442 
ARTESIAN WELLS IN THE DESERT. 
an artesian well is, therefore, often derived from distant 
sources, and may be wholly unaffected by geographical or 
meteorological changes in its immediate neighborhood, while 
the same changes may quite dry np common wells and springs 
which are fed only by the local infiltration of their own nar¬ 
row basins. 
In most cases, artesian wells have been bored for purely 
economical or industrial purposes, such as to obtain good water 
for domestic use or for driving light machinery, to reach saline 
or other mineral springs, and recently, in America, to open 
fountains of petroleum or rock oil. The geographical and geo¬ 
logical effects of such abstraction of fluids from the bowels of 
the earth are too remote and uncertain to be here noticed; * 
but artesian wells have lately been employed in Algeria for a 
purpose which has even now a substantial, and may hereafter 
acquire a very great geographical importance. It was ob¬ 
served by many earlier as well as recent travellers in the East, 
among whom Shaw deserves special mention, that the Libyan 
desert, bordering upon the cultivated shores of the Mediter¬ 
ranean, appeared in many places to rest upon a subterranean 
lake at an accessible distance below the surface. The Moors 
are vaguely said to have bored artesian wells down to this 
reservoir, to obtain water for domestic use and irrigation, but 
* Many more or less probable conjectures have been made on this sub¬ 
ject, but thus far I am not aware that any of the apprehended results have 
been actually shown to have happened. In an article in the Annales des 
Fonts et Ghaussees for July and August, 1839, p. 131, it was suggested that 
the sinking of the piers of a bridge at Tours in France was occasioned by 
the abstraction of water from the earth by artesian wells, and the conse¬ 
quent withdrawal of the mechanical support it had previously given to the 
strata containing it. A reply to this article will be found in Yiollet, 
Theorie des Puits Artesiens , p. 217. 
In some instances the water has rushed up with a force which seemed 
to threaten the inundation of the neighborhood, and even the washing 
away of much soil; but in these cases the partial exhaustion of the supply, 
or the relief of hydrostatic or elastic pressure, has generally produced a 
diminution of the flow in a short time, and I do not know that any serious 
evil has ever been occasioned in this way. 
