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178 THE Marine REVIEW May, 1919 Gatun Lake. Gatun Lake will cover an area of 164 square miles, with a depth in the ship channel varying from 85 to 45 ft. Throughout the first 16 miles from Gatun, the width of the channel will be 1,000 ft.; then for 4 miles, it will be 800 ft., and for 4 miles more 500 ft., when the entrance to Culebra Cut, at Bas Obispo, will be reached. The water level in the Cut will be that of the lake, and the bottom width of the channel will be 300 ft. The Canal Zone. The canal zone contains about 448 . square miles. It begins at a point three marine miles from mean low water mark in each ocean, and extends miles on each side of the center line of the route of the canal. It includes the group of islands in the bay of Panama named Perico, Naos, Culebra and Fla- menco. The cities of Panama and Colon are excluded from the zone, but the United States has the right to enforce sanitary ordinances in those cities, and to maintain public order in them in case the Republic of Panama should not be able, in the judgment of the United States, to do so. Of the 448 square miles of zone ter- _ritory, the United States owns about 322 square miles. Under the treaty with Panama, the United States has the right to acquire by purchase, or by the exer- cise of the right of eminent domain, any lands, buildings, water rights or other properties necessary and convenient for for five. GATUN DAM, SPILLWAY AND LOCKS. the construction, maintenance, operation, sanitation and protection of the canal, and it can, therefore, at any time, ac- quire the 126 square miles within the zone boundaries, which are now owned by private persons. The Locks. There will be 12 locks in the canal, all in duplicate; three pairs in flight at Gatun, with a combined lift of 85 ft.; one pair at Pedro Miguel, with a lift of 30 1/3 ft, and two pairs at Mira- flores, with a combined lift of 54 2/3 ft. at mean tide. The dimensions of all are the same--a usable length of 1,000 ft, and a usable width of 110 ft. Each lock will be a chamber, with walls and floor of concrete, and watertight gates at .each end. fou The side walls will be 45 to 50 ft. wide at the surface of the floor; will be perpendicular on the face, and will nar- row from a point 24 1/3 ft. above the floor until they are 8 ft. wide at the top. The middle wall will be 60 ft. wide, approximately 81 ft. high, and each face will be vertical. At a point 42.1/3. ft. above the surface of the floor, and 15 ft, above the top of the middle culvert, this wall will divide into two parts, leav- ing a space down the center much like the letter "U," which will be 19 ft. wide at the bottom. In this center space, which will be 44 ft. wide at the top, will be a tunnel divided into three stories, or galleries. The lowest gallery will be for drainage; the middle, for the wires that will carry the electric current to operate the gate and valve machinery, which will be. installed in the center wall; and the upper will be a passageway for the operators. The lock chambers will be filled and _ emptied through lateral culverts in the floors, connecting with main culverts, 18 ft. in ' diameter, in the walls, the water flowing in and out by gravity. (See cut.) The lock gates will be steel structures 7 it. thick, 65 ft. long, and from 47 to 82 ft. high. They will weigh from 300 to 600 tons each. Ninety-two leaves will be required for the entire canal, the total weighing 57,000 tons. [nter- mediate gates will be used in the locks, in order to save water and time, if de- sired, in locking small vessels through, the gates being so fixed as to divide the locks into chambers 600 and 400 ft. long, respectively. Ninety-five per cent of the vessels navigating the high seas. are less than 600 ft. long. In the con- struction of the locks, it is estimated that there will be used approximately 4,500,000 cu. yds. of concrete, requiring about the same number of barrels of cement. No vessel will be permitted to enter or pass through the locks under its own power. Electricity will be used to tow all vessels into and through the locks, and to operate all gates and_ valves, power being generated by water turbines from the head created by Gatun Lake. The time required to pass a_ vessel through all the locks is estimated at 3 hours, 1% hour in the three locks at Gatun, and about the same time in the three locks on the Pacific side. The time of passage of a vessel through the entire canal is estimated as ranging from 10 to 12 hours, according to the size of the ship, and the rate of speed at which it can travel.