Proceedings of Sixth Annual Meeting 



9 



Wilmington, N. C, had an unusual problem. Close to and even 

 within the town limits were extensive abandoned rice fields sub- 

 ject to overflow and generally wet. It was necessary to repair or 

 reconstruct dikes and use tidal gates to prevent mosquito breed- 

 ing; also a large shallow lake with about six miles of shoreline is 

 within flight range of both shipyards. 



Chattanooga, Tenn., eliminated some former anopheles breeding 

 areas by draining ponds to holes dug in limestone formation where 

 the water was absorbed ; also the mosquito breeding in the large 

 spring and lake near Camp Oglethorpe was controlled by using a 

 subaqueous saw to remove the aquatic vegetation that furnished 

 protection for Anopheles larvae. 



At Nashville, Tenn,, the stream beds are largely composed of 

 limestone. Where such formation can be economically channeled 

 the cross section of the drainage courses can be largely reduced 

 and oil spraying made less expensive. Where the limestone is hard 

 it is less costly to clear the stream beds of obstructions and rely 

 on oiling for control. 



Near Macon, Ga., were six lakes and a large heavily wooded 

 swampy area with a soft silt bottom. Its feeder stream was diverted 

 to the Ocamulgee River by means of a steam-shovel-dug ditch. 

 Ditches were extended into the main swamp which was several miles 

 long and had but little grade. After deepening these ditches to a 

 certain point the pressure of the banks would cause the bottom of 

 the ditch to raise. Saplings were used and laid parallel to the 

 banks as a ditch lining or wall to support the banks, stakes were 

 driven to hold saplings in place and then were fastened back to 

 living stumps or trees close to the ditch. Later, as the ditch banks 

 dried, it was deepened. The banks became solid and the bottom 

 held to grade. As the silt and mud in this swamp area were too 

 soft to dig to advantage a large part of the ditching was done by 

 dynamite. Several weeks after the swamp was drained its bottom 

 became very hard. In installing some of the ditches the semi-liquid 

 mud was so soft it could be bailed out. 



The problem near the aviation field at Millington, Tenn., was 

 the removal of drift in several miles of a deep creek bed with low 

 grade. Many of the collections of drift and log jams were six 

 to twelve feet high, 50,100, or more, feet long, and contained fallen 



