The experiment consists of two brass bells, each positioned beneath a dry pile (a form of battery), the pair of piles connected in series. The clapper is a metal sphere approximately in diameter suspended between the piles, which rings the bells alternately due to electrostatic force. As the clapper touches one bell, it is charged by one pile, and then electrostatically repelled, being attracted to the other bell. On hitting the other bell, the process repeats. The use of electrostatic forces means that while high voltage is required to create motion, only a tiny amount of charge is carried from one bell to the other, which is why the piles have been able to last since the apparatus was set up. Its oscillation frequency is 2 hertz.