The true reason for relinquishing the plan probably was that the Egyptians believed the Red Sea to have been higher in altitude than the Nile. They feared that if the canal were opened between the Nile and the Red Sea the salt water would flow in and make the waters of the Nile brackish. This explanation would indicate a lack of knowledge of locks and sluices on the part of the Egyptians.
The work of Necho was continued by Darius, the son of Hystaspes (520 B.C.). The natural channel of communication between the Heroopolite Gulf and the Red Sea had begun to fill up with silt even in the time of Necho, and a hundred years later, in the time of Darius, was completely blocked, so that it had to be entirely cleaned out to render it navigable. The traces of this canal can still be plainly seen in the neighbourhood of Shaluf, near the south end of the Bitter Lakes. The present fresh-water canal was also made to follow its course for some distance between that point and Suez. Persian monuments have been found by Lepsius in the neighbourhood, commemorating the work of Darius. On one of these the name of Darius is written in the Persian cuneiform characters, and on a cartouche in the Egyptian form. Until this date it therefore appears that ships sailed up the Pelusiac branch of the Nile to Bubastis, and thence along the canal to Heroopolis, where the cargoes were transhipped to the Red Sea. This inconvenient transfer of cargoes was remedied by the next Egyptian sovereign, who bestowed much care on the water connection between the two seas.
Ptolemy Philadelphus (285 B.C.), in addition to cleaning out and thoroughly restoring the two canals, joined the fresh-water canal with the Heroopolite Gulf by means of a lock and sluices, which permitted the passage of vessels, and were effective in preventing the salt water from mingling with the fresh water. At the point where the canal joined the Heroopolite Gulf to the Red Sea, Ptolemy founded the town of Arsinoë, a little to the north of the modern Suez.
The line of communication between the two seas was impassable during the reign of Cleopatra (31 b.c.). It is believed by some that it was restored during the reign of the Roman emperor Trajan (98-117). During this period the Pelusiac branch of the Nile was very low, the water having almost completely deserted this formerly well-filled course. If Trajan, therefore, undertook to reopen the water way, he must have tapped the Nile much higher up, in order to reach a plentiful supply of water. The old canal near Cairo, which elsewhere joined the line of the former canal on the way to the Bitter Lakes, was once called “Amnis Trajanus,” and from this it has been inferred that Trajan was really the builder, and that during his reign this canal was cleaned and rendered navigable. As there is no further evidence than the name to prove that Trajan undertook so important an enterprise, the “Amnis Trajanus” was probably constructed during the Arabic period.
When Amr had conquered Egypt, according to another account, the caliph Omar ordered him to ship rich supplies of grain to Mecca and Medina, because during the pilgrimages these cities and often the whole of Hedjaz suffered severely from famine. As it was extremely difficult to send large quantities of provisions across the desert on the backs of camels, it is supposed that to facilitate this transportation Omar ordered the construction of the canal from a point near Cairo to the head of the Red Sea. On account of his forethought in thus providing for the pilgrims to the Hedjaz, Omar received the title of “Prince of the Faithful” (Emir el-Momenéen), which thenceforth was adopted by his successors in the caliphate. One hundred and thirty-four years after this time, El-Mansur, the second caliph of the Abbasid dynasty, is said to have closed the canal to prevent supplies from being shipped to one of the descendants of Ali who had revolted at Medina. Since that time it is probable that it has never been reopened, although there is a report that the Sultan Hakim rendered it available for the passage of boats in the year A.D. 1000, after which it was neglected and became choked with sand. While not thereafter used for navigation, there were parts which during the time of the annual inundation of the Nile were filled with water, until Mehemet Ali prevented this. The parts filled during the inundation extended as far as Sheykh Hanaydik, near Toussun and the Bitter Lakes.
The old canal which left the Nile at Cairo had long ceased to flow beyond the outskirts of the city, and the still more ancient canal from the neighbourhood of Bubastis, now known as the Wady Canal, extended only a few miles in the direction of the isthmus as far as Kassassin. During the construction of the Suez Canal the need of supplying the labourers with fresh water was imperative. The company, therefore, determined in 1861 to prolong the canal from Kassassin to the centre of the isthmus, and in the year 1863 they brought the fresh-water canal as far as Suez. In one or two places the bed of the old canal was cleared out and made to serve the new canal. The level of the fresh-water canal is about twenty feet above that of the Suez Canal, which it joins at Ismailia by means of two locks. The difference of level between it and the Red Sea is remedied by four locks constructed between Nefeesh and its terminus at Suez. Its average depth of water at high Nile is six feet, and at low Nile three feet.
A canal from Bulak, near Cairo, passing by Heliopolis and Belbeys, and joining the Wady Canal a few miles east of Zagazig, restores the line of water communication between the Nile and the Red Sea as it existed perhaps in the time of Trajan, and certainly as it was in the time of the Caliph Omar. The improvement of this canal as a means of transit is local and external only.
Napoleon Bonaparte was the first in modern times to take up the subject of a water connection between the two seas. In 1798 he examined the traces of the old canal of Necho and his successors, and ordered Monsieur Lepère to survey the isthmus and prepare a project for uniting the two seas by a direct canal. The result of this French engineer’s labours was to discover a supposed difference of thirty feet between the Red Sea at high tide and the Mediterranean at low tide. As this inequality of level seemed to preclude the idea of a direct maritime canal, a compromise was recommended.