Q From Peter Grace: Over here in Queensland, it gets pretty cool in the evenings at this time of the year (though it’s probably pretty mild by UK standards). The other day, I used the expression brass monkey weather and was asked to explain. Any ideas?
A The full expansion of the phrase is cold enough to freeze the balls off a brass monkey and is common throughout the English-speaking world, though much better known now in Australia and New Zealand than elsewhere. This is perhaps surprising, since we know it was first recorded in the USA, in the 1850s. It is often reduced to the elliptical form that you give (perhaps in deference to polite society — for the same reason, it has been modified in the US into freeze the tail off a brass monkey).
There is a story, often repeated, that the phrase originated in the British navy at the time of the Napoleonic wars or thereabouts. It is said that the stack of cannon balls alongside each gun were arranged in a pyramid on a brass plate to save space, the plate being called a monkey. In very cold weather, the story goes, the cannon balls would shrink and they would fall off the stack.
Don’t let anybody convince you of this. It’s rubbish. There’s no evidence that such brass plates existed. Although the boys bringing charges to the guns from the magazine were known as powder monkeys and there is evidence that a type of cannon was called a monkey in the mid seventeenth century, there’s no evidence that the word was ever applied to a plate under a pile of cannon shot. The whole story is full of logical holes: would they pile shot into a pyramid? (hugely unsafe on a rolling and pitching deck); why a brass plate? (too expensive, and unnecessary: they actually used wooden frames with holes in, called garlands, fixed to the sides of the ship); was the plate and pile together actually called a monkey? (no evidence, as I say); would cold weather cause such shrinkage as to cause balls to fall off? (highly improbable, as all the cannon balls would reduce in size equally and the differential movement between the brass plate and the iron balls would be only a fraction of a millimetre).
What the written evidence shows is that the term brass monkey was quite widely distributed in the US from about the middle of the nineteenth century and was applied in all sorts of situations, not just weather. For example: from The Story of Waitstill Baxter, by Kate Douglas Wiggin (1913): “The little feller, now, is smart’s a whip, an’ could talk the tail off a brass monkey”; and from The Ivory Trail, by Talbot Mundy (1919): “He has the gall of a brass monkey”. Even when weather was involved, it was often heat rather than cold that was meant, as in the oldest example known, from Herman Melville’s Omoo (1850): “It was so excessively hot in this still, brooding valley, shut out from the Trades, and only open toward the leeward side of the island, that labor in the sun was out of the question. To use a hyperbolical phrase of Shorty’s, ‘It was ’ot enough to melt the nose h’off a brass monkey.’ ”
It seems much more likely that the image here is of a real brass monkey, or more probably still a set of them. Do you remember those sculptured groups of three wise monkeys, “Hear no evil, See no evil, Speak no evil”? Though the term three wise monkeys isn’t recorded earlier than the start of the twentieth century, the images themselves were known much earlier. It’s more than likely the term came from them, as an image of something solid and inert that could only be affected by extremes.