EXPERIMENTAL METHODS IN WATER- AND SEWAGE-WORKS 23 



structing and operating the required works, and to the educational 

 institutions which give technical training to young men desirous 

 of entering this field of work. 



NEW CONDITIONS WHICH HAVE BEEN ENCOUNTERED. 



Twenty-five years ago the large cities of America were, of course, 

 provided with public water supplies, and many of them had pro- 

 gressed considerably in adopting sewerage systems, although these 

 latter now appear to have been more or less crude. Sewage-purifica- 

 tion plants and water-purification plants, with perhaps half a dozen 

 small and scattered exceptions, were practically unknown. A 

 large proportion of the water supplies, especially in the Central 

 West, were seriously objectionable in the excessive quantities of 

 mud which they carried, and so different in their nature from the 

 comparatively simple filtration projects of Europe that engineers 

 naturally hesitated for financial reasons to attempt their construction, 

 to say nothing of the question whether they would be able to give 

 satisfactory service. The bacterial and hygienic aspects of these 

 problems, which are now recognized to be of so much importance, 

 were almost unknown. In fact, the germ theory of disease had 

 not risen to general acceptance. 



The medical man interested in public health knew in a general 

 theoretical way what he wanted, but he was ordinarily unable to 

 state his requirements in a manner understood by the engineer 

 or by the taxpayer. Engineers were able to build any reasonable 

 works, but were unable to learn in terms of the constructor what 

 was required with sufficient definiteness to allow them to make even 

 preliminary sketches and estimates of cost. The chemist and 

 bacteriologist occupying an intermediate position produced with 

 ill-suited methods analytical data full of mystery for everybody. 



Misunderstanding continued until men interested in various 

 lines of applied sanitary science co-operated in a manner to make 

 themselves mutually understood. The successful movement to 

 this end, at least in the United States, had its inception chiefly in 

 Massachusetts some 20 years ago. It has resulted during the past 

 dozen years in some notably well-balanced designs for American 

 water- and sewage-works, which have demonstrated their sound 



