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Battery-powered bell still rings after 182 years
The Oxford Electric Bell is an experiment showing the longest surviving non-recharged battery. After 182 years, it still powers a pair of bells that ring twice a second.
In 1840, physicist, clergyman, and professor Robert Walker purchased the device to add to his collection. His notes indicate the experiment was set up in 1840, though a later note suggests it was constructed earlier, in 1825, by Watkin and Hill, instrument makers in the early 19th century.
It comprises two batteries known as dry piles. We believe these to be Zamboni Piles or Voltaic Piles. Both were engineered in the early 1800s by alternatively stacking layers of silver and zinc, separated by brine-soaked cloth. In the Oxford Bell, the piles are encased in a sort of wax compound made from sulphur to insulate them. Because of the insulation, we don’t know exactly how the piles were constructed.
Beneath the batteries are two brass bells with a spherical clapper between them. The bell works through electrostatic forces. Each battery is charged oppositely. The clapper is drawn to the opposite charged battery, and charged when it touches it. Then it is repelled because of having the same charge, and touches the other battery where it takes on the opposite charge, and the process repeats indefinitely.