"In the past, war ships carried iron cannons, which required cannon balls nearby. The cannon balls were stored in a square pyramid with one ball on top, resting on four, resting on nine, which rested on sixteen. In order to prevent the sixteen balls from rolling away, a metal plate called a monkey with sixteen round indentations was secured near the cannon. As iron rusts quickly, the plate was made of brass. Whilst the rusting problem may have been solved, brass contracts much more and quicker than iron in cold weather. As a consequence, when the temperature was extremely cold, the brass indentations would shrink and the cannon balls would roll off the monkey. The temperature was therefore cold enough to [...]"
Well, you know the rest of the story.
