METEOROLOGY AND DEEP TEMPERATURES 465 



have, indeed, been fully confirmed by subsequent work, but he 

 could not reconcile them with the low temperature of the Swiss 

 lakes. He did indeed suggest the possibility of a rise of tempera- 

 ture in the deep sea due to fermentation ; but he did not lay 

 much stress on this, and looked on the matter as one only to be 

 settled by future observations. Had he only known that the 

 high temperature at great depths is confined to tropical and warm 

 temperate seas shut off by barriers from the ocean (in which the 

 bottom temperature rarely rises more than a degree above 

 R.), he would doubtless have elaborated a theory of the Earth 

 with a cold centre to which so many of his imperfect observations 

 pointed. As it was, however, he took the Mediterranean as 

 ' the sea,' and wisely turned his thoughts to more profitable 

 channels. 



The inventive power and the ingenious devices to avoid error 

 are as obvious in the work on deep temperature as on hygrometry, 

 but the latter subject was free from the disturbing causes which 

 baffled all eighteenth -century observers of the physical conditions 

 of lakes and seas. 



ERRATUM 



Graustock, p. 143. De Saussure did not climb this summit but the 

 Ochsenstock, or Kopf (see p. 342). 



2G 



