TEMPERATURE 



79 



ence of 15° may be found in the bottom tem- 

 peratures on the two sides of the ridge : 30° F. 

 on the polar side and 45° F. on the Atlantic 

 side. 



The seasonal variation in the temperature 



Sea Surface 



FiQ. 4. — Diagrammatic section across the Wyville Thomson Ridge, 

 showing distribution of temperature and currents. 



of ocean water becomes less and less on pas- 

 sing downwards below the surface, and seems 

 to disappear at a depth of about 100 fathoms, 

 beyond which depth temperature readings are 

 looked upon as good annual means. Neverthe- 

 less, some observations recorded by R. E. 

 Peake in the North Atlantic would seem to 



