Or do I need to go to Snopes? That would probably have been more sensible I suppose. But I also thought it might be an inter sting topic.
CANNON BALLS !!! ? 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 realise 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? You must send this fabulous bit of historical knowledge to at least a few uneducated friends.
That is the popular conception Bing, but a bit of Naval myth I'm afraid ... click here
The only monkeys on a ship, apart from those kept by sailors as pets, were the Powder Monkey's. A powder monkey was the term given to any member of the ship's company who passed filled cartridges and shot during action from the magazines below decks.
to keep a good supply of cannon balls on the deck near the cannon - that would have given rise to all kinds of problems, particularly in rough weather, and they would rapidly have rusted. In fact, cannon balls were stored in timber racks that had holes in them.
The difference in the relative contraction rates of iron and brass is nowhere near enough to allow cannon balls to roll out of indentations deep enough to hold the balls in the first place, no matter how cold it gets.