From the 1998 Old Farmer's Almanac. - Jonah

Balls and Brass Monkeys

The saying, "It's so cold out there it could freeze the balls off a brass monkey," comes from the Civil War. In those days, cannonballs were stacked beside cannons in a pyramid formation called a brass monkey. When it became extremely cold outside, these stacked cannonballs would crack and break off.

It doesn't end there, Gentle Reader. This from my pard Tim Kindred:

Dear Cousin Jonah,

I read with some amusement the article regarding Brass Monkeys, as told in the "Old Farmer's Almanac". As a former webfoot, I figured I just couldn't stand by and let some flatlander muckle on to, let alone claim, a naval saying. Seems like the Army is always taking credit for something the Navy was responsible for in the first place. Unless, of course it's some disaster they want to palm off on us (I.E. "Red River Campaign").

Back during the revolution, when many an enterprising gentleman (read Pirate) finagled letters of Marque to go off privateering (read legalized piracy), many an old sloop, brig, schooner, etc, was converted by arming it with whatever artillery was handy (and some Army cannon were thus deemed "handy"). Brass plates with holes about 1/3 the diameter of the roundshot were bolted to the inside of the hull near the guns so as to hold a few ready rounds. The idea was that one could have 4-6 shot handy for belaying some unsuspecting merchantman (I.E. "former business partners"), whilst the boys brought up more powder and shot.

Being a thrifty lot (read cheap), these New England (read Yankee) Privateers (read Pirate), depended on these plates (Brass Monkeys) to hold those rounds in place, without other rods alongside to secure them. When the weather dipped (read Nor'Easter) the brass would contract and force the balls out of place, where they often went rolling about the deck causing all sorts of mischief (read near-disaster). Thus the phrase " It was cold enough to freeze the balls off a brass monkey."

I hope this enlightens your readers (and those Secesh who wander in here looking for pictures, etc.). Until we meet again upon some contented field, I remain,

Your Pard
Tim Kindred

Well, it appears to be an Army vs. Navy thing now. Being a former Marine I'll just have to accept Tim's explanation. Go Navy! - Jonah

But, wait! It appears we may have been had! See this page from the Urban Legends site. - Jonah