342 DESERT SANDS 



they present a considerable diversity and variety of surface, 

 and their rocks are often unpleasantly obtrusive to the 

 tender feet of the pedestrian traveller. 



A desert, in fact, is only a place where the 'sveathor is 

 always and uniformly fine. The sand is there merely as 

 what the logicians call, in their cheerful way, * a separable 

 accident ' ; the essential of a desert, as such, is the absence 

 of vegetation, due to drought. The barometer in those 

 happy, too happy, regions, always stands at Set Fair. Ai 

 least, it would, if barometers commonly grew in the desert, 

 where, however, in the present condition of science, they 

 are rarely found. It is this dryness of the air, and this 

 alone, that makes a desert ; all the rest, like the camels, 

 the sphinx, the skcl.jton, and the pyramid, is only thrown 

 in to complete the picture. 



Now the first question that occurs to the inquiring 

 mind — which is but a graceful periphrasis for the present 

 writer — when it comes to examine in detail the peculiarities 

 of deserts is just this : Why are there places on the earth's 

 surface on which rain never falls ? What makes it so 

 uncommonly dry in Sahara when it's so unpleasantly wet 

 and so unnecessarily foggy in this realm of England? 

 And the obvious answer is, of course, that deserts exist 

 only in those parts of the world where the run of mountain 

 ranges, prevalent winds, and ocean currents conspire to 

 render the average rainfall as small as possible. But, 

 strangely enough, there is a large irregular belt of the great 

 eastern continent where these peculiar conditions occur in 

 an almost unbroken line for thousands of miles together, 

 from the west coast of Africa to the borders of China : and 

 it is in this belt that all the best known deserts of the 

 world are actually situatod. In one place it is the Atlas 

 and the Kong mountains (now don't pretend, as David 

 Copperlield's aunt would have said, you don't know the 



