The watertight compartments at the lower part of the caisson, as well as the bottom portion, arranged to serve as a working-chamber, were to communicate with the outer air by shafts, provided with air-locks, so that water or compressed air could be introduced at pleasure. This arrangement would enable the counterpoise of the caisson to be readily adjusted, the different chambers to be easily reached for repairs, and the working-chamber at the base to be used for cleaning the sill from silt or débris. The caisson gates, in a lock of 361⁄11 feet lift, would be 69 feet high, 71 feet long, 13⅛ feet broad at the tail, and 32¾ feet high, 71 feet long, and 9⅚ feet broad at the head of the lock. The locks, being situated in rock, would have the sides of their chambers formed of the natural rock, with a slight facing of masonry where necessary; but the side walls below the gates were to be iron caissons, 18 feet broad, filled with concrete. The swing-bridges, of iron or steel, were to be 18 feet wide, and 112 feet long, the swing portion being 78 feet; and the recesses for the caissons were to be 98½ feet long; and 23 feet wide at the top. The filling and emptying of the locks were to be effected by two cast-iron pipes, each 9⅙ feet diameter, and it was calculated that the required volume of 52,300 cubic yards of water could be admitted or shut out in fifteen minutes.[188]
Special Features of the Enterprise.—Probably no great engineering or constructive work of either ancient or modern times has been of such a gigantic and difficult character as that of the canalisation of the Isthmus of Panama. It is not that the length of the canal is exceptional; it is, on the contrary, shorter than that of many existing canals, some of which are of very small account indeed—being less than one-half the Suez Canal, less than one-third that of the canal of Languedoc, and less than one-fourteenth that of the Grand Canal of China. It is probable, also, that the building of the Great Wall of China, the Pyramids of Egypt, and several other works of antiquity that might be named, extended over a much longer period, and involved the employment of a greater number of men. The Royal or Grand Canal of China, which was completed in the year 980, is said to have occupied the labour of thirty thousand men for forty-three years.[189] But none of the great works of previous epochs have been environed with so many difficulties as the Panama Canal. The scheme, on the face of it, does not look so formidable. It is only when we come to look into its details, and compare them with those of other similar undertakings, that we realise its magnitude. And it is only when we, in like manner, compare its engineering features with those of the other great engineering works of the world that we can appreciate the vast energy, enterprise, and resource that has ventured to essay so colossal a task.
The first and the most serious difficulty to be encountered was that of controlling the waters of a torrential stream, almost equal to that of some of the chief rivers of Italy, through which the canal was to run. This stream, which crosses and recrosses the line of the canal twenty-seven times, as shown in the drawing attached hereto, has several different levels, and would, if left to itself, be certain to destroy the canal in a very short time. It had therefore to be dealt with by constructing an enormous embankment raised 45 feet above the waters of the Chagres, so as to allow of their gradual escape. In this dam there are 26 millions of cubic yards of cutting; in the Culebra Col, a channel cut right through a mountain more than 300 feet above sea level, there were estimated to be 37 millions more; and in the entire line of the canal there were calculated to be about 75 to 100 millions of cubic yards of excavation, to accomplish which a serious writer in the Edinburgh Review maintained that it would require the labour of 20,000 men for forty-two years.
Worse than all, however, was the dreadful and deadly climate. Five months of the year are continually wet. There are few fine days in the other seven months. The annual rainfall is twelve to fifteen times that of Europe. The mortality is excessive. The cost of labour is consequently high,[190] but pay what they may, the company could not command the amount of labour it was anxious to employ. For the most part the labour has had to be imported from Europe and the West Indies. The men were brought to Panama at the expense of the Company, but a very large proportion of them left again immediately, for various reasons, so that the company has not been able to keep up the proper quotas of men with which they undertook to provide their contractors, who were left at liberty to throw up their contracts when they ceased to be remunerative. The cost of the undertaking was thus enormously increased beyond the original estimates. The difficulty of procuring ways and means, and the high prices that had to be paid for borrowed money, have also seriously added to the expenditure. Another serious element of cost has been the outlay incurred in providing hospital and other facilities, and the maintenance of the usually very considerable numbers who were stricken with illness, induced by their unhealthy surroundings. These and other difficulties have so seriously weighed upon the undertaking that its accomplishment has been pronounced impossible, and M. de Lesseps and his colleagues have been denounced for following a “will-o’-the-wisp.” They have, however, persevered with their task for about eight years, and have made heroic, and almost superhuman efforts to keep the enterprise on its legs. In this effort they have had to depend absolutely upon their own countrymen, although they have much less maritime interest in the matter than the people of England and the United States of North America. In the latter countries the canal has all along been regarded with disfavour, not to say declared hostility. In the United States especially, M. de Lesseps has been told again and again that he was “beating the wind,” and that nothing but failure could come of his project. For the time being it looks as if his candid friends were right, and M. de Lesseps was wrong.
