In Franklin’s day, science was not merely the domain of scientists and traveling lecture-demonstrators. The general learned population had exposure to numerous mechanical tools to demonstrate scientific phenomena. Professor Herschbach displays one of these gadgets as pictured in Young Gentleman and Lady’s Philosophy, a popular book in Franklin’s day: the electrostatic generator.

Franklin’s electrostatic generator had a wheel turned by a crank, which would rub against fur pads. The static electricity that would build up would create sparks, creating electricity for experimentation.

His experiments with electrostatic generators led him to formulate the single fluid theory of electricity.

Portable Electrostatic generator