EFFECTS OF VAGRANT ELECTRICITY. 



359 



the rails and return feeders, and incliidiii<>' subten-a 

 courses, sewers, and metallic earth veins. 



In the light of our 

 experience of the last 

 eight years, it is easy 

 to identify as electroly- 

 sis the effects shown in 

 the accompanying cuts 

 of buried metals that 

 have been actually sub- 

 jected to a flow of elec- 

 tricity. It is not to be 

 inferred that the de- 

 structive action here 

 depicted is universal 

 throughout our towns, 

 but, rather, that the 

 damage occurs in spots, 

 its rate of progress be- 

 ing dependent upon the 

 amount of current and 

 the duration of tho 

 flow. Dry, sandy soil> 

 tend to keep down the 

 flow of current by in- 

 terposing a high resist- 

 ance, so that in such 

 localities electrolytic ef- 

 fects are not as pro- 

 nounced as in wet. 

 loamy soils. In the 

 same way, the charac- 

 ter of the pipe surface 

 ^or coating, if there be 

 any — acts as a partial 

 barrier to check the pas- 

 sage of electricity. 



Until recently it 

 was generally supposed 

 that cast iron was not 

 attacked — at least not 

 rapidly enough to cause 

 alarm. In Brooklyn the 

 water mains, of very- . %; - .^i^ ^^^ 



nean water 





