The Axiom of Choice (AC) was formulated about a century ago, and it was controversial for a few of decades after that; it might be considered the last great controversy of mathematics. It is now a basic assumption used in many parts of mathematics.
Henry Hall, the 94-year-old lighthouse keeper, discovered that a spark, probably from a candle in the lantern, had flown up and ignited the top of the tower. As Hall looked up to throw a bucket of water on the blaze, a stream of molten lead from the roof poured down his face and throat.