80 Dr Paterson on the Temperature of . 



ing to the depth of 69 fathoms (414 feet) from the bottom of 

 one of his coal-pits, that at that depth the rush of water was 

 so great, that they were obliged to stop the boring operations. 

 The quantity of water ejected by this bore has been roughly 

 calculated by Mr Johnston, to be about a hogshead per minute. 

 The quality of the water is excellent, and is used by many 

 families in the neighbourhood of these perforations in prefe- 

 rence to the surface- springs. It, in general, contains a quan- 

 tity of the hydrate of iron, received probably from the strata 

 of ironstone through which it has to pass ; this, however, is 

 soon deposited by the water in the shape of a hydrated oxide, 

 on the bottom of the water-course. In some instances, how- 

 ever, the quantity of iron is so great as to constitute it a 

 slightly chalybeate spring. 



It was previously mentioned, when speaking of the artesian 

 wells of Clackmannanshire, that the height to which the tide 

 rises causes the surface-springs to become brackish. Now, 

 it is a curious fact connected with the artesian springs there, 

 that some of them, and more especially those of least depth, 

 emit a much larger quantity of water when the tide is high. 

 This is a remai'k which has been made by Mr Bald, and by 

 various individuals in their neighbourhood. It is very evident 

 that this increase in the quantity of the water given out by 

 the spring has a connexion with the rise of the tide, and has 

 been most commonly, and in om' opinion very properly, re- 

 ferred to fissures extending into the strata, and to which the 

 sea- water has access. That no salt water can extend along 

 these fissiires is proved by the fact, that these artesian wells 

 are never brackish ; but to account for this, it has been sup- 

 posed that the percolation through the strata is sufficient to 

 remove the salt ; this, however, cannot be, as no percolation 

 which we are yet acquainted with, enables us to remove the 

 saline ingredients of sea-water. We are, therefore, inclined 

 rather to explain it after the following manner : — These fis- 

 sures extend, as we have formerly mentioned, through the 

 strata into the bed of the river ; these, however, are con- 

 stantly discharging water into the river, the quantity 

 of which, however, must materially vary according to the 

 superincumbent pressure. Thus, when the tide is high. 