As might be expected, there have been very conflicting calculations made as to the amount of traffic which an interoceanic canal on the American isthmus would be likely to carry. The Geographical Congress, held at Antwerp in 1871, did not venture to go beyond 4,000,000 tons per annum. When the Canal Company was started, the expected tonnage was raised to about 6,000,000 tons annually. In 1887 M. de Lesseps, in his letter to the French Premier, put the quantity at 7,500,000 tons. A writer in the Revue-Gazette Maritime et Commerciale (Paris) has estimated that if the Panama Canal had been opened in 1884, there would have passed through it the following tonnage:—
| Ships. | Tonnage. | |
|---|---|---|
| Europe | 4,226 | 4,650,390 |
| Asia | 2,255 | 1,212,178 |
| America | 2,987 | 3,441,598 |
| Totals | 9,468 | 9,304,166 |
This latter estimate appears to be greatly exaggerated. It is apparently founded on the assumption that the greater part of the Australasian trade would pass that way. But the fact is that the geographical distance to Sydney does not differ by quite 500 knots between any of the four routes that are, or would be, available—that is, the Cape of Good Hope, the Suez Canal, Cape Horn, and Panama, the distances increasing in the order stated. Nautical distance, moreover, as has been properly remarked, “is only one element in determining choice of route; prevailing winds and currents, avoidance of stormy seas or of rock-bound coasts, have all to be studied by the mariner; and the comparatively trifling difference in the length of the course from the Thames to Sydney by four such different routes is enough to show how important it is to have this question of routes illustrated by the experience of the skilled navigator. This consideration is enhanced by the remark that the dues for the passage of the canal would amount to as much as the cost of more than 800 knots of additional voyage.”[191]
A much more reasonable and modest estimate than that of either of the foregoing, is that made in a recent report on the proposed Nicaraguan Canal. This estimate, based ostensibly on the United States Treasury Reports, puts the total tonnage that would have made use of the canal in 1885 at 4,252,000 tons, which is stated to be an increase of 53 per cent. in six years. At the same rate of increase, the tonnage available in 1892, when the canal was expected to be completed, would be 6,506,000 tons.[192]
The diagrams attached hereto show the enormous difficulties that have just been referred to in a much more graphic way than any mere description could do. It will be observed from the illustration ([p. 298]) that the Rio Chagres crosses the course of the canal no fewer than five times in little more than five kilometres, and that the Rio Obispo also steps in to add to the complications of the situation. On the San Pablo section again, within a distance of three kilometres, the river crosses the line of canal three times.
The Chagres river, which is so great an obstacle in the project of the Panama Canal, rises on the western slopes of the Cordilleras, and runs through a broken and irregular country, to the north of the auriferous granite hills which branch off to Cruces and Gorgona. This river and its affluents is said to drain an area of about 1550 square miles.[193] From Matachin, where the Panama canal parts company with the valley of the Chagres, to the sea, there is a total distance of twenty-eight miles, in the course of which the river falls about 35 feet.[194] The rain of a single day is said to raise the waters of the Chagres from 35 to 40 feet, and below Matachin there is a cataract of 50 to 60 feet. It was part of the project to abandon at this point the valley of the Chagres, and to cut through the Cordilleras. The level of the bottom of the canal is here 100 feet below that of the bed of the Chagres, or 140 feet below the mean level of the nearest indicated points on the section of the plans above and below the intersection. In a length of nine miles, at the foot of the ascent of the Cordillera at Matachin, the lowest point is 166 feet, and the highest 333 feet above the bed of the canal. A tunnel of 7720 metres in length was at one time proposed to be cut through this section, but M. de Lesseps stood out for a cutting á ciel ouvert, and it has been remarked that according to the plans there has been an assumption that the sides of this vast cutting will stand so nearly perpendicular as to slope only one foot horizontal in every ten feet vertical. In a dry climate, with good firm clay or rock, this might not involve difficulty or danger, but the climate of Panama is exposed to a tropical rainfall. A rainfall of six or seven inches in a few hours is not uncommon.