Artesian Springs or Wells. 81 



\iie quantity emitted by the fissure into the river must be 

 c^jnsiderably less than when there is only a small quantity of 

 \vater in the river. Now, if there is a constant discharge of 

 fresh water from this fissure, we can easily understand that, 

 according to the laws of hydrostatic pressure, the quantity 

 emitted by the artesian spring when the tide is high, is just 

 so much greater as the quantity of water emitted by the fis- 

 ^ure into the river is less. This, it appears to us, will suf- 

 iiciently explain the phenomenon, without the supposition 

 that percolation, or any other process, removes the saline taste 

 of the sea- water. 



It may be remai'ked, in the second place, that the peiwious 

 stratum in which the water seems to be contained, is the sand- 

 stone. It is a very common idea among the borers and 

 miners, that, in general, the water proceeds from the coal, and 

 we can easily explain this by referring to several journals of 

 borings, in wbich this is said to have taken place. The mis- 

 take of these individuals seems to be, that, in general, after 

 piercing through a stratum of shale (which is well known to 

 mining engineers to be a rock very impervious to water), they 

 come to a small seam of coal, immediately under which lies 

 the pervious stratum of sandstone. When the coal is pierced, 

 the water from the sandstone immediately rushes up through 

 the innumerable cracks in it, and comes to the surface. Thus, 

 in many journals of borings which I have in my possession, 

 and in the one which has already been referred to in a pre- 

 vious part of this paper, it will be seen that the water really 

 came from the sandstone. In support of this idea I have 

 only to mention the name of Mr Bald, who has had so much 

 experience in mining operations, and that of Mr Johnston of 

 Meadowbank ; and the facts connected with the deep bore 

 which I have previously mentioned as sunk by that gentle- 

 man from the bottom of one of his coal-pits, is sufficient to 

 put this beyond doubt. " The rush of water (says Mr John- 

 ston) occurred at the depth of forty-seven fathoms, from a 

 stratum of white sandstone, having a seam of coal about thu-ty 

 inches thick above it ; the bore was continued to the depth 

 of sixty-nine fathoms, still through this sandstone, when they 

 were compelled to give it up owing to the rush of water." 



VOL. XXVII. NO. UU.— JILY 1830. *" 



