80 



On Artesian Wells, 



ascends through the bore, having previously descended or 

 filtered through the earth, from some higher ground in the 

 neighbourhood. 



But it is a well known fact, that in the vicinity of many 

 artesian wells there are no hills at all, nor any particular ele- 

 vation of the earth's surface ; and the supporters of the now 

 existing theory are driven to the necessity of seeking for these 

 heights at any supposable distance. M. Arago, indeed, him- 

 self says, " that they must be sought for even beyond the sphere 

 of vision, at the distance of forty, eighty, or a hundred and 

 eighty miles, or even more, if necessary." 



Many years ago it struck me, that a much more probable 

 and less complicated theory of artesian wells might be main- 

 tained, and which does not imply the necessity for there being 

 any higher ground in the neighbourhood, none indeed, at all 

 higher than the mouth of the tube inserted in the bore for the 

 supply of the springs. 



To elucidate my theory, let us suppose, immediately under 

 the surface where the bore is made, a superincumbent mass of 

 clay — such as the London clay — lying over chalk, or other for- 

 mation, containing water. A diagram will more clearly shew 

 this. . 



A denotes the bed of clay, a pipe is made to penetrate it 

 from C to D, where it reaches B, a bed of chalk containing 

 water. On known hydraulic principles it is demonstrative, that 

 the instant the pipe C D reaches the stratum B contain- 

 ing water, the water will be immediately forced up the pipe 

 from the pressure of the superincumbent mass of clay, and 

 will rise to the surface of the earth at the point C. 



