OF CERTAIN HOT-SPRINGS IN THE PYRENEES. 



469 



There is therefore a difference of half a degree of Fahrenheit between our 

 observations in the one case, and of nearly the same amount in the other. I 

 remember that Dr Garrigou explained to me that the difference was probably 

 due to a slight alteration in his thermometer. I made a note of his remark at the 

 time, but have mislaid it, and I can scarcely venture to repeat it from memory. 



But whilst, on the one hand. Ax is one of the best places for testing the con- 

 stancy of the temperature of hot springs, because of the locality not having un- 

 dergone any material change ; still, on the other hand, perhaps but little depen- 

 dence can be placed upon the results, in consequence of the exposure of the water 

 in its course to many external influences. Dr Garrigou has noticed that the 

 temperature of most of the springs at Ax varies with the season, and he adds : 

 II n' est pas etonnant qu'a Ax, oii les sources sont mal captees, au milieu d' alluvions, 

 et dans le voisinage de plusieurs rivieres, on ait ohserve des variations frequentes 

 dans les indications fournies par le thermometre. 



The following table shows the temperatures recorded by various observers at 

 different periods : — ' 



Name of Observer and Date of Observation. 



M. Pilhes (1786), .... 



Professor Forbes (1835), 



M. Fontan (1835), . . . 



M. Gintrac (1841), . . . 



M. Roux (1842), .... 



Professor Filhol (1853), . . 



Dr Garrigou (1861, summer), 



Dr Garrigou (1862, winter), 



Dr Garrigou (1863, August), 



Dr Scoresby- Jackson (1863, August), 



Canons. 

 Taps. 



Fahr. 

 168-98 

 1680 

 168-26 

 167-00 

 168-26 

 167-72 

 167-36 

 167-72 

 166-64 

 166-20 



Cent. 



7610 



75-6 



75-70 



75-00 



75-50 



75-40 



75-20 



75-40 



74-80 



74-55 



Rossignol. 

 Griffon. 



Falir. 



161-2 



166-12 



163-40 



166-12 



171-50 



17096 



172-04 



171-50 



171-00 



Cent. 



71-8 



74-50 



73-00 



74-50 



77-50 



77-20 



77-80 



77-50 



77-22 



From these observations it would appear that whilst there is, perhaps, in no 

 instance a permanent change of temperature, neither is there in any an undevi- 

 ating temperature. It is probable that the temperatures of these springs in the 

 interior of the globe have undergone no change, and that the changes observable 

 upon the earth's surface are due to superficial and evanescent causes, — such as 

 external temperature, the infiltration of cold surface-water, and the like. To a 

 certain extent, an allowance must be made for inaccuracies ; for it is scarcely to 

 be supposed that all the observers dipped their thermometers exactly at the same 

 points, nor do I know that, in all cases, errors of instruments were recognised and 

 corrected. 



i 



