The Mosquitoes of New Jersey 



6i 



More than i8 years ago. the late Dr. John B. Smith began to ex- 

 periment for the purpose of determining the type of ditching that 

 would accomplish this sort of drainage and could be put into the 

 marsh and maintained with a reasonable expenditure. After many 



BERGEN COUNTY 

 MAP NO. I 



LEGEND 



STATE DITCHING 



COUNTY DITCHING 



■SLUlCt CATW 



Fig. 31. Map of a ditching system. 



trials, he settled upon a ditch 10 inches wide and 30 inches deep, 

 with perpendicular, smooth sides, as the one most nearly fulfilling 

 the requirements. This depth normally reaches the bottom of the 

 sod and is maintained, except where a natural slope requires a 



