A bell has been ringing at Oxford for nearly two hundred years. Because no one is willing to stop the bell, and the demonstration that it represents, no one knows the exact mechanism that's making it ring. Learn of the mysteries of the Oxford Electric Bell.


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.

Make your own lightning alarm! Benjamin Franklin is famous for his experiment with a key and a kite — but that's not his only… Read more


The batteries have a lot of power, and the bell discharges a tiny part of that power with each ring, so the experiment has staying power. Its makers clearly wanted it to keep going, because they coated the batteries with sulfur to keep them insulated. They neglected, however, to leave a record of what's inside the coating.

We know that the batteries are what's known as "dry piles." These are very early batteries first put forward by Alessandro Volta. Volta showed that if you put a porous, wet bit of material between two different types of metal, you'll have an exchange of charge. The metals each have a different ability to hold on to electrons, and moisture between them will let the electrons pile up on one side while the protons stay cold and lonely at 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.



Image: RichardWheeler.net.

Via Kenyon and IOP.