I am in school for electrical Engineering right now, and for the life of me, I am brain dead on what he advanced!
Magnetism?
The Triode?
" The Supreme Court of the United States later invalidated the patent because of an improper disclaimer and, additionally, maintained the technology in the patent was known art when filed.[6]"
[From the article] ... is best known for developing the first successful thermionic valve (also called a vacuum tube, a diode, or a Fleming valve) in 1904. His invention was the ancestor of all electronic tubes, a development that gave birth not only to radio communications, but to the entire electronics industry.
Read the article!