Hot Springs, and other Natural Features of the Pyrenees. 443 



of tlie spring the temperature of the spring is taken, the point 

 at which the thermometer is inserted should always be 

 accurately noted. 



The instrument with which the following observations were 

 made in August 1865 was a Centigrade thermometer,, constructed 

 by one of the best makers in Paris. The total length of the 

 thermometer was about six inches, and the stem was engraved 

 with sixty-sis centigrade degrees. The extremity of the tube 

 being turned into a ring, to which a cord was attached, the 

 instrument could be completely immersed in tumblers, etc., at 

 the springs. The words, " Eectifie, No. 795," are engraved 

 upon the stem, and also the name and address of the person at 

 Pau through whose kindness I received the loan of the instru- 

 ment, for the purpose of making these experiments. Plunged 

 in melting snow, and afterwards in running water in a crack of 

 the Glacier du Yignemale, the mercury always marked within 

 a tenth of a degree the zero of the Centigrade scale. Placed 

 by the side of a standard thermometer in cool spring water at 

 the residence of Mr. Maxwell Lyte, at Bagneres de Bigorre, 

 the mercury in both instruments stood at 13° Centigrade. 

 From these observations, and from the sensitive character of 

 the instrument itself, it is assumed to have been free from 

 errors of graduation. A small additive correction of between 

 one and two-tenths of a degree Fahrenheit, for index-error, 

 has been left out of account in the following tables. 



Temperatures of five thermal springs at Cauterets.in 1835, 

 1863, and 1865. 



Name and point of Spring 

 obseryed. 



Temperatures, in 



degrees, Fahrenheit. 



August, 

 1835. 



August, 

 1863. 



August, 

 1865. 



In- 

 crease. 



De- 

 crease. 



La Kailliere, griffon 



Ditto buvette 



Manhourat (en haut), bu- 

 vette 



o 



101-90 



121-70 

 130-10 



110-30 



118-10 



o 



101-80 

 101-30 



121-00 

 131-00 

 119-00 

 109-75 

 102-30 

 117-40 

 116-30 



o 



101 : 2 7 

 120-35 

 120-17 

 102 ; 35 

 115-85 







0-90 

 1-17 



0-05 



o 



o-io 



0-03 

 0-65 



0-55 



0-70 

 0-45 



Les Oenfs, griffon 



7 O 



Ditto escape 



Panze vieux, griffon 



Ditto buvette 



Cesar (en haut), griffon. . . 

 Ditto, buvette 





For convenience of comparison with the earlier observations, 

 the indications of the Centigrade thermometer, No. 795, are 



