Popular Science Monthly/Volume 16/January 1880/Interoceanic Canal Routes
By CHARLES DE FOURCY, C.E.
INSTEAD of delaying the discussion by a series of resolutions, I ask your permission to develop, at some length, the question as it strikes me in its entirety; and, that you may know the drift of my argument, I will begin by stating the conclusion at which I have arrived, viz., that the Interoceanic Canal should be constructed in the Isthmus of Panama, between the Bay of Colon and the Gulf of Panama. This canal, using merely the water of the ocean, should have no appreciable current, and it should be of the same level as the average tide in the Bay of Colon, where the rise and fall are hardly perceptible. To show you why I am firmly convinced of this, I will enter with some detail into the labors of your second sub-committee, over which I had the honor of presiding, and of which you warmly received the report presented by M. Voisin Bey. The report of this sub-committee, which is to be printed, will show you how impartially, with what scrupulous care, with what exhaustive discussion, and finally with what unanimity its decisions were taken. I am wrong in saying decisions, for none were taken. Of every one of the plans submitted then to its examination, and now to your vote, it showed up the advantages and the difficulties, the strong and the weak side; it prepared no form of resolution, giving to each of its members full liberty to express an opinion, as you can now. It is therefore in my personal name and on my own responsibility that I offer you ray solution and the following explanations.
I shall examine successively the various plans for lock-canals, showing which one seems to me to be the best, if such a system should be regarded as most advantageous.
I shall compare, in the same way, the projects for a tide-level canal. Finally, I shall compare the best plan for a lock canal with the best one for a tide-level canal.
[Principal Projected Routes of the Interoceanic Canal examined by the International Congress. (See map on the following page.)
1. Plan by the Isthmus of Tehuantepec. Length, 148 miles; number of locks, 120; time for passage, twelve days.
Comparison of the Different Plans for a Lock-Canal.—I shall at once refuse a canal by the line of Tehuantepec, although it seems to me to be one of the easiest to be constructed: but it would demand a great number of locks; the passage through it would take a great deal of time comparatively; and, moreover, the canal would pass through a country which, from the unstable nature of the soil, is very undesirable for such a work. We have been told, I am aware, that these "movements," which I hardly dare to call earthquakes, were not to be feared; that during these "movements," to which the inhabitants of the country are well accustomed, sometimes in the walls of houses and of public buildings, cracks would appear wide enough for the light to be seen through them, but soon these cracks would be closed to crevices, mere lines, and that then the buildings threatened for the time would again become solid until there was a new "movement." These explanations do not entirely satisfy me, and I admit that such possibilities seem to me very objectionable for a canal with locks; simple crevices in the lateral walls, especially in the raised portions, would seriously compromise the working of the gates, and might necessitate, when least expected, long and costly repairs, and, what is more serious still, interrupt for a number of days, entire months perhaps, the passage of ships. Can one, therefore, readily imagine what would happen if fleets of vessels, becoming more numerous every day, should find themselves stopped in their passage, some on the Pacific and others on the Atlantic side, and compelled, in order to reach their destination, to continue their journey by Cape Horn or the Straits of Magellan, to
A GENERAL MAP OF THE ISTHMUS OF CENTRAL AMERICA, SHOWING THE VARIOUS PROJECTED ROUTES FOR THE INTEROCEANIC CANAL.
which they were no longer accustomed? What would then become of the insurance which had been arranged for the expected passage through a canal which was no longer of any use?
If, in speaking of Tehuantepec, which line, however, is no longer thought of for a canal, I have somewhat enlarged on the inconveniences which would arise from earthquakes, it is because they also appear to me to apply to the canal by Nicaragua, and to put it out of consideration, even were there no other reasons.
Let us look, all the same, at other contingencies which are noticeable at Nicaragua.
It would be a long and difficult task to actually begin the work, because, before the great dockyards of the canal could be built, it would be necessary to make a harbor at Grey town, the success of which does not appear to be assured, and which at any rate would be very expensive.
