272 G - F - Me E wen. 



That is, the greater the inclination of the bottom, in the neigh- 

 borhood of a coast, or the more rapidly the depth increases with the 

 distance from the coast, the narrower will be the belt near the coast 

 into which a given volume of cold water intrudes, and therefore the 

 greater will be the reduction of the surface temperature. 



For example, at the head of a submarine valley terminated at 

 the coast, a lower surface temperature than that on either side would 

 result from a wind so directed as to produce upwelling. 



Another factor affecting the upwelling is the steadiness of the 

 winds. The effect of the winds over the broad and deep regions, re- 

 quiring several months to become fully established, can not follow the 

 seasonal change in the wind velocity, but tends to agree with that due 

 to the average velocity 1 ), and approaches more nearly to that average 

 amount the more steady the wind. But the effect in narrower belts, 

 and in the shallower water of the continental shelves, requiring but a 

 few hours or days to become practically fully developed would change 

 more nearly in accordance with the monthly variation of the wind 

 velocity. 



We can now test the theory further by comparing the results of 

 the general conclusions just reached with the corresponding observations. 

 An estimate based upon the U. S. Coast Pilot Chart records of the 

 breadth of the wind belt was made for each station and these distances 

 were plotted as ordinates against distances from station (1) as abscissas 

 (Fig. 14, curve 2). That is, this line which practically touches the coast 

 at latitude (50), (500) miles north of Cape Mendocino marks the appro- 

 ximate western limit of winds whose velocities have a north and south 

 component. Between the coast and this line the winds tend more and 

 more to the west as the distance from the coast increases. Therefore 

 the system of streamlines due to the observed wind velocities that 

 would be expected from the theory would be limited to a narrow area 

 corresponding to the narrow wind belt off Cape Mendocino but would 

 spread out to the west and south, as the latitude diminished and the 

 wind direction shifted to the west. Thus a general surface drift 

 toward the south and bearing more and more to the west would 



*) Owing to the large value of the effective internal friction of the water which 

 tends to prevent the circulation, the motion would decrease nearly in accordance with 

 the decrease of wind velocity, but would not increase to the maximum value which 

 the wind velocity would generate if it continued for a sufficient length of time. 

 Therefore, the actual effect of a varying wind would be less than that due to a 

 steady wind of the same value as the average of the changing winds. 



