The 11-Inch Dahlgrens of USS Monitor
One of USS Monitor’s 11-Inch Dahlgrens undergoing conservation at the Mariners’ Museum in Newport News, Virginia
The USS Monitor’s turret was successfully recovered from the waters off North Carolina on August 5th, 2002. Since that time, the turret and it’s two 11-Inch Dahlgren guns have been undergoing preservation at the Mariners’ Museum in Newport News, Virginia. Both of the Dahlgrens and their carriages, along with the ship’s turret and machinery, may be seen from a viewing gallery above the conservation lab.
The superlative Monitor Center at the Mariners’ Museum also includes a recreation of the turret both as it was found on the sea floor and as it existed in 1862.
The two Dahlgrens were manufactured at West Point Foundry in Cold Spring, New York in 1859. The Dahlgren mounted on the port side of the turret was Registry Number 27. Number 27 was eventually nicknamed “Worden”. The starboard Dahlgren was Registry Number 28 and was nicknamed “Ericsson.
In addition to the carriages, a number of artifacts related to the Dahlgrens such as the sights, locks, and covers for the guns have been recovered. Some of these accessories are on display in the Monitor Center.
11-Inch Dahlgren and carriage undergoing preservation at the Monitor Center at the Mariners’ Museum in Newport News, Virginia
Sign overlooking the conservation lab in the Monitor Center
Walk through display showing the condition of the turret upon initial recovery.
Recreation of the turret and carriages
Impression of the engraving upon 11-Inch Dahlgren No. 28 “Ericsson”
Display showing sights and sight covers (and a lock and fuse) from Dahlgren No. 27 “Worden”
A model of USS Monitor in the galleries
Bronze shot for USS Monitor's 11-Inch Dahlgrens?
Two reports in the Official Records mention bronze shot being supplied to USS Monitor in the days after her March 9th engagement with CSS Virginia. The projectile seems to be a cast-iron 9-inch hollow shot (I believe what is sometimes referred to as a "cored shot") which has had bronze cast round it to bring it up to 11-Inch caliber. Presumably this means that the 9-Inch iron shot has about a 1-inch thick layer of bronze all around.
Has anyone run across more information about these projectiles?
The relevant portions of the two reports:
from the March 17th, 1862 report of Chief Engineer Alban C. Stimers, USS Monitor, to Commodore Joseph Smith, USN
"The bronze shot which Captain Dahlgren has sent us I consider as superior for our purposes to the wrought iron. Their weight (160 pounds) is in their favor, so far as the gun is concerned, over even the cast-iron shot, and from the experiments tried they will have superior penetration. Our difficulty, however, was not the want of penetration of the cast-iron shot - as we now have proof - but their want of homogeneity caused them to go almost anywhere except where the gun was aimed. The bronze cast over the hollow 9-inch shot must give a very well-balanced missile, and remove the only difficulty we had."
(Official Records - Navies. Series 1. Volume 7. Pg. 28)
March 16th, 1862 report of William N. Jeffers, Lieutenant Commanding USS Monitor to Flag Officer L.M. Goldsborough:
"Sir: In answer to your enquiry I have to report that the Monitor expended forty-one solid cast iron shot in her engagement with the Merrimack, equally dived between guns 27 and 28.
On inspection of the bore with a mirror no trace of injury can be observed. I have no means of examining the vent by taking an impression.
Unless absolutely necessary I shall fire no more cast-iron shot, as I am satisfied that shells are not more liable to fracture. The bronze coated shot I shall reserve for especial occasion. The wrought-iron shot I shall send on shore to remove the temptation to fire them. I am satisfied that the Merrimack can not seriously injure the Monitor, but an explosion of a gun might destroy the turret.
I have the honor to be, very respectfully, your obedient servant,
William N. Jeffers,
Lieutenant Commanding"
(Official Records - Navies. Series 1. Volume 7. Pg. 28-29)
The Turret of USS Monitor in 1862. Library of Congress Photo.
Further tests leading the the 30 Pound Charge.
John Dahlgren's November 1862 report as Chief of the Bureau of Ordnance of the US Navy includes a lengthy discussion on ordnance and ironclads. The entire report is worth a read, but below are three quotes from the report dealing with the experiments showing that the 11-Inch Dahlgren, which was designed to fire shell with a 15 pound charge, could successfully withstand firing shot with 30 pound charges.
Whereas his reports in the OR-N directly after the March battle show concern about overstressing Monitor's guns by using wrought-iron shot (which weighed several pounds more than cast iron) to the point that Dahlgren advocated the use of copper-coated hollow shot for a subsequent engagement, the November report shows that Dahlgren and BuOrd had been busy through the summer in pushing the 11-Inch to its limits - and found those limits to be quite a bit more than expected.
"The XI-inch guns of the "Monitor" were designed chiefly for shells, which were computed to leave with a velocity of at least 1,250 to 1,300 feet. In the action shot were used with an initial velocity of about 1,120 feet. But since that time the same class of gun has been ascertained to be capable of throwing solid shot of 169 pounds, with a charge of 30 pounds, giving an initial velocity of 1,400 feet."
"The cast-iron shot does break and the wrought-iron is only crushed; but while the latter lodges in the 4 1/2-inch plate, the former (both being of 11 inches) passes completely through the plate and nearly through the wooden backing of 20 inches, making a larger hole and badly cracking the plate. The proper mode of increasing the power of the Monitor's guns was to have increased the charge, which the gun was capable of enduring safely, to the extent of 30 pounds; but this was not known at the time, and all will admit that the occasion was not one when any risk was to be incurred unnecessarily."
"It was not to be expected that ordnance designed so particularly for a given effect upon wooden structures should be equally fitted to operate upon armored vessels. Their application to this service was, therefore, temporary; and yet, even under such disadvantages, the XI-inch shot, fired with 30 pounds, is known to act severely on targets plated with 4 1/2-inch iron, and to have an endurance with these excessive charges that could not have been expected."
"One of this class, now here, has been fired 155 times, as follows:
22 rounds with 20 pounds
101 rounds with 25 pounds
32 rounds with 30 pounds"
(Shot of 165 to 169 pounds)
Dahlgren's report may be found here: https://babel.hathitrust.org/cgi/pt?id=coo.31924112651967&seq=715
Armor plate from Civil War era tests at the Washington Navy Yard. I estimated the plate to be about 4.5-inches thick. Some of the impacts also looked like they could have been from 11-Inch shot. (Others looked more like 15-inch)
