The _Cumberland_ being destroyed, the _Merrimac_ headed for the _Congress_, which had run aground. She replied with her harmless broadsides, but the _Merrimac_ held her completely at her mercy, raking her fore and aft, and killing 100 of the crew, including the commander. It being evident that not a man could escape, the white flag was run up in token of surrender. The hot firing from the shore preventing Commodore Buchanan from taking possession of the _Congress_, whereupon he fired her with hot shot. During the fighting, Commodore Buchanan fearlessly exposed himself on the upper deck of the _Merrimac_, and was badly wounded in the thigh by a Union sharpshooter, whereupon the command was assumed by Lieutenant Jones. By that time it was growing dark and the _Merrimac_ steamed back to Sewall's Point, intending to return the next morning and complete her appalling work of destruction. CONSTERNATION IN THE NORTH. The news of what she had done caused consternation throughout the North. President Lincoln called a special cabinet meeting, at which Secretary Stanton declared, in great excitement, that nothing could prevent the monster from steaming up the Potomac, destroying Washington, and laying the principal northern cities under contribution. The alarm of the bluff secretary was natural, but there was no real ground for it. THE MONITOR. The Swedish inventor, John Ericsson, had completed his _Monitor_, which at that hour was steaming southward from New York. Although an ironclad like the _Merrimac_, she was as different as can be conceived in construction. She resembled a raft, the upper portion of which was 172 feet long and the lower 124 feet. The sides of the former were made of oak, twenty-five inches thick, and covered with five-inch iron armor. The turret was protected by eight-inch plates of wrought iron, increasing in thickness to the port-holes, near which it was eleven inches through. It was nine feet high, with a diameter of twenty-one feet. She drew only ten feet of water, and was armored with two eleven-inch Dahlgren guns, smooth bore, firing solid shot weighing 180 pounds. The pilot-house was made of nine-inch plates of forged iron, rose four feet above the deck, and would hold three men by crowding. The _Monitor_ was one-fifth the size of the _Merrimac_, and her appearance has been likened to that of a cheese-box on a raft. She was in command of Lieutenant John L. Worden, with Lieutenant S. Dana Green as executive officer. Her crew consisted of sixteen officers and forty-two men, and she left New York on the morning of March 6th, in tow of a tug-boat. The greatest difficulty was encountered in managing her, the men narrowly escaping being smothered by gas, and, had not the weather been unusually favorable, she would have foundered; but providentially she steamed into Hampton Roads, undiscovered by the enemy, and took her position behind the _Minnesota_, ready for the events of the morrow. [Illustration: JOHN ERICSSON.