Cold Enough To Freeze The Balls Off A Brass Monkey

 CANNON BALLS!!! DID YOU KNOW THIS?
 
 
 It was necessary to keep a good supply of cannon balls near the cannon
 on old war ships. But how to prevent them from rolling about the deck
 was the problem. The best storage method devised was to stack them as a
 square based pyramid, with one ball on top, resting on four, resting on
 nine, which rested on sixteen.
 
 Thus, a supply of 30 cannon balls could be stacked in a small area right
 next to the cannon. There was only one problem -- how to prevent the
 bottom layer from sliding/rolling from under the others.
 
 The solution was a metal plate with 16 round indentations, called, for
 reasons unknown, a Monkey. But if this plate were made of iron, the iron
 balls would quickly rust to it.
 
 The solution to the rusting problem was to make them of brass - hence,
 Brass Monkeys.

 
 Few landlubbers realize that brass contracts much more and much faster
 than iron when chilled. Consequently, when the temperature dropped too
 far, the brass indentations would shrink so much that the iron cannon
 balls would come right off the monkey.
 
 Thus, it was quite literally, cold enough to freeze the balls off a
 brass monkey. And all this time, you thought that was just a vulgar
 expression, didn't you?

SNOPES says this is not true, but isn't it a neat story?