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Thomas Edison: Years after Age 40

by Ron Kurtus (revised 22 January 2012)

In his early years, Thomas Edison started in telegraphy and went on to invent the phonograph and electric light bulb, as seen in Thomas Edison: Years to Age 40.

Then after he turned 40 years old, he had a few other major inventions, but also suffered setbacks in the area of promoting direct current (DC) electrical power.

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Ages 40 to 49 years

In 1887, at age 40, Edison moved his lab to West Orange, New Jersey, where he continued his invention development.

Invents motion picture camera

Then when he was 44 in 1891, Edison invented the motion picture camera. This was another major success and added to the amazing number and variety of inventions he made.

Although he was certainly instrumental in the development of his inventions, it is unclear how much of a role his various engineers had in the inventions. Most likely, Edison came up with an idea and let his workers do much of the time-consuming development and testing.

Fought AC electricity

Edison had invested much money in DC power transmission and fought bitterly against Tesla and Westinghouse's AC transmission. He was not about to let an upstart give him a financial loss. So he started a public relations promotion, showing the advantages of DC over AC.

Created electric chair

One effort was to show how DC could be used in electrocution. Edison created an electric chair and oversaw its first use. Unfortunately, the death-row inmate did not die immediately from electrocution, but instead suffered while almost starting on fire!

Public turns against Edison

This event and his other attacks on the use of AC electricity backfired and turned the public against his efforts. In fact, the public reaction was such that his investors wanted to remove Edison's name from the name of their electric company

AC Won Over DC

In the decision to promote DC, Edison was soon shown to be on the wrong side. AC was much more convenient to transmit electricity, because it could be produced at high enough voltages to be transmitted over large distances, whereas DC could not.

In 1892, at age 45, investors in Edison General Electric Company consolidated the company with Thomson-Houston to form the General Electric Company. Their goal would be to deliver Tesla's brand of AC electricity, using a similar system as the Westinghouse Company uses, which was gaining worldwide acceptance. Edison would have little say in the operation of the new company.

Edison was defeated and abandoned work concerning the electric company from that point on. He would now concentrate his efforts on other inventions.

Invented fluoroscope

Although this had been a major setback, Edison was still a good businessman and publicist. He was excellent at spotting trends and opportunities. After things calmed down, Edison started up new business ventures and devised some new inventions.

In 1896, at age 49, he invented the fluoroscope, which photographs x-rays. That same year, he also invented the fluorescent electric lamp.

Ages 50 years to death

In 1900, at age 53, Edison invented the nickel-iron-alkaline storage battery. Edison continued to operate his various businesses, but he really did not start anything new until he turned 60 in 1907 when he started the Edison Portland Cement Company.

Stubborn about improving phonograph

Although Edison had invented the phonograph in 1877, he did little to improve on the invention. He insisted that his company continue to use the wax cylinder as the medium to hold the sounds. Upstart companies such as Victor and Columbia had moved to the flat disc that was the precursor of the modern record.

Such a disc could hold more than four minutes of sound on a side, while Edison's format could only hold two minutes. Also, the flat disc was more convenient to use and store. Edison's stubbornness on keeping his original format, as opposed to going with technical improvements on his invention, was similar to what was seen in his insistence on DC electricity over AC, years before.

By 1912, the competition had signed some of the top opera stars, such as the famous Italian singer Enrico Caruso, to make recordings. Edison then launched a talent search throughout Europe. His talent scouts recorded almost 300 singers on the two-minute wax cylinders. Edison personally listened to all of the singers, but only found one of sufficient talent to sign to a contract. Unfortunately, the Italian opera singer died a few weeks later.

Edison sealed all of the cylinders in a vault. They were purchased in the late 1990s and made into a CD set called "The Edison Trials" by Marston Records.

Still inventing

Edison still continued to invent new devices. In 1914, at the age of 67, he invented the electric safety miner's lamp. His laboratory also discovered the process for making synthetic carbolic acid, giving Edison the credit for the work.

Refused to share award

In 1915, when he was 68, Edison actually turned down the nomination for the Nobel Prize in physics, because it was to be shared with Tesla. Edison apparently felt that it would be better to refuse the honor than to allow his rival the attention that would have come even from sharing the prize.

This certainly seemed to be mean-spirited, especially since it had been years since their rivalry and the fact that Tesla was now down on his luck, with little income.

Edison in his later years

Edison in his later years

Last years

In 1927, at age 80, Edison began testing various plants for rubber content as part of work for the Defense Department. At age 81 Edison received the Congressional Gold Medal.

He died at age 84 on October 18, 1931.


Thomas Edison was one of the world's greatest inventors, as well as being a astute businessman. He also was good at promoting his inventions in order to get funding for further work.

The impact of his inventions and improvements are still being felt today. His defeat in the promotion of DC electricity actually benefited mankind, because it allowed us to use the better AC electricity.

Persistence pays

Resources and references

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Thomas Edison: Years after Age 40

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