280 THE MOSQUITOES OF NEW JERSEY 



grassy ends out, enclosing a space twenty inches wide. Mud was then 

 tamped into the trench until its surface was flush with the upper surface 

 of the sod layer. Then another layer of sod composed of pieces ten 

 inches wide by twelve inches thick by twenty-four inches long was placed 

 on top of each of the other two rows. Again the grassy ends were out 

 but the ends of the upper layer were six inches nearer the dike center 

 than were the ends of the lower layer. The central cavity thus formed 

 was tamped full of mud. Then a third layer of sod was placed on the 

 second in a similar fashion with a similar approach to the center. The 

 space formed between the two parts of the layers was tamped full of 

 mud. In some cases the dike thus constructed was covered with a layer 

 of sod while in other cases the crest was simply rounded up with mud. 



The sod and the mud for making the dike came from the preliminary 

 trench and from a supply trench which was dug inside the protected 

 area about eight feet from the base of the dike. In some cases a supply 

 trench was dug on each side of the dike. In every case the supply trench 

 was of uniform width, did not exceed three feet in depth, and was prop- 

 erly connected with adequate outlets. 



During the summer the grass in the sods grew vigorously and trans- 

 formed the dike into a wall of green. The sods used in capping the 

 dike dried out and separated until they looked like the battlements 

 of a wall, and the layer became useless as a means of keeping water out. 

 The mud cap settled down and formed a continuous 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 paralleling the 

 work and giving useful drainage), and piled up until a dike of requisite 

 height with due allowance for shrinkage had been built. This was two 

 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. 



In more recent years many thousands of feet of dike have been con- 

 structed without any preliminary binding ditch, and it would seem in 

 general to be as successful in fencing the sea water out as the dike of 

 earlier construction. In certain sections of the Hackensack Valley the 

 idea has arisen that the dike should be constructed without a binding 

 ditch, but composed of sod containing the roots of the common foxtail 

 (Phragmites phragmites). The experience has been that dikes thus 



