The Isthmus of Suez Question

by Ferdinand de Lesseps

In fact, by reading all the accounts of ancient authors, and comparing them with what actually exists, we arrive at the conclusion that the shores of the Delta have varied very little in historic times.

The sea sands then have long ceased to accumulate, and the fact may be explained by assuming that the destruction of the coasts of Morocco, Algeria, Candia, and other parts,—which destruction, we repeat, alone furnishes the materials of maritime alluvium, —has abated from some cause or other. It may also be assumed, that the sands which were formerly driven by winds and currents into the Gulf of Pelusium, are now cast on the African coast between Tripoli and Alexandria, and driven inland in the shape of downs. The fact is, that no new downs are now seen forming in the Isthmus; those on the seashore being of ancient formation, and nearly all naturally fixed by vegetation. In conclusion, the extension of the Pelusiac shore, if such extension there be, is too insignificant to be taken into consideration.

Now, the direction of the jetties being nearly perpendicular to the shore, in order to be at right angles with the prevailing wind from W. N. W., the sand, when the wind is perpendicular to the shore, will be driven on to the coast and increase its height, as hitherto, no change being occasioned by the jetties. During the parallel winds, which mostly prevail, the littoral current, finding an obstacle in the jetties, will form an eddy to windward, which will increase the force of the current between the points of the jetties and the mole, so that the sand will be carried far away; and the probability is, that the bottom will become deeper.

It is only the oblique winds then, that will carry the sand into the angles formed by the shore and the windward jetty.

In calm weather, the sea-current which flows along the coast from west to east has not sufficient force to affect the equilibrium of the beach. Thus, to sum the matter up, the most that can be feared is the accumulation of a small quantity of the loose sand in the Gulf at the angle of the windward jetty. Supposing that even 10,000 cubic metres per ann. should be so deposited, which, according to what we have said, is an exaggeration, it would take 100 years to advance the beach 400 metres, and such an advance would produce no perceptible effect at the extremities of the jetties.

It may be objected, that by all these movements of the sands, some portion will necessarily find its way into the channel, and thus, by degrees, end in obstructing it. To obviate this inconvenience we have at our disposal dredging machines, and the most powerful means of clearance derived from a mass of 700,000,000 cubic metres of water, which can be stored up, above the level of low water in the two Seas, throughout the whole extent of the Canal, and in the immense reservoir of the Bitter Lakes.

But are jetties extending 6000 metres into the sea possible? and if possible, would they not require so much time and such an expenditure of money as, practically, to cause the undertaking to be given up?

With regard to the possibility, there can be no doubt, for more than a century ago the Dutch Government constructed a jetty 8000 met. in length in the Bay of the Lion, near the Cape, in water more than sixteen met. deep, in spite of the continued tempestuous weather which succeeds the settled calms in those latitudes. Such a work, considering the depth of water, must have required a quantity of materials at least four times as great as that required for the two jetties and the mole at Pelusium. It was undertaken by a nation not over rich, at a time when steam was unknown, and before the invention of machinery, which saves so much time, expense and labour. There can be no doubt then, that if the cutting of the Isthmus is admitted to be advantageous, it will be easy to overcome all difficulties.

With regard to the method of constructing these works, opinions are no less divided. Some engineers, grounding their opinions on ancient constructions, recommend that the moles should be formed of immense blocks of stone of thirty to forty cubic metres. Others are of opinion that the only means of preserving the roads from the accumulation of sand, is to construct the moles and dykes of open masonry. There are also some in favour of walls in hydraulic masonry with vertical facings. But, our own opinion is, that in so important an enterprise, every theoretical hypothesis should be discarded, and that we ought to be guided solely by the experience we have acquired in works of an analogous character already executed. And this is what we have done in adopting the system of loose stones, as it has been carried out with success: 1. For the dyke at Cherbourg which is 3768 met. long in a depth of water of 14 m., 80; 2. For the jetty at Plymouth which is 1364 met. long in a depth of 11 met. and more; 3. For the dyke in the Bay of Delaware 1200 met. long, with a depth of 14 met.; 4. For that of the Bay of the Lion 8000 met. long, in depths of more than 16 met.

Objections to this system may, indeed, be raised on account of the damage sustained at Cherbourg and Plymouth as well as at Algiers, before the introduction of factitious blocks, but it is necessary to observe, that both at Cherbourg and Plymouth, the tidal current is exceedingly strong, its velocity being as much as 4 met. per second; that the sea at these points is very rough, and that there is reason to suppose that the damage would not have occurred had the blocks been rather larger, and the interstices well filled up. With regard to the roadstead at Algiers, it is, as is well known, constantly beaten over by heavy seas, no other point in the Mediterranean presenting such difficult conditions. We have in favour of our system most of the moles erected in the various ports of the Mediterranean, Genoa, Cannes, Barcelona, Valencia, Cadiz, &c. &c., all of which are constructed of natural blocks, the largest not exceeding 2 m., 50 cube, and which are nevertheless established at considerable depths of water. Finally, we have on our side the opinions of the most distinguished English engineers; opinions which have prevailed in Parliament, and in accordance with which, all the moles in the harbours of refuge in course of construction are being made, according to the system of natural blocks sunk into the sea, at certain slopes.