The government graving dock at New York according to The rudiments of civil engineering: for the use of beginners of 1852

P. 95: “Graving docks (or dry docks) are docks constructed for the reception of vessels while undergoing repairs. They are usually made of such dimensions as to contain only one vessel at a time; their sides are formed in steps, so that the form of the dock is somewhat similar to that of the vessel which it is to contain, but sufficient space is left around it to enable the workmen to get at every part of the bottom of the vessel, and to afford sufficient light for the necessary repairs to be made. The entrance of the dock is closed with gates, precisely similar to those which we have described as belonging to canal locks, by which means, when the vessel has been floated into the dock and the gates closed, the water is pumped out of the dock, leaving it perfectly dry, the vessel being supported on timber struts and shores resting upon the steps already mentioned, as forming the sides of the dock. The accompanying plates are of a very fine graving dock, which is now being constructed by the American Government, at their dock-yard near New York. Figure 86 is a longitudinal section, taken along the center of the dock; figure 87 is a plan; figure 88, a front view of the entrance; figure 89, a transverse section through the center of the dock; and figure 90

p. 98: another transverse section through the recess for the lock gates. The dimensions of the dock are sufficient to contain the largest vessel in the American Navy, its length within the gates being 320 feet, its breadth 93 feet, and the width of the lock gates 70 feet. The manner in which the vessels are supported upon timber struts, when the water has been withdrawn from the dock, is shown in figure 89, from which it will be seen that ready access is afforded to every part of the vessel. In order that the bottom of the dock may be at all times dry and free from water, it is formed with a slight inclination from A to B (figure 86), and a gutter is carried across the dock at the lower end, leading into a drain or culvert, c c, which passes entirely round the dock, as shown in figures 86 and 89, with a gradual fall towards D ; and, the water being constantly pumped out of the culvert, it is impossible for any to accumulate at the bottom of the dock. Several flights of steps (E, E, E,) are provided in different parts of the dock for the use of the workmen, by which they are enabled to reach any part of the vessel with great facility.”

Source
Henry Law, George Rowdon Burnell. The rudiments of civil engineering: for the use of beginners. Vol II. London, 1852.