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THE POPULAR SCIENCE MONTHLY 



tubes, running from the inside of every trap-seal to the larger air- 

 pipes extending through the roof of the building. With this 

 double ventilation, the deleterious effect of air-currents on trap- 

 seals is, of course, greatly increased. 



Some idea of the complication and enormous expense of this 

 system may be formed from an illustration of its application to a 

 group of four plumbing fixtures in adjoining rooms on one floor 

 of an elegant residence recently built in New York city (Fig. 1). 

 It will be seen that the air-pipes require an almost complete 

 duplication of the waste and soil pipes. This, of course, adds 

 greatly to the cost of the plumbing, and increases the danger from 

 imperfections in the largely augmented number and length of 

 pipes with their multifarious joints. 



Fig. 2 shows the same number of fixtures in the same relative 

 position, but the plumbing is arranged in accordance with the re- 

 quirements of modern methods as developed by the application 

 of scientific principles. 



Not long after the adoption of the fallacious device of back- 

 venting, it became evident that more efficient means of guarding 

 against the dangers of sewer-air were necessary, ai^d persistent 



Fig. 5.— Second STi;p in the Development or an Anti sipnoNic Thap. 



efi'ort was directed toward devising better methods of house- 

 drainage. The result has been the attainment of a new order of 

 things by the recognition of scientific principles previously ig- 

 nored. 



For the development of this science, credit must be given 

 mainly to an accomplished sanitarist of Massachusetts, Mr. J. 

 Pickering Putnam, whose experiments and investigations on sub- 

 jects relating to household sanitation are unquestionably the 

 most thorough and complete that have ever been put on record. 

 The first of this series of experiments was made for the Board of 

 Health of Boston, in 1883. Subsequently, special demonstrations 



