I9J5- No. 2. SPITSBERGEN WATERS. 8 1 



The great periodical changes in the velocities and directions of the 

 currents, shown by our current-measurements, must inevitably cause vertical 

 oscillations of the water strata. If there is lateral equilibrium in a current 

 (i. e. if the inclinations of the strata exactly compensate the deflecting effect 

 of the Earth's rotation, produced at the given velocities of the current), 

 and then, for instance, the velocities in its upper layers, are much increased 

 relatively to those of its lower layers, the lateral equilibrium is dis- 

 turbed, and the strata will be depressed on the right hand side of the 

 current, and lifted on its left hand side, in order to re-establish the lateral 

 equilibrium. And vice versa, if the velocities in the upper layers are de- 

 creased relatively to those of its lower layers. Changes in the directions 

 of the current in the different layers will naturally also alter the inclina- 

 tions of the strata in a section, either the one way or the other. It is not 

 probable that the lateral equilibrium is ever attained, because the changes 

 both of velocity and direction are continuous. 



Periodical vertical oscillations of the water-strata must consequently 

 arrise in this manner; their magnitude will depend on the rate and mag- 

 nitude of the changes in the differences of velocity, vertically, also on the 

 changes in direction. 



The effect of the periodical changes, as to these vertical oscillations, 

 at any certain locality, will depend on -the situation of this locality, whether 

 it is near the left hand side or the right hand side of the current, or near 

 the middle of it. On the left hand side the strata will be lifted when they 

 are depressed on the right hand side, and vice versa. 



At our Stations 19, 20, and 41 there are not sufficiently numerous 

 measurements of the movement at different depths to ascertain the exact 

 relation between the vertical oscillations of the strata and the changes in 

 the currents at different depths. 



Let us look at the observations at Stat. 41, where there are the greatest 

 number of current-measurements, though even there the observations are 

 far from numerous enough for the determination of the real movements at 

 the different depths, at the moments desired. 



As was mentioned above (p. 67), several vertical series of observations 

 were taken at Stat. 41 which give different densities, especially at 20, 50, 

 .and 100 metres. On Aug. 19, at 10 a.m., a density* of 27.83 was found 

 at 50 metres. This is so much higher than the densities of the other 

 series at the same depth, that the water stratum observed at 50 metres 

 on Aug. 19, at 10 a. m., may have been about 10 metres lower at 3.20* 

 p. m. on the same day, and nearly 30 metres lower at 1.15 a. m. on 

 Aug. 1 8th. 



Vid.-Selsk. Skrifter. I. M.-N. K). 1915. No. 2. 6 



