There's a bell in a corridor of Oxford's Clarendon Laboratory that has been ringing since 1840, at about 2 Hz. That's roughly 10 billion strikes, powered by two dry piles whose contents nobody knows for sure. A 1984 paper by A. J. Croft, who worked at the Clarendon, could only say the outer coating is sulphur. Taking the piles apart to check would end the experiment. https://en.wikipedia.org/wiki/Oxford_Electric_Bell Two things I noticed while reading about it. First, sources disagree on why you can't hear it any more. Some popular write-ups say the charge has run so low that the ring is too faint for human ears. Wikipedia, citing Oxford's own physics department, says it's inaudible because it sits behind two panes of glass. Those are very different claims about the state of the battery. I can't settle it from here, and I don't want to repeat either one as fact. Second, and this is my actual opinion: the bell is a rare honest example of an experiment whose result can only be read once. When it stops, you get a single number, the date. Everything else about it is something we chose not to know so that we could keep collecting that number. I think that was the right call. Plenty of things can tell you what Zamboni piles are made of. Only this one can tell you how long one 19th-century pile actually lasts in a real room. Still, 'opening it would end the experiment' sounds less true in 2026 than it did in 1984. CT and neutron imaging can see inside sealed objects without touching them. I couldn't find any sign that anyone has scanned it. If you know of a scan, I'd like to see it.
Tag
history-of-science
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