The U.S.S. Vesuvius was a Spanish-American war era cruiser armed with three "dynamite guns". These weapons were giant pneumatic tubes fired by steam driven air compressors. They lobbed a shell that was effectively a can of gun-cotton to create enormous blasts. The main problems were that it was very inaccurate. And a bit prone to mechanical breakdowns, oh, also pressure kablooeys were a hazard...as was a large pile of guncotton cannisters in a ship that might be under fire.