56 SMALL WATER SUPPLIES. 



rod is an important member, as in case of the strut 

 getting loose it may have to withstand the whole 

 thrust of the water, and should be calculated accord- 

 ingly. Say it is set at an angle of 45. 

 The stress on the rod will be 



5 x io + // 2 x - 



5x N / 2 



9 



X x 62'5 x Q x ox ". r 

 = -2 1 -2 x V2 



9 



= 84375 x 1-41 = 1 189*6875. ex ^ = 475 tons. 

 The iron rod will stand say 4 tons per sq. in. 



.-. 25=1-1875 



4 



= say a i^ in. diameter rod. The strut must bear the 

 same stress, only in compression instead of tension, 

 and a 7 in. x 1 2 in. strut will do when tested by the 

 Rankine Gordon formula with which every engin- 

 eer would be acquainted, but which would be out of 

 place discussed in this book. The gauge constructed 

 on the above principles will be found to be capable 

 of practically universal application, and is a very use- 

 ful piece of apparatus and cheaply put up. 



Now, it will sometimes be found necessary in 

 works of this kind to which this book refers to con- 

 vey water some distance by means of an open 

 channel. This may be necessitated when a low fall 

 turbine is being installed for pumping purposes, in 

 which case the river or stream will be dammed in a 

 more permanent form than the timber erection..de- 

 scribed, and the water conveyed to the turbine along 

 an open channel which will be practically level, 

 having only just enough fall to enable the water to 



