466 AETESIAN WELLS EST THE DESEET. 



The Frencli Government lias bored a large number of artesian 

 wells in the Algerian desert within a few years, and the native 

 Bheikhs are beginning to avail themselves of the process. Every 

 well becomes the nucleus of a settlement proportioned to the 

 supply of water, and before the end of the year 1860, several 

 nomade tribes had abandoned their wandering life, established 

 themselves around the wells, and planted more than 30,000 palm 

 trees, besides other perennial vegetables.* The water is found 



in 1871 the drill had descended 5,500 feet below the surface, passing through 

 a stratum of salt for the last 3,200 feet ; but the drilling was still in progress, 

 the whole thickness of the salt-bed not having been penetrated. — Aus der 

 Natur, vol. Iv., p. 208. According to other authorities the depth reached 

 is 4,050 feet. 



"When in boring an artesian well water is not reached at a moderate depth, 

 it is not always certain that it will be found by driving the drill still lower. 

 In certain formations, water diminishes as we descend, and it seems probable 

 that, except in case of caverns and deep fissures, the weight of the superin- 

 cumbent mineral strata so compresses the underlying ones, at no very great 

 distance below the surface, as to render them impermeable to water and con- 

 sequently altogether dry. See London QuarUrly Journal of Science, No. xvii., 

 January, 1868, pp. 18, 19. 



In the silver mines of Nevada water is scarcely found at depths below 1,000 

 feet, and at 1,200 feet from the surface the earth is quite dry. — American An- 

 nual of Scientific Discovery for 1870, p. 75. 



Similar facts are observed in Australia. The Pleasant CreeTc JVews writes : 

 "A singular and unaccountable feature in connection with our deep quartz 

 mines is being developed daily, which must surprise those well experienced in 

 mining matters. It is the decrease of water as the greater depths are reached. 

 In the Magdala shaft at 950 feet the water has decreased to a minimum; in 

 the Crown Cross Reef Company's shaft, at 800 feet, notwithstanding the two 

 reefs recently struck, no extra water has been met with ; and in the long drive 

 of the Extended Cross Reef Company, at a depth of over 800 feet, the water 

 is lighter than it was nearer the surface." 



The facts that there are mines extending two miles under the bed of the 

 sea, which are not particularly subject to inconvenience from water, that lit- 

 tle water was encountered in the Mt. Cenis tunnel, 5,200 feet below the sur- 

 face, and that at Scarpa, not far from Tivoli, there is an ancient well 1,700 

 feet deep with but eighteen feet of water, may also be cited as proofs that 

 water is not imiversally diffused at great distances beneath the surface. 



* " In the anticipation of our success at Oum-Thiour, everything had been 

 prepared to take advantage of this new source of wealth without a moment's 

 delay. A division of the tribe of the Selmia, and their sheikh, Alssa ben ShS, 

 laid the foundation of a village as soon as the water flowed, and planted 

 twelve hundred date-palms, renouncing their wandering life to attach them- 

 selves to the soil. In this arid spot life had taken the place of solitude, and 



