Cannonballs

Some years ago, I came across the assertion, “cold enough to freeze the balls off a brass monkey.”  I interpreted the statement as a ribald connotation used to describe severe cold weather.  How wrong I was!

This past week I stumbled upon the true meaning.

Back in the days of the tall ships when every sailing vessel had to have cannon for protection, cannons of the times required round cannonballs that were cast from iron.  The captain or master wanted to store the cannonballs such that they could be of instant use when needed, yet not roll around on the gun deck.  The solution was to stack them in a square-based pyramid next to the cannon.  With multiple cannons, there were multiple stacks. 

Each stack was usually four balls high with the top level having one cannonball.  The succeeding levels of the stack down to the base contained four balls at level two, nine at level three and sixteen at level four.  Four levels would provide a stack of 30 cannonballs.  The only real problem was how to keep the bottom level from sliding out from under the weight of the higher levels.  To avoid this problem and the possibility of having cannonballs rolling free on the gun deck, a small brass plate was fabricated with one circular indentation for each cannonball in the bottom layer.  For the stack having a bottom layer of sixteen balls, the plate would have sixteen indentations.  Brass was used to prevent the iron balls from rusting to the plate.  Had iron been used, the plate would quickly rust at sea and the balls would adhere to the plate.  These plates were called brass monkeys. 

It is commonly known that with falling temperatures, brass contracts in size at a faster rate than iron.  As it got colder on the gun decks, the indentations in the brass monkey would get smaller than the iron cannonballs they were holding.  If the temperature was cold enough, the bottom layer of cannonballs would pop out of the now smaller indentations, spilling the entire pyramid of cannonballs over the deck.

Thus it was, quite literally, “cold enough to freeze the balls off a brass monkey.”

Prepared from material authored by Fernando Guzman as a source.  Some editing has been performed to fit the original material to this essay.

April 2004