IN THE DEPTHS 



63 



underlying waters are cold — intensely cold. 

 Not in the polar regions alone is this true, as 

 might naturally be supposed. The waters there 

 have given a temperature as low as 28° F. ; 

 but the temperature underlying the equatorial 

 waters is only a degree or more higher. Great 

 wastes of ice-cold water underlie all the seas. 

 The Pacific with its southern fields exposed to 

 the sun might be thought warmer than the 

 Atlantic, but in reality it is colder by about 

 two degrees — the register being some 33° F. 

 for the one and 35° F. for the other. Three 

 thousand fathoms down the temperature of all 

 the seas is practically the same. 



What heat if any comes from the underlying 

 earth to warm the great hollows of the sea can 

 only be surmised. None is derived directly 

 from the sun, because our sunlight is thought 

 not to penetrate more than five hundred feet 

 of water. And at the best water is not an easy 

 medium to warm. The sun's rays pass through 

 it, as through glass, leaving little heat behind. 

 To be sure, the surface of the sea in places 

 often takes a high temperature — the Eed Sea, 

 for instance, sometimes reaching 85° F. or even 

 90° F. ; but it is only a very thin sheet of water 

 that reaches that height. In the North At- 

 lantic the sun may beat all day upon the flat 



Intenne cold 

 of dee I) 

 waters. 



Water not 

 earn in 

 warmed. 



