9

In ordinary seasons it would appear that the flood of the Nile at Bubastes rises a little above the mean height of the tide at Suez, while in the dry season the level of the river at Bubastes falls 19 feet below the mean tide level of the Red Sea; and during this state of the Nile were all obstacles removed, a reverse order of currents would prevail, as the water of the Red Sea, after passing through the bed of the Bitter Lakes, would send a branch westward through the Wadis to the Delta, while the main stream (it may be presumed) flowed direct from Serapeum by Ras el Moyeh to Lake Mensaleh. But of the effect of a salt water stream passing through the Wadis to the Delta, the antients ap­pear with good reason to have entertained a great dread ; and to prevent the occurrence of the Delta of Egypt being invaded or submerged by a flood of salt water from the Red Sea, it would appear that they constructed the solid wall (observed by the French engineers) at the entrance of the canal to the Red Sea, and most probably, for the same reason, the mound which crosses the Wadi of Su- babyar near Serapeum, although by so doing they re­stricted their navigation to what the waters of the Nile permitted, and consequently to a limited portion of the year. It will, however, be obvious, that, by a proper dis­position of locks, the danger could have been avoided, and the navigation maintained for a longer period; and it is related by Strabo, that Ptolemy Philadelphus constructed a double gate or lock in the canal, which afforded facility of transit from the sea to the canal and from the canal to the sea. The French engineers gave the preference to the line of communication of the ancients between the two seas through the medium of the Nile, furnishing the canal with such a number of basins, locks, and sluices, as would prevent the danger of the Delta being invaded by salt