In the December 21st, 1861 issue of Harper’s Weekly, the following article appeared on page 806, with images to accompany it. Despite the fact that anyone who has ever fired a large gun could tell you that the particular layout shown in the left-hand image would be…problematic, if you will…the amount of information divulged here (in spite of the protestations that the editors did not wish to give the rebels any information) is rather impressive if not 100% accurate :
The Ericsson Steel-Plated Battery.
The Ericsson Battery, a sketch of which will be found on this page, is now in process of construction at the Continental iron Works at Green point, Long Island. She will be launched in the course of a few days. She is about 200 feet in length, with 36 feet beam and 11 feet depth of hold. Her hull is built of iron, and to protect her sides she is covered with a layer of oak 14 inches in thickness, another layer of pine 14 inches in thickness, the whole being pated with seven plates of one inch iron, making her shot-proof. A revolving fort, which contains two 12-inch guns, is placed upon the deck near the centre. This fort, or bomb-proof, is eight inches in thickness. The diameter of the fort is 20 feet inside, and it is 10 feet in height. She will be propelled by a powerful Ericsson engine. She is one of the most novel and interesting pieces of naval architecture constructed in this country. For proper reasons we forbear to give very full details in relation to this vessel, as we do not desire to give the rebels any information on such matters.
Other iron-clad vessels are being built at Philadelphia, Pennsylvania and Mystic, Connecticut. By next summer we shall have several afloat.