Question: Elmer T. Cunningham infringed on the vacuum tube patent of the British electrical engineer and physicist, born on what day?
Sentence (from "Triode"): Developed from Lee De Forest's 1906 Audion, a partial vacuum tube that added a grid electrode to the thermionic diode (Fleming valve), the triode was the first practical electronic amplifier and the ancestor of other types of vacuum tubes such as the tetrode and pentode.
Relevant evidence: No