580 



Dr. Harold Jeffreys on 



to calculate k\ on the assumption that it is independent of 

 the time and the depth. Now it! fl be the earth's angular 

 velocity of rotation, w is equal to fl sin\, where \ is the north 

 latitude. Putting 



12= 7-3x10-71 sec. and p = l*3 X lO^g/cm.*, 



we have 



S 4 

 £=5x10 8 — 5-cosecX. 



S and ia must be measured in centimetres per second. In 

 the following table such determinations have been made. 

 The winds have been taken from Bartholomew's Meteoro- 

 logical Atlas, 1899, Plate 14, and the currents from Berghaus's 

 Atlas der Hydrographie, 1891, Plate VI. 









Wind 



Wind 



Current 



Current 



Deviation 



k 

 jhi.»/s« 



Ocean. 



Latitude. Longitude 



velocity direction 



Telocity 



direction 



in 









ni/s. 



from 



(in n.m./h.) 



from 



direction. 



N. Atlantic . 



.. 40° N. 



60° W. 



8 



S.W. 



tf 



W. by S. 



33|° 



4 





40° N. 



20° W. 



10 



S.W. by W. 



1 



N.W.byW 



67|° 



120 





10° N. 



40° W. 



10 



n.e". 



2 



E. 



45° 



460 



S. Atlantic . 



.. 36° S. 



10° w. 



8 



N.W. 



1 



W. 



45° 



14 



Indian 



.. 10° S. 

 40° S. 



80° E. 

 40° E. 



10 

 >12 



S.E. 

 N.W.byW. 



1 



E. 

 W. 



45° 

 331° 



200 





30 



N. Pacific . 



. 40° N. 



160° E. 



7 



S.W. 



1 



W. by S. 



33f° 



8 



S. Pacific... 



. 10° s. 



100° E. 



8 



S.E. 



1 



E. 



45 q 



45 





40° S. 



120° E. 



10 



N.W.byW. 



1 



W. 



33|° 



120 



The above localities were selected as giving some repre- 

 sentation of each ocean and fairly determinate values of 

 the mean annual wind and current. Many other localities 

 were rejected on account of the large annual variation they 

 showed. The prediction that the deviation in direction 

 should be 45° is surprisingly well verified by these rough 

 numerical data, for in no case does it differ from this by 

 more than two points. The fundamental assumption that the 

 vertical variation of k is small as far down as currents extend 

 is therefore so far verified. The range of horizontal variation 

 of k is however surprisingly great, the largest value found 

 being over 100 times tbe smallest. Many factors may 

 cooperate to cause this. The turbulence probably depends 

 on the height of the waves produced, and this depends on 

 the distance from land. Accordingly it was to be expected 

 that the two smallest values of k would correspond to places 

 near the American and Japanese coasts that the prevailing 

 winds reach after traversing comparatively short distances 



