The Winter Night. 239 



afternoon, and in between we have always lain for some 

 part of the time in open water. The very great pressure 

 just now is probably due to the spring tide ; we had new 

 moon on the gth, which was the first day of the pressure. 

 Then it was just after midday when we noticed it, but it 

 has been later every day, and now it is at 8 p.m." 



The theory of the ice-pressure being caused to a 

 considerable extent by the tidal wave has been 

 advanced repeatedly by Arctic explorers. During the 

 Frauis drifting we had better opportunity than most 

 of them to study this phenomenon, and our experience 

 seems to leave no doubt that over a wide region the 

 tide produces movement and pressure of the ice. It 

 occurs especially at the time of the spring tides, and 

 more at new moon than at full moon. Curing the 

 intervening periods there was as a rule little or no 

 trace of pressure. But these tidal pressures did not 

 occur during- the whole time of our driftino-. We 



O O 



noticed them especially the first autumn, while we were 

 in the neighbourhood of the open sea north of Siberia, 

 and the last year, when the Fram was drawing near 

 the open Atlantic Ocean ; they were less noticeable 

 while we were in the polar basin. Pressure occurs 

 here more irregularly, and is mainly caused by the 

 wind driving the ice. When one pictures to one's self 

 these enormous ice-masses, drifting in a certain direction, 

 suddenly meeting hindrances for example, ice-masses 

 drifting from the opposite direction, owing to a change 



