Funny what you stumble on. Like the Edison effect, the inventor's only contribution to basic science.
One of History's marvelous ironies, that.
Edison noticed the effect in a little experimental light bulb he'd made up.
"Isn't that interesting," said he. "I've got a current that goes through nothing--a vacuum--and it will go from the plate to the filament, but not the other way."
"I don't see any real use for this, since all my current goes in only one direction anyway [Ed.: it's D.C.], but I'll dream up a gizmo that uses this doohickey and get a patent on it just the same."
"Maybe they'll invent Wireless someday, and then some Englishman will pull my device out of a dusty drawer, and find out that it makes a better detector than anything else out there."
"And then maybe an American will take this device, putz around with it, put in a third electrode, and make Radio broadcasting, TV, and computers possible."
IMHO, eureka is not the word a scientist would say upon an unexpected effect. I would bet "that's funny" (odd) is far more realistic. :-)