INLAND DRAINAGE 



135 



and be free from grass, sticks, stones or other obstructions that would 

 interfere with the current. These conditions are seldom found in 

 nature, but the nearer a stream approaches them the less will mosquito 

 breeding be found." 



(Photos by E. H. Magoon, C. E.) 

 Fig. 95. Fig. 96. 



Fig. 95. — This pretty pool in a stream-bed was a breeding-place for Anopheles. 

 Mosquito control was secured by connecting it with a nearby larger pool that 

 was stocked with minnows. 



Fig. 96. — Water in a ditch confined to a narrow channel in order to facilitate 

 mosquito control. The ditch is oiled by means of a drip-barrel at its 

 upper end. 



BLASTING NEW CHANNELS 



The writer has found that, if the stream is very crooked and 

 much regrading is necesssary, it frequently will pay to disregard 

 the old channel completely and make a new and straight one. 

 If the soil conditions are adapted to it — that is, if the soil is 

 wet and water-soaked — dynamiting probably will prove to be 

 the cheapest method. The writer once had occasion to re- 

 channel with dynamite about a mile of a large creek in Georgia, 

 which averaged 20 feet wide and from 1 to 6 feet deep. A hard 

 sand stratum which underlay the soft surface ooze at a depth 

 of about 6 feet provided an ideal base for reaction of the explosion. 



