PHYSICAL OCEANOGRAPHY 



27: 



is still much to be done in this line. But the fluctuations of the 

 ocean-currents are determined by more influences than tides, 

 for many other forms of motion supervene, rendering the whole 

 picture highly complicated. A careful analysis of the measure- 

 ments made on Storeggen in 1906, led to the conclusion that 

 there were certain regular variations which took the form of 



3, 55a.77t. 



JT 772 a.m. 



Fig. 183. — The Currents as determined by simultaneous measurements 



(3.35 A.M. AND 7.12 A.M.) at different DePTHS AT STATION 58. 



pulsations in the current. When the effect of the tide was Puis 

 subtracted it appeared that the ordinary current at lo metres "^ ^^ 

 ran for some time with considerable velocity (up to ^ metre 

 per second) ; then the velocity decreased during seven or eight 

 hours until it approached zero, increasing again during the next 

 seven to eight hours, and so on. The fluctuations had thus a 

 period of about fifteen hours, but we are as yet ignorant of the 

 particular cause, though it may be a usual phenomenon in the 



T 



