STORAGE AND DISTRIBUTION. 12$ 



Value of H. Value of T r 



21 24-50 



22 2575 



23 27-00 



24 28-50 



25 30-00 



26 31-25 



27 33'oo 



28 34*50 



29 36*00 



30 38-00 



When the above values are ascertained for a given 

 value of H, it will be necessary to ascertain if the re- 

 sulting structure will have the maximum pressure 

 at the toe within safe limits, and also that the result- 

 ant does not make an angle with the vertical greater 

 than the angle of repose. Referring again to fig. 88, 

 it is required to find the angle a and also the value 

 of P, the maximum pressure, at the toe as follows : 



and P= -0280 H '(r + .) , (39) 



and having found cot a we have another equation for 

 x which may be used as a check : 



that is, x = H cot a - ST - S( J|* rf} . . (40) 



If the value of a is limited to 35, which is the angle 

 recommended by Prof. Rankine, the value of x will 

 increase, but the writer is inclined to believe that 

 a may be as much as 42 and the wall quite safe. 

 The tension in the dam between the buttresses can 



