INJURIOUS INFLUENCES 87 



undoubtedly fare worst, for not only are they 

 subjected above ground to dust and fumes, but 

 beneath the surface the roots come in contact 

 with gas and water mains, drains, sewers, 

 electric and telegraph ways. Of all these, un- 

 doubtedly the gas main is most to be dreaded, 



Section of a town street. 



1. Water main. 



2. Telegraph. 



3. Electric. 



4. Surface water. 



5. Gas. 



6. Sewers. 



for with the smallest escape of gas, too small 

 to be detected by the company, the largest 

 and healthiest trees quickly succumb to its 

 poisonous effects. Even the escape of a few 

 feet per day is sufficient to poison the soil, 

 especially where such is clayey or where the 

 roadway is paved, for then the pent-up gas, 

 with no chance of escape, quickly permeates 



