154 



HYDRAULICS AND ITS APPLICATIONS 



temporary floor to investigate the effect of the depth of the channel of 

 approach upon the discharge. The results are given in Fig. 84, which shows 

 that the presence of the floor produces a slight diminution in the discharge, 

 and that this effect disappears when the channel depth is about three 



0-3100 

 90 



Head- 4 



V * 4 6 8 10 12 14 16 



Ratio of Width of Channel of Approach to Head/. 

 FIG. 83. 



times the head with a 3 inch head and about four times the head with a 

 4 inch head. 



Experiments were also made in which the head was varied. For the 

 results given in E (Fig 82) the floor was maintained level with the vertex 



03060 

 SO 

 40 



> 30 



, I LI I - 

 sad/ -3 



234-567 



Batio of Depth of' Channel of Approach/ 

 FIG. 84. 



of the notch, and it was at a depth 6 inches below the vertex for the 

 results given in D (Fig. 82). 



By coating the up-steam face of the weir plate with coarse emery the 

 discharge was increased by 2 '4 per cent, with a 3 inch head and by 1*7 

 per cent, when the head was 4 inches. 



The results of the whole series of experiments are in extremely close 

 accord with those previously obtained by Professor Thomson. 



