1 IS 



MOSQ UI TO ERA DIG A TION 



S 



the earth bottom, if the bottom is hard and smooth, or on 

 piling driven under the ends and middle of the box. Care should 

 be taken in installing a box to prevent any possibility of a leak 

 developing around or under it. 



Sluice-boxes are generally built on the dry ground and lowered 

 into place; to avoid difficulty in this connection, it is usually 

 well not to make them too large. Should the stream or ditch 

 carry off too much water for one box, two or more boxes should 

 be installed side by side. 



nWii. ,. ">., ti% 



Sketch of sluice-box and tide-gate. 



Sluice-boxes may range in size from a section of 1 or 2 square 

 feet and a length of 6 or 8 feet up to a section of 15 to 18 square 

 feet and a length of 20 to 30 feet. They are generally made of 

 2-inch planks nailed to outside ribs at distances of 1}^ to 2 feet 

 apart. In order to insure tight closing of the gate or shutter, 

 the outer end of the box is often given a slight slope, usually 

 about 1 inch per foot. 



According to Gies, 1 it is customary in New Jersey to put a 

 coarse rack or screen at either end of the box, made of 2 by 

 4-inch lumber, the pieces being spaced parallel to .each other about 



1 Transactions of the First Annual Conference of Sanitary Engineers, 

 U. S. Public Health Service, 1919. 



