Tides of the Oceans 



495 



5= [(2wsin0)/2.-r]r= 1 033 sin <p. Table 84 shows that in the whole, this relation 

 is satisfied. From the ratio of the minor to the major axis of the current 

 ellipse V/U and from the difference in time e between the current maximum 

 and that of the occurrence of high water, Proudman and Doodson derived 

 (see p. 565 (equation XI. 38)), two equations for the computation of the 



70° 60° 50° 40° 30° 20" 10" 0° 10° 20° 



y • ^ 



Fig. 204. Direction, phase and intensity of the semi-diurnal tidal current in the Atlantic. 

 ->, upper layer; <->, deeper layers. 



angle ip enclosed by the co-tidal line and the direction of the current maximum 

 for a certain locality. Thorade (1935, p. 93) has used these equations to com- 

 pute this angle for the stations in Table 83 by using time of high water as given 

 by Sterneck's map of co-tidal lines (1922) and compared this angle with those 

 given in the map. Table 83 gives in its columns the necessary data and it is 

 to be noted that the observations for different depths have been averaged 

 for the indicated ranges listed in the column denoted by depth. If we exclude 

 station 176, in which the values are too scattered, we find that, for ten out of 

 seventeen stations the difference is less than 30°, for five between 30° and 60° 

 and that only for two it exceeds 60°. This result is not bad considering all the 

 errors inherent in the different values. The two stations with the two greatest 

 discrepancies are close to the coast on the edge of the shelf, and must be re- 

 garded as disturbed. If one were to use the new presentation by Dietrich 

 instead of the one by Sterneck, there would be only minor changes because the 

 two presentations are very similar. This result shows that the map of the 

 co-tidal lines of the Atlantic Ocean and the results of the current measurements 

 are in satisfactory agreement and form an oscillatory system closed in itself. 



