EXPERIMENTAL METHODS IN WATER- AND SEWAGE- WORKS 31 



fications than those of a scientific nature. They must be able to 

 maintain amicable relations with executive superiors, to manage 

 laborers, to keep records in a manner fairly comparable with the 

 high degree to which the art of bookkeeping in large business houses 

 has advanced, to prepare reports containing essential features in 

 explicit but terse terms, and to make plain to non-technical men 

 in both public and private capacity the more essential features of 

 their own position and of the data by which their efforts show what 

 is being accomplished. This type of specialists will naturally develop 

 in efficiency as their responsibilities increase; but there is still much 

 work for the technical schools to do in preparing young men more 

 adequately for these duties. 



Tentative installations. As distinguished from the testing stations 

 built solely for the purpose of tests, there is, of course, one other 

 method of a somewhat experimental nature by which local data 

 are used in determining whether large works are most advanta- 

 geously constructed. I refer to the plan of constructing works 

 gradually, or tentatively, and of using data from the operation 

 of the first portion of the installation to serve as a guide in 

 arranging the details of the portions subsequently to be built, and 

 also in deciding upon the magnitude of the works sufficient for a 

 given capacity or to serve for a given term of years. This is the 

 style of works, from the experimental point of view, which frequently 

 obtains in Europe, and which will obtain in some places in this 

 country. As yet there has not been a wide application in America 

 of such data obtained on a large practical scale, although, of course, 

 they are availed of more or less in all works where extensions are 

 required. This condition has been reached at several sewage- 

 works in New England, and the results of experiences in the field 

 have been summarized by the Massachusetts State Board of Health. 

 It is gratifying to state that practical results are in general con- 

 formity with the principles of water and sewage purification as 

 developed by tests on a small scale. 



EXPERIMENTAL METHODS IN EUROPE. 



In Europe the water-purification problems do not cover nearly so 

 wide or difficult a range of natural conditions as those met in America. 

 Filtration has in recent years not received as much attention experi- 



