Tin-leaf Electroscope

[France], Late 19th century, glass, brass, tin. Instrument for demonstrating the electrical charge of a body. Developed in 1747 by Abbot Nollet with elderberry balls. Glass bell supported by a brass tray and closed by a stopper formed by a brass rod ending in a metal ball or button. Inside, two very light strips of tin are suspended from the rod. The upper part is painted red and garnished with two strips of tin on the opposite and internal faces of the glass. The electroscope is charged using an ebonite or glass rod previously rubbed with a cloth in order to charge it negatively. If we bring this rod closer to the metal button, we will see that the tin strips move away from each other. See ASEISTE - Francis Gires, Encyclopedia of instruments..., 2016, p. 877.