REPORT OF BOARD OF CONSULTING ENGINEERS, PANAMA CANAL.35


intervals, there is no continuous regular rock formation above a line of 40 feet below the sea level northward of Culebra; slate formations, shales, clays, sand, and gravel forming the greater mass of the material.
 During the progress of the surveys in the Chagres Valley, a party of topographic engineers under the direction of Mr. Ruggles was at work exploring'and carefully mapping the topography of the country between Obispo and Pedro Miguel, covering the section of the canal from the point where it left the valley of the Chagres through the continental divide and entered the low lands of the sea-level section in the valley of the Rio Grande on the Pacific slope.
 The object of Mr. Ruggles's surveys and investigations was to determine whether or not the French location could be improved upon, and also to ascertain the quantities of material to be excavated in accordance with -all of the various plans under consideration.
 The investigations of Mr. Ruggles determined the advisability of adhering to the location of the central axis of the canal as adopted by the French.
 During the year the various hydraulic and meteorologic observations which had been taken under the French 'administration were continued, and the compilation and analysis of these results was assigned to Mr. Arango, member of the American Society of Civil Engineers, who had charge and was at the head of the btireau controlling this part of the work.

 CULEBRA EXCAVATING WORK AND COST RECORDS.
 As the work of excavation under way by the French could be carried forward without interference with any future plan of work which might be decided upon, it seemed highly important to continue it and demonstrate by actual work the elements of cost and the efficiency of the various appliances and methods along the following lines to the endFirst. That the methods used be such as would enable the maximum number of excavating units of maximum capacity per unit to be employed.
 Second. That in selecting the various appliances the measure of utility should be the quantity of output and cost per unit.
 Third. That no appliances or methods be used that actual experience had not shown to be efficient.
 When a thoroughly competent, able, and Cflcient organization is at work on the Panama Canal, and the work is going forward at the maximum rate of progress possible under all the circumstances surrounding the situation, the larger part of the work will have been accomplished, and the results of the first or second year's work can not be fairly measured by the yardage of material removed.
 This work was carried on during the year, and expanded to such an extent as the many difficulties in the way of securing men and material would permit.
 The result of the experimental work between May 4, 1904, to January 1, 1905-eight months-was the excavation of 243,472 cubic yards of material, an average of approximately 30,000 cubic yards per month, at an average cost of 55 cents per cubic yard, the output varying from 27,000 cubic yards in May to 43,000 cubic yards in December; maxinium cost per cubic yard being 68.6 cents, in May, and the minimum cost being 50 cents per cubic yard, in December. The elements which entered into such costs were those which would necessarily be assumed by any contractor doing the work, and not including the, administrative or engineering expense which would be necessary, whether the work was carried on by contract or hired labor under direction of governmental supervision.
 During the next three months, ending March 31, 1905-the dry season-278,680 cubic yards were excavated, at an average cost of 45 cents per cubic yard, the maximum output being 133,000 cubic yards, in March, at a minimum cost of 43 cents per cubic yard; these figures, however, include an arbitrary of 6 cents per cubic yard to cover the average cost of new plant sufficient to absorb the entire cost of new plant and equipment needed in the work, and also the rebuilding of such of the old French plant as could be utilized.
 The result of the three months' work of April, May, and June, 1905, however, shows the amount excavated to be 279,589 cubic yards, at an average cost of 75 cents per cubic yard. In
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