Ahem. The patent does not actually talk about tuna. Here is a somewhat better copy:
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US223898.pdf The patent begins: "The object of this invention is to produce electric lamps giving light by incandescence, which lamps shall have high resistance, so as to allow the practical subdivision of the electric light." The next claim is about the carbon wire (filament) which offers great resistance. Then it does go on to talk about putting the "burner of great resistance in a nearly perfect vacuum, to prevent oxidation . . ." It says the vacuum has to be one-millionth of an atmosphere, and it says he uses a mercury pump, but I do not see anywhere in the patent that he claims a new method of evacuation. I do not see that he tried to patent his method of evacuation, and Edison was careful to patent every new aspect of his inventions. Perhaps I overlooked something. It is hard to read. - Jed
