540 H. MOHN. METEOROLOGY. [NORW. POL. EXP. 



THE TEMPERATURE OF THE POLAR ICE. 



Professor NANSEN has sent me the following note about the observations 

 of the temperature of the drifting polar ice made during the drift of the Fram. 



"I considered it very desirable that the seasonal changes in the thickness 

 of the ice covering the Polar Sea, as well as the seasonal changes in the 

 temperature at various depths in the ice, should be systematically investigated 

 during the years the expedition lasted. Such systematic investigations had 

 not, to my knowledge, previously been made, and they might evidently give 

 very valuable results, if only satisfactory methods for the observations could 

 be found. 



For measurements of the thickness of the ice, long, specially-constructed 

 augers were used, with diameters of 2 inches (5'1 cm.) and 4 inches (lO'l cm.). 

 The difficulty of these investigations proved to be that ice-pressure on several 

 occasions disturbed the ice, so that the investigations could not be carried 

 on at the same place during the whole expedition; and as the ice-floes were 

 often of different ages, their thickness might vary a good deal, even though 

 they were flat and not disturbed by ice-pressure. We did not therefore 

 succeed in getting a continuous series of observations of the growth of the 

 same ice-floe during the whole drift of the Fram ; but our observations, when 

 properly worked up, will nevertheless give valuable information as to the 

 formation of the ice and its relation to the temperature of the air. 



Observations of the Temperature of the Ice at Various Depths. 



For these observations I had ordered 3 "earth-thermometers" from 

 NEGRETTI & ZAMBRA, as described in their large illustrated catalogue, 57 

 (p. 42. See also figs. 48, 49). The thermometers (one maximum thermometer, 

 and one slow-action thermometer) were lowered into bore-holes in the ice; 



