OASES. 271 



firmament, as rain-clouds are called by the Arabs, 

 from passing over the desert, and fertilizing it as 

 they pass: hence no showers descend on the parched 

 soil, which remains destitute of vegetation, excepting 

 in those favoured spots, the Oases, which rise like 

 islands of verdure, surrounded by a waste of sand. 

 Beautiful they are : extensive too, and sufficiently 

 shady to screen large caravans from the burning 

 heat of the sun. They afford a resting place, where 

 weary men and camels may renew their strength, 

 and drink of the cool streams that flow among 

 them : where the date-palms also grow, those life- 

 sufficing trees, which yield both food and shade. 

 Without these fertile spots, no travellers, however 

 enterprising, might hope to cross the burning desert 

 of Sahara, which equals one half of Europe in 

 extent : an ocean of sand, with bays or gulfs of 

 lesser deserts branching off ; yet, by means of the 

 refreshment which the Oases afford, the Sahara is 

 often passed in safety. Travellers assign to natural 

 causes the existence of these wonderful spots amid 

 wastes of burning sand. They tell us that the 

 irregular ridges of high rocks, which rise in their 

 vicinity, attract the floating clouds, and cause them 

 to distil in rain, and hence the fountains of clear 

 water that nourish and flow beneath the palm trees. 

 There is not, throughout the whole extent of the 

 habitable globe, a more extraordinary spectacle than 

 the oases of which we speak. Travellers pass, by 

 an almost immediate transition, from the surface of 

 a burning desert to tread on soft and luxuriant her- 

 bage, to rest beneath the shade of noble palm trees, 

 and to quench their thirst at ample streams. So at 



