WATER-GATES. 



127 



Each portion of the meadow will be confined between 

 banks upon the sides, one of which will be upon the edge 

 of the river, and the other upon the opposite boundary, 

 which is the main supply canal, and between a canal of 

 distribution at the head and an open drain at the foot. 



Fig. 59. SELF-ACTING WATER GATE. 



This is shown in fig. 58, in which a, a, is the river; J, b, 

 the river bank; c, c, the opposite bank; d, d, the supply 

 canal; e, e, the distributing canal; and /, /, the drain. 

 The drain discharges into the river through the bank by 

 a self-acting gate, (fig. 59,) which yields to the outflow, 

 but is closed by an inflow from the riyer. Or the sur- 

 plus water from the upper level may be discharged into 

 the distributing canal of the next lower level. The water 

 is passed from the supply canals to those of distribution, 

 either by a gate raised by a winch and pinion and rack, 

 fig. 60, or a spout through the bank of the canal, which 

 is closed by a slide, seen in fig. 61, and at a, a, in'fig. 58. 



Fig. 60. WATER GATE. 



The water from the canal is first turned upon the upper 

 when this is covered to a proper depth the gate is 



level 



closed, and the water turned through the next gate upon 



