'The Galvanic Apparatus', 1804.
© Science Museum / Science & Society Picture Library
Engraving by J Pass after Henry Lascelles, showing apparatus for demonstrating 'animal electricity' as discovered by Luigi Galvani (1737-1798). Whilst investigating the effects of electrostatic stimuli applied to the muscles of frogs, Galvani discovered he could make a muscle twitch by touching the nerve with metal without a source of electrostatic charge. This showed that nerves and muscles in animals function by tiny electrical currents, and can be stimulated by the application of metal or electricity from outside. A pair of frog's legs is seen here at top right. The term 'galvanise' - to shock or excite into action - takes its name from Galvani. Illustration from 'Encyclopaedia Londinensis, or, Universal Dictionary of Arts, Sciences, and Literature' published in London, 1810-1829.