Electroscope made by Carlo Dell'Acqua in the workshop of the Museo di Fisica e Storia Naturale. There is a circular base with groove for the missing glass bell-jar. The single gold leaf (missing) was suspended in the bell-jar between two brass plates connected to two De Luc or Giuseppe Zamboni high-voltage dry piles (i.e., without liquid electrolytes). The electrically charged leaf would be deflected toward the plate with the opposite electrical charge. This type of instrument was developed by Johann Gottlieb Friedrich von Bohnenberger c. 1814.