362 MISCELLANEOUS STUDIES 



Consider two parallel stream lines, A and B, the velocity being 

 # A along the first and H B along the second, then the temperature in 

 A for any value of z minus the temperature in B for the same value 

 of z is 



Hz Zo) _ fc(z Zn) a 



UB+ y - l (H B H A )=M (74) 



(75) 



Denote H A H B by AH, then 



fc(z z) _ *r(z 



Also if -^ is small we have approximately 



? _ 9 \ 1 



-^ 



(76) 



THE RATE OF HORIZONTAL FLOW IN THE NORTH PACIFIC OFF THE 

 CALIFORNIA COAST FROM LAT. 40 N TO 30 N AND IN THE NORTH 

 ATLANTIC OFF THE WEST COAST OF AFRICA FROM LAT. 30 N TO 



20 N. 



The rate of flow deduced from surface temperatures. 



From the hydrographic charts (Thorade, 1909) of the region of 

 the Pacific off North America, it appears that that the average direc- 

 tion of the surface drift from Cape Mendocino, Lat. 40 N, does not 

 at any season differ greatly from a straight line determined by the 

 points, Lat. 40 N, Long. 124 W, and Lat. 30 N, Long. 126 W. 

 Assuming that there is a surface drift in this constant average direc- 

 tion which is proportional to the average wind velocity over this 

 course, will some numerical value of the drift account for the monthly 

 temperatures at the down-stream end of the line? From the 

 monthly isotherms worked out by Thorade (1909), the observed 

 mean monthly temperatures at any point of the region can be found. 

 From these observed monthly temperatures at the upper end of the 

 line and a mean value of the drift velocity determined by trial, the 

 temperatures at the down-stream end will be computed according to 

 the theory on page 359. A comparison of these theoretical tempera- 

 tures with the observed ones and of this theoretical value of the drift 

 with estimates made in other ways will indicate the practical value of 

 the theory. The observed temperatures taken from Thorade 's chart 

 (1909), and the numerical values of the other quantities computed 



