Professor Aldini began by swabbing the ears with salt water. Then he attached a metal wire to each ear and proceeded to connect them to a battery. Almost immediately the subject’s face contorted into a grimace and his eye-lids fluttered uncontrollably. The onlookers were absolutely horrified. Not because the facial expression was particularly scary, but because there was no body attached to the head! The headliner for this ghoulish event that took place at the end of the eighteenth century was a professor of physics at the University of Bologna in Italy. Giovanni Aldini, being a nephew of Luigi Galvani, had a natural interest in “galvanism,” the application of an electric current to body tissues. It was back in the 1780s that Galvani carried out the experiment that would forever enshrine his name in physics texts. By poking a dead frog simultaneously with rods made of different metals, he had managed to make its muscles twitch! Galvani misinterpreted his finding, believing that his manipulations had released some form of “animal electricity.” It was Galvani’s countryman Alessandro Volta, who correctly concluded that the dissimilar metals, and not the frog, were responsible for the generation of an electric current. The frog was just providing a medium through which current could flow, and it was this flow of electricity that caused its muscles to contract.
While he was a dedicated scientist, Aldini was also a showman, carrying out his experiments in a theatrical atmosphere open to spectators. He stimulated the severed heads of cows, horses, dogs, and people with an electric current and demonstrated that the teeth could be made to chatter and the eyes roll. But Aldini’s most dramatic experiments involved intact bodies. Perhaps his most famous “performance” took place in 1803 at the Royal College of Surgeons in London. George Foster had been sentenced to hang for murder, and the judge had decreed, in a fashion not unusual for the times, that his body be used for anatomical dissection. In front of a large crowd of doctors and other spectators, Aldini went to work. As always, he generated an electric current with a “voltaic pile,” the forerunner of the modern battery. Developed by Volta, based on Galvani’s observation, the pile consisted of a set of alternating zinc and silver plates separated by pieces of paper soaked in salt or sulphuric acid. In such an arrangement electrons flow from the zinc to the silver, generating a current. Aldini connected a pair of metal rods to the top and bottom of the pile and proceeded to use them to prod Foster’s body. When he attached one probe to the ear and the other to the mouth, the jaw quivered and an eye opened. But the most spectacular result was produced when Aldini maneuvered one of the probes to the rectum. Foster’s body went into convulsions and his arms flew up! It seemed to the spectators that the dead man was on the verge of standing up! Of course he did nothing of the sort, but the audience did leave with some novel insight into the dramatic effects that an electric current could produce on muscular systems.