REPORT OF BOARD OF CONSULTING ENGINEFRS, PANAMA CANAL.


and accumulate on this berm, preventing its entrance into the regular canal section. The location of the railroad on this embankment will do away with the construction and maintenance of bridges, except in such places as it may be necessary to connect the diversion channels with the canal axis in order to admit the surplus water from the Gamboa dam or from other sources into the canal section.
 in the opinion of the writer the operation of the canal will increase rather than diminish the necessity for railroad communication across the Isthmus, and between Colon and Panama and intermediate towns. This line, however, should be operated with electrical power, which can be furnished from the Gamboa dam.
 It may also be advisable to construct a single-track railroad through the central excavation and along a portion of the embankment thrown up on the west side of the canal for use in its maintenance.
 The dredgable section through the lowland between La Boca and Miraflores should also be constructed in the same manner.
 While the work of dredging the two ends of the canal can be quickly and economically performed it would be of great advantage in the general handling of the work to have these two end sections completedas soon as possible, in order that dredges might work as far inland as practicable to assist in the attack on the principal excavation through the divide. This work can be performed by dipper dredges of from 5 to 10 cubic yards in capacity, loading the material on seagoing barges, and dumping it in deep water beyond the harbor limits.
 The cost of the dredgable work, including plant, should not exceed a maximum of 20 cents per cubic yard for the soft dredgable material, varying from 10 cents where it can be pumped by hydraulic dredges over the embankment to 20 cents where it is necessary to load it in barges and subject it to the extreme haul seaward.
 The various compact clays which will be encountered in places, and at times have been considered and classified as rock, will be easily dredgable, at least with modern clam-shell or dipper dredges, and so far as the dredging is concerned, after they are broken up by blasting, should not exceed 10 or 12 cents per cubic yard. The extra cost of this work will be due entirely to the amount of money spent in blasting.
 As the work of boring will be handled by machinery and will not necessitate drilling, but be done by augers driven with power and working in gangs, the principal cost will be in explosives. This work should be performed at not to exceed 50 cents per cubic yard.
 The small amount of coral rock encountered may possibly exceed this in cost, although in the opinion of the writer it should be removed with powerful dredges for less than 50 cents per cubic yard. In driving the piles for the wharves in Cristobal Colon, wooden piles were driven through this coral without great difficulty. Where encountered in the canal section, while of various thickness, it was generally underlaid with soft material, and its removal should not be difficult.
 In order to construct a sea-level canal and excavate to the elevation of 40 feet below the sea level, some basaltic and trap rock may be encountered, and in other places a small amount of limestone, sandstone, or conglomerate. The removal of this rock outside of that encountered in the central excavation will doubtless vary from $2 to $5 a cubic yard in cost, dependent upon the local conditions. That encountered in the central location below sea level, if the work is conducted upon proper lines, will probably cost from $1 to $2 per cubic yard; but as the amount is limited the extra cost will doubtless be absorbed in the general estimate for the central excavation.
 The limit of time that it will require to complete the canal or put it in operation wl depend upon the removal of the eight miles of central excavation, containing approximately 100,000,000 cubic yards, this being based on Mr. Dose's estimate of a canal section averaging 200 feet in bottom width, 50-foot berms, and slopes 1 to 1.
 The time required to do this work is dependent upon the excavating units which can be installed and the capacity per unit, which in turn is dependent upon the promptness with which empty cars are furnished to the steam shovels and loaded cars removed. The efficiency of the


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