148 Till-: AMEKICAS MlSl-JM .lOmSM. 



iinitci'ial while llic spiiccs hctwccii -dvr cdiit iiiiuilly filled with ;iir. The 

 I riekliiii;' hed, which may he (lefiiie(| simply as a heap of stones or other 

 material of swell size, depth and t(>\ture ;is to siipjjort a liacterial jirowth 

 sulKcient for the work in hand, is eoiisidereij on<' of the mo>t promisiiitr and 

 effective of any known dex^iee for sewage pnrilieation and particularly well 

 adajjted for irse in larji'e cities, for it exhihits the simplicity which dis- 

 tinguislies the best scientific applica tion a pile of stones on which huc- 

 terial growth tnay gather and a regnlatecj snpply of air and sewage being 

 the only desiderata. In this way the dangerons organic waste material 

 produced in the city of liiunan habitations is carrie(l out to the city of 

 microbes on their hills of rocks and it is their duty to tnrn it into a 

 harmless mineral form. 



The removal of disease bacteria is not iiecessariK accomplished by these 

 newer processes of sewage disposal which are primarily designed to remove 

 putrescible organic matter. This end, which is an important one in a sea- 

 hoard city because of its adjacent shellfish industries, can l)e met l)y special 

 chemical treatment. The application of ordinary bleaching jjowder or 

 chloride of lime in small amounts of fifteen to thirty parts of powder to a 

 million parts of sewage will effect a satisfactory reduction of bacteria at a 

 \ery reasonable cost. 



There are yet many unsolved problems in the piu'ification and disposal 

 of a city's sewage, yet the work of the last ten years in the I'nited States 

 and England foreshadows ultimate success. To-day the engineer is limited 

 in the perfection of his work only by the amount of money the connmmity 

 is prepared to expend; and the City of New ^'ork can go as far along this 

 line as its citizens choose to afford. It should mnpiestionablx- go farther 

 than it has s'one to-dav. 



