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 a vulgar expression, didn't you? You must send this fabulous bit of historical knowledge to at least ten unsuspecting friends. If you don't, your hard drive is going to fall off and kill your mouse.