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FunctionWhen the seven tubes of this demonstration apparatus are electrified, the spinning rod starts its movement. When it comes in close contact with the fixed tubes, a spark is discharged, making its way along the helical spotted and creating a wonderful glow. As the rod spins, the glow goes from one tube to the other. Lecture demonstrators used it to create amazement and to explain basic concepts of electrostatics.
Published ReferencesLewis Pyenson and Jean-François Gauvin, eds., The Art of Teaching Physics: The Eighteenth-Century Demonstration Apparatus of Jean Antoine Nollet (Sillery, Qc: Editions du Septentrion, 2002), 186.