it would seem as if a school boy might determine to a fraction the time when the canal will be finished and what it will cost. Nothing could be more illusory. There probably was never a more complicated problem-a problem embarrassed by a larger proportion of uncertain factors-presented to an engineer. All the conditions under which this work is to be conducted are peculiar and exceptional. It is in a foreign State; under a weak and unsettled government; in one of the most unhealthy regions on the continent; subject to earthquakes; within 450 miles of the equator, and under a tropical sun where acclimated laborers only are of any service. Everything required for the prosecution of the work-utensils; machinery; the plant for constructing and repairing machinery; for the most part the provisions and houses for the sustenance and shelter of the men, and even the men themselves-have to be imported from foreign countries. The country practically contributes nothing but the site for the canal. This work, which, for its inevitable cost, and, if accomplished, for the magnitude of its material results, has no parallel among private enterprises in all history, is attended by so many uncertain and unknowable conditions that the estimates of the most gifted and experienced engineers are at the best but conjectures. Every step that is taken, therefore, is more or less experimental, and defies any attempt at reduction to a scientific equation. The most serious difficulties with which the Company has to contend may be classified under four heads: First. The control of the waters of the Chagres River, which, in the rainy season, if unrestrained, is liable to flood the larger portion of the canal every year. Second. The cut through the Andes at Culebra. Third. Keeping that section of the canal which runs from La Boca towards the Island of Perico in Panama Bay from being filled in by the ocean and the Rio Grande. Fourth. Securing the amount of labor required at practicable rates. THE WATERS OF THE CHAGRES RIVER.-This river, which, in the dry season, with its three or four tributaries, has a normal flow of only between 450 and 500 cubic feet per second, discharges from 23,000 to 25,000 cubic feet at times in the wet season, and has been known within recent years to discharge between 68,000 and 69,000 cubic feet per second, and to rise from 40 to 50 feet above its normal level. Of course, no canal with such a neighbor at large, could live through a single rainy season. Two plans for its subjugation have been discussed, one to construct a dam across the head waters of the Chagres at Gamboa and before they enter the valley through which the canal is to pass, large enough and strong enough to hold all the water that may fall, over and above what can be carried away safely by the ordinary channel of the river, which is to be straightened at several points for the double purpose of increasing the discharging capacity of the channel, and also to avoid the intersection of the natural by the artificial waterways. Auxiliary to this work, derivative canals or water courses are to be cut, to separate from the canal the waters of the Chagres and its tributaries, and carry them directly to the sea. Another plan which has been discussed and is now under consideration, is to dispense with the dam altogether, and to enlarge the derivative channels sufficiently to carry off the greatest volume of water by which the Chagres is liable to be swollen. This would involve a very considerable increase in the width of the derivative channels. Whether it will cost more or less than the dam is a question which I understand M. BOYER, the new Director-General, is investigating. Till that question is settled, the work on the dam will not be started. At present, however, the presumptions are all in favor of the dam, and the work now in progress on the derivative channels is prosecuted on that theory. Nature, too, seems to have favored this solution of the Chagres difficulty. After passing Matachin the Chagres River turns sharply eastward in its course, leaving the line of the canal between the 44th and 45th kilometres, and passing between two hills or Cerros, about a mile distant from the canal at Gamboa, called the Cerro Obispo and the Cerro Santa Cruz. It is between these two hills that it is proposed to erect a dam about three-quarters of a mile long, 140 feet high, and about 1,300 feet wide at the base, with an exterior slope of four to one, of broken rock, to be brought from the Emperador and other most convenient cuts; this to be revetted with heavy rock. On the basin side clayey earth is to be dumped and allowed to take its natural slope, on a presumption that the pressure of the water upon the clay, aided by deposits brought down by the river, will gradually make it water-tight. From the basin thus formed an outlet is to be provided by cutting a tunnel through the Cerro Azul to the left of