Mystery of the Silent Bell

Energy innovation with an eye to past successes


There’s a quiet bell at Oxford University that has been ringing non-stop for 175 years. It’s powered by a battery installed in 1840.

According to the University, the Oxford Electric Bell rings as a clapper oscillates back and forth to contact a chime mechanism. It has rung an estimated 10 billion times and, as you can hear in the video below, it is barely audible.
The device is powered by a dry pile, a type of electrostatic battery invented by Giuseppe Zamboni in 1812 that uses alternating discs of silver, zinc, and sulfur to generate electricity. The battery pulls only 1 nanoAmp each time the clapper oscillates.

“What the piles are made of is not known with certainty, but it is clear that the outer coating is of sulphur, and this seals in the cells and the electrolyte,” AJ Croft, a former researcher at the Clarendon Laboratory, wrote in a 1984 paper describing the bell in the European Journal of Physics.

Researchers are curious to learn from the battery’s success. But while they would like to study the device built by London instrument-maker Watkins and Hill, they fear that opening the casing could damage the battery. Instead, they have decided to wait to see how long it will last. And some speculate that the clapper component may wear out before the energy source.

For the past decade, the industry’s primary focus has been on innovating new battery technologies. But perhaps there is valuable insight to be gained by studying the functional simplicity of older technologies. The Oxford Electric Bell is a remarkable device that makes us wonder: What lessons can we glean from mature energy storage concepts?



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