Rodman and the Courthouse Cannons
By Johnny E. Nolen, May 15, 2018
In the year 1841, Thomas Jackson Rodman graduated from West Point Military Academy; number 7 in his class of 52. His first assignment from West Point was ordinance Corps officer at the U.S. Army Allegheny Arsenal in Pittsburg, PA.
In 1844 he began working on the problems of cannon-barrel design after a 12″ naval gun exploded on the U.S.S. Princeton, killing Secretary of the Navy, Thomas Gilmer, Secretary of the State, Abel P. Upshur and almost killing president John Tyler. By the early 19th century most of the cannons were made of bronze like the one on the Princeton.
Bronze barrels cast with fewer flaws but were not capable of withstanding the high breech pressures that the larger calibers produced. Most of the barrels were cast solid then bored to the needed caliber. The alternate method was using a sand core and smooth out bore by machining. The casting cooled and hardened from outside, causing stress cracks. It was found in most cases that the boring process did not remove all the cracks, leaving gun barrels weak to higher breech pressures.
Rodman tried to compensate for this problem by wrapping barrels with wire or using bands like iron tire rims used on cannon wheels. Both methods lacked in uniform barrel pressures. Rodman’s new modified system of hollow casting replaced the sand core with an insulated iron pipe through which large amounts of water was circulated quickly. The barrel, as it cooled from the inside out, would cause each successive layer of metal to shrink upon the cooler inner layers.
The U.S. Army Ordinance department was hesitant to approve this process, thinking the design would cause steam to build up and cause an explosion. In 1845, after three trips to Washington and the approval of the Ordnance Department, Rodman entered into a partnership with the Pittsburg Foundry.
In 1849, Rodman produced two 8″ cannons that were identical in every way except for the method of casting. The conventional cast gun burst after 85 rounds of test firing. The Rodman hollow cast system guns were still firing in good condition after 251 test rounds.
In 1851, six guns on the Rodman principle were fired. 5,515 rounds and none failed. In 1859, the government approved the Rodman casting process.
On February 6, 1864, Rodman testified before the congressional joint committee. He was asked if he believed smooth bore guns within their range were superior to rifled guns, to which he replied “yes”. This answer put him on the wrong side of history on this one issue.
In the 1850’s, he also developed and performed extensive experiments with artillery propellants, which led to his greatest and most lasting contribution to ordinance engineering. During the 1870’s and 1880’s, many attempts were made to convert existing Rodman smooth bores to rifled guns, but new technology in wrought iron and forged barrels was becoming more common.
The overall attempt to convert Rodman smooth bore to rifled guns failed, but the smooth bore Rodman guns remained in service well into the final decade of the 19th century.
There are several 8″ Rodman guns at Fort Henry, which were installed during the Civil War when the fort was still operational. At the end of the Civil War, Rodman was investigated by a U.S. congressional committee on charges of “mismanagement” of the Watertown Arsenal near Boston, a clearly trumped up charge of “disloyalty.” Among the elements of that charge were his failure to order the firing of a salute when Lee’s surrender was announced and his lack of an appropriate “sorry” at the death of President Lincoln. Once cleared of all charges, Rodman was promoted to Brevet Brigadier General and assigned to establish and command the Rock Island Arsenal in Illinois. (I guess politics will always be politics.)
General Rodman was still in command of the arsenal when he died in 1871 at the age of 54. He is buried at Rock Island National Cemetery.
In 1901, two smooth bore Rodman cannons converted to 8″ rifled guns were shipped to the Martinsville train station on Broad Street. The guns were dragged through mud and water by mules to the courthouse square and placed on granite stone mounts, flanking the Confederate statue. Because of weather conditions, this task lasted for about 1 month.
The cannons have been moved twice more from their original location where they were mounted upside down since 1901. The bores were plugged to keep “want-to-be” robbers from shooting the bank.
These coastal rifled cannons were made at West Point Foundry most likely after the Civil War and restored in 1885. They were placed at Fort Henry, Maryland, until 1901 until finding their final resting place in the old courthouse yard. For more information go online to: www.myhenrycounty.com