REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.


entire operation rests upon the plan of tracks, the quality and amount of motive power, the number, capacity, and character of the cars, the provision of adequate and proper dumps, and dumping facilities. The limit of the capacity of the steam shovels will practically be determined by the efficiency of the personnel of the organization conducting the work and the adequacy of the equipment.
 The writer sees no reason why the following scheme of progress is not practical and conservative:
 There are now on the ground, and should be in active operation by the 1st of January, 1906, at least 10 steam shovels. From that time on it should be reasonably possible to furnish and install an average of at least 24 steam shovels per annum. Even under the restrictions of the eight-hour day these steam shovels, even in large numbers, should average 200,000 cubic yards of excavation per annum at least.
 This estimate is based on 800 cubic yards per day of twenty-one working days in the month. These 10 steam shovels in operation in 1906 should excavate 2,000,000 cubic yards in one year. The 24 steam shovels installed during the year, on account of the fact that proportionately a greater number will be started during the dry season than later on, should yield a total of 3,000,000 cubic yards, making the total excavation for the year 1906, 5,000,000 cubic yards.
 At the commencement of 1907, 34 steam shovels would therefore be in operation, with an annual capacity of 6,800,000 cubic yards. The 24 additional steam shovels installed during the year 1907 would yield 3,000,000 cubic yards, which would make a total for 1907 of 9,800,000 cubic yards of material.
 At the beginning of 1908, there would be in operation 58 steam shovels, with an average annual capacity of 11,600,000 cubic yards. The installation of 24 steam shovels in 1908 would make the total output for the year, 14,600,000 cubic yards.
 With 82 steam shovels installed and at work at the commencement of 1909, having an annuil practical capacity of 16,400,000 cubic yards, which would be the output for the year 1909, at the end of the year there would therefore have been removed from the central excavation 45,800,000 cubic yards.
 Continuing this rate of progress during the years 1910, 1911, 1912, and 1913, the amount of the excavation would amount to 111,400,000 cubic yards at the end of eight years from January, 1906.
 In the meantime the excavation of other portions of the central excavation outside of the eight miles could be carried on partly by steam shovels, partly by the methods used in the construction of the Chicago Drainage Canal, with side dumps where the depth of the excavation and the character and topography of the ground alongside of the canal would admit of this treatment, and by dredging at both ends. It would therefore seem reasonable on this basis, and even discounting these figures 20 per-cent, that the canal could be opened for navigation within eight years and completed in ten-at the most in twelve years.
 As the actual working capacity of the steam shovels now employed in the Culebra cut, if properly and continuously supplied with cars, is from 400 to 500 cubic yards per hour, varying with the capacity of the machines and the personnel of the men running them, it would seem reasonable and conservative that one-fourth of this capacity should be actually attained as the constant average, although it will of course be necessary to provide a sufficient additional margin of machines to maintain the number constantly at work as herein outlined. Under the practical difficulties at Panama the writer has assumed that 100 machines actually on the Isthmus would yield a constant average working number of at least 82 when the work is under full headway, even under extremely unfavorable conditions. This, of course, does not provide for the additional machines to be engaged on the excavation of that portion of the canal outside of the eight miles of maximum excavation which is used as the basis of this calculation.
 By using the terrace method of excavation, with horizontal spacing of, say, 25 feet, giving a width sufficient for two tracks at a perpendicular face of approximately 28 feet, with intermediate slopes of 1 to 4 being used, steam shovels could be worked, upon each terrace. For the purpose of calculation, assuming four terraces in each 100 feet of depth of excavation and that


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