462 AETESIAN" WELLS. 



are seen to pour into chasms opened, as it were, expressly for 

 their reception ; and in others, where no apertures in the crust 

 of the earth have been detected, their existence is proved by the 

 fact that artesian wells sometimes bring up, from great depths, 

 seeds, leaves and even living fish, which must have been carried 

 down through channels large enough to admit a considerable 

 stream.* But in general, the sheets and currents of water reached 



pose in Piedmont, with complete success. See the interesting pamphlet, Sulla 

 Estrazione delle Acque Sotterranee, by C. Calandra. Torino, 1867. Also 

 another pamphlet by the same author, Sui Pozzic Fontane Modenese, 1874. 



The most remarkable case of infiltration known to me by personal observa- 

 tion is the occurrence of fresh water in the beach-sand on the eastern side of 

 the Gulf of Akaba, the eastern arm of the Red Sea. If you dig a cavity in 

 the beach near the sea-level, it soon fills with water so fresh as not to be un- 

 drinkable, though the sea-water two or three yards from it contains even more 

 than the average quantity of salt. It can not be maintained that this is sea- 

 water freshened by filtration through a few feet or inches of sand, for salt- 

 water can not be deprived of its salt by that process. It can only come from 

 the highlands of Arabia, and it would seem that there must exist some large 

 reservoir in the interior to furnish a supply which, in spite of evaporation, 

 holds out for months after the last rains of winter, and perhaps even through 

 the year. I observed the fact in the month of June. See RoBrNSON, Biblical' 

 Researches, 1857, vol. i., p. 167. 



The precipitation in the mountains that border the Red Sea is not known by 

 pluviometric measurement, but the mass of debris brought down the ravines 

 by the torrents proves that their volume must be large. The proportion of 

 surface covered by sand and absorbent earth, in Arabia Petraea and the neigh- 

 boring countries, is small, and the mountains drain themselves rapidly into 

 the wadies or ravines where the torrents are formed ; but the beds of eax'th 

 and disintegrated rock at the bottom of the valleys are of so loose and porous 

 a texture, that a great quantity of water is absorbed in saturating them before 

 a visible current is formed on their surface. In a heavy thunder-storm, ac- 

 companied by a deluging rain, which I witnessed at Mount Sinai in the month 

 of May, a large stream of water poured, in an almost continuous cascade, 

 down the steep ravine, north of the convent, by which travellers sometimes 

 descend from the plateau between the two peaks ; but after reaching the foot 

 of the mountain, it flowed but a few yards before it was swallowed up in the 

 sands. 



Fresh-water wells are not unfrequently found upon the borders of ocean 

 beaches. In the dry summer of 1870, drinkable water was procured in many 

 places on the coast of Liguria by digging to the depth of a yard in the beach- 

 sands. Tubular wells reach fresh water at twelve or fifteen feet below the 

 surface on the sandy plains of Cape Cod. In this latter case the supply is 

 more probably derived directly from precipitation than from lateral infiltra- 

 tion. 



* Charles Martins, Le Saha/ra, in Bevue des Deux Mbndes, September 1^ 



