en.wikipedia.org/wiki/Incandescent_light_bulb#History
2 corrections found
Lewis Latimer, employed at the time by Edison, developed an improved method of heat-treating carbon filaments
Latimer was not working for Edison when he developed and patented this filament improvement in 1882. He was then working for Hiram Maxim’s U.S. Electric Lighting Company, and joined Edison’s company later, in 1884.
Full reasoning
This sentence misstates Lewis Latimer's employer at the time of his 1882 filament work.
Authoritative U.S. government and National Park Service sources agree that:
- In 1880, Latimer was hired by Hiram Maxim of the U.S. Electric Lighting Company.
- In 1882, he patented his carbon-filament manufacturing improvement while associated with that company.
- He did not join the Edison Electric Light Company until 1884.
So the article's wording that he was "employed at the time by Edison" is anachronistic by about two years. A more accurate phrasing would be that Latimer developed this method while working for Maxim's/U.S. Electric Lighting Company, and was later hired by Edison.
2 sources
- Latimer (1848) - Energy Kids: U.S. Energy Information Administration (EIA)
In 1880, he was hired by Hiram Maxim of the U.S. Electric Lighting Company... In 1882, Latimer invented a device for efficiently manufacturing the carbon filaments... In 1884, Latimer became an engineer at the Edison Electric Light Company.
- A Few Gifted Men Who Worked For Edison - Thomas Edison National Historical Park (U.S. National Park Service)
While working for Hiram S. Maxim, a competitor with Edison in the power and lighting business, Latimer patented his own improved method to make carbon filaments. From 1884 to 1896 he worked in New York City for the Edison Electric Light Company.
The 1902 tantalum filament light bulb was the first one to have a metal filament.
This caption is incorrect. Metal-filament incandescent lamps predated tantalum lamps: platinum filament lamps were being tested in the 19th century, and Carl Auer von Welsbach patented the first metal-filament lamp in 1898 using osmium.
Full reasoning
The caption overstates the historical priority of tantalum lamps.
Two separate lines of evidence contradict it:
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Metal filaments were used before 1902. The Thomas A. Edison Papers at Rutgers describe Edison's own pre-carbon work with platinum filaments in the late 1870s. That alone means a 1902 tantalum bulb was not the first incandescent bulb to use a metal filament.
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The first patented metal-filament lamp is attributed earlier to osmium, not tantalum. The Auer von Welsbach Museum states that Carl Auer von Welsbach patented the first metal filament lamp in 1898, and that the first industrially manufactured metal-filament lamps launched in 1902 were osmium lamps.
So the caption should be narrowed substantially—e.g., tantalum lamps were an early and commercially important kind of metal-filament lamp, but not the first one to use metal.
2 sources
- The Platinum-Filament Lamp - Thomas A. Edison Papers, Rutgers University
Edison had focused his initial lamp experiments on two materials-carbon and platinum... Edison instead focused his research on platinum filament lamps that used a regulator to prevent the metal from reaching its melting point.
- Biography - Auer von Welsbach Museum
1898 ... Patenting the first metal filament lamp using the invented powder metallurgy for refractory metals. 1902 Market launch of the first industrially manufactured metal filament lamps (Osmiumglühfaden) with the name "Auer-Oslampe".