I was just watching a BBC4 show on astronomy. They were talking about the first telescopes.
On the 2nd of October 1608, Hanse Lippahay went before the Estates General in Holland and tried to patent the telescope.
I guess during the "discovery period" before the patent would be granted, two other Dutchmen popped up with telescopes of their own, and the patent was declined due to what we now call "prior art".
"And because he didn't get a patent, these devices went on sale across Europe. They were available in Frankfurt, in Paris and various other places by the end of 1608."
I submit that the non-granting of a patent was a GoodThing(tm, reg us pat off), and demonstrates perfectly the principle that a patent would have only retarded progress.