Was the Biblical Ark of the Covenant an early form of electrical capacitor? A theory along these lines was presented in issue 207 of Fortean Times (March 2006) in an article by Michael Blackburn and Mark Bennett ("Re-engineering the Ark"). Specifically, they argued that the Ark was essentially a Leyden jar: a type of capacitor that was popular with electrical experimenters in the eighteenth century. The article contains no references (which is unusual for FT), and the authors present the idea as if they had thought of it themselves. They may well have done, but they weren't the first to do so. I've found exactly the same idea in an obscure journal published sixty years earlier -- the October 1946 issue of the Quarterly Review of the Institute for Experimental Metaphysics (in fact the journal is so obscure it doesn't show up in a Google search, so I've included a photograph below to prove I'm not making it up).
The paper in question is by one Captain Q.C.A. Craufurd (sic), and is entitled Experiments with a Psychic Condenser ("condenser" is the old British word for capacitor). Captain Craufurd was a spiritualist, and was looking for a physical device that could be used in séances to amplify psychic signals. He took his lead from the Biblical description of the Ark of the Covenant, which he believed had been a device of this type. He says: "What we managed to produce was an electrical instrument which fulfilled the main requirements of the Ark described in the Old Testament. It was a 'chest' of hard wood, put together without nails or screws and plated with gold within and without. In the case of my model, this plating consisted of gold leaf. The wooden box, having been carefully dried out, was varnished thickly with a coating of resin and shellac so that it became a kind of Leyden jar, capable of accepting a powerful charge of electricity. The wings of the Cherubim arching over the Mercy seat formed a spark gap at the wing tips, not a single pair of points however, but several points forming a collector." A description really very similar to the one presented in FT sixty years later!