Apr 7, 2015

The battery that lasted 175 years, manufactured by London instrument makers Watkin and Hill

Mother Jones -  There sits, in the Clarendon Laboratory at Oxford University, a bell that has been ringing, nonstop, for at least 175 years. It's powered by a single battery that was installed in 1840. Researchers would love to know what the battery is made of, but they are afraid that opening the bell would ruin an experiment to see how long it will last.

The bell's clapper oscillates back and forth constantly and quickly, ?meaning the Oxford Electric Bell, as it's called, has rung roughly 10 billion times, according to the university. It's made of what's called a "dry pile," which is one of the first electric batteries. Dry piles were invented by a guy named Giuseppe Zamboni (no relation to the ice resurfacing company) in the early 1800s. They use alternating discs of silver, zinc, sulfur, and other materials to generate low currents of electricity.

"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. "Piles similar to this were made by Zamboni, whose batteries were constituted of about 2,000 pairs of discs of tin foil glued to paper impregnated with zinc sulphate and coated on the other side with manganese dioxide."

The bell didn't necessarily start as an experiment. It was manufactured by London instrument makers Watkin and Hill, and has a handwritten note that says "set up in 1840" displayed alongside it. It was eventually purchased by a researcher, who continued to allow it to ring (Oxford University suggests there's evidence that it may have actually been set up as early as 1825). The Guinness Book of World Records has named its power source the "world's most durable battery."