opened up the great question which has been pending before humanity until our time. I hope to have the honour of making it evident to your minds: first, that this great secret is now discovered; secondly, that its principles were found about the year 1887, during the period when the old Panama Canal Company was at work; and thirdly, that science possessing henceforth all the solutions and all the practical elements necessary, the realization of veritable Straits" between the Atlantic and the Pacific will take place, and that the work now being carried on by the Americans is only the preliminary phase of this great undertaking.

This secret that Fernando Cortez and his successors believed they would find in a line of fracture concealed between the two continental masses, resided in reality, not in the natural geography, but in the natural topography and hydraulics of the American Isthmus; not in disposition of its ground alone, but in the disposition of its waters and of its ground. Nature has certainly united the two continents together, but it has provided the connection with a hydraulic power such as it is only necessary to harness properly to allow it to displace the mass which obstructs the communication between the oceans, and to transport this mass into spaces which appear to be reserved and ready to receive it.

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Definition of the "Straits."-Let first give a few definitions so that our mind may be clear on this subject. What are we to understand by "Straits of Panama"? How does this new conception of the interoceanic water-way differ from the sea-level canal, the construction of which was undertaken in 1881 by Mr. de Lesseps, or from the sea-level canal as it was conceived by the American Government and the Isthmian Canal Commission, and submitted by that last body to the International Board of Consulting Engineers assembled in September 1905 by President Roosevelt at Washington ?

The sea-level canal of M. de Lesseps and that of the Isthmian Canal Commission were both canals with an invariable level, communicating freely with the Atlantic (the tides of which at Colon are insignificant-30 centimetres, or about 1 foot) and closed on the Pacific by locks. These locks prevent the Pacific tides (which attain 3 metres, or 10 feet) from penetrating into the canal, and from producing therein currents which might interfere with navigation. These two projects of a sea-level canal are similarly disposed in

plan; the dimensions of their cross section only differ.

M. de Lesseps' sea-level canal had 9 metres (29} feet) depth of water, 22 metres (72, feet) width at the bottom, and 40 metres (131 feet) width at the water line.

The sea-level canal of the Isthmian Canal Commission had 35 feet (10.67 metres) depth of water, 150 feet (45.75 metres) width at the bottom, and 220 feet (67.10 metres) width at the water line.

The water-way which I called the "Straits of Panama" when I submitted it to the Consulting Board in September 1905, is free of all locks. It communicates freely with the Atlantic and the Pacific. It is 500 feet (152.50 metres) wide at the bottom; 45 feet (13.75 metres) deep at the lowest tides, and its average breadth is 600 feet (183 metres) at the water line. It may be said, in round figures, that this new water-way would be three times broader and one-fourth deeper than the widest and deepest canal ever conceived across the Isthmus of Panama. It may also be said that its breadth, which is about equal to that of the Thames at London-bridge at low tide, is three times less than that of the Bosphorus at Hussein Pacha and at Kawak.

It is a water-way, the dimensions of which are exactly intermediary between those of a natural Straits like the Bosphorus and those of the widest artificial roads planned. It is a water-way of a width similar to those of the great navigable rivers. Strictly speaking one has the right to call such a water-way "Straits" as well as "Canal." (See explanatory note of Fig. J. in appendix, page 273.)

Straits of Panama (Bunau-Varilla Plan, 1905.)

150

Sea Level Canal (Isthmian Commission's Plan, 1905.) FIG. J.-COMPARATIVE CROSS SECTIONS.

I selected the first appellation in order to characterise the suppression of all artificial work, such as tide locks, with which the plans of the Panama sea-level canals have always been encumbered, and in order also to charac

terise the absolute liberty of navigation and of crossing which the ships will enjoy. Because of the great width and of the great depth given to the "Straits of Panama," it deserves an appellation which recalls the natural not the artificial navigable channels.

Tidal Currents and Currents of Fluvial Water in the "Straits of Panama."At the simple announcement of a free interoceanic communication a preliminary question rises in all minds. Is it possible? Is there not a difference of level between the oceans which makes irrealisable such an open communication? My immediate reply is: No, there is no appreciable difference between the average level of the two oceans, but, as I have already said, the Pacific at Panama has tides which make it rise 3 metres (10 feet) and cause to descend 3 metres below the average level. On the other hand, the Atlantic at Colon has

tides worth mentioning. Variations of level from 30 centimetres (1 foot) above or below the average level that is all that has been observed. This being laid down another question arises which has often been answered carelessly n the negative. Will not the periodical variatoos of level of the Pacific cause currents in de canal incompatible with navigation? The same question was raised about Suez a bag time ago. The Red Sea at Suez has ties like the Pacific, but about one-third the amplitude of the Pacific tides. At a distance from the Red Sea equal to about also onetrd of the distance between the Pacific and the Atlantic is a vast surface of water-the Etter Lakes. They have an almost invariable level like the Atlantic. On the Suez Canal, Serefore, the same conditions which are found Panama are reproduced on a scale of onetord.

