Page:Popular Science Monthly Volume 41.djvu/424

Various stories are told of the manner in which Galvani's discovery of galvanic action, or "animal electricity," as he called it, was brought about. According to one version, he was preparing a frog-broth for his invalid wife, and some skinned frogs were lying on a table by the side of an electrical machine. One of his assistants accidentally touched the crural nerve of one of the frogs with the point of a scalpel, when all the muscles of the limbs seemed to be taken with strong spasms. Madame Galvani, a bright, thoughtful woman, who was present and witnessed the shock, was struck with the novelty of the phenomenon, and thought that she noticed along with it a disengagement of the electric spark. She informed her husband at once, and he lost no time in verifying the extraordinary fact. The point of the scalpel being again applied to the frog, while a spark was drawn from the machine, the contractions were resumed. To determine whether they were not due to the simple contact of the scalpel, Galvani touched the same nerves of other frogs without turning the machine, and got no contractions. Repetitions of the experiments were accompanied with corresponding results. Another account makes Galvani himself the chief actor in the incident; while, according to a third account, Galvani, having dissected some frogs, in a study of their nervous system, hung them on an iron railing with a copper hook thrust in their lumbar nerves, and the contractions took place whenever, in the vibration of the specimens, these nerves touched the iron too. According to the documents in the possession of the Museum of Bologna, the discovery was not all a matter of accident, as these stories would make it appear, for it is shown there that Galvani had been engaged, for twenty years before the publication of his Commentary, in investigations of the action of electricity on the muscles of frogs. The thought involved in these experiments had also been more or less vaguely suggested by other writers. Sulzer, in his Nouvelle Thdorie du Plaisir, published in 1767, had spoken of the peculiar taste produced when two pieces of different metals were put, under certain precautions, into the mouth. A pupil of Cotugno, Professor of Medicine at Naples, in dissecting a mouse about 1786, perceived a movement at the moment when his scalpel touched one of the animal's nerves. Galvani described his experiments, and claimed that he had discovered a kind of electricity having remarkable peculiarities, in the Commentary (De Viribus Electricitatis in Motu Musculari) already mentioned, which was published in 1791 and 1792. One of the immediate results of his discovery was the invention of his metallic arc, the first experiment with which is described in the third part of the Commentary, with the date September 20, 1786. This arc was constructed of two different metals, which, placed in contact, one with a nerve and