Jusaying#1460
In days of tall ships cannon balls were stacked in a pyramid on a steel plate called a monkey. The sea water would corrode the steel balls and the steel plate. The plate and the bottom row would rust together making balls hard to remove.
So the US Navy began to see that the monkeys were made of brass so they could not corrode. Being brass and steel contract and expand at different rates with temperature changes. When it was extremely cold the brass would contract faster than steel knocking the balls off the plate.
At times like this it was cold enough to freeze the balls off a brass monkey.
Carry on.