At Gatun ships pass from the sea to the lake level, and vice versa, by three locks in flight. On the Pacific side there is one lowering of thirty feet at Pedro Miguel to a small lake fifty-five feet above sea level, held by dam at Miraflores, where two lowerings overcome the difference of level to the sea. The channel between the locks on the Pacific side is five hundred feet wide at the bottom and forty-five feet deep, and below the Miraflores locks the sea-level section, about eight miles in length, is five hundred feet wide at the bottom and forty-five feet deep at mean tide. Through the lake the bottom widths are not less than one thousand feet for about sixteen miles, eight hundred feet for about four miles, five hundred feet for about three miles and through the continental divide from Bas Obispo to Pedro Miguel, a distance of about nine miles, the bottom width is three hundred feet. The total length of the canal from deep water in the Caribbean, forty-one-foot depth at mean tide to deep water in the Pacific, forty-five-foot depth at mean tide, is practically fifty miles, fifteen miles of which are at sea level. The Hydroelectric Station. The hydroelectric station uses water from Gatun Lake for driving three turbo-generators of 2,000-kilowatt capacity each, which supply electricity for the operation of the lock and spillway machinery, the terminal shops and adjacent facilities, and for the lighting of the locks and the canal villages and fortifications. Transmission over the Zone is effected through four substations and a connecting high voltage transmission line which follows the main line of the Panama Railroad. [Illustration: SUBMARINES USED IN DEFENDING THE PANAMA CANAL The vessels here shown are used in defense of the Pacific side of the canal. They appear as anchored in the new concrete docks at Colon, preparatory to their passage through the canal, after having made the longest sea voyage then on record for submarines. _Copyright by Underwood & Underwood, N. Y._] [Illustration: _Copyright by the International News Service._ THROUGH THE PANAMA CANAL The U. S. battleship “Ohio” in the east chamber of the Pedro Miguel Locks. On the left is seen the electric locomotive used in drawing vessels through.] [Illustration: LADDER DREDGE, PANAMA CANAL] [Illustration: SUCTION DREDGE, PANAMA CANAL The upper view shows a ladder dredge, which operates by means of buckets on a continuous chain, dipping the contents of the buckets into the scow which lies alongside. The lower view shows a suction dredge, which operates on soft mud or sands, pumping the discharge through the pipe seen at the left of the illustration. The pipe may be carried to any desired point and used for filling.] [Illustration: _Copyright, C. H. Graves Co._ GATUN LOCKS