Upon our first arrival in Khartoum, from 11th June until early in October, the heat was very oppressive, the thermometer seldom below 95 degrees Fahr. in the shade, and frequently 100 degrees, while the nights were 82 degrees Fahr. In the winter, the temperature was agreeable, the shade 80 degrees, the night 62 degrees Fahr. But the chilliness of the north wind was exceedingly dangerous, as the sudden gusts checked the perspiration, and produced various maladies, more especially fever. I had been extremely fortunate, as, although exposed to hard work for more than a year in the burning sun, I had remarkably good health, as had my wife likewise, with the exception of one severe attack while at Sofi. Throughout the countries we had visited, the temperature was high, averaging about 90 degrees in the shade from May until the end of September; but the nights were generally about 70 degrees, with the exception of the winter months, from November until February, when the thermometer generally fell to 85 degrees Fahr. in the day, and sometimes as low as 58 degrees at between 2 and 5 A.M.
I shall not repeat a minute description of Khartoum that has already been given in the "Albert N'yanza;" it is a wretchedly unhealthy town, containing about thirty thousand inhabitants, exclusive of troops. In spite of its unhealthiness and low situation, on a level with the river at the junction of the Blue and White Niles, it is the general emporium for the trade of the Soudan, from which the productions of the country are transported to Lower Egypt, i.e. ivory, hides, senna, gum arabic, and bees'-wax. During my experience of Khartoum it was the hotbed of the slave-trade. It will be remarked that the exports from the Soudan are all natural productions. There is nothing to exhibit the industry or capacity of the natives; the ivory is the produce of violence and robbery; the hides are the simple sun-dried skins of oxen; the senna grows wild upon the desert; the gum arabic exudes spontaneously from the bushes of the jungle; and the bees'-wax is the produce of the only industrious creatures in that detestable country.
When we regard the general aspect of the Soudan, it is extreme wretchedness; the rainfall is uncertain and scanty, thus the country is a desert, dependent entirely upon irrigation. Although cultivation is simply impossible without a supply of water, one of the most onerous taxes is that upon the sageer or water-wheel, with which the fields are irrigated on the borders of the Nile. It would appear natural that, instead of a tax, a premium should be offered for the erection of such means of irrigation, which would increase the revenue by extending cultivation, the produce of which might bear an impost. With all the talent and industry of the native Egyptians, who must naturally depend upon the waters of the Nile for their existence, it is extraordinary that for thousands of years they have adhered to their original simple form of mechanical irrigation, without improvement.
If any one will take the trouble to watch the action of the sageer or water-wheel, it must strike him as a most puny effort to obtain a great result, that would at once suggest an extension of the principle. The sageer is merely a wheel of about twenty feet diameter, which is furnished with numerous earthenware jars upon its exterior circumference, that upon revolving perform the action of a dredger, but draw to the surface water instead of mud. The wheel, being turned by oxen, delivers the water into a trough which passes into a reservoir, roughly fashioned with clay, from which, small channels of about ten inches in width radiate through the plantation. The fields, divided into squares like a chess-board, are thus irrigated by a succession of minute aqueducts. The root of this principle is the reservoir. A certain steady volume of water is required, from which the arteries shall flow throughout a large area of dry ground; thus, the reservoir insures a regular supply to each separate channel.
In any civilized country, the existence of which depended upon the artificial supply of water in the absence of rain, the first engineering principle would suggest a saving of labour in irrigation: that, instead of raising the water in small quantities into reservoirs, the river should raise its own waters to the required level.
Having visited every tributary of the Nile during the explorations of nearly five years, I have been struck with the extraordinary fact that, although an enormous amount of wealth is conveyed to Egypt by the annual inundations of the river, the force of the stream is entirely uncontrolled. From time immemorial, the rise of the Nile has been watched with intense interest at the usual season, but no attempt has been made to insure a supply of water to Egypt during all seasons.
