == |
== Design == |
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The experiment consists of two [[brass]] [[bell (instrument)|bells]], each positioned beneath a [[Voltaic pile|dry pile]] (a form of [[Battery (electricity)|battery]]) |
The experiment consists of two [[brass]] [[bell (instrument)|bells]], each positioned beneath a [[Voltaic pile|dry pile]] (a form of [[Battery (electricity)|battery]]), the pair of piles connected in series. A metal sphere approximately 4 mm in diameter is suspended between the piles, and rings the bells by means of electrostatic force. As the clapper touches one bell, it is charged by one pile, and then electrostatically repelled, being attracted to the other bell. On hitting the other bell, the process repeats. The use of electrostatic forces means that while high voltage is required to create motion, only a tiny amount of charge is carried from one bell to the other, which is why the piles have been able to last since the apparatus was set up. Its oscillation frequency is 2 [[hertz]].<ref>[http://atlasobscura.com/place/oxford-electric-bell Oxford Electric Bell], ''[http://atlasobscura.com/ Atlas Obscura]''.</ref> |
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Probably the most interesting part of the bell is the pair of dry piles. Nobody is certain what they are composed of |
Probably the most interesting part of the bell is the pair of dry piles. Nobody is certain what they are composed of, but it is known that they have been coated with molten [[sulphur]] to prevent effects from [[Earth's atmosphere|atmospheric]] moisture and it is thought that they may be [[Zamboni pile]]s. |
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At one point this sort of device played an important role in distinguishing between two different theories of electrical action: the theory of [[contact tension]] (an [[obsolete scientific theory]] based on then-prevailing electrostatic principles) and the theory of [[electrochemistry|chemical action]] |
At one point this sort of device played an important role in distinguishing between two different theories of electrical action: the theory of [[contact tension]] (an [[obsolete scientific theory]] based on then-prevailing electrostatic principles) and the theory of [[electrochemistry|chemical action]]. |
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The Oxford Electric Bell does not demonstrate [[perpetual motion]]. The bell will eventually stop when the dry piles are depleted of charge – that is, if the clapper does not wear out first.<ref>[http://thelongestlistofthelongeststuffatthelongestdomainnameatlonglast.com/long203.html The World's Longest Experiment], ''[http://thelongestlistofthelongeststuffatthelongestdomainnameatlonglast.com/ The Longest List of the Longest Stuff at the Longest Domain Name at Long Last]''.</ref><ref>[http://improbable.com/airchives/paperair/volume7/v7i3/long-run-7-3.html The Latest on Long-Running Experiments], ''[http://improbable.com/ Improbable Research]''.</ref> |
The Oxford Electric Bell does not demonstrate [[perpetual motion]]. The bell will eventually stop when the dry piles are depleted of charge – that is, if the clapper does not wear out first.<ref>[http://thelongestlistofthelongeststuffatthelongestdomainnameatlonglast.com/long203.html The World's Longest Experiment], ''[http://thelongestlistofthelongeststuffatthelongestdomainnameatlonglast.com/ The Longest List of the Longest Stuff at the Longest Domain Name at Long Last]''.</ref><ref>[http://improbable.com/airchives/paperair/volume7/v7i3/long-run-7-3.html The Latest on Long-Running Experiments], ''[http://improbable.com/ Improbable Research]''.</ref> |
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==See also== |
==See also== |
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* [[Franklin bells]] |
* [[Franklin bells]] |
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* [[Beverly Clock]] ( |
* [[Beverly Clock]] (1864) |
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* [[Pitch drop experiment]] ( |
* [[Pitch drop experiment]] (1927) |
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==References== |
==References== |
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Revision as of 06:13, 11 March 2013
The Oxford Electric Bell or Clarendon Dry Pile is an experimental electric bell that was set up in 1840 and which has rung almost[clarification needed] continuously ever since. It was "one of the first pieces" purchased for a collection of apparatus by clergyman and physicist Robert Walker.[1][2] It is usually located in the foyer of the Clarendon Laboratory at the University of Oxford, England, but as of December 2009[update] it has been moved into an adjacent corridor due to construction work, and is still ringing, though inaudibly, because it is behind two layers of glass.
Design
The experiment consists of two brass bells, each positioned beneath a dry pile (a form of battery), the pair of piles connected in series. A metal sphere approximately 4 mm in diameter is suspended between the piles, and rings the bells by means of electrostatic force. As the clapper touches one bell, it is charged by one pile, and then electrostatically repelled, being attracted to the other bell. On hitting the other bell, the process repeats. The use of electrostatic forces means that while high voltage is required to create motion, only a tiny amount of charge is carried from one bell to the other, which is why the piles have been able to last since the apparatus was set up. Its oscillation frequency is 2 hertz.[3]
Probably the most interesting part of the bell is the pair of dry piles. Nobody is certain what they are composed of, but it is known that they have been coated with molten sulphur to prevent effects from atmospheric moisture and it is thought that they may be Zamboni piles.
At one point this sort of device played an important role in distinguishing between two different theories of electrical action: the theory of contact tension (an obsolete scientific theory based on then-prevailing electrostatic principles) and the theory of chemical action.
The Oxford Electric Bell does not demonstrate perpetual motion. The bell will eventually stop when the dry piles are depleted of charge – that is, if the clapper does not wear out first.[4][5]
See also
- Franklin bells
- Beverly Clock (1864)
- Pitch drop experiment (1927)
References
- ^ "Walker, Robert". Oxford Dictionary of National Biography (online ed.). Oxford University Press. doi:10.1093/ref:odnb/38098. (Subscription or UK public library membership required.)
- ^ "Exhibit 1 - The Clarendon Dry Pile". Department of Physics. Oxford University. Retrieved 8 January 2012.
- ^ Oxford Electric Bell, Atlas Obscura.
- ^ The World's Longest Experiment, The Longest List of the Longest Stuff at the Longest Domain Name at Long Last.
- ^ The Latest on Long-Running Experiments, Improbable Research.
Further reading
- Willem Hackmann, "The Enigma of Volta's "Contact Tension" and the Development of the "Dry Pile"", appearing in Nuova Voltiana: Studies on Volta and His Times, nb Volume 3 (Fabio Bevilacqua; Lucio Frenonese (Editors)), 2000, pp. 103–119.
- "Exhibit 1 - The Clarendon Dry Pile". Oxford Physics Teaching, History Archive. Retrieved 2008-01-18.
- Croft, A J (1984). "The Oxford electric bell". European Journal of Physics. 5 (4): 193. Bibcode:1984EJPh....5..193C. doi:10.1088/0143-0807/5/4/001.
- Croft, A J (1985). "The Oxford electric bell". European Journal of Physics. 6 (2): 128. Bibcode:1985EJPh....6..128C. doi:10.1088/0143-0807/6/2/511.