One of the most popular images found in the Vail Collection is that of the friction machine – the first electrostatic generator. The image here, taken from Jean Antoine Nollet’s Essai sur l’électricité des corps, depicts a typical friction machine from the 18th century. The principle is simple: one person rotates the large wheel on the left, which in turn rotates the glass sphere on the right. A second person places his hands (or perhaps a wool cloth) on the glass sphere as it rotates. This friction produces static electricity.
These machines were commonly used to demonstrate electrical forces, whether in the classroom or the public lecture hall. The demonstration could be complicated in any number of ways. Pictured here, for example, a woman has placed her hands on the rotating glass sphere. The static electricity generated by this friction is running through a conductor, which is suspended just above the glass sphere, and into a Leyden jar, where it can be stored for future use.
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