294 



HYDRAULICS AND ITS APPLICATIONS 



When badly choked with weeds the value of N in Kutter's formula may 

 become much greater than *035. The following values of N in the latter 

 formula are taken from Jackson's tables, and are probably slightly more 

 accurate than those given above. 



N. 



009 

 010 

 012 

 013 

 015 

 017 



Planed timber accurately jointed glazed or enamelled surfaces 

 Smooth cement or plaster ....... 



Unplaned timber well jointed new brickwork well laid 

 Unglazed stonework iron brick and ashlar 

 Wooden troughs with battens inside, J inch apart 



Bubble set in cement 



If any of these are in bad order the next higher value for N is to be 

 taken. 



For convenience in applying the results of these formulae the values of 



/ in the formula h = ^ , and of G in the formula v = C V m i have 



2 g m 



been calculated and are tabulated opposite. 



The following table gives values of C in the formula v = C Vm i t 



calculated from Bazin's formula in which C = - 



Vm 



Hydraulic 

 mean Depth. 



Values of JV. 



