There's an urban myth about the brass monkey saying, which claims it refers to the dimpled brass plate on which was stored a pyramid of cannonballs on old sailing warships. In very cold weather, supposedly the plate contracted far more than the iron cannonballs, which then became unstable and tumpled off the plate, ie the monkey, hence 'cold enough to freeze the b**** off a brass monkey'!
In fact the different contractions or expansions of the two metals, in the temperatures likely to be encountered at sea, is almost unnoticeable. In any case storing cannonballs in a pyramid formation would have been totally impractical in a sea going ship.
It's a nice story though, I have to admit!
