torn of the collector, and the valves are here shown as 

 they appear when arranged for drawing the water from 

 the x3oad. at ebb tide. The inner valve has been slightly 

 raised, as will be observed, by sliding upward its sup- 

 port g through the gi'ooved trunnion a: and the pressure 

 of the water flowing through the flume, in the direction 

 indicated by the arrow, serves to siting open the outer 

 valve, and to keep it open until the x^ond is emptied or 

 the tide turns. In the latter event the outer valve closes 

 automatically until the level of the water without again 

 falls below that of the water remaining in the pond 

 when its operation is resumed. 



Should it be desired, on the other hand, to admit 

 water from the river into the pond — at the proper levels 

 — the relative positions and operations of the valves 

 would of course be reversed. The outer valve should 

 then be raised so as to allow the water to enter the 

 flume from the river : and the inner valve should be low- 

 ered, in turn, to permit it to swing with the current, and 

 to close automatically witli the cessation of its flow. 



The accompanying figures represent portions of the 

 above considerably enlarged for the purposes of a more 

 detailed description of the several parts. 



The flap valve d — which is here represented as being 



