REPORT ON MINERAL AND THERMAL WATERS. 9 



where volcanic phaenomena are of rare occurrence, as in the 

 Scandinavian Peninsula*, Russia, and Poland, it would be well 

 to learn, whether the temperature of springs more nearly corre- 

 sponded with that of the climate, than is the case in the parts 

 of Germany where igneous action may still be suspected. Such 

 an inquiry would not be without its bearing upon those pro- 

 blems concerning the origin of thermal springs in general, which 

 will be discussed in a subsequent part of this Report, for if ther- 

 mal springs derive their temperature from a remnant of volcanic 

 energy existing beneath, they ought to be most frequent in coun- 

 tries where such energy has at one time or other been mani- 

 fested ; whilst if they simply proceed from a generally diflfiised 

 heat pervading the interior of our planet, they might be expected 

 to appear in countries of every geological structure. 



Independently, however, of the mere question, as to whether Periodical 

 there be any evidence of the existence in the springs of a coun- Variations 

 try of an excess of temperature beyond the mean of the climate, °ature°hi^' 

 and the determination of this question by accurate thermome- Springs. 

 trical observations both on the air and the spring, neither of 

 which has in most cases been done in a satisfactory manner, 

 two points of inquiry present themselves ; first, as to whether 

 there be any periodical variation of heat in the latter from day to 

 day, or at different seasons of the year ; and secondly, whether, 

 in the course of the ages that have elapsed since they were first 

 known, any augmentation or diminution of temperature had oc- 

 curred. 



Prof. Bischof t has shown, that in some cases the variations of 

 external temperature do manifest themselves in the thermal 

 springs of a district; but this only happens when their excess 

 of heat is inconsiderable. 



A similar variation has been observed, as I am informed in a 

 letter with which I was favoured from Mr. Jephson, M.P. for 

 Mallow, in the thermal spring of that town, and it would be 

 desirable that exact observations should elsewhere be instituted 

 on the same point. 



A variation of temperature at different periods of the year has 

 heen observed in the spring of Bourboulc in Auvergne X, and in 

 that of Balaruc near Montpellier. 



Still more important is the question relative to the secular Secular va- 

 variation of temperature in thermal waters. riation of 



In countries where traces of former or present volcanic action ^rTiT*" 

 are discoverable, and where earthquakes are frequent, the tem- Springs. 



* I shall allude to Wablenberg's observations on this country in a subse- 

 quent part of this Report, 

 t Edinhuryh Journal, loc. cif. 

 X Lecoq, Annales Scicntifiques dc I'Auveryne, 