Starting at this harbor, the canal, when leaving the San Juan River, would for several kilometres be suspended over the valley by immense dikes holding continuously a weight of water 8·50 metres high. There the slightest leak would become a breach, any breach a serious rupture, and any rupture a complete disaster. At what possible expense could the absolute security of these great dikes be assured?
To continue: we enter the San Juan River, kept in bounds by a large dam, which, however, is not enough to assure everywhere sufficient depth of water in the shallowest parts; where there is not depth enough it would be necessary to blow up or excavate by dredges a channel one hundred metres wide by eight and a half metres deep. To make this channel would be difficult, to maintain it against what would constantly come in to fill it up might be still more so.
Let us go on until we reach the lake; here comes another difficulty. At the place where the San Juan leaves it, other torrents bring sand into it, and also mud to a considerable extent. A new bar would have to be dredged, but probably only for a time; a channel would have to be kept open in an immense sliding sand-bank by very long and costly dikes, an objection which does not seem to have been provided for in any of the plans offered.
The passage of the lake seems easy; the cut to be made to reach the Pacific offers no remarkable difficulties; but this descent, on account of its short length, can only be done by locks close together, and locks so arranged offer for a quick movement of vessels serious objections, and necessitate a considerable loss of time.
Without dwelling too much on this subject, let us be content to take as an example the Caledonian Canal. In visiting it some years ago, as an engineer and a tourist, I was struck at seeing that, to avoid passing through it, a reshipment was considered preferable. I have said enough to show my reasons for refusing to accept the Nicaragua plan.Next comes the project by Panama with locks. Here, as if
A MAP OF THE WORLD, SHOWING THE GREAT COMMERCIAL ROUTES TRIBUTARY TO THE PROPOSED CANAL.
Nature herself had wished to get ready for man's work, the soil, as at Darien, has for a long time been free from earthquakes. The study for a lock-canal was made in 1845 by Garella, Engineer-in-Chief of Mines, sent there on a mission by the French Government. I desire to bring to your attention this name, which has been too much forgotten, because-this mission, courageously and conscientiously performed, honors not only the man who carried it out, but also the administration which confided it to him, and because his splendid studies seem still to be the best that have been made there, and which should now be taken, in part at least, if it should be desirable to connect the two oceans by a lock-canal.
Condensing this too long exposé, of the situation, I conclude by saying that, of all the lock-canals studied or proposed, the least objectionable is that which would go from the Bay of Limon to the Gulf of Panama.
Comparison of the Tide-level Canals.—Let us now examine the different plans for level-water canals which have been presented to our consideration.
The one which is called Atrato-Napipi would have our entire sympathy if we could thus adequately express our appreciation of the devotion of Commander Selfridge, who for several years has been exploring that part of the country, so wild and difficult of access; and yet, interesting as this plan seems to be, we must absolutely refuse to accept it.
The Atrato is neither the Mississippi nor the Amazon, but it is, nevertheless, a very powerful river, with heavy overflows, which bring to its mouth immense deposits, forming a great bar. To make artificially across this bar, and to keep it always open, a channel wide enough and deep enough for the largest vessels, is a very great undertaking, the success of which, however, should not be regarded as impossible or even as improbable. But still there is no instance of a work of such importance, and we find ourselves facing a problem the solution of which—a very laborious and very expensive matter—is by no means certain.
With such an obstacle before us, and with no certainty of overcoming it, would it be prudent to undertake a canal, the expense of which is estimated at more than eleven hundred million francs?
On the other hand, the canal, properly considered, would be on the Pacific side a branch of the Atrato, and, to a great degree, unless it was entirely shut off by a sluice-gate, subjected to the variations of the Atrato. Would it be, moreover, easy to keep up, where it branches from the river, a channel with a depth always assured of eight and a half metres? Would not the point of branching, under any circumstances, be liable to be filled up with sand, which doubtless it would be difficult and expensive to keep continually removed?
