The Athai. 87 South of the Gabgaba Basin, the drainage from the watershed descends nearly due west by several large wadis, which have at various times given trouble to the railway. Owing to the outcrop of rocks near the river between Abu Hamed and Berber, the beds of these wadis become restricted as they approach the river, with the usual result as regards spates and floods.

On the east of the watershed the wadis, after leaving the hills on which they rise, traverse a range of granite hills, and thence flow, generally in a north-east direction, to the maritime plain of the Red Sea.

The principal wadis, from north to south, are Hasium, Di-ib, and Haieit. The Wadi Hasium, after emerging from the hills of Abu Hodeid, skirts the Kajoj and Musa ranges, which it leaves some distance to the south, and flows through open country to the sea. It contains the wells of Kajoj and Shalatein.

The Wadi Di-ib, perhaps the most important wadi of the Eastern Atbai, rises in the Amarar country, probably as far south as the 20th parallel, and flows generally northwards. About 20 miles before it turns eastwards to traverse the open maritime plain, it opens out into a wide basin, a mile in breadth and 8 to 10 miles in length, containing a bed of rich alluvial soil. This basin forms the principal cultivable land in the Um Ali Bisharin country. It is the property of the Shantirab, but portions are allotted both to the Amrab and Belgab in good years. An important tributary on the left bank of the Di-ib is the Wadi Hufra, which, rising in the Amrab country in the hills to the north-east of Onib, joins it at the north end of the J. Elba range. It receives all the drainage from the hills of the southern Belgab country by the Wadis Is and Legia. At several places in its bed, the Arabs cultivate and obtain good crops of dura.

Wadi Haieit, in the southern Atbai, is also said to be cultivated. The ranges of Elba and Asotriba are composed of red granite, whilst at the foot of the latter are small hills of very beautiful hornblende porphyrite.

The climate of the Atbai is probably the best in the Sudan. The air is of absolute purity, and the elevation, 1,500 to 3,000 feet above sea level, very considerably mitigates the shade temperature. The heat of the sun, however, is intensely fierce in warm weather, owing to the glare from the sand and rocks. During the summer, waves of superheated air are occasionally known, such as that which destroyed a convoy on the march from Korosko to Abu Hamed in 1897.

In winter, the cold is quite severe, and anyone proposing to travel there in December or January should make sure he has plenty of bedding and warm clothes.

Though it is essentially a very dry climate, dew falls at Deraheib on the west of the watershed in December, and a misty haze, which seems to be connected with moisture in the air, frequently covers the whole country. The climate of the littoral is, as may be supposed, much warmer than that of the interior.

The rain falls in violent local showers during the months of July and August, called the " Shuti " rains. In exceptional years, showers occur in May and June.

Many places go without rain for several years in succession, but during the above-mentioned months it is always risky to camp in the bed of a wadi, as a spate may come down, though no rain nor clouds have been visible to the traveller.

The dew is very heavy on the littoral, and suffices to keep the bush grazing in good condition, though it is insufficient to raise the short grass, which sprouts after rain, and which forms the principal pasture for sheep.

There are nowadays no towns or villages in the Atbai. The Arabs live by families in groups of tents made of dompalm matting. These, of course, move according as it suits them.

There are, however, throughout this district, the remains of quite large stone-built villages, formerly inhabited by the miners of the ancients. Those at Deraheib are particularly striking. Deraheib (Der — castle, aheib — beautiful) was evidently at one time the seat of a colony of miners. On the right bank of the wadi are the broken walls of 500 or more houses, arranged in streets. The castle, a large square building, stands under the hills on the left bank. The pointed arches of the castle and portions of some of the houses are set in Hme. The majority of buildings, however, are constructed of stone and mud.

The vegetation, generally, is rare and scanty, though in some of the large wadis, even west of the watershed, it is surprisingly luxuriant. Perhaps the Wadi Alagi, with its fine sayal and heglig and abundant marakh, arak and other green trees, is the most striking instance. West of the Gabgaba, and immediately east of it, selem is chiefly met with, but as one ascends the wadis one comes on sayal and the rare palm, " Medemia argun."

The latter is especially numerous in the Wadis Abaraga and Terfaui, and is found in many other khors in the neighbourhood, especially in those descending from J. Rafit to the Gabgaba.

No adult specimens were noticed east of the Wadi Abaraga, though there are many young plants trying to sprout at Abu Tabag.

This palm is largely used for mat-making, and the Arabs are fully alive to the advantage of preserving it, as well as other trees.

The grazing is not confined to the actual beds of the wadis. There are many flat or depressed places where, for some months after good rain, excellent grazing is found for camels, sheep, and goats.

Drainage east of watershed.

Climate.

Rainfall.

Towns or Villages.

Deraheib.

Vegetation,