On 20 March 1800, Volta described in a letter to Sir Joseph Banks, president of the Royal Society of London, the construction of a new instrument he had invented, which he called an artificial electric organ. It is a device capable of producing electricity continuously, without needing to be recharged.
Volta uses two different types of metal discs, preferably silver or copper and zinc, accompanied by discs made of porous material, such as cardboard or leather, soaked in water or, better still, salt water. The shape and size of the discs are not important, as long as they can be easily stacked on top of each other.
The construction of the pile is simple: Volta alternately stacks one type of metal disc on top of another, followed by a soaked disc, always maintaining the same order. By repeating this sequence, it forms a stable column composed of numerous layers, each of which contributes to the overall effect.
A column composed of about forty pairs of metals is already sufficient to produce noticeable effects: it can charge and discharge an electrometer, generate sparks and even cause slight shocks to the fingers when touching the ends of the pile. Unlike Leyda’s bottle, the battery provides a continuous current and does not require subsequent recharging.
Volta compares the functioning of the battery to that of the electrical organs of certain animals, such as the torpedo ray. The analogy with nature reinforces the idea that electricity can be produced and maintained by an orderly system of repeated elements.
In the rest of the letter, written in French, Volta also refers to the artificial electric organ as an appareil à colonnes. This expression gave rise to the term appareil à pile, which in turn became the name by which the device is known today: the battery.
