"An instrument for observing or detecting the existence of free electricity, and, in general, for determining its kind. ... In Volta's condensing electroscope, in place of the gilt knob there is a flat metal plate upon which rests another similar plate, which may be removed by an insulating handle." -Whitney, 1911

Condensing Electroscope

"An instrument for observing or detecting the existence of free electricity, and, in general, for determining…