EFFECT OF ICEBERGS IN THE OCEANS 133 



warm water of the superficial [)()rtions of the sea, and the 

 deeper portions of their masses in a fluid which is a 

 Httle above the point where ice melts, is due to certain 

 circumstances which we shall have now to note with some 

 care. The icebergs, as they slowly melt, chill the water 

 about them to very near the freezing-point. This very cold 

 state extends, in the case of large masses, to the distance of 

 some miles from the face of the ice-cliffs. Next the berg 

 the temperature is always but a shade above that of a vessel 

 in which there is just enough water to float fragments of ice. 

 Only a very small part of this cooled portion of the sea is 

 derived from the melting berg ; in the main it consists of 

 that portion of the ocean which has been deprived of its 

 heat by the contact with the glacial mass. Here we must 

 consider the fact that the process of melting ice calls for a 

 great deal of heat. If we take a cubic foot of the frozen 

 water and put it over a regulated fire, as, for instance, that of 

 gas-flame, we observe that it requires a much longer time to 

 melt the mass than it would to bring an equal amount of ice- 

 cold water to near the boiling-point. If we conduct the 

 experiment in a more careful way, we may easily determine 

 that, starting with a block of ice at a temperature just a frac- 

 tion of a degree below the freezing-point, it takes more units 

 of heat to bring it to a point where it becomes molten than 

 is necessary to raise its temperature after it is melted to 74° F. 

 This heat, which the water hides away in the process of melt- 

 ing, is so great that it much affects not only the history of 

 icebergs, but all the phenomena of the seasons in countries 

 where a thick envelope of snow gathers during the winter 

 season. It is this peculiar absorption of heat which makes 

 it so difficult for the warm sun of spring to clear away the 



