When the Civil War began, Edwin Stevens offered the Federal Government, at his own expense, a small vessel called the _Naugatuck_. This was a twin-screw vessel, which could be immersed two feet below her load-line and raised again in eight minutes by pumping out the water admitted into the tanks. The solitary gun was mounted on a revolving carriage, and the recoil taken by rubber disc springs. It was loaded, directed and fired from below the deck, the loading being accomplished by bringing the depressed gun opposite a hole in the deck, provided for the purpose.[39] She carried a Parrott gun, a 100-pounder, and was one of the fleet that attacked the _Merrimac_. Her twin screws enabled her to turn from end to end in seventy-five seconds. She did good service on the James River, until her gun burst; her crew, thanks to her protecting deck, escaping injury. This vessel is chiefly of interest because of the method of placing and loading the gun. [Illustration: THE _NAUGATUCK_.] [Illustration: THE GUN-CARRIAGE OF THE _NAUGATUCK_.] Ericsson’s inventive genius was responsible in 1861, before the war broke out, for a vessel of 3,033 tons, which he named the _Dictator_, but she was not launched until 1863, the builders being the Delamater Iron Works. She was an iron-framed vessel, and had a wooden skin 3½ feet thick. The iron protecting her sides was 11 inches thick, 5 inches of which were solid bars measuring 3 inches by 5 inches, and the other portion was built up in single 1-inch plates. Her ram, a heavy structure of oak and iron, projected 22 feet beyond the bow. On deck she carried a single turret with an inside diameter of 24 feet. The walls of the turret were protected by 15 inches of iron plates, each 1 inch in thickness, and weighed 500 tons. Her engine was of Ericsson’s vibrating lever type with two cylinders 100 inches in diameter, and indicating 5,000 h.p. The screw was 21 feet 6 inches in diameter, with a pitch of 34 feet, and was cast in one piece, its weight being 17⅖ tons. The _Dictator’s_ armament was two smooth-bore 15-inch guns, known as Ericsson guns, which were of the same type as he introduced into America on behalf of Col. Stockton, and with a charge of 80 lb. of powder, threw a round shot weighing 460 lb. The ship was 320 feet long, 50 feet broad, and drew 22 feet of water. In the subsequent monitors the conning tower was placed above the turret as in the case of the _Passaic_. Monitors were built later with two turrets, and a flying deck connected them. They were of much greater dimensions than the single turret ships, and carried twice the number of guns, and being considerably heavier and faster and more extensively armoured, were exceedingly capable fighting machines.