PRINCIPLES OF MOSQUITO CONTROL 277 



the greater is its efficiency and its ability to keep clean. Every ditch 

 should have a strong tidal outlet and no ditch depending on a single 

 outlet should be over one-fourth of a mile long. 



MACHINERY 



While the hand tools have made little if any advance, the Manahan, 

 Skinner, and Eaton spades being still prevalent, power machinery used 

 in cutting ditches has undergone some important changes. 



The power machine invented by Mr. Eaton has been replaced by a 

 power ditcher designed by Fred A. Reiley. Both the Eaton and the 

 Reiley ditcher consist of separate power and plow units. The Eaton 

 plan required first the movement of the power plant from point to point 

 and then the dragging of the plow across the marsh to the new location 

 of the power plant. The Reiley plan includes the attachment of the 

 plow to a mobile power plant which pulls the plow cutting the ditch 

 as it goes. The original Eaton ditching plow has been greatly modified 

 and improved by Mr. Reiley. In both cases the sod was cut from the 

 meadow and deposited on one or both sides of the ditch, ready to dry 

 up and float about with the high tides. 



Realizing the very serious disadvantage of these sods the New Jersey 

 State Agricultural Experiment Station has developed a salt marsh 

 ditch-cutting machine which cuts the trench for at least as low a figure 

 as the Eaton or Reiley machines for from one-half to one cent a linear 

 foot, and which grinds up the sod and disperses it on the marsh surfaces 

 in the form of mud in a layer so thin that the grass readily grows up 

 through it and no floating takes place. 



MAINTENANCE OF SALT MARSH DITCHING 



There is now about 38,000,000 linear feet of ditching, reckoned in 

 units ten inches wide, on the New Jersey salt marsh. Experience shows 

 that on an average these ditches have to have blockages removed an- 

 nually and to be recut once in three years. Blockage removal is inex- 

 pensive and quite within the means of the mosquito commissions but the 

 problem of proper recutting is greater. In a county having 12,000,000 

 hnear feet of salt marsh ditching, 4,000,000 linear feet would have to 

 be recut yearly. Recutting this amount with present machine equip- 

 ment means an expenditure of about $20,000. The largest annual ap- 

 propriation ever received by this county commission was $60,000. 



The New Jersey State Agricultural Experiment Station is develop- 

 ing a salt marsh ditch recutter designed to recut at one-tenth of a cent 

 a linear foot. This development is already well along and when com- 



