On a square painted wood base are fixed four wooden cylinders which support four column piles. Each cylinder contains three glass rods, held in place by a lathe-turned, painted wooden cap. Between the rods are placed a series (originally 50 in each pile) of pairs of copper and zinc discs separated by a felt disc (not original) soaked in water to which sulphuric acid has been added. Metal plates, the terminals of the battery, are connected to the first copper disc and the last zinc disc. The potential difference generated is equal to the sum of the potential differences of each copper-zinc pair.

The instrument is equipped with a copper bar shaped so that it can be inserted between two columns; the elements of two batteries may thus be connected, giving a greater potential difference.

Archive documents record that the piles were ordered in 1803 by Francesco Maccarani (1776 – 1846), teacher of physics and chemistry at the Liceo Dipartimentale in Bergamo.

Device on display.