11 



PURIFYING INFLUENCE OF FORESTS ON WATER. 

 We could not find that any investigations on this subject have ever 

 been made. It seems reasonable to suppose that forests do exert some 

 influence in this direction, because water is purified by percolating 

 through the earth, so that a seepage run-off should yield a better supply 

 of water than a run-off from the surface. In a table taken from Mr. 

 Safford's report, which gives the results of analyses made by the State 

 Board of Health on samples of water from the pond and from its 

 various feeders, we find that the water in the pond is considerably the 

 purer. As only about 50 per cent, of the water supply of the pond 

 conies through the brooks or by direct precipitation, the remainder 

 must be fed to it by springs in the bottom of the pond. We conclude, 

 therefore, that the water from these springs (deep seepage flow) is 

 purer than that of the brooks, which carry a deal of surface run-off, 

 and the standard of purity of the whole pond is raised thereby. 



