Edison's Patent for the Electric Light Bulb

After reading some fascinating books about innovation recently, like The Idea Factory, John Gertner's in-depth look at Bell Labs, and The Innovators, Walter Isaacson's story of the digital revolution, I started pulling historic patents relating to some famous inventions (e.g., telephone, airplane, transistor). I was curious to see how these fundamental technologies were originally described and claimed.  

What better place to start than with Thomas Edison's patent on the “Electric-Lamp.” Indeed, the light bulb is basically THE symbol of invention. Here we have U.S. Patent No. 223,898, which issued in 1880. (I love that back then, the inventor's and attorney's signatures were printed on the cover of the patent.) This is a short patent. Only three figures and less than four columns of description leading to a claim for:

An electric lamp for giving light by incandescence, consisting of a filament of carbon of high resistance, made as described, and secured to metallic wires, as set forth.

You can't get away with vague claim terms like “made as described” and “as set forth” anymore, but the patent details Edison's design and explains how it improves upon previous lamps that used low-resistance carbon rods and gas-filled vessels. At one point, Edison declares “I have reversed this practice” by providing a high-resistance carbon filament in an evacuated glass bulb. Edison's innovations as reflected in this patent apparently paved the way for reliable, safe, and practical light bulbs and thus, universal electric lighting.  

Additional historic patents to follow.

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