- No. 2. SPITSBERGEN WATERS. 51 



40 cm. per second, to less than could be registered by the current-meters, 

 and during the same period the directions shift as a rule continuously 

 towards the right, on the whole about 360. This continuous turning 

 towards the right of the direction of the observed movements at all depths, 

 is obviously due to the effect of the tidal wave, and the chief period 

 observed seems also to coincide, approximately with the tidal period, though 

 possibly somewhat shorter. 



Our curves show, however, many irregularities. Some of them may 

 naturally be due to irregular movements of the ship moored to the ice- 

 floe, e. g. caused by turning of the floe, or by pressure against other 

 floes, though on the whole the ice seemed to be very quiet. On account 

 of such sudden irregular changes in the movements it may be difficult 

 to draw the curves correctly where the intervals between the observa- 

 tions are not sufficiently short; and in many parts they cannot be consi- 

 dered as more than rough approximations. 



But even if the movements observed had not been influenced by irre- 

 gular, accidental movements of the ice-floe, and if the curves were cor- 

 rectly drawn, we must expect them to show many apparent irregularities; 

 for the currents observed are obviously influenced by several factors. 

 The permanent or average currents would naturally have a certain perma- 

 nent direction at each depth, if not influencd by other agents; but the direc- 

 tion and velocity are, on the one hand, continuously being altered by the effect 

 of the tidal wave coming from the Atlantic, which evidently causes the chief 

 periodicity of the curves, of about twelve hours. On the other hand there 

 must be a local tidal wave of the circumpolar North Polar Basin which also 

 has a periodical effect upon the current, naturally much smaller, but still 

 complicating the phenomena. Besides these more or less regular influences 

 there may be apparantly quite irregular effects caused by incidental vortex- 

 movements in the different strata. It is also possible that stationary sub- 

 marine waves of different kinds, and pulsations of the prevailing currents 

 may occur. The result must be very complicated movements giving appar- 

 antly very irregular curves of velocity and direction. 



Amongst our curves those for the deepest strata, giving the drift of 

 the ship moored to the ice-floe (see later), are the most accurate, as they 

 are based on the greatest number of observations (3* in 40 hours). They 

 also show most irregularities, probably because the details are better 

 known; and if still more observations had been taken the number of ir- 

 regularities would probably have been increased. As it is, the curve o^ 

 velocity in particular shows a slight tendency towards a division of the 

 great period of about twelve hours. In the first great wave of this curve 



