The control of the water in the culverts of the locks is taken care of by an ingeniously designed series of valves. The big wall culverts, 18 feet in diameter, are divided into two sections at the points where the valves are installed, by the construction of a perpendicular pier. This makes two openings 8 by 18 feet. The big gates of steel are placed in frames to close these openings just as a window sash is placed in its frame. They are mounted on roller bearings, so as to overcome the friction caused by the pressure of water against the valve gates. They must be mounted so that there is not more than a fourth of an inch play in any direction. The big wall culvert gates will weigh about 10 tons each, and must be capable of operating under a head of more than 60 feet of water. They will be raised and lowered by electricity. The electric locomotives which will be used to tow ships through the locks are one of the interesting features of the equipment. There will be 40 of them on the 3 sets of locks. The average ship will require four of them, two at the bow and two at the stern, to draw it through the locks. They will run on tracks on the lock walls, and will have two sets of wheels. One set will be cogged, and will be used when the locomotives are engaged in towing. The other set will be pressed into service when they are running light. When a vessel is in one lock waiting for the water to be equalized with that in the next one and the gates opened to permit passage, the forward locomotives will run free up the incline to the lock wall above, paying out hawser as they go. When they get to the next higher level they are ready to exert their maximum pull. Each locomotive consists of three parts: two motors hitched together, and the tandem may be operated from either end. The third part is a big winding drum around which the great hawsers are wound. This towing windlass permits the line to be paid out or pulled in and the distance between the ship and the locomotives varied at will. The locomotive may thus exert its pull or relax it while standing still on the track, a provision especially valuable in bringing ships to rest. In the main, however, the pull of the locomotive is exercised by its running on the semi-suppressed rack track anchored in the coping of the lock walls. Each flight of locks will be provided with two towing tracks, one on the side and one on the center wall. Each wall will be equipped with a return track of ordinary rails, so that when a set of locomotives has finished towing a ship through the locks they can be switched over from these tracks and hustled back for another job. When they reach the inclines from one lock to the next above the rack track will be pressed into service again until they reach the next level stretch.