254 



G. F. Me E wen. 



and that these conditions have continued long enough to establish a 

 stationary state of motion. Introducing the deflecting force (P) into the 

 equations of motion of a viscous fluid and solving in the usual way 

 gives the following results for the northern hemisphere. The velocity 

 of the surface water is directed at an angle of 45 to the right of the 



Fig. 5. 



The arrows show the velocities of the water at the depths 0,0 D, 0,1 D, etc., below 

 the surface. V is the surface velocity. 



wind velocity (Fig. 5). The magnitude of the velocity of the water 

 decreases as the distance below the surface increases, the direction of 

 the velocity of each layer being to the right of that above it. At 

 the depth 



2. D = 



where (ft) is the coefficient of viscosity and (q) equals the density, the 

 magnitude of the velocity is only 1 / 20 of that at the surface, and is in 

 the opposite direction. This distance (D) is called the "depth of the 

 wind-current", and the motion at greater depths is assumed to be 

 negligible. Another result is 



3. 



where (V ) is the surface velocity of the water and (T 3 ) is the tangen- 

 tial pressure at the surface due to the wind. 



The general character of the motion may be illustrated as follows. 

 Imagine a spiral stairway so situated that the edge of the top step is 



