The brass monkey story

Many colorful expressions in the English language come from the days when wars were fought with sailing ships. "Freezing the balls off a brass monkey" is one of them.

A fighting ship had rows of cannons on each side.

To stop the iron cannon balls rolling about on the deck they were piled up in a pyramid structure on a brass plate with dents in it, called a monkey. In very cold conditions the different thermal expansion rates for brass and iron dislodged the balls - literally -

"Froze the balls off the brass monkey."

There are pictures of cannon on the web, but none of a brass monkey. They probably melted them down in the nineteenth century?