The colorized drawing is based on the diagram located in the files at the Newport Naval Museum archives, dated 1863. The title "Sea Miner" Major E.B. Hunt US Corps of Engineers, 1862-63. West Pointer, did his work in New York Brookline Navy Yard. It was fired underwater from a gun and it was a solid projectile with negative buoyancy. Wont spoil the story but is a good read and fits in the ordnance history as a never would have guessed column.