Inventor: Alexander Fleming
What Happened: Halfway through an experiment with bacteria, Alexander Fleming up and went on vacation. Slob that he was, he left a dirty petri dish in the lab sink.
Big Discovery: When he got back, he found bacteria had grown all over the plate, except in an area where mold had formed.
As a Result: That discovery led to two things: 1) penicillin and 2) Mrs. Fleming hiring a maid. Few other inventions can top that one, though these four discoveries rank right up there as most useful and unusual.
Inventor: Horace Wells
What Happened: In its salad days, nitrous oxide was strictly a party toy, since it made people howl like hyenas. But a friend of the dentist took too much of the stuff at a laughing-gas stage show and gashed his leg.
Big Discovery: The friend hadn’t realized he’d hurt himself.
As a Result: Nitrous oxide became an early form of anesthesia.