REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


softer it was not necessary to go into it to as great depth, although in places we went probably 15 or 20 feet, and in addition excavated a cut-off trench that went 15 feet deeper; but on the whole, in the schist, I think we did average more than 10 feet. In the granite we went down in two places 45 feet before finding material that was suitable for the foundation. This rock was either rotten or had seams in it so that it was desirable to take it out. When we reached the part where the spillway was located, the height of masonry was so small that we excavated very little, so that, on the whole, the estimate of 15 feet was to a slight extent an overestimate; but taking the main dam alone, 15 feet would have been none too much to allow.
 Mr. QUELLENNEC. I do not remember the additional expense involved in the deepening of the Assuan foundations, but it was very great. The material to which I referred was a hard rock of old formation.
 The CHAIRMAN. You will find, gentlemen, that the material we have to deal with at Gamboa is of very uniform character, not a very hard material, but there is very little tilting and very little disturbance of the masses; no dikes, no faults or other characteristics which you find in the older rock. You will find in the geological notes of Messrs. Bertrand and Znircher much information concerning the geology of the Isthmus; it is very well summarized in that paper. (See Appendix B.)
 Mr. BURR. I may state, in connection with the studies that are being made for the Gamboa dam, that it is quite possible to design a partial masonry dam, and one study will be of that type, in which the foundation pressures are of considerably less importance than with an all masonry dam.
 The CHAIIiMAN. The remark that Mr. Quellennec made in regard to the dam at Gamboa will apply, of course, to a dam at Alhajuela. I thinly the barrage at Assiut raises the water about 40 feet and is founded on sand.
 Mr. QUELLENNEC. Yes, with a large concrete apron; but that is a relatively small barrage; it is a barrage for the control of the river to allow the introduction of water into irrigation canals.
 The CHAIRMAN. It has a maximum head against it of something like 40 feet.
 Mr. QUELLENNEC. Yes.
 The CHAIRMAN. Do you know the type of construction of the Assuan dam?
 Mr. QUELLENNEC. It is equipped with sluices of the Stoney system. They are now having some difficulty owing to impact of the water falling on the rock in front of the dam. They are now making very great repairs to prevent this damage. I was always in favor of the project of the dam as executed, because the Nile is a river which rises slowly and gives warning beforehand. The river carries no debris, neither sand, stone, nor wood, because between the Assuan dam and the first affluent is a distance of 2,000 kilometers (1,243 mi.); the water of the Nile carries nothing excepting a certain quantity of very light mud. In such a river it is possible to use this system, but in another river which brings down trees, stones, etc., it is not a good system.
 The Chairman presented to the Board an itinerary of inspection on the Isthmus, which was approved.
 At 11.40 o'clock the Board adjourned, to meet to-morrow at 10 a. m.
 JOHN C. OAKES,
 Captain, General Staf, Secretary.


 TWELFTH MEETING.
 S. S. HAVANA, AT SEA, October 3, 1905.
 The meeting was called to order at 10 a. m. by the Chairman.
 Present: The CHAIRMAN, and Messrs. PARSONS, BURR, ABBOT, STEARNS, RIPLEY, RANDOLPH, HUNTER, TINCAUZER, GUE RARD, QUELLENNEC, and WELCKER.
 The reading of the minutes of the preceding meeting was postponed until later in the, session.


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