Ar(esUin Springs or IFells. 73 



In all springs, therefore, of this description, in which we 

 can tell the depth from which the water comes, we may safely 

 rely upon the temperature of the water at the mouth of the 

 bore being similar to that at the bottom of it, and conse- 

 quently of the stratum from which it came. And, in those 

 instances in which we have reason to suspect that the Avater 

 is mixed with springs from a higher level, the use of an instru- 

 ment similar to that above described will settle the question. 

 At this stage of our inquiry, it may be proper to remark, 

 that in all cases the method of ascertaining the rate of increase 

 as we descend under the sm'face of the earth as deduced from 

 artesian wells, is, by comparing the temperature of the spring 

 with that of the mean of the district in which it is situated. 

 This is a most important part of the inquiry, and one which 

 requires om* especial attention. 



It is a very connnon idea and practice, to compai'e the heat 

 of a spring of this description with that of an ordinary surface- 

 spring in its immediate neighbourhood, and certainly nothing 

 can give more fallacious results. Thus, we have seen the 

 temperature of an artesian well, on which we were experi- 

 menting, 52^ while that of a sm^face-spring hard by, was at 

 the point of freezing. It is, therefore, proper to gain as much 

 information as we can regarding the probable mean of the 

 place, if no thermometrical obsenations have been made on 

 the district. 



It is unfortunate that many of those interesting springs, 

 which I am about to mention, occur in a district on which no 

 ascertained mean temperature, as deduced from thermometric 

 observations, has been drawn ; and we have, therefore, been 

 left to our own resources in fixing them, partly by their proxi- 

 mity to a spot, the mean temperature of which we know, 

 partly from their level as regards, and proximity to, the sea, 

 and partly from observations on well-shaded springs at differ- 

 ent periods in the course of a twelvemonth. 



Having thus given a few preliminary statements, for the 

 purpose of enabling the Society the better to understand the 

 detail of our observations, we shall now proceed to lay before 

 them our experiments on the artesian wells of Mid-Lothian, 

 Stirlingshire, and Clackmannanshii'e, with oneortwo elsewhere. 

 . Our first experiment was made on an artesian spring in the 