While keeping honorably the name of Commander Selfridge in our thoughts, with all regret we must put out of sight a plan the success of which is at best doubtful, while its cost would be relatively enormous.
Shall we now take up the San Blas project? This line is the shortest which joins the two oceans, but to carry it out a harbor must be built on the Atlantic, and then you soon find yourself facing a mountain-chain which has to be passed by a tunnel sixteen kilometres long; next you come to the Bayano, with elbows in its course too square to be straightened out, and a bar also on the Pacific side, which it is not certain could be mastered. The expense calculated for all this is fourteen hundred million francs.
The plan of a tunnel does not frighten M. Favre, the contractor of the one through the St. Gothard Mountain, nor would it frighten me, especially if he were willing to undertake it; but shipmasters do not take kindly to so long a passage without fresh air and the light of day; and, although it is proposed to give electric light instead, which will be as bright as day, there would still be an unconquerable antipathy against this project.
For these reasons I decline to accept the San Blas plan, which, moreover, has only been hastily surveyed, and it is possible that a more careful examination of it would bring to light other difficulties of which we are not now cognizant.
Therefore, throwing out other plans, we find ourselves in a position to examine the project of a tide-level canal from Colon (Aspinwall) to Panama, a project which has been so patiently and courageously explored and worked out by Messrs. Wyse and Reclus, lieutenants of the French navy.
This plan demands two changes, important and absolutely necessary, the success of which, while not easy, seems to me perfectly certain.
In the first place, a large part of the ship-canal must be made in the valley of the river Chagres, a river so inconvenient and dangerous that we must have nothing to do with it, at no matter what cost, if we desire that the canal should have a regular water-level—a condition absolutely necessary for its success.
For this, two plans offer themselves. The first is to keep the canal above any possibilities of overflow. Theoretically, nothing is easier; the railroad, now in operation between Colon (Aspinwall) and Panama, which the canal should follow, and as near as possible, is above the overflow of the Chagres. By prolonging the level of this roadway to the sides of the valley a winding line would be traced, bringing us to the place beyond which the canal can be constructed, without danger from the highest overflow of the water; but this line will, doubtless, be too tortuous to enable one to follow it correctly, or to be always above it; one should, in order to obtain reasonably straight lines, or curves not too sharp, bring the canal partially to the Thalweg of the valley; it will therefore be necessary at several places to change the bed of the Chagres, the bends of which multiplied would encroach upon the route of the canal. But the land, coming from this partial changing of the line, as well as that which would come from digging out the canal itself, turned up to a moderate height, quite equal to the corresponding height of the embankment of the railroad, would make a dike which the water of the Chagres could not pass over. At the place where the line of the canal will necessarily cross the bed of the Chagres to fall into the Bay of Limon, the Chagres will be turned from its course to allow the canal to pass at its left.
On the other bank the river Trinidad, a left tributary of the Chagres, would be, on the contrary, kept on the right side of the canal, and, by means of an easy change of its course, would flow in the actual bed of the Chagres to that very river to the north of Limon Bay, taking therefore, to become itself a river, the river of which it was only a tributary. What, then, would be the expense of this radical change? We have not at hand all the details necessary to calculate it; but, allowing an expense of fifty million francs for this work, we think it would amply be provided for.
But, should this plan not prove successful, there is another suggested by Messrs. Wyse and Reclus, which is also perfectly feasible, and the expense of which can be more closely calculated. This is, to build over Cruces an immense reservoir, capable of holding more than six hundred cubic metres of water—that is to say, more than the volume of water which could possibly be formed during several days of the greatest overflows of the Chagres, which, we are told, amount to occasionally, but for a very short time, twelve hundred cubic metres a second. This work would cost twenty-five million francs, but it would free us from all apprehension of the devastation occasioned by this river, which at times becomes a torrent, for the letting it off under the reservoir would be done gradually and without danger into a bed arranged beforehand, leaving the canal always on the left. For opening this bed, which would not at all be the same one as that of the Chagres, for straightening it at different places, and for doing the same for the river Trinidad, seventeen million francs should amply suffice.
