Hot aiid Thermal Springs. 283 



■without effect. No. 1, the well under the chemical laboratory, 

 alone seems to be no longer affected by it, because its tempe- 

 rature is almost constant. On the ISth June 18-36, I found 

 its temperature to be the same, Si°.23 as in 1835. Lastly, No. 

 17 the one which shews the most considerable variations of 

 temperature of all, and therefore takes its rise very near the 

 surface, also shews the greatest differences between the two 

 years ; and it is very plain how much it was affected by the 

 cold weather which set in at several periods of the winter of 



1835-36. 



In order to have a numerical value of the influence of the 

 temperature of the air on that of springs, I subjoin a table of 

 the mean temperatures of the following months of the years 

 1834, 1835, and 1836, according to the observations of Mr 

 Heis at Cologne. 



The year 1835 was, therefore, with the exception of Septem- 

 ber, always colder than 1834, and hence the depression of the 

 temperatures of the springs in 1835. The higher temperature 

 in September, was distinctly shewn in the temperatures of the 

 springs in October and November. 



Before I had made my own experiments, as above given, on the 

 temperature of mountain springs, I gave myself a great deal 

 of trouble to find out the decrease of temperature in the soil 



