10-Inch Rodman and 8-Inch Rodman Rifle Conversions at Fort Monroe
10-Inch Rodman displayed at Fort Monroe in Virginia
Additional Images of the 10-Inch Rodman No 457
Three cannons originally cast as 10-Inch Rodmans (Seacoast 10-Inch US Model 1861) are preserved at Fort Monroe in Virginia. Together they form a display in a small park showing the original form of the cannon as well as two different attempts to convert the type into an 8-Inch rifle in the years after the Civil War.
The unmodified example is displayed with a plaque that gives an overview of the type as well as the history of this specific piece:
“This gun, known as Number 40, formerly stood in the last casemate of the water battery. It acquired the name ‘The Lovers Gun’ as it was a favorite rendezvous of sweethearts from the garrison, the Hygeia Hotel, and the Old Chamberlin Hotel.
“Commonly known as the 10-Inch Rodman, after designer Lieutenant Thomas J. Rodman, this piece is a smoothbore, muzzle-loading weapon. The inscription on the muzzle, 14956 LBS., 1865, SCL, Fort Pitt, PA, NO 257, indicates the gun weight, the year of casting, the Ordnance Inspector Stephen C. Lyford, the foundry, and the serial number.
“Length - 137 Inches; Diameter - 35 Inches; Range with 100.67 LB shell - 4836 Yards; 127.5 LB shot - 5654 yards; Charge 15-20lbs Black Powder.”
(Note: The plaque gives the registry number as “257”, but the muzzle seems to indicate a registry number of “457” - though much of the marking is obscured by heavy layers of paint. The registry of surviving Civil War artillery gives this piece’s registry number as “457”.)
Total production for the 10-Inch Rodman totaled 1,291 cannons produced from 1861-1867. As I have previously discussed, Rodman’s hollow-casting method produced a stronger and more reliable cast iron cannon than traditional solid-casting. In the 1870s and 1880s, 210 of these 10-Inch Rodmans were converted into 8-Inch Rifles. The US Navy created such conversions of 11-Inch Dahlgrens into 8-Inch Rifles. Given that the US already had an 8-Inch Rifle in its inventory in the form of the 8-Inch Parrott, I wonder if existing stocks of Parrotts in good condition were insufficient or the Parrott was seen as less reliable than desired.
The first type of these Rodman conversions is of a gun that was originally cast at Alger in 1866. It’s original weight was 15,130 lbs, and it’s registry number was 110. In 1876 it was converted into an 8-Inch Rifle at West Point Foundry by reaming out the bore to 13.5 inches prior to inserting a wrought iron, rifled sleeve into the barrel. As converted its registry number is 5.
10-Inch Rodman, converted to 8-Inch Rifle in 1876, Registry Number 5
Additional images of 8-Inch Registry Number 5.
The third Rodman again was cast as a 10-Inch smoothbore at West Point Foundry in 1866. It’s registry number was 98 and its original weight was 14,742 pounds. In 1884 it was converted at the South Boston Foundry into an 8-Inch Rifle by a different method which involved inserting a steel sleeve through the breech. This piece may be visually distinguished from the other by the rectangular extension protruding from the breech which was the means by which the threaded breech plug of the sleeve was engaged into the original tube. The Rodman’s weight as converted was 15,900 lbs. As converted, its registry number is 68.
It is unclear to me how the breech insertion type would have been elevated as many of the sockets were replaced by the breech plug and the extension would have interfered with the elevating post on the standard Rodman carriage. I also wonder if both types of rifles would have balanced on their trunnions differently than a “stock” Rodman - also making the elevation which was based on neutral preponderance more difficult. Ripley indicated that he presumed that the extension was not a permanent feature of the conversion - rather a temporary fixture to allow subsequent work on an experimental piece. However, since all of the type that I am aware of - including Rodmans converted in 1879 and 1887 continue to have this extension, that seems not to be the case.
Also, I believe that Olmstead/Stark/Tucker’s The Big Guns implies that the reason that the breech insertion was necessary was the steel sleeve was reinforced (of larger diameter?) around the chamber. If the sleeve was larger around the chamber than around the chase, it would have to be inserted via the breech.
The wrought iron muzzle insertion conversions were not thought to be successful. The fact that West Point Foundry returned to the earlier muzzle insertion conversion for the last conversions which were completed from 1885 to 1887 suggests that the breech conversion was not seen as being superior enough to warrant the more involved process.
Again, is interesting to compare these Rodman conversions to a similar conversion in 1879-1880 of 11-Inch Dahlgrens to 8-Inch Rifles which was the subject of a previous post. Four of the converted Dahlgrens may be seen at Patriots Point near Charleston, South Carolina.
10-Inch Rodman converted to 8-Inch Rifle via breech insertion, registry number 98
