When Alessandro Volta began his experiments, only static electricity could be produced artificially. Luigi Galvani had studied "animal electricity" by touching the nerve and leg of a dissected frog with a wire, making it twitch. Volta substituted metal discs for the wire, and discs of brine-soaked cardboard for the frog's tissues. The result was the Voltaic Pile, which first made available current electricity in the laboratory. Piles were wired together into a battery to increase the effect. Static electricity was easily produced in large quantities by the electrical machines of the day, and stored in so-called "Leiden Jars." This electricity was used in numerous experiments, pranks, and even by Benjamin Franklin to kill a turkey (which caused a fad among cooks in Philadelphia). Certain electric fishes were known to shock their handlers, and eventually dissection revealed organs that resembled Volta's pile. Galvani, Volta, and others engaged in a vigorous debate over whether this "animal electricity" was really just Voltaic. This reached popular culture in the writings of Mary Shelley, who incorporated it into her novel, Frankenstein. Michael Faraday later used a huge battery of piles for his experiments. He was able to convert the various electricities into one another, as well as affecting magnetism, light, and chemistry. This led to the concepts of energy and the electromagnetic field, as well as practical devices like the dynamo and electric motor.