Z T)r. Darwin's Account of 



two or three caufes, but particularly to the lefs condenfed flate 

 ■of the air upon hills, which thence becomes a better conduclor 

 of heat, as well as of eleclricity, and permits it to efcape the 

 fader; it is from the water condenfed on thefe cold furfaces of 

 mountains, that our common cold Iprings have their origin ; 

 and which, fliding between two of the ftrata above defcribed, 

 defcend till they find or make themfelves an outlet, and will in 

 .confequence riie to a level with the part of the mountain where- 

 they oripinated. And hence, if by piercing the earth you gain 

 a fpring between the f^cond and third, or third and fourth 

 flratum, it mull: generally happen, that the water from the 

 loweff ftratum will rife the higheff, if confined in pipes, be- 

 'raufe it come6 originally from a higher part of the country in 

 its vicinity. 



I'he increafing quantity of this new fpring, and its increafing 

 purity, I fuppofe to be owing to its continually diflblving a 

 part of the earth it pallies through, and hence making itfelf a 

 wider channel, and that through materials of lefs folubility. 

 Hence it is probable, that the older and ftronger fprings are 

 generally the purer ; and that all fprings were originally loaded 

 with the foluble impurities of the llrata, through which they 

 tranfuded. 



Since the above- related experiment was made, I have read 

 with pleafure the ingenious account of the King's wells at 

 Sheernefs, in the laft volume of the Tranfadions, by Sir 

 Thomas Hyde Page, in which the water rofe three hundred 

 feet above its fource in the well ; and have alfo been informed, 

 that in the town of Richmond, in Surrey, and at Infhlp near 

 Frefton in Lancafhire, it is ufual to bore for water through 

 a lower flratum of earth to a certain depth ; and that when it 



is 