In 1956, Lieussou, a member of the Naval Hydrographic Engineers Corps of France, calculated that the maximum of the flood Curent between the Red Sea and the Bitter Lakes would be 116 metre per second and the maximum of the ebb current would be o*97 metre per second. This calculation, formulated thirteen years before the inauguration of the Suez Canal, was almost rigorously confirmed by experience. After many years it was established that the maximum flood current was 1.20 metre per second, and the maximum ebb current, was II metre per second. Between theory and experience there was, therefore, only a difference of eight hundredths of one knot for the flood and twenty-five hundredths of one knot for the ebb

currents. This proves what degree of confidence we may have in such calculations.

The slope between the Atlantic and the Pacific at high or low tide being about the same as between the Bitter Lakes and the Red Sea at high or low tide, the tidal currents must be about the same in the two cases. A Commission of the Academy of Sciences of France calculated these currents for Panama. (Report of the Academy, May 31, 1887.) The maximum calculated for the current was 1'17 metre per second, that is 2.27 knots an hour, and this with an exceptional tide of 6.76 metres of amplitude, which can only occur once a year. This current was calculated for a canal with restricted dimensions (about equal to those of the De Lesseps canal), 9 metres in depth (29 feet) at Colon and 11.50 metres (377 feet) at Panama, and 21 metres (69 feet) in width at the bottom.

If the climate of Panama were as perfectly dry as that of Suez, there would not be a shadow of justification for not admitting for Panama the solution that succeeded so admirably at Suez. The conditions of the fluvial waters is the reason to be invoked as an explanation of the rejection of the free opening with a narrow canal. The only complete solution of the management of fluvial waters of the rainy Isthmus of Panama leads us to admit a direct flowing into the canal of a volume of about 800 cubic metres per second, in case of exceptional swellings of the rivers. Even if we suppose that one-half shall flow into the Atlantic and the other into the Pacific, that would generate an additional current of nearly two knots in the sea-level canal projected by the Isthmian Canal Commission and still more of course in the narrower de Lesseps Canal.

In a canal as narrow and as shallow as the so-called sea-level canal, currents superior to two and a half knots would be inadmissible; we are, therefore, naturally led to increase the section in order to free the vessels from the objectionable action of the cumulated tidal and fluvial currents. Naturally the tidal currents will increase a little with the width and depth of the water-way, but the fluvial currents will decrease much more quickly, exactly in inverse proportion to the wet section of the navigable highway.

If we make again the calculations of the Academy of Sciences and apply them to the dimensions I have quoted above for the "Straits of Panama," we find that for the usual maximum tide of 6 metres of amplitude, the maximum current will be 2.93 knots. As

the wet section will be about six times greater than in the sea-level canal of the Isthmian Canal Commission, the flowing into it of 400 cubic metres a second will not produce more than a current of 0.3 knot. We may say then that the maximum current to which vessels will be exposed will not reach 3.3 knots, an absolutely insignificant velocity considering the width of 500 feet (152.50 metres) at the bottom, and the depth varying from 45 feet (1372 metres) to 65 feet (19.82 metres).

The exceptional tide of the Academy of Sciences, which can only occur once a year, in September, would bring about a maximum velocity of 3.14 knots. If, by an extraordinary coincidence, it should meet with one of these exceptional floods, which requires the flowing during several hours of 400 cubic metres, we should not attain 3 knots and a half. This would probably not occur once in a century and would only last a few hours. We may, therefore, say that the real maximum current will be 3.3 knots.

We see, then, that the precedent of Suez guarantees the certain success of such an undertaking, as far as the currents are concerned. But even without this precedent we should have a right to rely on it implicitly, for I repeat that the "Straits of Panama " will have the dimensions of a very large navigable river, like the Thames or the Seine, flowing like them into a sea that has tides of 6 metres of amplitude. There cannot therefore be currents in the "Straits of Panama " more inconvenient to navigation than those of the Seine or the Thames.

As the maximum currents will occur in the neighbourhood of the Pacific (5 lunar hours. after low tide), the question may be asked whether the soil of this region is consistent with the velocity of the water.

On this point there is no reason for alarm; the subsoil through which the bottom of the bed of the Straits will be dug is compact and resisting everywhere. It will be only necessary on the last eight kilometres on the Pacific side to protect the sides of the canal with stone embankments, the upper strata of the soil being soft there. This is an easy as well as, inexpensive matter.

locks or dams, the only one protected from accidents, explosions, destruction (in case of war), or earthquakes.

The Indispensable Tool for the Realisation of the "Straits of Panama”—the Dredge. It is not sufficient to define the ideal type of communication between the oceans; it must also be practically realisable. Now, with the means generally employed, with those used by the Company presided over by M. de Lesseps during almost the entire duration of its existence, with those employed by the second Panama Company, the new Company, with those that the American Government is employing at the present day, such a conception is radically chimerical.

In the three cases quoted above the organ of excavation is the excavator or steam shovel, rolling on rails; the organ of transportation and dumping of the spoils is the car, rolling on rails. With this method, the method in the dry, the difficulties caused by the diluvian rain, in the preservation of the railroad tracks, are enormous. It is necessary for a relatively feeble production to have a considerable number of workmen in constant attendance. Accidents and running off the rails occur incessantly, because in a vast excavation work the tracks often have to be shifted to follow the terraces. Consequently they can neither be well fixed, nor well ballasted, nor well drained.

