THE NEW AGRICULTURE. 141 



efactor of the human race, who has not only succeeded in making 

 two blades of grass grow where one was wont to appear ; but who 

 has also taught them by simple method, and at cheapest cost, the 

 way to secure for themselves a sufficiency of one of the most im- 

 portant of God's gifts to man, and beast, and nature. 



This letter requires no answer it is written to testify my appre- 

 ciation of the merits of the invention of an old friend, and he is 

 at liberty to use it as he may deem proper. 



With sentiments of respect I am, as ever, yours truly, 



JOHN SWINBURNE. 



The case of water poisoning, at Plymouth, Pennsylvania, should 

 operate as a warning that all over our land water works have been 

 and are being constructed, in the sources and supplies of which 

 are found the germs of disease and death. "Whatever the source 

 of water supply filtration is imperatively necessary, except where 

 springs or spring brooks discharge their waters so directly into 

 reservoirs as to prevent infection, pollution, or even the existence 

 of roil. Can waters admixing with those of the surface be render- 

 ed pure and healthful, is the paramount question. This brings us 

 to the introduction of an article by Professor De Smedt, District 

 Chemist, of "Washington, D. C., as published under date of June 

 26th, the subject being the water of the Potomac river. 



" Is perfect filtration and aeration possible in a volume of water 

 sufficient- to supply large cities ? This is a question for the consid- 

 eration of engineering science; the chemist can determine only the 

 results of the scheme should it prove to be practical. 



" "Water, in the order of its purity, may be divided into three 

 classes: First, rain water, which is the most impure; second, river 

 water; and third, spring and deep well water, which are the purest 

 The purity of the spring water is owing to the fact that it has been 

 filtered and aerated through sandy soil, which is indisputably the 