the Cerro Santa Cruz, which is to have a diameter of about twenty feet, and to be lined with iron, through which the waters in the basin are to be discharged in quantities which the Chagres can carry to the sea without overflowing its banks. The tunnel will be prolonged by a cut to the bend of the Chagres at about kilometre 44. Its length from the basin side of Cerro Azul to the river will be between 500 and 600 yards, with a fall of about 30 feet. The inner orifice of the tunnel will lie between the 25th metre and the 31st metre levels. Complete surveys have not yet been made, but levels and contours had been run, we were assured, to exhibit a basin capacity of 3,000,000,000 cubic metres, with an indefinite capacity beyond the line surveyed. With these data it has been calculated that it would require eight or nine days of exceptionally heavy and continuous floods to fill 40 per cent. of the basin space; that the outflow through the tunnel would be about 26 per cent. of the amount retained, and leave the surface of the water at least 30 feet below the top of the dam. An inflow of 1,600 cubic metres a second, which is the discharge of the Chagres at Gamboa at extreme high water, as determined by Colonel TOTTEN in 1857, is taken as a basis of these calculations, being the largest inflow yet recorded. The discharge at Gamboa during the extreme high water of the 25th of November last was 954 cubic metres a second-a figure not likely to be often reached, and never much, if at all, exceeded. Such are the plans and calculations of the Company's engineers. To construct this enormous dam it is estimated that about 9,000,000 of cubic yards of earth and stone will be required. The cuttings at Emperador and the neighborhood will furnish an abundance of both. That such a dam, if built with the capacity attributed to it, will hold all the water that can be accumulated at Gamboa at any season, there can be little doubt. The floods at Matachin are of short duration, resulting from rapid local rainfall, not from an extensive water shed. The water shed, on the contrary, is comparatively inconsiderable, and if the rain did not fall there more rapidly than it usually falls in the State of New-York, the freshets of the Chagres would probably be less formidable than those of the Hudson. They result from the rapidity rather than the quantity of the rainfall. By the artificial tunnel which it is proposed to provide, the water will be allowed to enter the lower bed of the Chagres only so fast as it can be carried off without overflowing the river's banks, and, therefore, will remain in the basin and a pressure on the dam only so long as it will take to run off through the tunnel at the rate of between 12,000 and 15,000 cubic feet of water per second, when not re-inforced by rain. I did not hear any doubts expressed in any quarter of the practicability of building such a dam as an engineering problem, nor is there any greater difficulty, theoretically, in building a dam a mile. long and ten rods high than in building one a rod long and one foot high. The difference is rather a question of cost than of practicability. It seems to be assumed by all the eminent engineers who have studied this question, that such a dam, if built with the proportional derivations and embankments, would give the canal ample control of its turbulent neighbor at all seasons. I am aware of no reason for questioning the soundness of their judgment. THE CULEBRA CUT.-At about the 15th kilometre from Panama, and 55th from Colon, canal encounters the Cordilleras chain of mountains, and one of the most formidable obstacles which a sea level canal here, presents to an engineer. To cut this hill down to nine metres below the level of the ocean at low water, involves the removal of a body of earth and rock amounting in the aggregate to some 22,000,000 of cubic yards. This enormous body lies within a span of only about two kilometres, or less than a mile and a half. The necessity of discharging the excavated material exclusively at the ends of the cut when the men get below the surface of the canal must reduce the product of a day's labor.* The contract for this work was taken some years ago by an Anglo-Dutch Company, who bound themselves to remove 700,000 metres a month. This contract was subsequently modified so as to require the removal of only 610,000 monthly for the eighteen months following January 1st, 1886, making 11,000,000 cubic metres, and 330,000 a month for the succeeding twenty-four months, to July 1st, 1889, making 8,000,000, which amounts added to the amount removed before January 1, 1886, say 1,000,000, would give the required result-20,000,000 cubic metres. For this the contractors were to receive eight francs the cubic metre, or 32,000,000 of dollars, the Canal Company engaging to furnish them, as to the other contractors, their machines and the men, the contractors only paying the men's