Thomas Edison's Bright Idea: The incandescent light bulb, and its inventor

Electric light bulbs had been around for decades by the 1870s. Most demonstration systems used arc lamps, which seemed far too bright and burned much too hot for indoor household use.

In 1878, Thomas Edison — already an internationally famous inventor in his early 30s, set out to create an incandescent light bulb that provided enough light to illuminate a home but would last long enough to be affordable.

An Early Interest in Science

Thomas Alva Edison was born in 1847 in MIlan, Ohio. He attended a formal school for only a few months and was instead homeschooled by his mother, a former school teacher.

He read extensively and developed an enormous interest in chemistry and electronics. He developed hearing problems at an early age due to a case of scarlet fever.

Edison sold newspapers and candy on the streets, worked nights as a Western Union telegraph operator and conducted scientific experiments in his spare time. In 1869, when he was just 22 years old, Edison filed his first patent for an electric vote recorder — a device he soon discovered for which there was no demand at all.

Learning his lesson, Edison began to look for specific needs and then to develop technology to fill those needs. His next efforts went into improving the efficiency of existing telegraph systems.

In 1876, Edison used his profits from his multiplex telegraph system — which allowed multiple messages to be sent at once — to establish a research lab in Menlo Park, New Jersey. He hired inventors he called “muckers” to work there under his direction.

Edison in 1879

Edison, 'The Wizard of Menlo Park'

By the time he died in 1931, Edison held 1,093 patents, but not all of the work done at Menlo Park was his. While Edison directed the work of his staffers and offered frequent input, much of the actual development was done by others.

One of Menlo Park’s first giant successes was the invention of the phonograph in 1877. Instead of the vinyl disc we’re so familiar with today, the sound was stored in grooves made in tin foil, wrapped around a cylinder.

In 1876, Edison had his team work on an improved carbon microphone for new telephone devices. By 1890, all new phones used Edison’s microphone system.

A key staffer on that project was Lewis Howard Latimer, a patent draftsman who had worked with Alexander Graham Bell at one time.

Latimer would also play a big role in developing Edison’s carbon filament light bulb. He would own two patents himself relating to the carbon filament at the heart of that bulb. In 1890, while still on Edison’s payroll, Latimer wrote the first book on electric lighting.

By 1887, Edison’s Menlo Park lab had expanded to fill two city blocks. He and his team would go on to invent dozens of other technical marvels including the motion picture camera, the alkaline battery and an electrical transmission system.

In the 1880s, Edison opened another research laboratory in Fort Myers, Florida. Edison died of complications of diabetes in 1931 at age 84.

Making The Incandescent Bulb Glow

In 1878, Edison — now 31 years old — became interested in electric lighting. He visited a demonstration “light farm” built by William Wallace in Ansonia, Connecticut, where Wallace built a device that powered a string of eight outdoor arc lamps. The visit inspired an “aha” moment for Edison.

Light bulbs had been invented in 1840, but either used platinum filaments — making them very expensive to produce — or used so much electrical current that they burned out after a short time. Therefore, most folks at the time relied on gas- or oil-based systems to light their homes.

Wallace’s “light farm” proved to Edison that electricity and electrical devices were the next big thing. But he also felt that arc lighting was far too bright and far too hot to be used indoors. What the world needed, Edison thought, was a cheap, reliable, long-lasting incandescent electric light bulb. And he and his team were the ones to meet that need.

But first, Edison established the Edison Electric Light Co., assigned 2,500 shares to himself and sold 500 shares to investors including William Vanderbilt.

Edison’s team made two major innovations. The first was the composition of the filament. His team tried celluloid, hemp, fishing line and long whiskers, snipped from the beards of two of his staffers.

The second was to create a vacuum inside the bulb, which would allow Edison’s team to reduce the voltage running through the bulb, which might allow it to last longer.

It took two of Edison’s staffers 10 hours to pump the air out of a bulb that used a filament made of cardboard, coated in lampblack and baked to “carbonize” it. The result lasted for 13 and a half hours. Feeling he was on the right path, Edison announced the breakthrough to reporters on Oct. 22, 1879.

Not long afterward, Edison and his team switched from cardboard to bamboo filament. That resulted in a bulb that lasted more than 1,200 hours.

Edison filed for a patent for his electric lamp on Nov. 4, 1879. It was granted on Jan. 27, 1880.

“The electric light has caused me the greatest amount of study and has required the most elaborate experiments,” Edison would later write. “I was never myself discouraged, or inclined to be hopeless of success. I cannot say the same for all my associates.”

By December, Edison arranged for a gigantic demonstration. He had his latest light bulbs strung on wires mounted on poles between the buildings at Menlo Park. On New Year’s Eve 1879, he invited newspaper reporters, his investors and the general public to view the results. Three thousand people showed up to see the light show.

The Menlo Park team’s work on the incandescent light bulb had paralleled work going on in England by Joseph Wilson Swan. When Edison tried to sell his bulbs in Great Britain, Swan sued him. Eventually, Edison solved the dispute by merging his light bulb company with Swan’s. The bulbs they sold in the U.K. used Swan’s design but Edison’s filaments.

In 1883, Edison lost his light bulb patent when the U.S. Patent Office ruled his work had been based on that of another inventor, William Sawyer. After a number of court hearings, that ruling would be overturned in 1889.