REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


data-at least several days longer. The definite quantity of rock and other material to be excavated could not be known until arrival on the Isthmus and the receipt of the report of the chief engineer showing the resftlts of the completed borings along the canal line.
 The Board then discussed tidal variations as affecting the various canals of the world and other relevant subjects, no action being taken thereon.
 At 12.30 p. m. the Board adjourned, to meet Monday, October 2, at 10 a. m.
 JOHN C. OAKES,
 Captain, General Staf, Secretary.


 ELEVENTH MEETING.

 S. S. HAVANA, AT SEA, October 2, 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, GUERARD, QUELLENNEC, and WELCKER.
 The Secretary read the minutes of the ninth and tenth meetings, which were adopted.
 The Chairman laid before the Board a letter he had received the day after the Board adjourned in Washington from Mr. C. D. Ward, a member of the American Society of Civil Engineers, inclosing a copy of his paper on "The Gatun Dam," which was read before the American Society of Civil Engineers on May 18, 1904, and asking that his plan be given due consideration.
 On motion of Mr. Parsons it was directed that Mr. Ward's paper be printed in the appendix. (See Appendix I.)
 On behalf of the committee appointed to prepare a plan for a sea-level canal, the Chairman reported progress, and stated that the work would be completed in a very short time.
 The Chairman stated that the Isthmian Canal Commission caused to be made plans and computations of a dam at Gamboa with its crest raised to a height of +200. The drawing on which these computations were based was at hand, and the chief draftsman had given the quantities for a masonry dam carried to rock, including in his computation all work necessary to close the gaps in the hills adjacent on either shore or bank, but not including the spillway. He estimated for a dam of typical profile the total quantity of 879,000 cubic yards of concrete masonry. The committee had had computations made to show what the quantities would be in a similar dam if reduced to a height of 150 feet. The quantities for the latter dam were about 370,000 cubic yards. That presupposes the diminution of the original quantities by a reduction of 50 feet from the height of the dam (using the same profile) taken from the bottom. The draftsman was also computing quantities for a dam of 150 feet (using same profile), the diminution being effected by cutting off 50 feet from the top of the dam as planned. This computation will be completed to-day.
 The Board discussed the formation of the strata underlying the proposed dams.
 Mr. QUELLENNEC. I think it would be impossible by borings to determine at what depth the underlying material is suitable for a foundation; that it would be necessary to uncover the strata before determining the question. I visited the Assuan dam during construction and this difficulty was experienced there. The English engineers had considered a certain depth as proper f or the foundations, but on uncovering the strata it was found necessary to deepen the level from 6 to 8 meters (20 to 26 ft.), the surface rock being poorly adapted for foundations, although it is a granite of first quality showing clearly above the water level at the time of low water of the Nile.
 Mr. STEARNS. Mr. Chairman, my experience has been similar. In the construction of the Wachusett dam we made borings with diamond drills and got all the information we could. We then considered the matter as thoroughly as possible and concluded that if we allowed an average depth of rock excavation of 15 feet it would be sufficient. As a matter of fact, we went te variable depths. On one hillside was granite and on the other schist, and while the latter was very much


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