INLAND DRAINAGE 



137 



with stone in such manner as to prevent further extension of 

 them. 



Sometimes streams will be found clogged up with log jams, 

 started by individual logs catching against stumps and trees on 

 the bank. Such jams will range in size from 20 to 30 logs up to 

 more than a thousand. According to Williams 1 the best way to 

 deal with them is to explode three or four bundles of dynamite 

 (20 pounds each) among the logs at the lower end of the jam; 



PcnVS of 



planted dynamite^ ' 



) j^O/d channel 



Bewre After 



Fig. 98. — Creek before and after straightening by blasting. 



the explosion will loosen the logs and the majority of them will 

 start downstream; a sufficient force of laborers should be posted 

 along the banks to prevent any new jam formations. 



Where the logs are not so numerous but are scattered out 

 along the banks, they may be cut loose by laborers and then 

 hauled up out of the water by means of teams. 



Any other obstructions, together with weeds, grass, algae and 

 similar growths, should be removed from streams periodically. 



1 Transactions of the First Annual Conference of Sanitary Engineers, 

 U. S. Public Health Service, 1910. 



