CHAPTER IV 



THE WATERS OF THE OCEAN : TEMPERATURE 



Properties of Fresh and Salt Water. — Before 

 considering the distribution of temperature 

 in the ocean it is desirable to recall some of 

 the well-known properties of water. Although 

 the significance of the term " temperature " 

 has frequently been changed in scientific 

 discussions, still the modern kinetic theory of 

 heat appears to give a quite definite meaning 

 to the word. The heat energy communicated 

 to a material substance increases the kinetic 

 energy of translation of the molecules as a 

 whole, and it is this portion only of the heat 

 energy which influences the temperature ; 

 monatomic molecules alone retain all the heat 

 they receive as heat " sensible " to the ther- 

 mometer. In addition, heat energy may 

 produce in all substances except monatomic 

 gases, certain other kinds of motion, as for 

 instance rotatory motion on the part of the 

 molecules, or oscillatory motion on the part of 

 the atoms within the molecule. These mole- 

 cular motions are spoken of as path heat, spin 

 E 65 



