404) Questions for Solution i-elating to Navigation. 



greater pari^ and they in fact indicate precisely the question 

 wliich remains to be answered. If it could be proved that all 

 the warm water of the baths of Sextius originated from the 

 cold water of the basin of Barret ; that the phenomenon does 

 not consist merely of an intermixture which may take place near 

 the surface, between the water of Barret and that of an ordinary 

 thermal spring nearer Aix ; that in its passage the fluid does not 

 become chemically charged with any foreign substance, the theory 

 of thermal springs would have made a decided step in its pro- 

 gress. Every one would then be satisfied of their similarity to 

 the Artesian springs, the high temperature of which is evidently 

 to be ascribed to the great depth from which they issue. 



Without pretending to devise better means of investigation 

 than the aspect of the places might suggest, I conceive that if 

 permission were obtained to withdraw the waters of Barret, only 

 for a few days, the principal question would be solved. From 

 the time that the thermal spring intermediate between Barret 

 and Aix should begin to flow to Sextius alone, there would be 

 a considerable diminution of the quantity of water, and an in- 

 crease in the temperature of the baths. A comparative chemi- 

 cal analysis of the respective waters, if performed with that 

 scrupulous accuracy of which we have now many examples, 

 would be attended with much interest. Neither should it be 

 forgotten to repeat the experiment mentioned by the locksmith 

 Dauphin, either employing lime or bran, or some tinctorial mat- 

 ter, were it only for determining the rapidity of the fluid in the 

 subterranean passages which it traverses in passing from Barret 

 to Sextius. 



The temporary derivation of the waters of Barret, is the most 

 decisive mode of obtaining the solution of the very ancient pro- 

 blem of physical geography to which thermal springs have given 

 rise ; but should this derivation be impossible, there still seems 

 to be a method of attaining this object. The waters of Sextius 

 are said to diminish with drought, and to increase in rainy wea- 

 ther. It is very improbable that the increase and diminution 

 should follow exactly and simultaneously the same relations in 

 the cold, nearly superficial waters of Barret, and those of the 

 thermal fountain nearer the town. If a mixture of the water 

 takes place, we ought, therefore, to expect, that great variations 

 of temperature would be observed at Sextius. 



