Page:Africa by Élisée Reclus, Volume 1.djvu/187

 However, the banks of the lake are traversed in safety by hundreds of Taltals, who here procure nearly all the suit required for the Abyssinian market, and the little salt bricks used as a small currency in southern Abyssinia. According to Munzinger, they procure from the bed of this lake some thirty millions of bricks annually, equivalent at Antalo, on the plateau, to a sum of £320,000. The islands of the neighbouring coast, notably that of Dahlak, the largest in the Red Sea, which shelters Massawuh Bay from the cast, are partly of coral and partly of volcanic origin. They are skirted by headlands and lava streams, and in many places the land is intersected by deep crevices, apparently due to subterranean disturbances. The two walls of these chasms do not always stand at the same elevation, in some instances showing discrepancies of some fifty feet. During the rainy season the water collects in these hollows, and when evaporated verdant meadows spring up from the damp soil, contrasting pleasantly with the bare rocks surrounding them. The island of Dahlak is subject to earthquakes, which the natives say are caused by the movements of the " bull who supports the world." Hot springs are found in the interior, in which fish are said to live, although their temperature exceeds 172" F. Abyssinia, whose summits rise above the snow-line, while their base sinks to the level of the Torrid zone, naturally presents every diversity of climate according to the altitude and aspect of its uplands. On the slopes of the plateaux and mountains, the seasons are diversely distributed, continually overlapping the network of isothermal lines so regularly placed on our climatological maps of Abyssinia. How often have travellers, facing the bitter cold wind of the plateaux, succumbed to that frosty sleep which ends in death ! On military expeditions whole battalions have been frozen whilst crossing these snowy passes, and d'Abbadie quotes a chronicle, which states that a whole army thus perished in Lasta. But at the bottom of the narrow amhas death is more frequently caused rather by the intense heat, for under the summer sun these gorges become veritable furnaces, the soil glowing at times with a heat of some 190" lo 200° F. The air is generally calm in these apparently closed ravines; but if the equilibrium is suddenly disturbed, a raging tempest tears up the valley, the air soon returning to its former tranquillity. The absence of regular currents sweeping oway the impurities of the air, renders the amhas extremely dangerous to traverse. Before or after the rainy season they must be crossed rapidly, in order to reach the slopes above the fever zone. Although exposed to on almost equal degree of heat, the plains bordering the Red Sea are much more sulubrious, and are dangerous only in those years when the rainfall is excessive.

But these extremes of heat and cold are unknown in the central districts, where