ARTESIAN WELLS IN THE DESERT. 
445 
portion of mineral matter to be acceptable to a European palate, 
it answers well for irrigation, and does not prove unwholesome 
to the natives. 
The most obvious use of artesian wells in the desert at 
present is that of creating stations for the establishment of mil¬ 
itary posts and halting places for the desert traveller ; but if 
the supply of water shall prove adequate for the indefinite 
extension of the system, it is probably destined to produce a 
greater geographical transformation than has ever been effected 
by any scheme of human improvement. The most striking 
contrast of landscape scenery that nature brings near together 
in time or place, is that between the greenery of the tropics, 
or of a northern summer, and the snowy pall of leafless winter. 
Next to this in startling novelty of effect, we must rank the 
sudden transition from the shady and verdant oasis of the 
desert to the bare and burning party-colored ocean of sand and 
rock which surrounds it.* The most sanguine believer in 
* The variety of hues and tones in the local color of the desert is, I 
think, one of the phenomena which most surprise and interest a stranger 
to those regions. In England and the United States, rock is so generally 
covered with moss or earth, and earth with vegetation, that untravelled 
Englishmen and Americans are not very familiar with naked rock as a con¬ 
spicuous element of landscape. Hence, in their conception of a bare cliff 
or precipice, they hardly ascribe definite color to it, but depict it to their 
imagination as wearing a neutral tint not assimilable to any of the hues 
with which nature tinges her atmospheric or paints her organic creations. 
There are certainly extensive desert ranges, chiefly limestone formations, 
where the surface is either white, or has weathered down to a dull uni¬ 
formity of tone which can hardly be called color at all; and there are 
sand plains and drifting hills of wearisome monotony of tint. But the 
chemistry of the air, though it may tame the glitter of the limestone to a 
dusky gray, brings out the green and brown and purple of the igneous 
rocks, and the white and red and blue and vioiet and yellow of the sand¬ 
stone. Many a cliff in Arabia Petrsea is as manifold in color as the rain¬ 
bow, and the veins are so variable in thickness and inclination, so contorted 
and involved in arrangement, as to bewilder the eye of the spectator like a 
disk of party-colored glass in rapid revolution. 
In the narrower wadies, the mirage is not common ; but on broad ex¬ 
panses, as at many points between Cairo and Suez, and in Wadi el Araba, 
it mocks you with lakes and land-locked bays, studded with islands and 