These necessities, combined with the brusque and violent tropical rain, the bad quality of the workmanship in that country where depression. and fever are rife, and the clayish and slippery nature of the soil of the Isthmus, end in runnings off the rail, in accidents which occur over and over again, and which are the great, the only and the essential difficulty of the excavation of the Panama Canal.

The estimates prepared by the Isthmian Canal Commission, the American official authority entrusted with the execution of the Panama Canal gave, in September 1905, as the cost of the sea-level canal excavated in the dry, the following figure:-321,779,731 dollars, that is £64,355,946 sterling. This valuation comprised 7,000,000 dollars for the tidal locks, and 10,394,794 dollars for the masonry walls at Culebra, an erroneous conception now entirely abandoned.

We may, therefore, say that by overlooking these two elements of the work, the estimated cost of digging a lockless sea-level canal, 35 feet deep and 150 feet wide, was, in 1905. in round figures, 300,000,000 dollars, that is

£60,000,000.

These figures were arrived at by the official American Commission after six years of study, and two years of effective work under its own management in the Isthmus.

The length of time for the execution of this canal was estimated at more than twenty years by the Commission in 1901, and in 1905 one may conclude from the documents of the Commission that it allowed twenty-two years. The volume of the excavations to be extracted for the sea-level canal thus conceived, having 35 feet depth below mean level from the origin on the Atlantic to Miraflores, K. 62, and 45 feet depth below mean level from Miraflores to the Pacific end, K. 75, with 150 feet bottom width, lateral slopes of 45° and bermes of 50 feet on each side of the canal at 10 feet above the water, is 205,000,000 cubic yards (156,000,000 cubic metres).

The volume of the navigable highway that I have called the " 'Straits of Panama," with an average depth of 50 feet below mean tide (45 at Colon, 55 at Panama), the width at the bottom being 500 feet, slopes at 45°, and bermes of 100 feet on each side, is about 600,000,000 cubic yards (457,000,000 cubic metres). The completion of the "Straits" would necessitate, roughly speaking, an outlay three times greater than that of the sea-level canal. According to the Isthmian Canal Commission's own figures,

would be necessary to spend 900,000,000 dollars, that is £180,000,000 sterling, or 4,500,000,000 francs, and to wait about 60 to 70 years to see the first vessel pass through it. Such figures explain sufficiently why the rational and complete solution of the Panama problem, the opening of a water-way unobstructed by locks, having free openings on the two oceans, sufficiently wide to allow ships to navigate and to pass each cther without being inconvenienced by the tidal and fluvial currents, has never been examined or discussed before September, 1905, when I submitted it to the International Consuiting Board which met at Washington.

If I acted thus, it was not for the vain satisfaction of fixing a theoretical and chimerical term to the efforts of the engineers. In showing them the enviable and desirable end, I showed at the same time the practical way to reach it.

Since 1879, when the first International Congress was assembled by M. de Lesseps, until 1905, when the last one was assembled by Mr. Roosevelt, all the numerous Commissions by whom the Panama Canal was discussed, have all, without exception, forgotten one

thing. This was the most important, the essential question-the mode of execution.

All these Commissions have admitted as implicit truth, as an axiom, that the Panama Canal would be excavated in the dry. They then discussed the maximum and minimum form compatible with this mode of execution from the narrow level canal closed by tidal locks on the Pacific side to the lock canal with a summit level, more or less high, in the centre of the Isthmus. (See Fig. K., p. 244.)

Now this particular mode of execution is not the only one as the various Commissions have thought. The excavation, transportation, and dumping may be effected in the dry, on rails, but it may also be effected on water. The excavation in the dry is not the only mode of excavating-it is also the worse, the more expensive and the poorer one. The defects which exist in temperate regions increase in incredible proportions under the climatological conditions of the Panama Isthmus.

With the excavation by floating dredges, transportation by barges and dumping in deep water, all the Isthmian difficulties vanish as if they had been touched by a magician's hand. (See Fig. M., p. 245.)

There is no more need of an enormous army of workmen, changing every minute some of the tracks, in order to follow the progress of the earthwork. There is no more need for the ceaseless care to be taken with the moveable tracks, which have necessarily poor foundations and cannot be disposed for supporting any heavy traffic. There is no more need for struggling against the sudden tropical floods which bring down on the tracks the mud torn up from the slopes of the cut, submerge them, ruin their foundations or bury them. There is no more need of stopping series of steam-shovels for the frequent runnings off the rails, which these unavoidable conditions of the soil and climate bring about constantly, blocking for whole days communication between the points of loading and points of unloading. There is no more need to struggle against the landslips which stop the excavation work, and when they take place on the lines of communication paralyze, by repercussion, both a considerable plant and a great number of hands. There is no more need to tax one's ingenuity to enable the trains to circulate over the dumping places where the rain causes frequent landslips. There is no more need for hesitation between this Scylla and that Charybdis, which is, either to have heavy trucks and powerful locomo