78 N. J. Agricultural Experiment Station, Bulletin 348 



and firmly spiked together. The gate shall be hung in front of the opening 

 with a suitable link hinge so that it will readily open with the falling tide and 

 readily close with the rising tide. 



Lighter sluice-gates have been employed but no larger or heavier 

 ones. If the capacity of more than one was needed duplicates have 

 been installed. This plan has been followed because gates larger 

 than this have elsewhere proven difficult to keep in working order. 



Recently, Mr. Brooks has devised another type of sluice-way and 

 tide-gate, which the writer has since found to have been antedated. 

 In this case no box is constructed. Heavily timbered bulkheads are 

 built on both sides of the stream approximately 6 feet apart. To 

 render their relation to each other constant they are bound together 

 by heavy cross timbers. (A floor is laid from one end of the open- 

 ing to the other.) At a point half-way between the two ends, 

 a pair of heavy 6 by 6-inch well braced timbers are set down in 

 such a fashion as to form the support and resting place for the 

 tide-gate. Of course, the joints between each of the upright posts 

 and bulkhead against which it stands and between the lower cross- 

 timbers and the bottom are made tight. 



The tide-gate is suspended from a cross-timber located well above 

 extreme high tide, and hangs against the upright posts. At each end 

 the bulkheads are fitted with slots in which planking can be dropped 

 to form a cofifer dam. The water between the two bulkheads has 

 merely to be pumped out, when these dams are in place, to expose 

 the gate for repairs and the sluiceway for cleaning. The top of the 

 sluiceway thus formed is left open. Mr. Brooks holds that the 

 greater ease with which this type of gate can be kept in good work- 

 ing order is sufficient to warrant its adoption. 



Experience in 1918 has clearly demonstrated that for all types of 

 tide-gates the piling must be driven well into the solid substratum or 

 the structure is likely to go out. Any movement whatever of the 

 sheet piling seems likely seriously to damage the latter type of gate 

 described. 



The problem of preparing a proper dike, sluice-boxes, and tide- 

 gates for draining a given area is an engineering one. Suffice it to 

 say that the trenching, diking, sluicing and tide-gating must be so 

 planned as to keep out all but the most extraordinary high tides and 

 to free the surface from water within 5 days after a heavy rainfall. 



The last step in the initial treatment of this type of marsh to pre- 

 vent maturing of mosquitoes is the arrangement of the drainage 

 system and the manipulation of the tide-gates in such a fashion that 



