Every sailing ship had to have cannon for protection.
Cannon of the times required round iron cannon balls. The master wanted to
store the cannonballs such that they could be of instant use when needed, yet
not roll around the fun deck. The solution was to stack them up in a square-
based pyramid next to the cannon. The top level of the stack had one ball, the
next level down had four, the next had nine, the next had sixteen and so on.
Four levels would provide a stack of 30 cannonballs.
The only real problem was how to keep the bottom level from sliding out
from under the weight of the highter levels. To do this, they devised a small
brass plate ("brass monkey") with one rounded indentation for each cannon-
ball in the botom layer. Brass was used because the cannonballs wouldn't
rust to the "brass monkey," but would rust to an iron one.
When temperture falls, brass contracts in size faster than iron. As it got
cold on the gun decks, the indentations in the brass monkey would get smaller
than the iron cannonballs they were holding. If the temperature got cold enough,
the bottom layer would pop out of the indentations spilling the entire pyramid
over the deck. Thus it was, quite literally,
"cold enough to freeze the balls off a brass monkey."
World War II fighter planes had 50 caliber machine guns. The ammunition belts used were 27 feet long. In a dog fight it was not uncommon to use the entire belt of ammo. Back in the ready room the pilots on the carriers would describe such
an engagement as getting on an enemy and giving him "the whole nine yards."
After that the aircraft was useless for further attacks and just became a high
speed transport.
Many people today use the term of "giving the whole nine yards" with no
idea of its source.