Sewage Irrigation and Healthfulness 413 



main object, together with the disposal of the sewage, lands 

 may be irrigated at once after the removal of a crop, such as 

 wheat or any of the small grains, so that there may be ample 

 latitude for distributing the water at almost any season of 

 the year. 



In climates where the winters are severe, it is necessary to 

 apply the sewage to land not in grass or other perennial crop, 

 as the freezing of thick coats of ice over the meadows is quite 

 certain to greatly injure if not kill the grass. Another point 

 which the agriculturist should keep in mind and guard against, 

 is the application of sewage to crops in too concentrated a form, 

 and especially should it be so much diluted or strained that the 

 sludge will not collect upon the surface in sufficient quantity 

 to close up the pores of the soil and interfere with proper 

 aeration. 



INFLUENCE OF SEWAGE IRRIGATION UPON 

 THE HEALTH 



Reference has been made to experiments and observations 

 which show that the feeding of grass from sewage farms to 

 milch cows produces no injurious effects upon the milk itself. 

 The late Colonel Waring states that the health of the people 

 living upon the sewage lands at Gennevilliers is generally excel- 

 lent, and that "even in 1882, when there was a cruel epidemic 

 of typhoid fever in Paris, there was none here." He further 

 says : " If there is still room for doubt on any point, it is as 

 to the character of the few bacteria which escape the action of 

 the process employed, and are found in the effluent. It is not 

 known that disease germs exist among these, and it is altogether 

 probable that they do not. So far as these organisms are 

 understood, it is thought that they cannot withstand the 

 destructive activity of the oxidizing and nitrifying organisms 

 which are always present, and it is believed that only these 

 hardier organisms exist in the effluent of land -purification works. 

 Certain it is that no instance has been reported where con- 

 tagion was carried by such effluents, and experience at Genne- 



