REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


it is thought advisable to enlarge very much the sea-level passage, in which case the transportation to the dumps of the ground above level 130 will be effected by scows ascending into the lake.
 A cheap and quick method of excavating the ground above 130 would be to unload it into the partially opened channel B C (see diagram, p. 226) with the Brown transporting-hoisting machines, or similar appliances, then to dredge it and load it on scows.
 It must be also remembered that the excavation between Bohio and Obispo on the Atlantic side, and between Paraiso and Miraflores on the Pacific, will have to be prosecuted as soon as the summit level will be brought down to elevation 60. This will only mean an addition of dredges in these two sections. The locks, as we propose to make them, will always have a surplus power to raise scows which 4s much larger than will be necessary to make the seven years' plan of transformation a reality.

 SIZE, LOCATION, AND COST OF THE LOCKS UNITiNG LAKE GAMBOA TO SUMMIT LEVEL.

 It remains for me to show how the locks ascending into the lake from the summit level will be established, what will be their arrangement, location, and cost:
 There will be two chains of five locks, one for ascending, one for descending. Each lock will have 40 feet fall, a useful length of 450 feet and a useful width of 85 feet, and a depth of water at the low stage of 15 feet. They will be able to take in one lockage four scows 200 feet long, 40 feet wide, and drawing 14 feet of water. Such scows can take easily 750 cubic yards measured in the excavation; each lockage therefore will lift 3,000 cubic yards.
 As it may be admitted that a lockage will last a maximum of forty-five minutes, the output will be 4,000 cubic yards an hour, or 96,000 cubic yards every twenty-four hours. This would correspond to a production of 30,000,000 cubic yards a year, and insure the accomplishment of all the work to be done below 130 between Gamboa and Paraiso in three or four years, with the increase from 150 feet to 300 feet of the bottom width, admitting a cross section consisting simply in 450 slopes on the side for the purpose of general valuation only. It would be necessary to obtain such production to place one dredge every half mile, or 16 in the summit level.
 The lockages will not take more than half an hour; there is, therefore, an ample margin of safety if we base our calculation on forty-five minutes. It will cover amply the time eventually to be lost by' an accident to the locks. Such an accident would have no bearing on the operation of the canal; it would paralyze the excavation, of course, but the cost of such interruption would be small, on account of the very limited number of men employed. The probability of such a delay can be estimated from the operation of great lock canals. It is insignificant, compared to the margin of safety of one-third we allow to cover it.
 Such an extraordinary capacity of supposed production is not'like what results from the supposed development of a large system of steam shovels, railway trains, and dumps. The defect of these large combinations is that they want a very able body of coworkers to make them a success, and this is and will be always wanting on the Isthmus. Outside of that, every instrument of work is depending on its neighbor. A derailment or landslide will paralyze a series of trains and leave idle for long hours 10 to 15 steam shovels.

 EXTRAORDINARY SUPERIORITY OF EXCAVATION ON WATER COMPARED WITH DRY EXCAVATION.

 On the water every instrument is perfectly independent of all others. An accident, if it happens to one, does not affect ten or fifteen. An accident on the water is exceptional, but in the dry excavation they are the normal rule on account of the condition of the tracks on which they must be executed.
 On the water there is not the terrible difficulty of handling a large number of heavy trains on tracks tnat can not be ballasted; on tracks which have to be moved and shifted every day, as the works progress; on tracks where drainage is impossible on account of the provisional character of their establishment, and this in a country of diluvial rains during three-quarters of the year; on tracks which would require very heavy rails to increase their resistence, but where heavy rails can not be easily used on account of the want of strength of the colored laborers.


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