Take a look:
http://is.gd/lvKcThe reason I looked this patent up is that in the National Archives I found the Navy test report of the 12-pounder version of this gun, conducted at the Washington Navy Yard in 1851, by a board composed of Farragut, Harwood, and Dahlgren. They fired about 20 rounds or less and the bolts holding the breech hinge onto the gun worked loose. This was an inconvenience but not dangerous. The breech was also hard to operate when it got dirty from powder residue. Otherwise it seemed to work fine. They gave it a mediocre report.
They were then asked if the gun might be something useful to put in service. Their reply was rather snotty I thought, when they wrote that they really couldn't tell anything from a gun this size, they'd have to test two guns in the size used in the Navy, 32 pounder and 8 inch. The poor inventor probably went broke building the one 12-pounder gun he brought to the test, much less two much larger ones.
If you look closely, this gun uses an INTERRUPTED THREAD BREECHBLOCK which didn't come into common use until something like the 1890's, then lasted until, well it is still in use in 155mm Army guns.
I think the Navy really missed a bet there. Had they been a bit less conservative history could have been changed, like the Civil War might have been shorter, etc.
I found a large, old handcolored diagram of this gun, badly foxed, at the archives, and it may be the only original diagram of it showing all the parts in some detail. Maybe I can get them to do some preservation on it. I took pix anyway.
