Another Type of Drag 



Now let us take up another condi- 

 tion where the current is swift at the 

 opposite bank and slow in the centre 

 of the stream. The natural direction 



Fra. ? 



of the fly (Fig. 7) would be from A to 

 B, but the centre of the hne would 

 travel much more slowly, and again 

 the fly would have a tendency to take 

 a direction somewhat similar to the 

 course shown by the dotted line A C; 



[97] 



