ClipArt ETC
"The electroscope is an instrument for detecting and testing electrification. A metallic rod passes through the cork of a glass vessel, and terminates on the outside in a ball or a disk. The lower end of the rod carries two strips of gold-leaf or of aluminum foil that hang parallel and close together. When an electrified object is brought near the knob or into contact with it, the metal strips below become similarly charged and are, therefore, mutually repelled." — Avery, 1895

Electroscope

"The electroscope is an instrument for detecting and testing electrification. A metallic rod passes…

"One of the simplest instruments of this kind consists of a metallic needle, terminated at each end by a light pith-ball, which is covered with gold leaf, and supported horizontally at its centre by a fine point.." -Comstock 1850

Electroscope

"One of the simplest instruments of this kind consists of a metallic needle, terminated at each end…

"Apparatus used to detect current and its direction." -Avery 1895

Galvanoscope

"Apparatus used to detect current and its direction." -Avery 1895