Before considering these important questions, it will be right to investigate the natural causes which have formed the Isthmus of Suez. I think we may conclude that Africa was originally an island, and that by degrees the waters of the Red Sea, driven in by the southerly winds, and those of the Mediterranean, driven by the northerly winds, brought with them a great quantity of alluvial matter; at the junction of these waters the currents would be destroyed, and the alluvium with which the waters were charged would be deposited and form a bank or bar, which by degrees rose above the ordinary level of the sea. This bank, once formed, would continually increase, not only from the alluvium brought in by the seas, but also from the sands blown in by the northerly and southerly winds from the surrounding deserts; and thus, in the process of time, the present isthmus would be formed. I think that the practical evidence of this is undoubted. The same operations are still in existence, and it is simply a question of time as to the increase.
Having discussed the cause of the formation of the isthmus, I will now proceed to consider the objections or obstacles above mentioned. With regard to the first, the waters of the Nile are constantly bringing down alluvial matter, but whether the quantity brought down now is the same as formerly, or greater or less, is a question which nothing but experience can decide. But as far as experiments have already been made, it appears that the accumulation which has already taken place is considerable, and if it proceeds in the same ratio as hitherto, it must shortly become a very serious question whether it should be removed or not, and whether it might not be remunerative to do so.
Secondly. With regard to the sands driven in by the northerly winds; these must be very considerable, and not being able to escape, they must accumulate and tend to fill up the harbour; this will necessitate constant dredging to keep it open.
Thirdly. The sands driven by the tide and the southerly winds into the Suez end of the canal. These also must be very considerable, as is already evinced by the great extent of shallow water at the northern extremity of the Red Sea. This also must be reduced by dredging.
Fourthly. With regard to the quantity of sand which may be expected to be driven into the other parts of the canal from the surrounding deserts, during the winter and spring prevailing kamsin, or southeasterly gales. This quantity has been proved by one year’s experience to be not less than 310,000 cubic yards, and at times it may possibly be much more. It is proposed to check this by planting the sides of the canal with trees. Still a great deal of dredging must be constantly required.
Fifthly. The evaporation from the Bitter Lakes, and parts of the canal adjacent, is said to be 250,000,000 cubic feet of water, which is equivalent to about three-quarters of an inch daily. This water will have to be supplied chiefly from the Red Sea; and as it will have to pass through such a narrow channel, the velocity of the current will probably amount to two or three miles per hour, and if the banks of the canal are not well secured by paving, or similar works, they will be liable to be seriously affected. The constant indraught of the current will impede vessels coming from the Mediterranean, whilst it will facilitate the passage of vessels coming from the Red Sea; and in the same manner there will be a constant current from the Mediterranean, but by no means to so great an extent. These currents will also very probably bring in a considerable quantity of alluvium. They will not, however, very materially interfere with the passage of steam-vessels, although, if the latter are permitted to go at full speed, the waves produced by them will scour away the sides considerably, unless well protected by stone paving, fagoting, or similar works.
Upon the whole, viewing the difficulties above mentioned, the question naturally arises, whether they are of such a character as to be insurmountable; and to this I think we may safely say that they are not. What has been done once, as has been proved by the completion of the canal, can be done again, and will be maintained with much less difficulty. So far, therefore, viewed simply as a work of engineering, it resolves itself into a question of cost, or in other words, will the work pay as a commercial speculation, seeing that it has already cost 20,000,000l., and a great deal more is still required before it can be said to be quite complete, besides a very large sum for annual maintenance, and what this last item will be it is very difficult to decide, and nothing but experience can prove; still the more the canal becomes known, the more in all probability will it be used, and therefore the more money will be available for keeping it in repair. In addition to the dredging, it is very probable that the piers, both at Port Said and Suez, will have to be extended considerably.
The whole of the valley of the Nile, from the head of the delta below Cairo, is bordered by ridges of sandstone hills a few hundred feet high, with generally a plain monotonous tableland above, intersected by numerous ravines; no granite appears until we reach Assouan. In the vicinity of this place there are numerous quarries of fine granite, chiefly red; the masses are so compact that blocks of almost any size may be obtained from near the surface. From this district all the granite for the obelisks, statues, and columns of the various buildings, temples, and pyramids on both sides of the valley have been taken. Transported in flat-bottomed boats and rafts to the places where they were intended to be used, they were landed by means of inclined planes of wood, with rollers, and wedges, assisted by numerous rough capstans or windlasses, worked by countless gangs of men. This work appears to have been done with considerable skill, and the necessary combined operations were carried on simultaneously, by means of well-concerted signals. These operations are very clearly explained by the sculptured figures, and have been published by Sir Gardner Wilkinson and others.
Whilst examining the granite quarries near Assouan, I observed several imperfect blocks, which the Egyptians had commenced quarrying, but found them defective, and ceased working them. The mode of quarrying seems to have been nearly the same as we employ at the present time, namely, by wedges, levers, and pickaxes. Even if gunpowder had been known it would have been of very little use, for it would have in most cases destroyed the blocks, and the waste would have been enormous.
It does not quite clearly appear of what metal the tools were composed with which they worked the granite, whether of iron or bronze; if of the former, it must have been case-hardened. The polishing would be done by attrition with emery or sharp silicious sand. As for the stone, being sandstone, it was easily worked, and softer tools only were required.