248 THE MONTHLY BULLETIN. 



to the injured, and (at least to the man who is not of a scientific turn 

 of mind) the problem sometimes seems bewildering. 



EFFECT UPON AGRICULTURE. 



The general effect of sulphur dioxide gas injury in regions of smelters 

 has already been briefly described, but is more far-reaching than one 

 niiglit imagine without careful consideration of all the phases of the 

 problem. In most cases smelters are located in mountainous regions 

 where the timber and grazing interests are often very great. Thus there 

 may be a direct bearing upon the lumber and the livestock industries, 

 to say nothing of the destruction of timber which is valuable for other 

 purposes besides that of being made into lumber. It is a well known 



Fig. 53.-^Bare hills with remains of vegetation killed by smelter fumes. 



(Original.) 



fact that the destruction of timber along with all underbrush and other 

 vegetation sometimes creates a dangerous condition relative to floods, 

 and one can conceive of a vast amount of destruction that might easily 

 take place by floods because of no timber to hold the water back in case 

 of heavy rains. 



As the grass seems to be very susceptible to damage from fumes there 

 is a tremendous injury to pasture lands, often rendering them absolutely 

 worthless for grazing purposes, and the livestock industry may be prac- 

 tically ruined over a territory many miles square. 



The destruction of vegetation has another effect which is sometimes 

 detrimental, and that is the washing or erosion of hills once protected 

 but wholly unprotected after the vegetatitm has been killed, and with 

 every heavy rain there is a washing of the soil from the high land to 

 the low. This might not always be a disadvantage, for it can be con- 

 ceived that there might be cases where a poor soil miglit be built up 

 from this wash, but the general eft'ect is undoubtedly bad. Fig. 55 shows 

 clearly how this erosion takes place. At one time this hill was covered 



