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Posted by Gary on March 15, 2003

In Reply to: Meaning of expression "cold enough to freeze the balls off a brass monkey posted by Chris Roberts on March 15, 2003

: Dear Sir/Madam, A brass monkey is a triangle on a ships
: deck that holds cannon balls.Why is it
: called a monkey.

It would be fairer to say, 'some people say that', a brass monkey was a triangle on a ship's deck that held cannonballs.

Having researched this when it has come up here before I can find no evidence that such devices were called monkeys, or even that they existed.

The Royal Navy records that, on their ships at least, planks with circular holes were used to store cannonballs. Also, a little geometry shows that a pyramid of balls will topple over if the base is tilted by more than 30 degrees. This movement is commonplace on sailing ships and it just isn't plausible that cannonballs were stacked this way.

If we discount all of the above and assume that the contraction of a brass triangle would cause a stack of balls to fall over, science comes to the rescue again. It has been pointed out here before that the coefficient of expansion of brass is 0.000019. That of iron is 0.000012. If the base of the stack were one metre long the drop in temperature needed to make the 'monkey' shrink relative to the balls by 1 millimetre (just 1 folks), would be more than 700 degress. In weather like that the sailors would probably have better things to think about.