Posted by Gradivus on January 27, 2003
The archives here contains much discussion about this and the URBAN MYTHS that "Cold enough to freeze the balls off a brass monkey" had to do with ships, cannon balls, or pawn broker signs.
The best evidence I've seen is that whencever it derived, "brass monkey" originally meant a "really tough monkey" or person (racist reference to dark-skinned laborers?).
The reason I say this is that "When references to 'brass monkeys' started appearing in print in the mid-19th century, they did not always mention balls or cold temperatures. It was sometimes cold enough to freeze the ears, tail, nose, or whiskers off a brass monkey. Likewise, it was sometimes hot enough to 'scald the throat' or 'singe the hair' of a brass monkey." (source of quote: http://www.snopes.com/language/stories/brass.htm)