Static electricity tube, ca. 1747
Photo by Peter Harholdt, 2004
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Photo by Peter Harholdt, 2004

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The slender cylindrical tube of blown glass is sealed at one rounded end, and has rounded shoulders and an almost cylindrical mouth at the other. The tube is heavy: the glass is +1/16-inch thick. Franklin used tubes like this in public demonstrations of static electricity and in private experimentation. By sealing the open mouth of the tube with a cork and rubbing the exterior briskly with a piece of leather, Franklin produced a strong electrical charge within the bottle. After long experimentation, he became convinced that the charge was not being created within the bottle, but was being transferred from the atmosphere outside of the bottle to the atmosphere trapped within it. He used the terms "minus" and "plus" to designate the depletion and enrichment, and said that there were two states of electricity: positive and negative. The terms are still those we use; and the concept of this transference of electrical power remains essential to modern physics. Terms of Use Credits