Incandescent light bulb
Edison files the application that becomes U.S. Patent 223,898
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Original prompt & settings (JSON) ↗The application said an ordinary cotton thread, properly carbonized, could offer 100 to 500 ohms of resistance.
Filed 4 November 1879
Thomas Alva Edison signed the specification at Menlo Park on 1 November 1879 and filed it at the Patent Office three days later. It became U.S. Patent 223,898, titled “Electric Lamp.”
On 22 October he had recorded his first successful experiment with a high-resistance carbon filament. With rival inventors chasing practical lamps, he turned the late-October results into an application quickly.
What the specification claimed
It sought an improvement in incandescent lamps: a high-resistance carbon light-giving body in a nearly perfect vacuum, connected to conductors passing through the glass. The stated objective was high resistance so that electric light could be practically subdivided into numerous lamps.
The text was broader than one carbonized sewing thread. It discussed cotton, linen, wood splints, paper, lampblack, plumbago and other carbon forms, gave 100–500 ohms for properly carbonized cotton thread and as much as 2,000 ohms for a coiled fibrous filament, and specified a bulb evacuated to one-millionth of an atmosphere.
Neither a patent nor a lighting service yet
The patent itself calls the work an improvement in electric lamps, not the invention of incandescent light. The application stayed pending until the Patent Office granted 223,898 on 27 January 1880.
A working lighting service also needed generators, wiring, meters, switches, sockets and distribution. Edison demonstrated the Menlo Park system publicly on 31 December 1879, using horseshoe-shaped bristol-board filaments rather than the spiral shown in the patent drawings.
Sources
Researched 23 Aug 2026 5 sources 2 audit passes
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