The principal novelty of this vessel is the cylindrical revolving turret, rising from its exact centre, in which the guns are placed. This is formed of rolled one-inch iron plates bolted together to the thickness of eight inches; its internal diameter is twenty feet, and it is nine feet high. It rests at its lower edge on a smooth, flat ring of composition metal, but when in action the principal portion of its weight is sustained by a central shaft, about which it revolves; a massive wedge being driven below the steps of the shaft on such occasion to raise it, and thus cause it to bear up the turret. A large spur wheel upon the shaft is connected by a train of gearing with a small steam-engine, which supplies the power for turning the turret. Two eleven-inch guns are placed within the turret, in position precisely parallel with each other, on smooth ways, or slides; a clamp being arranged upon the sides of the ways for adjusting the friction and taking up the recoil in such distance as may be desired. The turret is pierced in different places with four holes for the insertion of telescopes, and just outside of the holes reflectors are fixed to bend the rays of light which come in a direction parallel with the guns through the axis of the telescope, which is crossed by a vertical thread of spider’s web through the line of collimation. The sailing-master takes his position in the turret, with his eye to the telescope, and his hand upon the wheel that governs the motion of the small engine, and turns the turret so as to keep the guns always directed with absolute precision to the object against which the fire is directed. A scale is also arranged for adjusting the elevation of the guns with similar engineering precision. Upon the sides of the turret that have the port-holes through which the guns are discharged, the massiveness is increased by an additional plating three inches in thickness; making the sides of the turret presented to the enemy eleven inches. In preparing for action, the awning over the turret is removed, and the square smoke stacks as well as the shorter pipes, through which air is drawn into the vessel, are taken down. A small, square tower at the bow is the wheelhouse, in which the steersman stands. It is made of bars or beams of iron nine by twelve inches, interlocked at the corners. After a preliminary trial trip, the Monitor sailed from the Brooklyn Navy Yard for Fortress Monroe, on the 6th of March, and at five o’clock on the afternoon of that day, discharged her pilot off Sandy Hook. Her officers at this time were as follows: