Alexander Cumming

The S-bend. Flushing toilets existed before him, but in 1775 the Scottish watchmaker Cumming patented a valve closet with a bend in the waste pipe that kept a pool of water standing in it, sealing out sewer smells. That small piece of plumbing, refined by Joseph Bramah and others, is what made indoor toilets bearable, and a water trap still sits under every sink and toilet today.