[sooty]

You've all probably all had this story forwarded to you in the past few years
"Royal Navy sailing ships needed to store iron cannonballs near the cannons so they would be ready for instant use, but in a manner that would not let them roll around the gun deck. The answer was to stack them up in a square-based pyramid near the cannon so that four levels would provide a stack of 30 balls. The problem was to prevent the bottom level (16 balls) from sliding out from under the weight of the higher levels. They devised a small brass plate referred to as a "brass monkey", with an indentation for each cannonball in the bottom layer. As temperature falls, brass contracts faster than iron and when it got cold on the gun decks, the indentations in the brass monkey would get smaller than the iron cannonballs. If the temperature became cold enough, the bottom layer of cannonballs would pop out of the indentations, spilling the entire pyramid over the deck. Thus it was, quite literally, "cold enough to freeze the balls off a brass monkey".

Checking on the website for the Townsville Maritime Museum (Australia) tells a different story. Here is a snapshot of their observations.
Why?
Sailing ships were completely at the mercy of the wind, so coming into battle often took hours and even days. In fact, the guns were kept loaded at at all times and surplus shot was stored in the hold as ballast.
In fact, they did keep surplus shot near the guns while in action, but they were either kept in indentations in the wooden hatch coamings or in wooden troughs along the bulkheads between the gun ports.

When not in use, the guns themselves were lashed to the bulkheads to prevent them from causing damage by running around the deck (hence the term "loose cannon") so the thought of 2220 iron balls (30 for all 74 cannons) being free to roll where gravity took them beggars belief and invites derision.

The case against this story being true seems incontrovertible, but there is a simpler way to check it. Consult any of the plethora of books and almanacs on naval matters published to commemorate the 200th anniversary of Trafalgar (October 21). In none of them will you find any reference to a "brass monkey". QED

After all of that if your balls are still there and working then hopefully you will enjoy these photos that I found on Tumblr and other sites. Sorry for any reposts or Pro Pics.