VARIOUS CASES OF THE MOVING JUMP 



57 



of course the distance for Vq must be measured in the opposite direction, 

 that is, horizontally from the intersection of the Di and D2 lines towards 

 the left to the intersection of the Vi and V2 lines. This may lead to 

 negative values of Vi and V2, which, of course, are quite possible. 



O S /O /S 20 2S 



\/a!ues of \^, the velocity after the jump, in feet per second 



Fig. 502, Diagram for the Hydraulic Jump in a Rectangular Channel. 

 May be used for the moving jump. Scale for Fo same as for Fi and Fj. 



Various cases of the moving jump. In the kinds of moving jump 

 most frequently occurring in nature, such as the ocean surf and the 

 tidal bore, Fq is negative. It is found rather difficult in the laboratory 

 to produce a satisfactory moving jump having much velocity in the 

 positive direction. Apparently this is because the high velocities neces- 

 sary produce such high friction as to interfere with the formation of the 



