232 



IRRIGATION. 



charge of the water, which include the pipes, the valve 

 tower, and the culvert. For convenience and safety, in 



Fig. 114. DAM WITH CULVEBT AND TOWEE. 



case of the giving way of a joint in the discharge pipe, 

 this should be carried out through a culvert of masonry, 

 of sufficient size to admit a man. This culvert com- 

 municates with the valve tower as shown in fig. 114. The 



valve is a circular plate, which 

 slides between two flanges 

 within the pipe, the surfaces 

 which come into contact be- 

 ing ground to fit accurately 

 together. This is raised by 

 means of a screw attached to 

 a rod having a horizontal 

 wheel for turning it at the 

 top. A form of valve frequent- 

 ly used is shown at fig. 115, 

 the section of pipe contain- 

 ing the valve being bolted by 

 the flanges to the discharge 

 pipe. A valve, in common 

 use in Italian and French ir- 

 rigating works, is shown in 

 section at fig. 116. This, A, 

 may be made of wood, shod 

 at the foot with a plate of cast iron, ground to fit an- 

 other similar plate attached to the opening of the pipe, E. 

 It is raised by the rod, B, keyed to the upper part, and is 

 guided by means of eyed wings, D, D, which work up 

 and down upon the rods, C, 0. 



Fig. 115. DISCHARGING PIPE 

 VALVE. 



