The Leyden Jar represents "electricity in a bottle". The first Leyden jar was just that: a bottle of water held in the hand. Water conducts electricity, and so does the human body. Somebody (candidates for the honor are Petrus Musschenbroek, Ewald Jurgen van Kleist, and Andreas Cunaeus) tried electrifying water. He put some in a bottle, dipped a wire in, and while holding the bottle, touched the wire to an electrostatic generator. Nothing happened for quite some while, so he gave up, took the bottle away from the generator, and started to remove the wire. At that point, as Musschenbroek wrote in a letter to a friend,

"Suddenly I received in my right hand a shock of such violence that my whole body was shaken as by a lightning stroke. The vessel, although of glass, was not broken, nor was the hand displaced by the commotion: but the arm and body were affected in a manner more terrible than I can express. In a word, I believed that I was done for." Musschenbroek had just gotten a really strong electrical shock, one of the first man-made electrical discharges powerful enough to be frightening.

Here is an extremely early illustration of the Leyden experiment, extracted from Nollet's Essai sur l'électricité des corps. The experimenter at the left is holding a jar full of water in his right hand, and is about to touch the main terminal with his left hand. The right hand acts as the outer conductor of the Leyden jar, while the water (connected to the main terminal by a wire) acts as the inner conductor.

The modern descendant of the Leyden jar is the capacitor. When you need a great deal of electrical power in a very short instant of time, it is the device of choice. Huge banks of capacitors are used to drive the most powerful lasers known, because they can deliver so very much energy in a - flash.

A5.1 - single Leyden jars
A5.2 - batteries of Leyden jars
A5.3 - complex medical jars (Cavallo type)
A5.4 - other forms of high-voltage capacitor

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© The Bakken Updated: April 6, 2007