Freed, therefore, from all fear, nothing more remains but to regulate, I can say even to a few centimetres, the height of the water in the ship-canal; and then comes in the second change that we suggest to the plan of Messrs. Wyse and Reclus, which is, merely to provide against the occasionally very rapid currents which would come from the great rise and fall of the tide on the Pacific, which sometimes amount to six metres. This can easily be managed by a tide-barrier in such a way that the level of the water in the canal will be regulated by that of the Atlantic, which varies but very little.
With these two modifications that we have pointed out to the plan of Messrs, Wyse and Reclus, and in fixing at four kilometres the greatest length of the tunnel—which can probably be reduced in length when the work is actually in hand, and perhaps be entirely done away with by a deep cut—your first sub-committee, over-estimating perhaps the expense calculated, brings the sum total to somewhat less than eleven hundred million francs, including the interest on the capital embarked during the time of construction, and the working expenses capitalized at five per cent. I feel confident that this figure will not be exceeded, and I am even confident that it will not be reached. Indeed, it is well known that the building of the railroad from Colon (Aspinwall) to Panama did not cost much more than such a work would had it been done in Europe; and here we shall have to aid us in putting up the great workshops of the canal, at short notice, a railroad already built, which is in excellent running order from one end to the other, and has a good harbor on either side.
I have said enough to show, I think—and here is the second point in the programme of my address—that, whatever may be the plan adopted, canal with locks or canal on a tide-level, it is from the Bay of Colon to the Gulf of Panama that it should go.
Comparison of the Tide-level Canal with the Lock-Canal.—Let us now compare the relative advantages of these two systems. In a technical point of view the preceding discussion would seem to make any further development superfluous. Moreover, have we not heard, in the first sittings of the committee, M. Cotard himself, an advocate, I believe, of the former system, declare without contradiction that, if the tide-level canal was possible and could be made to pay, it would be preferable to one with locks? Have we not heard and applauded the report of M. Fontane, the General Secretary of the Suez Canal Company, in which he tells you, in behalf of the Committee on Statistics, of which he is a member, that a tide-level canal is the only one that can supply the demands of the navigation of the entire world?
After having shown that the construction of a tide-level canal is possible, and under what conditions it is possible and assured, it would only remain to prove that it would pay. Here the fine report of M. Levasseur, in behalf of the Committee on Statistics, a report which you heartily applauded at the last meeting of the Congress, makes my task an easy one. The report declares and proves that, at the time when the canal should be opened, it can reasonably count upon a commerce of more than seven million tons. Very well, the Suez Canal, which cost almost five hundred million francs, with three million tons only, and subjected to demands which the Interoceanic Canal will not have to undergo, is proposing a diminution of its charges to only seven or eight francs for actual tonnage, a tariff which could easily be doubled without depriving the canal of a ton of the merchandise which is passing through it to-day. Under these conditions the Suez Canal is a prosperous enterprise. Its stock, which was issued at 500 francs, is now quoted at 750 francs, and its bonds, payable at only 500 francs, are sold for 570 francs.
Suppose, then, for the Interoceanic Canal an original outlay of double this sum, more than double, if you please, and put opposite this figure a traffic reduced in the first years to four million tons, instead of seven, and a charge of fifteen francs, which will be a very slight tax on commerce.
Can it therefore not be admitted that this great enterprise is of a kind to attract large capital seeking an advantageous investment? But these large sums will not be the only ones on which we can count. Let us not pay our century the poor compliment of supposing that everything is done on a mere money-making basis. The Interoceanic Canal will bring in subscribers from those who, captivated by the grandeur of the work, will wish to help it with their mite, without thinking whether or not they will get anything back. These subscribers—who will come from America, from Asia, and from Europe—these subscribers will have for their name legion. Once already, and under less favorable circumstances, they have answered the appeal of him who built the Suez Canal; they will not be wanting for the Interoceanic Canal Company, which will have as its chief and responsible head Ferdinand de Lesseps.