Subject: Cannon Balls

Some sailors may know this already very interesting.
In the heyday of sailing ships, all war ships and many
freighters carried iron cannons. Those cannons fired
round iron cannon balls. It was necessary to keep a
good
supply near the cannon. But how to prevent them from
rolling about the deck?

The best storage method devised was a square based
pyramid with one ball on top, resting on four resting
on nine which rested on sixteen. Thus, a supply of 30
cannon balls could be stacked in a small area right
next to the
cannon.

There was only one problem -- how to prevent the bottom
layer from sliding/rolling from under the others. The
solution was a metal plate called a "Monkey" with 16
round indentations. But if this plate was made of iron,
the iron balls would quickly rust to it. The solution
to the rusting problem was to make "Brass Monkeys".

Few landlubbers realize that brass contracts much more
and much faster than iron when chilled. Consequently,
when the temperature dropped too far, the brass
indentations would shrink so much that the iron cannon
balls would come right off the monkey.

Thus, it was quite literally, "Cold enough to freeze
the balls off a brass monkey"! (And all this time, you
thought that was an improper expression, didn't you?)