50 



IRRIGATION FARMIXG. 



in plan. Both gate standards and the ends of levers are 

 lined with cast plates to prevent the bolts from being 

 pressed into the wood, to allow the gate to move with 

 the least possible friction. The opposite ends of the 

 levers (2) join in a single lever (3), likewise with a bolt 

 joint and cut plates. These levers (3) are connected with 

 two levers (4) by being placed upon the same axle, and 

 also connected with a triangular brace (5). 



At the end and between the top levers (4) is suspended 

 upon an axle a weight box (W), in which is placed rocks 

 or other heavy material to counterpoise the pressure of 



FIG. 15. AUTOMATIC \VASTK li.VTE. 



water in the canal against the surface of the gate. AVhen 

 the water pressure becomes greater than the counterpoise, 

 by reason of increased depth of water in the canal, the 

 gate swings open in an outward direction from the 

 canal, and levers 3 and 4 are forced back till the weight 

 box goes past the center or perpendicular over the main 

 axle just enough so as to nearly counterbalance the 

 weight of the gate and levers 1 and 2, so that the gate is 

 floating loose on the surface of the freely escjipinir water 

 with nothing to obstruct it, and no opportunity for drift 



