THE PHYSICAL CONDITIONS OF THE ABYSS 33 



' Cliallenger ' to be 0-6° 0. at a cleptli of 2,150 fathoms. 

 In a similar latitude nortli of tlie equator at a depth of 

 2,900 fathoms the temperature was found to be 2*2° C, 

 and at a point near Porto Rico there is a deep hole of 

 4,561 fathoms with a bottom temperature of 2-2° 0. 



Again it has been shown by the American ex- 

 pedition that the temperature of the water at the 

 deepest point in the Gulf of Mexico, 2,119 fathoms, 

 is the same as that of the bottom of the Straits of 

 Yucatan, 1,127 fathoms, namely 4*1° 0. And, passing 

 to another part of the world altogether, we find in the 

 small but deep sea that lies between the Philippines 

 and Borneo that, at a depth of 2,550 fathoms, the 

 temperature is 10-2° C. 



These facts then show that, although at the 

 bottom of the deep seas the water is always very 

 cold, the degree of coldness is by no means constant 

 in the same latitude for the same depth. 



We must now return to the polar currents. We 

 have assumed above that these currents do exist, and 

 it is probable that by this time the reader must have 

 seen why they are assumed to exist. 



The water at the bottom of the ocean is exceed- 

 ingly cold. Where does this coldness come from? 

 It is obvious that in temperate and tropical climes 



