has been noticed before, that the farther the Delta advances, the deeper the sea that is to be filled up; and consequently the slower the rate of encroachment must be1. There seems to be little or no alteration at the Canopic and Pelusiac mouths of the Nile, since the time of Herodotus; which has been owing to the choaking up of those branches; in which no water now runs, but during the season when the Nile is swoln. But the intermediate part of the coast, between those branches, has doubtless received great additions, by the waters of the Rosetta and Damietta branches: though, perhaps, a few miles only may have been added 3.

Herodotus says, that Busiris (taken for Abusir) is situated in the middle of the Delta. Euterpe, 59. It is remarkable, that Abusir stands so precisely in the middle of the ancient Delta, that there is no sensible difference between the distance at which it lies from Pelusium, and from Canopus, respectively, on the east and west; and from the site of Cercasora, at the apex of the Delta, and the most prominent points on the Delta, on the N. and S.

There is something very remarkable in this coincidence.

There was a celebrated temple of Isis, near Busiris. Herodotus says, at Busiris; but the magnificent remains of the temple at Baalbeit, (no doubt those of the temple of Isis) which are particularly described by Pococke, appear to be situated at 4 G. miles to the NW of Abusir, which stands at the side of the Sebennitic river, as Busiris did. See Pococke, Vol. i. p. 21.

4

The sea is now eleven fathoms deep, at a little more than three miles from the shore, between the ancient Canopic and Bolbitine mouths.

5 It is by no means certain, how far the city of Bolbitine stood from the sea; but probably much nearer than the ruins of Abumander (taken for Bolbitine) now are; these being upwards

Considering, then, the extreme flatness of the Delta; the quality of its soil, which is totally different from that of the adjacent countries; its form, which projects so far into the sea, beyond the general line of the coast, on the one hand; and on the other, filling up a space, which, reasoning from appearances, looks like a bay or gulf of the sea; one can hardly doubt that the space which it occupies, was originally a part of the sea, from the neighbourhood of Pelusium, or of mount Casius, to that of Alexandria; and southward to the foot of the hills of the Pyramids, and of Mokattam: which is yet allowing little more for the depth of the bay, from the supposed line of the coast, than the lower point of the Delta now advances beyond it.

No doubt, when we carry back our ideas to the time when the sea washed the base of the rock, on which the Pyramids of Memphis stand, the present base of which is washed by the inundation of the Nile, at an elevation, most probably, of 70 or 80 feet above the surface of the same sea; we are lost in the contemplation of the vast interval of time, that must necessarily have elapsed since the foundation of the Delta was first laid. But appearances speak too clear a language to be misunderstood and we are borne out in the supposition that the Delta has been formed piece-meal, by a process which we shall now endeavour to describe. The following may ac

of eight G. miles; and M. D'Anville places Bolbitine less than four from the sea. More than twenty marble columns had been dug up from the sand at this place, about the time of M. Niebuhr's visit to Egypt. (Niebuhr, Vol. i. p. 45.)

cordingly be taken as a specimen of the progress of alluvion; and which may be seen, in all the different stages of the process, at the mouth of any large river, that deposits rapidly and plentifully.

All rivers preserve, to a certain extent of space, which is proportioned to the velocity of their streams, a current of water, into the sea, beyond the points of land, that form their embouchures; when, by the continued resistance of the sea, they at last lose their motion. The mud and sand suspended in these waters, during their motion, are deposited, when that motion ceases; or rather, they are gradually deposited, as the current slackens: according to the gravity of the substances that are suspended. This deposition, then, will form a bank or shallow, in the sea; and which will be of a fan-like shape, consistently with the form in which the water of the river disperses itself. This bank is of very considerable breadth; and is, of course, constantly on the increase, in height, as well as extension: and the additions constantly made to its breadth, will be on the side towards the sea. Until the bank rises up nearly to the surface, the river water, which is continually poured into the sea, escapes freely over it: but when the bank has risen so high, as to inclose the water in a kind of lake, it is then compelled to force its way through the bank: although the passage will be both narrow and shallow, whilst the bank remains under water. This passage is technically named a BAR: for such it is, in respect of the channel of the river, although it be the deepest part of the entrance to it.

The position of this opening through the bank, will be regulated by the direction of the stream of the river, at the place where it terminates in the sea; and this direction, again, by the prevalent motion of the sea, along the coast; the mouth of the river always falling obliquely into the line of the sea current. Accordingly, when the river enters the sea obliquely, the bar will be at one side of the bank; and on that side which is the farthest down, in respect of the sea current. But if the river enter the sea, in a line perpendicular to its shore, the opening, or bar, will be through the middle of the bank 7.

Here it is proper to observe, that although the general motion of the sea is to the east, along the coast of Egypt, yet that there is a counter current, from the Rosetta river, through the bay of Abukeir; at whose point, it falls into the general easterly current, which is thrown off from the coast by the projecting form of that point.

The position of the bar of any river may commonly be guessed, by attending to the form of the shores at the embouchure. The shore on which the deposition of sediment is going on, will be flat, whilst the opposite one is steep. It is along the side of the latter, that the deepest channel of the river lies; and in the line of this channel, but without the points that form the mouth of the river, will be the bar. If both the shores are of the same nature, which seldom happens, the bar will lie opposite the middle of the channel. See the Map, No. VII. at page 55.

Rivers, in general, have what may be deemed a bar, in respect of the depth of the channel within; although they may not rise high enough to impede the navigation: for the increased deposition that takes place, when the current slackens, through the want of declivity, and of shores to retain it, must necessarily form a bank.

Bars of small rivers may be deepened, by means of stockades to confine the river current, and prolong it beyond the natural

As the bank rises to the surface, the opening increases in depth and width, until it becomes absolutely a continuation of the course of the river; since its waters require the same breadth and depth to escape here, as in the inner parts of its course. And thus the upper part of the bank becomes gradually a portion of the firm land; whilst the outer part goes on accumulating, and the bar is gradually removed farther out in effect, there will be a repetition of the same order of things. And hence it will clearly appear, that the bank thus laid in the sea, by the current of the river, is, in reality, the GERM of the growing alluvion.

The bars of certain rivers are swept away every season, by the periodical flood; which, although it cannot rise to a higher level than the sea, is increased in velocity, by the increase of the body of water above; and also by that of its descent; as the flood swells to a greater height above, and therefore forms a slope towards the sea. These floods also bring the greatest addition to the growing alluvion and, not unfrequently, change the direction of the channel, and with it, of course, the position of the bar: their depositions being laid farther out in the sea, by reason of the greater velocity of the current.

Having endeavoured to explain the mode in which the alluvion gains on the sea, we shall next endeavour to explain the manner in which the changes

points of the river's mouth. They would operate to remove the place of deposition farther out, and into deeper water.