Wednesday, January 20, 2010

The glass jar that delivered a JOLT

Electrical Sportsman

A polychromed, hand-painted model of a hunter resting on a walnut base measuring 13" x 4" with a Leyden jar and pith birds (missing.) This electrostatic demonstration apparatus was sold by many different manufacturers of philosophical instruments, including Benjamin Pike, in the 1840's. He writes, "When the bottle is charged to a certain extent, the distance between the muzzle of the gun and ball near it will not be sufficient to restrain the passage of the [electric] fluid, which will therefore pass between them, occasioning at the same time a flash of light, a loud report and the falling of birds."

Bill Ashworth wrote in the Linda Hall Library Newsletter:

Pieter van Musschenbroek was a Dutch experimental scientist who, on Jan. 20, 1646, excitedly wrote a letter to a French colleague, Rene Reaumur. Musschenbroek had succeeded in finding a way to store electricity in a bottle. His apparatus consisted of a glass jar, coated inside and out with metal foil, into which a rod with a knob on the end was inserted, to connect with the foil inside. If you then grasped the bottle in one hand and held the knob up to an electrical generator, electricity flowed into the jar. You couldn't see it, but it was definitely there, because if you now touched the knob with your other hand, the shock would knock you off your feet. Musschenbroek wrote to Reaumur: "I would like to tell you about a new but terrible experiment, which I advise you never to try yourself, nor would I, who have experienced it and survived by the grace of God, do it again for all the kingdom of France." The device came to be known as the Leiden jar, from Musschenbroek's place of residence, and it was in truth the first electrical capacitor, the first device capable of storing electricity. In spite of Musschenbroek's warning, lots of investigators subjected themselves to the thunderbolt from the Leiden jar, and more than a few wives, children, and barnyard animals were involuntarily enlisted as subjects for hair-raising electrical experiments.

Leiden jar

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