SALT MARSH DRAINAGE 



149 



4 inches apart, to keep out heavy floatage and debris, which 

 might interfere with operation of the gate. 



GATE CONSTRUCTION 



The gate, like the sluice-box, is usually built of 2-inch plank, 

 tongue-and-groove material being best. Sometimes, two thick- 

 nesses of plank are used. To prevent floating of the gate on the 



(a) O/wiNfiRy Strap 



HINGE 



il 



a 



Tbp of D/*e 



Sluicc Box 



( lr) TlKBER HlNCE 



65\ 



(c) Bolt Eye 



HlNCE 



(d) Screw Hook-3oi.t 



£YE HlNCE 



(e.)ScK£\n Ere -Bolt- 

 Strap H /*/&£■■ 



Fig. 105. — Types of hinges for tide-gates. {After Fuchs, U. S. Public Health 



Service.) 



rising tide, it is often weighted with a piece of old iron nailed or 

 bolted on the gate near the bottom. 



Many kinds of hinges for the gate have been tried out. Fuchs 1 

 discusses several different kinds of hinges as follows: 



(1) "The common strap hinge does not permit enough freedom of 

 movement of the shutter so it can automatically adjust itself against 

 the end of the box. Also, it does not permit the easy removal of the 

 shutter for repairs. (2) The rice-field timber hinge, in which the 

 shutter is attached to two vertical planks, which swing from a bracket 

 supported by posts. This type works well and is easily removed, but, 

 being above water, permits of tampering and rots quickly. (3) Two 



