Mr. Horner selected for the point of research the site of the ancient city of Memphis, situated about thirty miles above the apex of the actual Delta of the Nile. The date of the construction of this city is estimated by the best authorities as having been about 4000 years before the Christian era. This ancient city was built on land which, from its vicinity to the Nile, must have been annually overflowed, doubtless for many previous ages, and which consequently must have been covered with the sediment deposited by the annual inundations. The alluvial soil here is the same as that presented through the whole valley to the sea; and the remains of the ancient city are almost entirely buried by similar material. One statue (that of Rameses II., the Sesostris of the Greeks), described by Herodotus, thrown down from its pedestal, was uncovered by making an excavation round it of five feet; and eight inches below is the top of two courses of cyclopean masonry-the platform on which the statue stood, whose total height was five feet seven inches, resting on an artificial foundation of sand. With regard to the age of this statue, Dr. Lepsius says, "If we may assume that the Memphis statue represents Rameses while a young man, of which the absence of a beard would not be of itself a decided proof, we should then be justified in assigning it to the beginning of the fourteenth century before Christ. According to my estimate, Rameses Mianun reigned from about 1394 to 1328 B.C." It would appear from this that the actual thickness of mud deposited during the last thirty-two centuries cannot be more than eleven feet three inches, or about four inches on an average in each century.

Within an area of a square mile east and south from this statue, and in places selected for the purpose, as many as nineteen pits were sunk, and borings made to the depth of the filtration of water, every where through similar material, and the depth generally approaching, sometimes much exceeding, forty feet. In every case human remains were met with, sometimes carved stone, but more frequently brick and pottery; and these continued, with few exceptions, to the lowest depth reached. surface of the ground over the square mile experimented on was slightly uneven, and the difference between the highest point of the inundation of the Nile at that spot in 1851, and the mean level of the Mediterranean at the mouth of the river, was seventy-eight feet three inches.

Besides the nineteen pits on the site of ancient Memphis, twenty-seven were opened in a belt about a mile wide across the valley of the Nile on the parallel of Memphis, the breadth of the valley at this place being about five miles. The work was conducted in the same manner, by pits and borings to water, and

always with the same result; bricks and pottery occurring at intervals in most of the pits.

To test still further the general condition of the Nile deposit, as many as fifty-one pits were afterwards sunk on the parallel of Heliopolis, considerably below Memphis, and about ten miles below Cairo; about half the trials being on the east and the rest on the west bank, and the extreme distance of the east and west pit being sixteen miles. Some of the borings reached a depth of from 50 to 70 feet from the surface. Here also the soil penetrated consisted of Nile sediment, and fragments of pottery were brought up at various depths. In no instance did the boring reach the solid rock.

Ever since the publication of the great work on Egypt by the French naturalists who accompanied Bonaparte's expedition, it has been assumed as a settled point that the mean increase of land owing to the deposit of the Nile mud has been from time immemorial at the rate of five inches in a century. Judging from other data, and especially from the obelisk at Heliopolis, believed to have been erected 2300 years B.C., and now buried 12 feet 4 inches, of which he considers the 16 inches to have been originally sunk, Mr. Horner reduces this rate to 3.18 inches in the century at Heliopolis, and by a similar calculation to 3 inches at Memphis.

Taking, however, the estimate which allows of the most rapid deposit, and making a small allowance for the occasional layers of sand, of which there are not many, and which would on the whole produce little effect; we find by a simple calculation from the depth at which human remains are found, that we are obliged to carry back the history of Egypt to a very ancient date. Thus in the lowest part of the boring, near the statue at Memphis, the instrument brought up from a depth of 39 feet of true Nile sediment a fragment of burnt pottery about an inch square, of a brick-red colour, the interior being dark gray, which must have been lying there, according to Mr. Horner, upwards of 13,000 years. In some places, indeed, the fragments must have been obtained from a level sometimes far below, and often only a little above, low-water mark in the Mediterranean. These were no doubt brought down by the river from the higher and inhabited part of the valley, at a time previous to the formation of that part of the Delta; thus carrying back the records of the human race to a period which under no conceivable hypothesis can be reckoned

* Besides Mr. Horner's pits sunk and bored expressly to determine the scientific question, numerous wells and borings for water have brought up fragments of pottery from a depth sometimes of upwards of 70 feet, in various parts of Lower Egypt. But in these cases there was no starting-point that could be depended on, and the boring may have been through sand to some extent.

at less than one hundred, but is much more likely to have been two hundred, centuries. Mr. Horner very pertinently remarks, at the close of his memoir already cited:

"There is every reason to believe that the whole of the area now occupied by the alluvial land of Lower Egypt was at one time a bay in the Mediterranean, which in the course of ages was gradually filled up by deposits from the numerous branches of the Nile not confined by artificial embankments, and aided by sand blown from the adjacent high desert land; and that at a time when the shore of the bay had advanced, first to the parallel of Sigioul and Bessousse, and afterwards to that of the present apex of the Delta, by means of the accumulations at the embouchure of the Nile, the fragments of brick and pottery that had fallen into the river above were carried forward by it into the bay. This process appears to have continued as the shores of the bay gradually advanced northward even to its present sea-line; for in borings made in 1854, at a village about forty-five miles above Rosetta, the supposed site of the ancient city of Sais, and also in the neighbourhood of Rosetta itself, similar fragments were found at depths of nineteen and twenty feet. The rubbish soil extends to considerable depths under the foundations of stone buildings, below the lowest level of the Mediterranean, and quite close to the sea" (Phil. Trans. for 1858, pt. i. p. 76).

