SALT MARSH DRAINAGE 151 



by running a 3 by 8-inch stringer along the outside and inside surfaces. 

 Each pile shall be bound to this stringer by a }i-mch bolt, which shall be 

 furnished with large washers and a suitable nut. The opening for the 

 sluice-boxes shall be made closely to fit the boxes. The cut ends of the 

 piling above the box shall be bound together by 3 by 8-inch stringers, 

 which shall extend, one on the inside and one on the outside, from a point 

 2 feet beyond one edge of the opening to a point 2 feet beyond the oppo- 

 site edge of the opening. These stringers shall be set flush with the 

 cut ends of the piling, and each pile which they cover shall be bound to 

 them by a J^-inch bolt, properly washered and fitted with a nut. The 

 cut ends of the piling below the box shall be bound together in the 

 fashion above described. 



INSTALLATION 



3. "All sluice-boxes shall be laid on two extra rows of sheet-piling 

 composed of 3-inch long-leaf pine closely set together. The planking 

 shall be 10 feet long and driven in until the top shall be 9 inches below 

 mean tide. The above provision regarding injury due to driving and its 

 correction shall be observed here. Each row of this sheet piling shall 

 extend 4 feet each side of the sluice-boxes. Each row shall be bound 

 together at the top in a fashion similar to that provided for the dike 

 facing, and the piling at the sides of the boxes shall extend up through 

 the stringers 1 foot, and the rectangle thus formed shall be made closely 

 to fit the boxes. 



4. "At the sluice-boxes, the inner side of the dike shall be protected 

 by sheet-piling wing-walls made of 2-inch long-leaf pine without serious 

 blemish, 14 feet in length, driven in until the top is 1 foot below the level 

 of the dike. The above provision regarding injury due to driving and 

 its correction shall be observed here. They shall be bound together at 

 the top in the same fashion as the dike facing, and shall extend 6 feet on 

 each side of the sluice-boxes. 



5. "The river side of each sluice-box shall be furnished with a 7 by 

 4-foot gate made of tongued and grooved white pine. It shall be com- 

 posed of two layers, the inside one being made of 3-inch, 7-foot planking 

 and the outside one of 2-inch, 4-foot-long planking, laid at right angles 

 to one another and firmly spiked together. The gate shall be hung in 

 front of the opening with a suitable hinge, so that it will readily open 

 with the falling tide and readily close with the rising tide." 



OTHER TYPES OF TIDE-GATES 



Headlee 1 describes another type of tide-gate, said to be advan- 

 tageous on account of the greater ease with which it can be kept 

 in order, as follows: 



1 "Some Recent Advances in Knowledge of the Natural History and the 

 Control of Mosquitoes," New Jersey Agricultural Experiment Stations, 

 Bulletin 306, 1916. 



