REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


trains to the same dumps. Nothing would be changed except a little prudence in the blasting to avoid damage to the ships; but, as I have shown in my letter to the President, even with the enormous transit of 35,000,000 tons, there would not be more than one passage of ships in each direction every two hours. The limitation of the hours of blasting due to such rare passages is practically immaterial and can have no influence whatever on the rapidity and on the price of excavation.
 This very important part, therefore, of the total excavation (the ground above the 130-foot level) can be executed under the same conditions which are to-day contemplated, or even under much better conditions, if the art of engineering makes, as we shall see later on it can, a decided progress upon the methods actually known and on which this statement is based.
 Let us now consider the ground below the 130 level. This ground will be excavated by mining and then dredging. The mass of earth above 130 being removed, the ground below may be attacked down to 80, and the first slice of ground between 130 and 80 opened on the side of the navigation channel from B to C.
 In order to prevent any contact between any of the instruments of work-dredges, mining and stone-breaking apparatus, scows, tugs, etc.-a first channel will be opened between B and C with the depth sufficient for the circulation of the floating apparatus and in order to give access to the dredges. Such a channel may be opened by dredges or from the surface of B C by excavators working below the surface of the ground.
 In any case, neither for the installation of the working dredges nor for the circulation of the scows, will it be permitted to use the channel from A to B, which will be from the first day to the last of the first period we speak of reserved for the circulation of the interoceanic shipping. Therefore it is obvious that during all this work there will be no contact whatever between the mining or dredging apparatus and the navigation channel.
 When this new channel, 50 feet deep, shall have been opened, we shall shift the navigation tracks into it; the ships will abandon the old channel, which in its turn will be mined and dredged to the level 80.
 At this moment the whole section from A to C will have a depth of 50 feet; the water will then be dropped 15 feet and the navigation channel will be brought again toward the left-hand side of the cut, as it was originally.
 The ground which remains free on the right-hand side will be again mined, dredged, and so deepened 15 feet again. The navigation channel will be shifted again to the right and the navigation channel excavated, and so on.
 I think this demonstration is perfectly sufficient to exclude any objection about the perfect theoretical, as well as practical, compliance of the method I propose with the first of the three conditions which it has to fulfill. Not an inch of the standard channel is used for the work.
 The two other conditions are met by a simple way of disposing of the spoils; we shall therefore examine them both at the same time.

NOT. A MINUTE OF THE TIME OF THE INTERNATIONAL NAVIGATION LOCKS, NOT A DROP OF THE
 WATER STORED FOR THE INTERNATIONAL NAVIGATION, WILL BE USED FOR THE WORKS OF
 TRANSFORMATION.
 If the problem of mining and dredging the ground can be solved, as we have seen, in such a manner that the international navigation will keep the constant use of its standard channel without any contact with the works of excavation nor with the instruments of excavation, the other and not less important problem of transporting by water and disposing of the dredged material can receive an equally perfect solution.
 The lake formed by the erection of the Gamboa dam will have a surface of 14.9 square miles at 132 feet of elevation and of 43.3 square miles at 200 feet of elevation. It would hold many times the quantity of ground to be dredged during the transformation from the high-level lock canal into the sea-level passage.
 It may be stated that the quantity of ground to be dredged between the Obispo and the Paraiso flights of locks for the transformation would be approximately 70,000,000 cubic yards if


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