There appears, then, to be no escape from the conclusion that in Egypt, for a distance of nearly seven hundred miles of country traversed by the Nile, between the mountains and the Mediterranean, and across the whole breadth of the river valley, the vast accumulation of mud forming the Delta of the Nile has been gradually deposited at an average rate of only a few inches in a century; and that, certainly during a very large part of the period that has been required for this deposit, men having a certain amount of cultivation, and at least making bricks and pottery, have lived in the country. Looking back more than three thousand years, however, we find the Delta of the Nile already formed, a city founded, and great monuments of granite erected, which serve to mark the epoch. In one place we find this lapse of time represented by a thickness of about 20 feet of actual Nile mud accumulated; while not far off other human remains of carlier and less civilised races are met with at a depth twice as great; and elsewhere, though perhaps under different conditions and with a greater thickness of loose sand, the

"There must have been a time when the Delta was not only a marsh, but was even covered with water, and when the sea must have advanced so near to the site of Memphis as to allow the annual flood to rise no higher than eight cubits, or twelve to fourteen feet, at that place. Herodotus afterwards remarks that it rose fifteen or sixteen cubits in his time, which was the natural progress of things, as the point of contact of the land-waters with those of the sea was removed further out" (Rennell's Geography of Herodotus, p. 112).

depth of such remains is as much as 70 feet below the present surface.

In no instance have the remains of extinct races of animals been mixed up with these fragments of pottery and brick; so that the evidence obtained refers to the actual duration of the human family on the earth, and nothing more. It must not be supposed, however, that any rapid accumulation of mud can have taken place before the building of Memphis, suddenly washing into one heap the débris of a large district, and thus accounting for the phenomena. Nile mud is a peculiar substance, easily recognised, slowly deposited, and requiring a certain state of water for its formation. It is not, and, as far as we know, could not be produced by diluvial rushes of water, which give a totally different result.

The evidence of the antiquity of the human race obtainable from deposits in caverns, differs a good deal in many respects from that just stated; for in these localities there are no data from which we can calculate the accumulation of material as it goes on century by century.

Their

Caverns have doubtless been formed in all geological periods, and filled up at intervals without regularity-partly by their animal inhabitants, when such were present, partly with matter drifted in from the outside, and occasionally with the coats of limestone left behind after the evaporation of water. evidence being of a different kind from that just discussed, requires special consideration; but before coming to this point, it will be well that the peculiar circumstances under which these receptacles have been formed, and more or less filled, by natural causes should be explained.

Caverns are found in all rocks, but those interesting for their organic contents are almost limited to limestone districts. They are generally natural fissures originally produced by the drying and hardening of limestone, which must have been deposited as fine mud; and these cracks have been enlarged by the mechanical upheavals and displacements to which all rocks have been subjected. Water containing carbonic-acid gas in solution, or mere rain-water under ordinary circumstances, trickling down through the limestone, has often first dissolved and carried away part of the rock itself, and afterwards deposited it elsewhere on evaporation; and thus are produced both the large open spaces of the caverns and also the stalactites and stalagmites with which they are partly filled, and on which for the most part the picturesque effect of caverns depends. Such caverns,

"Water in penetrating through limestone strata often becomes impregnated with particles of the calcareous carbonate of which the limestone is composed, and which on exposure to air it again deposits either in the form of pendulous

consisting of large open spaces communicating by narrow passages, may evidently reach as far as the mass of limestone rock itself; and the deposits have generally taken place in the hollow spaces. In some the accumulation has taken place near the entrance; but occasionally it has been drifted far into the interior, and is deposited in the deep and remote cavities.

Among the more remarkable of these caverns are the mammoth cave of Kentucky, the Adelsberg cavern in Carinthia, the grotto of Antiparos, and the labyrinth of Crete in Greece; the caves of Franconia in Germany, and in our own country those of Derbyshire, Yorkshire, and Somersetshire. There are also remarkable and interesting examples in France and Belgium, and others in Australia. All of these have been the subject of description, and in all of them the essential features are the same. In almost all the state of the air shows a tolerably free communication with the surface, whether traceable or not; and the supply of water, either within the cave itself, or in the form of subterranean rivers issuing from limestone rocks, sufficiently marks the wide range of the crevices communicating with each other and with the surface.

The cavern of Kirkdale in Yorkshire was the first to which the special attention of English geologists was directed as containing the remains of animals in great abundance. Most of these remains belonged to kinds now and from time immemorial strangers to this part of the world; and on further examination, they were found to prove the existence, at the time of the filling up of the caverns, of great bears, hyænas, and tigers, not at all identical with the species met with at present in any part of the world. With them appear to have been associated species of elephant, rhinoceros, and hippopotamus, whose bones are mixed up with those of wolf, fox, weasel, horse, ox, deer, hare, rabbit, water-rat, and mouse, and several birds.

"The bottom of the cave, on first removing the mud, was found to be strewed all over like a dog-kennel from one end to the other with hundreds of teeth and bones, or rather broken and splintered fragments of bones, of all the animals above enumerated: they were found

masses that hang like icicles from the roof, or of strong concretions adhering to the sides of cavities into which the water thus impregnated finds admission; to such deposits the term STALACTITE is applied.

"If the percolation of water containing calcareous particles is too rapid to allow time for the formation of a stalactite, the earthy matter is deposited from it after it has fallen from the roof upon the floor of the cavern, and in this case the deposition is called STALAGMITE; the substance deposited is the same as in the case of stalactite. Stalagmites are commonly, at least in the early stages of their formation, of a mammillary shape; by gradual accumulation they become conical, and at length form pillars by the continual addition of their materials, till they meet and become united with the stalactite that depends from the roof immediately above" (Buckland's Reliquiæ Diluvianæ, p. 9).