At all events no one can doubt that the Canal would be really and practically navigable for all vessels willing to avail themselves of the passage. But it will be asked whether jetties extending 6000 _met._ into the sea do not present great difficulties; whether a trench of 65 _met._ in width, dug 16 _m._, 50 deep, a part of which is under water, is not an impossibility; and whether, supposing the engineering difficulties to be surmounted, the results obtained would be in proportion to the expenses incurred. Doubts have also been started on the navigation of the Red Sea; finally, several authors have put the question, without however solving it, whether, even if the Canal were once established, commerce would not prefer the old way by the Cape as the safest and most advantageous. These questions we are about to examine: these doubts we shall endeavour to clear up. The Gulf of Pelusium is said to be constantly filled with sand or mud brought down by the Damietta branch of the Nile, and it is objected that the advanced works to be established on that part of the shore would only have the effect of increasing the accumulations. We admit that this portion of the Egyptian shore has been formed by maritime alluvium brought by the ground swell, as we have already proved at the commencement of our memorial. We also admit, that the object of the dykes forming the entrance channel to the Canal, would be to stop the sand thus brought by the waves, and to accumulate it against the dyke opposed to the prevailing wind, namely, against the western dyke. But most of the ports already in existence are open to the same objections; and if they were sufficient to prevent the construction of a port, we may safely say that very few of those we are at present acquainted with would ever have been formed. According to our idea the essential question is, to know whether, when once the port is established, it can be maintained without too great an expense. Now it appears, that for many ages the sands have ceased to extend the Pelusiac shore, as is manifest from the well ascertained position of Pelusium, the ruins of which still remain. Strabo, in his Itinerary, says that Pelusium is situated at the distance of twenty stadia from the sea. The French engineers of the expedition have verified this distance, by measuring 1600 toises, or 3000 _met._ from its remains to the shore. In 1847, the distance between these two points had not varied, as it is marked on the plan with the figure 3000 _met._, and at the present day it is still the same. 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.