206 M. Arago on Artesian Wells 



credibly informed, that there are very ancient artesian wells at 

 Stuttgard, but their exact date cannot accurately be ascertained. 



The inhabitants of the desert of Sahara have, for a long pe- 

 riod, been acquainted with these wells, as we learn from the fol- 

 lowing passage taken from ShaitPs Voyages. " The Wad-reag 

 is a group of villages lying in the depth of the Sahara. These 

 villages have neither springs nor fountains, and the inhabitants 

 procure water by a singular method. They sink wells an hundred, 

 and sometimes two hundred fathoms, and thus always succeed in 

 finding water in abundance. During the process they meet 

 with various beds of sand and gravel, and at length reach a 

 rock which very much resembles slate-clay, and which they know 

 immediately overlies what they call the Bahar taht el Erd, in 

 other words, the sea underneath the earth, and which is also their 

 name for the abyss. They pierce this stone without difficulty, 

 and instantly the water gushes up in such abundance, that those 

 who are immediately engaged in the operation are sometimes 

 surprised and drowned, though they endeavour to ascend with 

 the greatest possible speed *." 



Previous to his arrival in France, about the middle of the 

 seventeenth century, Dominico Cassini sank a well, at Fort Ur~ 

 bino, in the ecclesiastical dominions, the waters of which pro- 



" It has been said that the Chinese have been acquainted with these wells 

 for some thousands of years. The evidence for this, however, does not ap- 

 pear very satisfactory. M. Dupresse, bishop of Tabraca (See Nouvelles Let- 

 tres edifiantes, torn iv.) speaks of artesian wells, of small diameter, sunk many 

 hundreds of feet, which lie in the province of Kia-ting-fou, and which furnish 

 subterranean saltwater. The letter of this missionary is dated 11th Octo- 

 ber 1804, and in it he says nothing of the antiquity of the date of the con- 

 struction of these Chinese wells. M. Imbert, another French missionary, 

 who is still resident in that country, has also given a description of these wells, 

 from which we may conclude that the waters are not projected above the 

 level of the neighbouring earth. " In drawing the salt water," he remarks, 

 " the hoUow tube of a bamboo, twenty-four feet in length, is lowered into 

 the well. At the lower extremity of this machine there is a valve, and when 

 it has reached the bottom, a strong man seats himself on a cord, and works 

 the pump ; every strol e opens the valve, and the water rises." It cannot be 

 denied that it is very possible, that a people who set about finding salt springs 

 at the depth of fifteen or eighteen hundred feet, may sometimes do so in lo- 

 calities, where the geological structure would give rise to the appearance of 

 spoutuig fountains : But this is nothing more than conjecture ; and it is suf- 

 ficiently apparent, that at least the springs of Kia-ting-fou cannot be regarded 

 as such, although they have been ranked in tins class. 



