HOW THE WORLD TURNED ELECTRIC

FROM BATTERY TO BULB, FIND OUT HOW ELECTRICITY WAS USED TO LIGHT UP THE PLANET, SPARKING AN AGE OF TECHNOLOGICAL INNOVATION

MENLO PARK WAS AGLOW. AFTER MONTHS OF WORK AT HIS LABORATORY IN New Jersey, not to mention many 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 vacuum equipment, the bulb was sealed. Inside, a small cotton sewing thread that had been lightly burned to coat it with carbon connected 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 power for the whole world.

While the light bulb had already been invented, what Edison successfully 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 in 1780 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, philosopher and biologist, he was investigating all kinds of things with gusto, and on this occasion, it was bioelectricity.

The global switch-on

The UK and US received the first infrastructure

1 Paddington to Slough 1843