Tuesday, March 17, 2015

The Oxford Electric Bell

by Regina Jeffers

Minus the occasional disruption because of humidity, for some 175 years a bell has rung at Oxford. The Oxford Electric Bell is something of a mystery for it has rung continuously since 1840. Because it is encased in two layers of glass, the sound of the ringing is nearly inaudible. According to io9.com, “The Oxford Electric Bell works using the same basic principle as Franklin's Bells the lightning alarm credited to, but not invented by, Benjamin Franklin. Because it's hooked up to early versions of batteries, and not dependent on the weather, the Oxford Bell works more reliably. If anything, it works too reliably, as it has been continuously ringing since 1840. A tiny metal bead is wedged between metal bells attached to two of the world's earliest version of batteries. The bead hits one bell, and the battery discharges a tiny portion of its charge - let's say electrons - into the bead. The bead, having acquired a negative charge, is repelled by the negatively charged battery and bell. It zooms away, hitting the other battery. There it empties its charge, takes on the same charge as the battery, and zooms back. At each hit it rings.”
The makers of this device coated the batteries with sulfur to insulate them. The batteries are known as “dry piles,” first designed by Alessandro Volta. “Alessandro Volta was a physicist, chemist and a pioneer of electrical science. He
• Invented in 1800 the first electrical battery – which people called the “voltaic pile.” With this invention, scientists could produce steady flows of electric current, unleashing a wave of new discoveries and technologies.
• Was the first person to isolate methane.
• Discovered methane mixed with air could be exploded using an electric spark.
• Discovered “contact electricity” resulting from contact between different metals.
• Recognized two types of electric conduction.
• Wrote the first electromotive series.  This showed, from highest to lowest, the voltages that metals produce in a voltaic pile. (We now talk of standard electrode potentials, meaning roughly the same thing.)
• Discovered that electric potential in a capacitor is directly proportional to electric charge. In recognition of Alessandro Volta’s contributions to electrical science, the unit of electric potential is called the volt.” (Famous Scientists)

Volta placed a porous, wet bit of material between two different types of metal to create an exchange of charge. The metals hold on to electrons, while the moisture between them permits the electrons pile up on one side while the protons stay cold and lonely on the other. “Layer the pieces of metal like a club sandwich, and more and more charge difference builds up between the ends of the battery. The most popular kind of dry pile was copper, acidified water on material, and zinc, stacked up again and again - but there were all different kinds. No one knows what kind of metal is making the Oxford Bell ring. We'll have to wait until it winds down to see.” (io9.com)

Although the composition of the “battery” and its power is uncertain, the Oxford Electric Bell (also known as the Clarendon Dry Pile) is currently located in the Clarendon Laboratory at the University of Oxford. Reverend Robert Walker, a professor of physics, purchased the bell from instrument makers, Watkin and Hill. “The Bell is an experiment consisting of two brass bells each stationed beneath a dry pile battery, with a metal sphere (or 'clapper') swinging between them to produce a ring that has occurred on the order of 10 billion times. The sphere suspended between the two bells is 4mm in diameter, perpetually alternating between the bells by way of electrostatic force and producing an oscillation frequency of 2 Hertz. As the sphere hits one of the bells, the corresponding dry pile battery gives off a small charge thus electrostatically repelling the clapper, causing it to be attracted to the opposite bell. The process repeats with only a tiny amount of charge being carried between the two brass bells, so while a high voltage is required to create the motion, it is only a small drain on the battery, so the dry piles have continued to ring the bell for over 170 years, making it one of the longest lasting scientific experiments in the world.” (“Oxford Electric Bell,” Atlas Obscura)

What is most interesting, and mysterious, about the apparatus is the internal composition of the 'dry pile' batteries. It is known that they have been coated with an insulating layer of molten sulphur in order to protect against atmospheric damage (i.e. moisture), then connected in series at their lower end to the two bells. Their interior is suspected to be similar to that of Zamboni piles (an early electric battery invented by Giuseppe Zamboni in 1812), as records of popular curiosities of the same time period have been found. This indicates that the dry pile batteries are probably composed of alternating layers of metal foil and paper coated with manganese dioxide that may be several thousand layers, or discs, thick. While devices such as these can be considered a novelty, at the time they helped to distinguish the outdated scientific theory of contact tension (a theory that attempted to account for all known sources of electric charge) and the theory of chemical action (also known as 'electrochemistry' and involved the transfer of electrons between the electrode and electrolyte).” (Atlas Obscura)

Despite claims to the contrary, the Oxford Electric Bell does not represent perpetual motion because eventually either the dry piles or the clapper will wear out, and the bells will cease to ring. (The World’s Longest Experiment)

Image of Alessandro Volta vis Famous Scientists
Image 1 of the Oxford Bell via Physics Department at Oxford University
Image 2 of the Oxford Bell via http://www.RichardWheeler.net

 Meet Regina Jeffers: A master teacher for thirty-nine years, Regina “passionately” taught thousands of students English, speech, journalism, and theatre in the public schools of West Virginia, Ohio, and North Carolina. Yet, “teacher” does not define her. Ask any of her students or her family, and they will tell you Regina is passionate about so many things: her son and grandchildren, children in need, truth, responsibility, the value of a good education, words, music, dance, the theatre, pro football, classic movies, the BBC, track and field, books, books, and more books. Holding multiple degrees, Jeffers often serves as a Language Arts or Media Literacy consultant to surrounding school districts and has served on several state and national educational commissions.

 Coming in 2015:
The Prosecution of Mr. Darcy’s Cousin: A Pride and Prejudice Mystery 
Angel Comes to the Devil’s Keep 
A Touch of Emerald: The Conclusion to the Realm Series 
Mr. Darcy’s Fault: A Pride and Prejudice Vagary 
Elizabeth Bennet’s Deception: A Pride and Prejudice Vagary

3 comments:

  1. Interesting tidbit of information. I also have a nephew who lives in Oxford and would find this fascinating.

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  2. Very interesting article. It should be on the TV program "Ancients Impossible" about all the inventions from way back in history that we think all these people would not have known about.

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  3. Anything that lasts over 10yrs deserve the term 'perpetual motion'

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