wages, and a certain rent for the use of the machines. Of course, any failure to supply men enough or machines enough, leaves the contractors at liberty to abandon the contract whenever it ceases to be profitable. The results are such as might be expected. Though bound to remove monthly 610,000 metres, they have not yet, I am assured, been successful in getting away in any one month with 100,000 cubic metres. Should they not increase that average, it will take from ten to fifteen years to finish their contract, even should they suffer no unforeseen delays or interruptions. Doubtless means will be found to expedite this work, which, in its present stage, could be readily effected by an increase of men and machines. The last 30 metres of the cut, however, must necessarily prove tedious and costly. Apprehensions have been expressed that during the later stages of the work at this point the banks might wash or slide, and fill up the cutting, as well as endanger the lives of the workmen. That, however, could only result from bad engineering. Perhaps those who give most importance to this criticism do not properly estimate the rapidity with which vegetation would cover the slopes, and bind them so compactly that in a few months a yoke of oxen would hardly be able to haul a plow through them. I did not hear of any insuperable difficulty in the accomplishment of this work, but I cannot but think that Mr. DE LESSEPS will be disappointed in his calculations, both in regard to the time and the cost of it. It certainly is not progressing at present at a rate which warrants the hope of its completion in 1889. THE PANAMA SECTION.-But little work has been done at the easterly extremity of the canal in the way of excavation, and none was in progress when we visited it. A channel about sixty yards wide has been dug to sixteen feet below mean low water, from the end of the proposed canal, a distance of three miles, and a little It is hoped that inclined planes may be successfully employed to expedite, if not to cheapen the process of disposing of the waste material; and a number of these contrivances, I am told, are now on their way to Panama, I presume, for that use. cutting has been done at the mouth of the Rio Grande, but no excavation has been made in the Panama section inside of the shore line. The difficulties which beset the work on this section may prove to be, to some extent, imaginary, but they seemed to me quite serious. The disposal of the dumps is tedious and expensive; a dyke will probably have to be run from Gama Point nearly to Naos Island, some four miles, to keep the sand from washing into the canal, and a temporary dam to keep the water high enough to float the dredges, at low tide, must be built across the Rio Grande. All the works for the construction of dredges and other machinery were erected at La Boca, that is, at the mouth of the Rio Grande, and constantly exposed to the pestilential exhalations of the mangrove swamps through which that stream finds its way to the sea, and through the bed of which the canal is expected to flow. To keep up the force requisite for the mechanical operations to be carried on at this point will prove extremely difficult, on account of its insalubrity. Owing to the impracticability of bringing dredges around Cape Horn or across the Isthmus, it has been deemed necessary to provide a plant for the construction and repair of such, with their accessories, as may be required on the west side of the mountain. For this kind of work, but few of the acclimated operatives are available, and to expert machinists the climate is very unfriendly. Plans are in contemplation-the dam across the Rio Grande is one of them-which, by overflowing the marshes, it is supposed, may improve the sanitary condition of La Boca. Should they altogether fail, it is not easy to calculate the time when the work on the canal west of Culebra will be finished, notwithstanding the fact that human life is about the cheapest article to be purchased on the Isthmus. Aside from the three places of work I have just indicated, the damming of the Chagres, the cut at Culebra and the Panama section, I am aware of no good reason for doubting the ability of the contractors to finish the rest of the canal by 1889. It is all under contract, and the work is going on at different points along the line.* THE LABOR SUPPLY.-This is a question which presents more *The following list of contractors, and the cost of the work expected of them, were furnished me by an officer of the Company: Names of Contractors. American Contracting and Dredging Company, (dredging,) (from Cost of their Work. Colon to Kil. 23,). .fcs. 22,500,000 BARBAUD, VIGNAUD & BLANTEUIL, (from Kil. 23 to Kil. 44,). Société de Travaux Publiques et Construction Company, (from Kil. 44 to Kil. 55,).... 70,000,000 280,000,000 CUTBILL, DE LUNGO, WATSON & VAN HUTTON, (Culebra,). 160,000,000 9,000,000 80,000,000 |