Perhaps, like the propeller, the rudder also has been granted too scanty a consideration by most general readers, although its action is of the greatest interest. First of all, we must remember that the rudder is useless in the case of still water; that is to say, the ship must be going ahead or astern and not be stationary, and the speed of the vessel must be greater or less than that of the water. Thus, when a ship is riding to her anchor in a tide-way, the rudder is operative, and the vessel can be steered across the stream; but supposing she were to be steaming at the rate of 4 knots, and had with her a 4-knot tide, she would not answer her helm. We mentioned at an earlier stage that the ship when going ahead caused a column of water to follow after her. The screw itself drives a column of water astern, and it must be obvious that these masses of water must act on the rudder of the ship, and so on her steering. Thus, the column of following water causes a decrease in the pressure on the rudder, and so makes the rudder less operative. The column of water, however, which is driven astern by the propeller will cause a greater pressure on the rudder, and thus it is possible for steamships propelled by a screw to use a small rudder, and by cutting away the deadwood of the ship just forward of the rudder, the latter is less interfered with by the hull, and the steering qualities are improved. We quoted just now the expert opinions that better speed is obtained when the screws are outward turning rather than inward. The outward-turning screws also give superior steering results in the case when the screws are placed near the hull, though when the propellers are well out, this is not so noticeable. If one desires to have a ship which shall turn quickly this characteristic is obtained by cutting away the deadwood aft, and also the ship’s forefoot. An extreme instance of this is found in the case of a centre-board sailing craft, which, as anyone who has handled her knows full well, will turn round with a remarkable and surprising celerity.