Gassiot’s Cascade

A goblet lined for half its interior surface with tinfoil. It is placed in the receiver of an air pump from the top of whose bell a conductor descends into it, not touching the foil. On producing a good rarefaction, and discharging high tension electricity from between the conductor just mentioned and the metal of the machine, a luminous effect is produced, as if the electricity, pale blue in color, was overflowing the goblet.