The mystery of the Nile has been dispelled; we have proved that the equatorial lakes supply the main stream, but that the inundations are caused by the sudden rush of waters from the torrents of Abyssinia in July, August, and September; and that the soil washed down by the floods of the Atbara is at the present moment silting up the mouths of the Nile, and thus slowly, but steadily, forming a delta beneath the waters of the Mediterranean, on the same principle that created the fertile Delta of Egypt. Both the water and the mud of the Nile have duties to perform,—the water to irrigate; the deposit to fertilize; but these duties are not regularly performed: sometimes the rush of the inundation is overwhelming, at others it is insufficient; while at all times an immense proportion of the fertilizing mud is not only wasted by a deposit beneath the sea, but navigation is impeded by the silt. The Nile is a powerful horse without harness, but, with a bridle in its mouth, the fertility of Egypt might be increased to a vast extent.
As the supply of water raised by the sageer is received in a reservoir, from which the irrigating channels radiate through the plantations, so should great reservoirs be formed throughout the varying levels of Egypt, from Khartoum to the Mediterranean, comprising a distance of sixteen degrees of latitude, with a fall of fifteen hundred feet. The advantage of this great difference in altitude between the Nile in latitude 15 degrees 30 minutes and the sea, would enable any amount of irrigation, by the establishment of a series of dams or weirs across the Nile, that would raise its level to the required degree, at certain points, from which the water would be led by canals into natural depressions; these would form reservoirs, from which the water might be led upon a vast scale, in a similar manner to the insignificant mud basins that at the present day form the reservoirs for the feeble water-wheels. The increase of the river's level would depend upon the height of the dams; but, as stone is plentiful throughout the Nile, the engineering difficulties would be trifling.
Mehemet Ali Pasha acknowledged the principle, by the erection of the barrage between Cairo and Alexandria, which, by simply raising the level of the river, enabled the people to extend their channels for irrigation; but this was the crude idea, that has not been carried out upon a scale commensurate with the requirements of Egypt. The ancient Egyptians made use of the lake Mareotis as a reservoir for the Nile waters for the irrigation of a large extent of Lower Egypt, by taking advantage of a high Nile to secure a supply for the remainder of the year; but, great as were the works of those industrious people, they appear to have ignored the first principle of irrigation, by neglecting to raise the level of the river.
Egypt remains in the same position that Nature originally allotted to her; the life-giving stream that flows through a thousand miles of burning sands suddenly rises in July, and floods the Delta which it has formed by a deposit, during perhaps hundreds of thousands of inundations; and it wastes a superabundance of fertilizing mud in the waters of the Mediterranean. As Nature has thus formed, and is still forming a delta, why should not Science create a delta, with the powerful means at our disposal? Why should not the mud of the Nile that now silts up the Mediterranean be directed to the barren but vast area of deserts, that by such a deposit would become a fertile portion of Egypt? This work might be accomplished by simple means: the waters of the Nile, that now rush impetuously at certain seasons with overwhelming violence, while at other seasons they are exhausted, might be so controlled that they should never be in excess, neither would they be reduced to a minimum in the dry season; but the enormous volume of water heavily charged with soil, that now rushes uselessly into the sea, might be led throughout the deserts of Nubia and Libya, to transform them into cotton fields that would render England independent of America. There is no fiction in this idea; it is merely the simple and commonplace fact, that with a fall of fifteen hundred feet in a thousand miles, with a river that supplies an unlimited quantity of water and mud at a particular season, a supply could be afforded to a prodigious area, that would be fertilized not only by irrigation, but by the annual deposit of soil from the water, allowed to remain upon the surface. This suggestion might be carried out by gradations; the great work might be commenced by a single dam above the first cataract at Assouan, at a spot where the river is walled in by granite hills; at that place, the water could be raised to an exceedingly high level, that would command an immense tract of country. As the system became developed, similar dams might be constructed at convenient intervals that would not only bring into cultivation the neighbouring deserts, but would facilitate the navigation of the river, that is now impeded, and frequently closed, by the numerous cataracts. By raising the level of the Nile sixty feet at every dam, the cataracts would no longer exist, as the rocks which at present form the obstructions would be buried in the depths of the river. At the positions of the several dams, sluice gates and canals would conduct the shipping either up or down the stream. Were this principle carried out as far as the last cataracts, near Khartoum, the Soudan would no longer remain a desert; the Nile would become not only the cultivator of those immense tracts that are now utterly worthless, but it would be the navigable channel of Egypt for the extraordinary distance of twenty-seven degrees of latitude—direct from the Mediterranean to Gondokoro, N. lat. 4 degrees 54 minutes.