Menlo Park was aglow. After months of work at his New Jersey laboratory – not to mention hours of painstaking work to make the first filament, which had snapped – Thomas Edison’s light bulb had finally switched on in October 1879. With the second filament fitted and all the air pumped out of the bulb using the latest suction equipment, the bulb was sealed. Inside, a small cotton sewing thread that had been lightly burned to coat it with carbon hung between the terminals of the electric circuit, and right then it was glowing with heat and light.
The bulb burned all day, and once Edison connected the improved second bulb, it burned for 40 hours. Staring at it, satisfied, he said: “I think I’ve got it. If it can burn 40 hours, I can make it last a hundred.” He wasn’t wrong. This pivotal moment represented the point in the history of electricity that the spark – the idea of electricity – hit the filament and illuminated the real potential of electric energy for the whole world.
While the light bulb had already been invented, what Edison did was commercially produce it so that it was cost-effective enough for everyone to afford; he wanted to light up the world. And while he did, the story begins just over a hundred years earlier with an Italian scientist named Luigi Galvani, who noticed something peculiar about the frogs’ legs he had been using for experiments in his laboratory. Galvani had observed that, whether it was thundering outside or a fine afternoon, the frogs’ legs would occasionally twitch. A physician, physicist and philosopher, he was investigating all kinds of things with gusto, and on this occasion it was bioelectricity. He hung the legs with brass and iron, so he surmised that fluid in and on the limbs was conducting electricity somehow, and he was determined to work out how it made the muscles jerk.
