For some months we resided at Khartoum, as it was necessary to make extensive preparations for the White Nile expedition, and to await the arrival of the north wind, which would enable us to start early in December. Although the north and south winds blow alternately for six months, and the former commences in October, it does not extend many degrees southward until the beginning of December. This is a great drawback to White Nile exploration, as, when near the north side of the equator, the dry season commences in November and closes in February; thus the departure from Khartoum should take place by a steamer in the latter part of September. That would enable the traveller to leave Gondokoro, lat. N. 4 "degrees" 54', shortly before November. He would then secure three months of favorable weather for an advance inland. Khartoum 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 beeswax. 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.