The jolt in ‘galvanize’ used to be literal

Two readings of a twitching leg

In 1786, in Bologna, Luigi Galvani watched a severed frog's leg kick. He had touched its nerves with scissors during an electrical storm. Later he saw the same twitch when a copper hook pushed into the spinal cord was hung on an iron railing, the leg contracting on nothing but the contact of the metals.² He published his conclusion in 1791: living tissue held a charge of its own, an innate “animal electricity,” and the nerve fed the muscle the way a Leyden jar discharges.²³

Alessandro Volta looked at the same leg and read it the opposite way. The electricity was not in the frog. It came from the two unlike metals, the copper hook and the iron rail, touching across the wet tissue; the leg was only a conductor and a very good detector.³ Both men were reading a real thing, and for a while both readings stood.

Volta answers with a battery

To prove the current needed no animal at all, Volta stacked alternating copper and zinc discs between brine-soaked pads and got a steady current out of dead metal. The pile, built about 1800, was the first battery.³ It won the narrow point: contact between dissimilar metals is a source of electricity. Galvani never conceded, and Volta never sneered. He named the effect “galvanism” after his rival and called the frog work one of the most beautiful and surprising discoveries in the science.² The loser's name is the one that entered the language.

Aldini's stage at Newgate

Galvani's nephew Giovanni Aldini helped publish the animal-electricity findings and took over his uncle's chair at Bologna after Galvani died in 1798.⁴ He also took the demonstration out of the lecture hall. Aldini ran current through the carcasses of oxen and deer and through human cadavers, using frog legs as detectors and Volta's pile as the source, and made severed heads grimace.⁴

On 18 January 1803, after George Forster was hanged at Newgate for murder, Aldini worked on the fresh corpse. The jaws clenched, the muscles convulsed, one eye opened, and the dead man's right hand rose and his legs moved.⁴ The name is also spelled Foster; it is one man. It has often been said that this scene fed Mary Shelley's Frankenstein. She was five years old in 1803, and the record holds something narrower: the Shelleys are known to have discussed galvanism before she wrote the novel.⁴

The word keeps the jolt

The verb entered English around 1801 or 1802, meaning to stimulate by galvanic electricity, straight from Galvani's name.⁵¹ A second, literal branch grew from it in 1839, when to galvanize meant to coat iron with metal; that is the sense in galvanized steel, and it is not the one people reach for today.⁵ The figurative sense, to excite as if by electricity, is first recorded only in 1853.⁵

That is the year Charlotte Brontë used it in Villette, for a languid young man snapped back into motion by a small girl's arrival.

The metaphor holds because the charge comes from outside and comes all at once. A cause that galvanizes a crowd does to it what Aldini's current did to a dead man's arm: it moves the thing from the outside, in one stroke, whether or not anything inside had decided to act. That is why a slow build never galvanizes, and why the word still asks for a jolt.