1915- ^O. 2. SPITSBERGEN WATERS. 83 



changes in the horizontal movements is hardly possible. At Stat. 19 the 

 densities differed, c. g. at 100 metres between 27.84 and 27.89, and there 

 ma}' have been vertical oscillations of the layers of 30 or 40 metres. 



It is obvious that the changes in the velocities and directions at the 

 different depths of a current, must cause such vertical oscillations of the 

 strata, and they must also cause much transport of the water-masses from 

 one side of the current towards the other. Much force is therefore always 

 spent on this great work towards establishing lateral equilibrium, and a 

 considerable and continuous resistance must be offered to the currents 

 in this manner. 



Vertical oscillations of the water-strata may also be caused in other 

 ways, c. g. b}' intermediate waves of various kinds, which may aquire 

 great hights in the intermediate layers. 



It was pointed out above (pp. 28, 37) that vertical movements of the 

 strata probably occurred at several stations, even in the fjords, e. g. Stats 

 25, 27, 44, 50. and 53, as there were considerable differences between 

 observations taken at short intervals of time. 



The Tidal Wave in the North Polar Basin. 



Our curves of velocity and direction for the surface-drift (Figs. 36 &: 

 37, see also the central vector-diagram, Fig. 43) show that the greatest 

 m.axima of velocity coincide with a south-westerly or westerly drift, while 

 at the minima of velocity there is no current, /'. e. the tidal current must 

 have been sufficiently strong in the opposite direction as to entirely check 

 the surface-drift, and also the current in the deeper layers. As the tidal wave 

 must evidently be moving in some north-easterly direction in this region, 

 we ma}^ conclude that low-water coincided with the maxima of velocity, 

 while high-water coincided with the minima. We should consequently have 

 had low- water at 8 a. m. and about 10 p. m. (/'. e. 7 a. m. and 9 p. m. 

 Greenwich time) on August i8th, and at about 10 a. m. (9 a. m. Green- 

 wich time) on August 19th, while high-water would have occurred at about 

 4.30 a. m. and about 5 p. m. on August i8th, and at 2 a. m. and about 

 3 p. m. on August 19th. 



Taking Greenwich time, the hours of the transits of the moon across the 

 Greenwich meridian, the hours of high- water at our Stat. 41, the medium 

 hours between every two transits of the moon, and the hours of low- 

 water at Stat. 41, are given in the following tables: 



