148 



HYDRAULICS AND ITS APPLICATIONS 



Effect of a Change in Head on the Discharge from a Rectangular Weir. 



" d~H ~ 



* rt iK^rrlfrr ]SO K & H 



="****. -I #=WTP 



i.e., the proportional change in (^ is 1*5 times that in 7Z. 



Effect of Inclination of Weir Pace. 

 As might be expected from its effect on the crest contraction, an 



Fm. 78. 



up-stream inclination of the weir face (Fig. 78 a) reduces, while a down- 

 stream inclination (Fig. 78 b) increases, the discharge. 



Bazin obtained the following comparative results with inclined weirs : 



The maximum discharge was obtained with a down-stream inclination 

 of 7 to 4. 



Professor G. S. WiUiams, in experiments on weirs with a down-stream 

 inclination of 1 to 1. obtained a mean comparative increase of 7'2 per 



