"Generally, any small or light gear or structure, such as a monkey chain, monkey bridge, gaff, or rail. It appears to have been a XIX century slang term for anything diminutive." Origins of Sea Terms, John G Rogers."Shot-garland: a wooden rack running along the ship's side from one gunport to another and holding the Round Shot for the GREAT GUNS." A Sea of Words, Dean King.Several references claim there is no evidence of this term or item in the British Navy, and no use of the term brass monkey until 1857. Monkey was also a cabin boy, hence powder monkey came from the boy who carried powder. There seems to be several scientific tests to see if the brass ring could contract enough to squeeze cannonball out with negative results.