gift of the Nile, this hypothesis which I maintain, supposes no other change and alteration to happen, in process of time, to the plains about Memphis and the Lower Egypt, than what have already happened to the Upper *; agreeably to its higher antiquity, and to the longer course of ages, that the Nile has been bestowing its bounty upon it. The present state and condition therefore of the Upper Egypt, is so far from being an objection, that it proves the very point in dispute; viz. that the Nile, in a term of years, may so far accumulate its soil upon the adjacent plains of the Lower Egypt, as it hath already done in the Upper, that it will not be capable to overflow

them.

As to the other objections, we may even dispute the very facts upon which they are founded. For, as to the first, it can hardly be admitted that any of the original stony particles, brought down from Ethiopia by the Nile, should be so strongly buoyed up by the stream, as not to subside a long time before their arrival at the Cataracts. ther could any further accession of stony particles, that should be engaged afterwards by the stream, either in passing by these Cataracts, or the sandy islands that lie in its course afterwards, continue long to be supported, let the stream be

Nei

never

This is even acknowledged by the author of the Description of the East. 6 At that time,' says he, before the canals were made, and when Lower Egypt was a morass, the upper 'parts of Egypt might be overflowed, and receive that acces⚫sion of a rich soil, which makes it so fruitful,' vol. i. p. 197.

never so rapid and violent. They, from thei own weight and specific gravity, must either be dropped of course as soon as the extraordinary rapidity of the current ceases, or else they must be lodged immediately at the very foot of those very rocks, or along the skirts of those very islands, from whence they may be supposed to have been thus violently rubbed off and obtained.

Nay, it may well be imagined, that the beds of rivers, particularly those which, like the Nile, are of a rapid nature, do rather grow lower than rise or increase. For their bottoms being constantly disturbed, by the violent motion and friction of the current, one particle of sand or gravel must impel another, till the velocity of the stream abates, or till these particles meet with some impediment or obstruction. And this may be the cause why rivers are generally the deepest in their middle channel, because the current is there the strongest. It may be the cause likewise, why eddies, whirlpools, the immediate outlets from mills, sluices, &c. are usually of great depths; because the stream, in these cases, plunges itself here with greater violence, and putting thereby the neighbouring particles of sand and gravel in motion, protrudes them before it. It is owing also to the same impulsive force and action, that the ordinary depths of rivers are deeper in some places than in others, the deeper being usually succeeded by flats and shallows, whither these loose sandy particles are driven; and where they

remain quiet and undisturbed, till the next inundation.

Of the same nature and origin likewise are the bars, as they are called, of rivers; which are a like collection of sand and gravel, forced down by the impetuosity of the stream, till, upon their nearer approach to the sea, they become themselves retarded, and the more weighty contents of them stopped and arrested, by the heavier column of the sea-water, or by the more violent and superior force and activity of its waves. As the mouths of the Nile therefore, and particularly the Canopic, which is the largest, are remarkably incommoded with banks of this kind, which render the navigation oftentimes exceedingly dangerous, there is no small probability, that the bed of the Nile must be so far from receiving any annual increase, as it is objected, from these stony particles, that it must be a considerable loser, by such large contributions of them as areconstantly accumulated at those places. As to the mud, properly so called, it seems to make little or no part of these obstructions; for, being itself of a light nature, and easily buoyed up by the stream, it is visibly carried off into the sea, to the distance of several leagues, where it is laying a foundation for future accessions to the land of Egypt.

Besides, if the bed of the Nile was raised by the subsiding of the stony particles brought along with the stream, the like would happen to all rivers, in proportion to their muddiness. Because

it

it may be presumed, that the mud buoyed up by rivers, is all of the same light nature and consistence, however it may accidentally differ in colour or other respects. As then there are few or no rivers, but what are muddy in some degree or other; and not only so, but are at some seasons, for several days or weeks together, no less-muddy than the Nile; why should not they, by precipitating the stony particles (provided there were any) of their mud, have the like property of raising their beds and channels? We need not indeed insist upon their receiving equal augmentations with the bed of the Nile; it is enough in the present question if they receive any at all, in as much as this, let it, have been annually never so small and inconsiderable, yet, in process of time, and in the course of four thousand years, (reckoning from the deluge, or the beginning of rivers), must have become visible and apparent. But notwithstanding the want of that annual increase and addition to their banks, which the Nile can boast of, (and whereby it keeps up, as is pretended, the balance betwixt the quantity of water and the capacity of the channel that is to convey it), nothing of this kind has been observed in the Danube, the Rhine, the Thames, or any other noted river. These have always continued the same; their channels still contain the same quantity of water, which they may origi nally be supposed to have done, and except upon extraordinary rains, and the floods and inundations consequent thereupon, are never known to

be

be too full or overcharged. Whereas, had there been any gradual additions made by these means to their beds, these very beds must have been gradually filled up, and their streams consequently would have been gradually excluded; and being thus excluded, and thereby under no confinement, they would long ago have converted all their adjacent plains into lakes or marshes,

But it is further urged, that, provided the Nile should lodge any considerable quantity of sediment upon the surface, yet a great part of it 'would be carried off annually by the crop or produce of the soil.' Yet, it may be replied, that if the whole of it is not carried off, that which remains will still contribute, though in a smaller degree, to the supposed augmentation. By this means indeed the operation will be slower, though no less sure and certain upon that account. For the precise time when this augmentation is to be brought about, is not disputed; but whether such an augmentation will happen at all. And that there is and has been an augmentation, which consequently may, and probably will continue, is even acknowledged by this author, as well as proved in the foregoing chapter*. Little stress therefore can be laid upon this objection, which does not deny the fact, but only retards the progress of it.

It appears, by several experiments †, that earth, commonly so called, or mould, is very little con

*Not.*, p. 240-1.

Vid. Boyle's Works abridged, vol. iii. p. 282, &c.

cerned