An electrical circuit makes acoustic or ultrasonic vibrations in the piezoelectric material, which produce linear or rotary motion. In one mechanism, the elongation in a single plane makes a series of stretches and position holds, analogous to the way a caterpillar moves.

Joule's apparatus for measuring the mechanical equivalent of heat

Discovery of the Leyden jar in Musschenbroek's lab. The static electricity produced by the rotating glass sphere electrostatic generator was conducted by the chain through the suspended bar to the water in the glass held by assistant Andreas Cunaeus. A large charge accumulated in the water and an opposite charge in Cunaeus' hand on the glass. When he touched the wire dipping in the water, he received a powerful shock.