The Mosquitoes of New Jersey 



75 



During the summer of 191 5 the grass in the sods grew vigorously 

 and transformed the dike into a wall of green. The sods used in 

 capping the dike dried out and separated until they looked like the 

 battlements on a wall, and the layer became useless as a means of 

 keeping water out. The mud cap settled down and formed a con- 

 tinuous solid cap serving much better the purpose for which it was 

 intended than did the sod layer. 



Some dikes have been constructed entirely with mud but always 

 in places where sod was not available. In such instances the mud 

 has been scooped from a trench back of the dike (forming a ditch 



Fig. 42. Tide-gate completed. (Courtesy of the Union County Mosquito 

 Extermination Commission). 



paralleling the work and giving useful drainage), and piled up un- 

 til a dike of requisite height with due allowance for shrinkage had 

 been built, which was 2 feet wide at the top and as broad at the 

 base as was demanded by the normal angle of repose. This type of 

 dike does not withstand the weather or the water as well as the sod 

 type but is efficient if carefully looked after. 



At points where streams or larger ditches cross the dikes sluice- 

 boxes and tide-gates were introduced. The largest sluice-box used 

 measured inside 3 feet high, 6 feet wide and 24 feet long. It was 

 made of 2-inch lumber nailed to outside ribs at a distance of 18 

 inches apart. The box was set on 2 rows of 2-inch sheet piling 

 and then covered with soil. A large heavy wooden door was sus- 

 pended over the down-stream end of the box to serve as a tide- 

 gate. The following specifications have been used in the construe- 



