The Phrase “It’s cold enough to freeze the balls off a brass monkey” is said to originate from nautical gunnery phraseology, although there are many who disagree. It should be remembered that illiterate yet highly imaginative sailor were not above exagerating the conditions they served in, and scientific properties concerning the rate of contraction and expansion of metals probably did not enter into their thought process.
In in the Navy the young boys who carried the powder and the shot (cannonballs) were known as powder monkeys. It is extrapolated on from there that any other object or device that holds or carries cannon balls could be termed a monkey.
Legend has it that on some ships it was common practice to have some cannon balls at close readiness, and these were held on either wood or brass frames. Brass was used to prevent the iron cannon balls rusting to the frame.
The story would be told that on a particular voyage it was cold enough that the frame or ‘monkey’ would contract, thereby becoming too small to hold the balls in place., and in telling this yarn the bragging sailor would no doubt be aiming to get a pint or two for his story.
While the exact origin of the term ‘brass monkey’ is unproven it’s 200-plus year usage history indicates its original meaning is related to the Kelvin Spheres that are positioned on either side of a ship’s binnacle. The balls, which are iron, help offset magnetic shifts so the compass inside the binnacle remains pointed toward magnetic north. The two balls are traditionally mounted on brass arms, which were called ‘monkeys’ by sailors in the 18th and 19th centuries.
