A number of the Spanish cannons at USNA have Roman numerals carved into the top of the basering. Here's a specific example from the cannon named "Jesus."
The upper mark is a weight mark, possibly meaning 29 quintales and one arroba, something over 2900 Spanish pounds. ??
The lower mark seems to be "XXXIIII (diamond) 1A" or
"34 (diamond) 1A."
Was this mark one applied at the foundry as a sort of serial number for the gun?
I recall a scene from one of the "National Geographic" special shows about treasure hunter Mel Fisher's exploits in finding the ATOCHA treasure. In it, his helper, Dr. Eugene Lyone supposedly used a similar number on one of the recovered cannons to determine that the wreck was indeed the ATOCHA. He located the number in the ship's manifest in "Archive of the Indies" in Spain.
The slideshow contains a number of views of these carved-in markings on this particular cannon. This set of marks is about the best-preserved on any cannon at USNA. Some are barely legible or perhaps gone due to acid rain corrosion over the years.
Maybe Bob Smith would know this?
http://s17.photobucket.com/albums/b62/cannonmn/miscforumsetc/forums47/?action=view¤t=36bf39b0.pbw