Consolidated Electric Light Co. v. McKeesport Light Co. (The Incandescent Lamp Patent Case)
United States Supreme Court
159 U.S. 465 (1895)
Sawyer and Man's patent claimed an incandescent light conductor made of "carbonized fibrous or textile material" broadly, though their specific tested example was carbonized paper; Edison independently tested numerous vegetable materials over months before discovering bamboo's parallel fiber structure made it an unusually effective conductor, unlike most other fibrous materials tested. Consolidated Electric (plaintiff), holding the Sawyer and Man patent, sued McKeesport (defendant) for infringement based on Edison's bamboo-conductor lamps, and the circuit court held the patent invalid as impermissibly broad.
Whether, if the written description of a patent is so vague and uncertain that no one can tell, except by independent experiments, how to construct the patented device, the patent is valid.