Dec. 18, 1878: Let There Be Light — Electric Light

__1878: __Joseph Swan demonstrates the electric lamp to the Newcastle Chemical Society in northern England.

The incandescent light bulb has become synonymous with Thomas Edison. But Swan was the first to show a more-or-less workable version of this remarkable creation.

Swan, though, wasn’t the first person to make electric light. English chemist Humphry Davy connected two wires to a battery in 1809 and inserted a charcoal strip between the other ends of the wires. The strip glowed, making it the first electric lamp.

Inventor Warren De la Rue about 10 years later enclosed a platinum coil in an evacuated tube and passed electric current through it to make it glow.

That set the stage for the electric bulb and turned the focus on what filament would best make the bulb glow. Early efforts focused on charcoal and bamboo, but the filaments couldn’t last long enough to create a real bulb.

Swan had apprenticed with a pharmacist and become a partner with a firm of manufacturing chemists. His interests, however, were varied, and he decided In 1860 to make an electric light using a carbon filament inside an evacuated glass chamber.

It was a rather primitive creation. The glass chamber didn’t offer a good enough vacuum, and without a steady connection to an electric source, the bulb blew out quickly. Also, the filament in the bulb was closer to a rod than a slender piece of wire. Swan’s electric lamp deposited a dark layer of soot inside its inner surface, obscuring the light.

Swan experimented with a filament of carbonized paper, but it burned out quickly. The bulb lasted just about 13½ hours. Still, that was long enough to signal that there could be a real future for this invention.

The improved pumps that were developed over the next decade made it easier to create a stronger vacuum in the glass chamber. It was an important requirement for Swan, because too much residual oxygen in the vacuum tube would ignite the filament. A good vacuum allowed the filament to glow without catching fire.

But the carbon filament had low electrical resistance. That meant it consumed a lot more current to heat up and glow. The conductor bringing in electricity would also have to be short or very thick, which made it difficult to create commercial systems.

After the initial demonstration to the members of the Newcastle Electric Society, Swan did another presentation in February 1879 with more than 700 people in the audience. His lamp then burned for about 40 hours.

Swan’s success also highlighted the shortcomings of his invention. For the electric lamp to be truly successful it would need to burn longer.

And that’s where Edison stepped in. Edison realized that the bulb would need a filament that would require high electrical resistance, so that longer copper lines and lower current could be used to heat it.

His early lamps in 1879 could last for nearly 150 hours, and those with the bamboo filaments introduced later could last 1,500 hours. That — along with a talent for self-promotion — is why Edison came to be widely credited with inventing the first practical incandescent bulb.

Swan still had a trump card. He had first filed a patent for his idea in 1861 and revised it in the next decade when he improved the design. The patent was strong enough for Edison Electric to go for a merger with the Swan Electric Light Company. The duo combined to create the British firm Edison & Swan United.

The electric bulb was not Swan’s only contribution. He also developed a method of drying wet photographic plates in 1871. Eight years later, he patented bromide paper, which is still used in photographic prints today.

Source: Various

Photo: An early carbon-rod-filament incandescent electric lamp (left) made by Joseph Swan stands next to one made by Thomas Alva Edison.
Courtesy Science Museum (London) Library & Archives