But the dangerous enemy was destined to be disposed of in a more novel and dramatic way. In August, 1861, the Navy Department had advertised for plans for steam batteries, to be iron-clad and capable of fighting the _Merrimac_ and other similar armored vessels that the Confederates were known to be constructing. The plan adopted was that presented by Capt. John Ericsson. Its essential features were an iron-clad hull, with an "overhang" to protect the machinery, all of which was below the waterline, surmounted by a round revolving tower or turret, in which were two heavy guns. The idea of a revolving tower was not Ericsson's; it had been put forth by several inventors, especially by Abraham Bloodgood in 1807. But this special adaptation of it, with the application of steam power, was his. The vessel was built in Brooklyn, and was launched January 30, 1862, one hundred days after the laying of the keel. She was named _Monitor_, for the obvious significance of the word. The extreme length of her upper hull was one hundred and seventy-two feet, with a breadth of forty-one feet, while her lower hull was one hundred and twenty-two feet long and thirty-four feet broad. Her depth was eleven feet, and when loaded she drew ten feet of water, her deck thus rising but a single foot above the surface. The turret was twenty feet in diameter and nine feet high. The only conspicuous object on the deck, besides the turret, was a pilot-house about five feet square and four feet high. This was built of solid wrought-iron beams, nine by twelve inches, laid {85} one upon another and bolted together. At a point near the top a slight crack was left between the beams all round, through which the commander and the pilot could see what was going on outside and get their bearings. The guns threw solid shot eleven inches in diameter. The advantage of presenting so small a surface as a target for the enemy, having all the machinery beyond reach of any hostile shot, carrying two large guns, and being able to revolve the turret that contained them, so as to bring them to bear in any direction and keep the ports turned away from danger except at the moment of firing, is apparent. This novel war-machine sailed from the harbor of New York on March 6, in command of Lieut. John L. Worden, destined for Hampton Roads. She was hardly out at sea when orders came changing her destination to Washington; but fortunately she could not be reached, although a swift tugboat was sent after her. She had a rough passage of three days, the perils of which were largely increased by the fact that her crew did not as yet understand all her peculiarities. They neglected to stop the hawse-hole where the anchor-chain passed out, and large quantities of water came in there, besides what poured down the low smoke-stacks when the waves broke over her.