Electrometer invented by Luigi Palmieri consisting of a base with three leveling screws and a glass cylindrical case, with, at its base, a small vessel for sulfuric acid, used to dry the air inside the instrument. A light aluminum index is suspended from a bifilar silk fiber housed in a long glass tube. The index is repelled by a horizontal brass rod insulated from the base. The rotation angle is read on a scale engraved on the glass. The charge was introduced by a small sliding probe. The instrument, mainly used to measure atmospheric electricity, was common in Italian meteorological observatories. This specimen was made by G. Caputo.