REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


and nowhere below. Even assuming the pressure would determine a communication near the dam below, the blanket above would prevent tiltration to reach more than 4 or 5 cubic feet a second.
 The Bohio dam will, therefore, if so conceived, be a perfect structure from whatever point you examine it.

 SYSTEMS PROPOSED IN THE PAST FOR THE CONTROL OF THE CHAGRES FLOODS.

 After having presented what may be considered as a complete solution of the Chagres flood question; after having not only justified the dispositions recommended but also explained the system of construction of its vital elements; after having shown that this system enjoys the precious quality of adapting itself to all the forms the canal will have between the high-lock form and thesea-level form during the transformation, it is not useless to show how the same question has been treated in the various projects submitted heretofore. We have thrown sufficient light on the solution presented by the Comit6 Technique of the New Panama Canal Company in 1898; it is therefore completely explained. Let us consider now, by order of dates, the solution I presented in 1892 and which was explained in my book, "Panama-Le Pass6, Le Pr6sent, L'Avenir," and the solution adopted by the Isthmian Canal Commission in 1901.
 Both are inspired by the same conception, both consist in receiving the waters of the Chagres in a large lake formed by a dam at Bohio, and in letting the Chagres waters flow into the Chagres bed below Bohio on the North American side of the canal, which leads them to sea without any more contact with the canal, through its wide and deep channel, rectified in two places, from kilometer 22 to kilometer 16 and from kilometer 10 to kilometer 8.
 If the general plan is identical in both projects, the altitudes of the lakes are different. I proposed in 1892 a lake oscillating between 52 feet 6 inches and 62 feet 4 inches (16 and 19 m.). The Isthmian Canal Commission proposed a lake oscillating between 85 feet and 92 feet (25.92 and 28.06 m.). The reason of that difference in the proposed levels can be found in the difference of conception of the two plans.
 My project was drawn as a preliminary step toward the conclusion of the sea-level plan. The project of the Commission was a definitive and not a temporary solution. I considered the Bohio Lake in the first phase of the life of the canal as simply a means of expanding at Bohio the Chagres in such a way as to suppress any trace of any current whatever. The Chagres, thus made still and inoffensive, could be tapped on the North American side of the canal and thrown into the bed that remains entirely (except for 5 miles) on this same side of the canal until it reaches the sea.
 In other words, the Bohio Lake was in my mind an organism eabling me to bring the Chagres from the South American side of the canal, where its head is, to the North American side of the canal, where its mouth is, without disturbing the navigation in the canal. For this limited purpose a lake oscillating between 16 and 19 meters was ample. It presented the inestimable advantage of requiring a low earth dam easy to build and presenting perfect guaranties of safety.
 I admitted freely the waters of the Chagres in the part of the canal between Gamboa and the Bohio Lake proper. I increased the horizontal and vertical dimensions of the canal prism in this section in order not to have more than 2 knots with an 800 cubic meter a second freshet (27,000 c. ft.), and I intended to close navigation in case of one of these rare and short high floods, which might have caused a 4-knot current in said section. The sediments could not stay in the canal bed but would have been precipitated in the Bohio Lake, a danger which I accepted readily in view of 'the short space of time that this first period was to last. The outlet of the lake was insured by the opening of the gates from the maximum to the minimum level as soon as a tendency to increase of level would show itself.
 The conditions in the river below Bohio were not ameliorated by a reduction in the amount of water due to a storage of any importance, but were, however, improved by the reduction of distance between Bohio and the sea resulting from the short cuts.


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