DAHLAK ISLAND.— CLIMATE. 139 



However, the banks of the lake are traversed in safety by hundreds of Taltals 

 who here procure nearly all the salt required for the Abyssinian market, and the 

 little salt bricks used as a small currency in southern Abyssinia. Accordino- 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, 



Dahlak Island. 



The islands of the neighbouring coast, notably that of Dahlak, the largest in 

 the Red Sea, which shelters Massawah Bay from the east, 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 sub- 

 terranean 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. 



Climate. 



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 net- 

 work 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 

 Las ta. But at the bottom of the narrow ambas death is more frequently caused 

 rather by the intense heat, for under the summer sun these gorges become verit- 

 able furnaces, the soil glowing at times with a heat of some 190° to 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 away the impuri- 

 ties of the air, renders the ambas 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 an almost equal degree of heat, the plains 

 bordering the Bed Sea are much more salubrious, and are dangerous onl}^ in those 

 years when the rainfall is excessive. 



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



