REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


the bottom width of 150 feet should be maintained, and of 110,000,000 if the bottom width of the sea-level passage is brought to 300 feet (admitting a theoretical cross section 150 feet at the bottom, with 450 slopes, in order to get an approximate idea of the time required).
 The mass of 70,000,000 cubic yards, if it were distributed on a surface equal to that of the lake at 132 feet elevation, namely, on 14.9 square miles, would form a deposit about 5 feet high. A mass of 110,000,000 would form a deposit about 8 feet high. It is easy to imagine how many times .this lake, which will be 145 feet deep near the dam, will furnish room for the dumping of the dredged material.

GAMBOA LAKE, ALREADY A FLOOD CONTROLLER AND A WATER STORER, TO PLAY A THIRD AND
 MOST IMPORTANT PART-IT WILL RECEIVE ALL THE SPOILS OF THE GREAT CUT.

 The solution I propose consists in disposing of the dredged ground by dumping it in the Gamboa Lake.
 This solution can be easily realized by connecting the waters of the lake with those of the summit level by a double flight of five locks. The material extracted by the dredges would be dumped into scows, which would go along the summit level, in the channel opened outside of the navigation channel, and after ascending the flight of locks, enter into the Gamboa Lake and simply unload themselves by opening their bottom gates.
 This would be the most ideal method of excavation, the most simple, and the only one necessitating no intervention at all of the hand of man, and the total execution by powerful, simple, purely mechanical methods.
 The extreme simplicity of the solution, as well as the power of its elements, will be shown by the fact that only eight dredges working in the summit level (about 8 miles long) would dispose in seven years of the 110,000,000 cubic yards corresponding to a sea-level passage with 300 feet at the bottom, and in less than five years of the 70,000,000 cubic yards corresponding to a sea-level passage of 150 feet as it is actually contemplated.
 COMPUTATION OF TIME OF TRANSFORMATION A CONSERVATIVE ONE.

 The type of dredge on which these calculations are made is the one I already referred to when speaking of the Bohio dam-a dredge having buckets of 1 cubic yard capacity, a theoretical excavating power of 22,000 cubic yards in twenty-four hours, and a practical output of 6,500 cubic yards measured in the excavation. Very likely the size of the buckets would be still largely increased; there is no practical limitation to that, owing to the indefinite power of the water to carry heavy machinery.
 The output of the eight dredges would reach 52,000 cubic yards a day, or about 2,000 per hour. Therefore three scows only, holding 750 cubic yards or more, would pass every hour through the locks, which, if taking four at a time, would remain far below their working capacity. By this solution the transportation and dumping can be obtained without leaving the summit level otherwise than by the flight of locks ascending to the Gamboa Lake.
 The locks for the international navigation will therefore remain entirely free from any service necessary to the excavation of the sea-level canal, and, like the channel itself, will remain completely independent of these operations.
 The water necessary to lift the scows to the lake and to return them will fall into the summit level and will form only a fraction of the flow that it will be necessary to send from the lake into this summit level in order to feed it; in fact, it is not the water that will be utilized, but its mechanical power to raise the scows. The locks, the channel, and the water devoted to the international navigation will therefore remain entirely free from the works of transformation.
 The transformation in five years, if the bottom width is preserved, or in seven years, if the bottom width is doubled, would of course be realized provided the ground above level 130, which will have to be excavated, partly at least, by steam shovels on rails, is removed beforehand. It seems logical to admit that this excavation will be ordered before the sea-level transformation is decided, and that the ground would be free at this moment unless, as will be seen later,


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