The Crown of Cups is a modification of the Voltaic Pile. A rectangular plate of copper and zinc are connected by a wire soldered to both plates and thus an "electric element" is defined. One of the plates is plunged into salt water in one cup, its opposite goes into the next cup. Here a second element is used (with the same plate beginning as in the first cup) to make a connection to the third cup and so forth. Hence in every cup of the crown you will find both elements except for the first and the last cup.
The Crown of Cups can be used to experience the effect of electricity physiologically. Just place a finger of one hand into the first cup and a finger from the second hand into any other cup!
Volta, A. (1800). On the Electricity Excited by the Mere Contact of Conducting Substances of Different Kinds. Philosophical Transactions of the Royal Society of London, 90, 403-431.
Pera, M. (1992). The Ambigious Frog: The Galvani-Volta Controversy on Animal Electricity. Princeton (NJ): UP.
Pancaldi, G. (2003). Volta : science and culture in the Age of Enlightenment. Princeton: Princeton University Press.