LONDON -- During a wartime visit to Moscow in 1942, Winston S. Churchill discovered a marvel of modern technology: hot and cold water flowing from the same faucet.

The plumbing in the villa where he stayed as a guest of Stalin was unlike the primitive British standard of separate taps for hot and cold. Rather than having to fill up the sink to achieve the right blend, the British leader could wash his hands under gushing water "mingled to exactly the temperature one desired," as he put it in his memoirs. From then...