294 THE POPULAR SCIENCE MONTHLY. 



ous when applied to actual use, but the profits on their sales are 

 large, and the introduction of better and more simple forms of 

 apparatus would seriously disarrange the existing order of things. 

 The abolition of the trap-vent laws, for example, would cut out a 

 thousand pounds or more of useless iron and lead pipes from the 

 plumbing of every good-sized house. Manufacturers and dealers 

 v^ould suffer heavy losses, and so the vast interests involved are 

 carefully guarded by all the resources which money can com- 

 mand in municipal legislation. This influence has extended even 

 to the press; and we see tradesmen's journals persistently ignoring 

 scientific progress and upholding still the old methods which are 

 to enrich unscrupulous manufacturers and their clientage of un- 

 educated mechanics. It is for the interest of invested capital that 

 plumbers be kept as ignorant and as unprogressive as possible. 



In this conflict of ignorance and prejudice with science, it is 

 not difficult to trace still further the cause for so much popular 

 distrust. If the most common defects in the apparatus for or- 

 dinary house-drainage could be clearly understood, it would be 

 readily seen that the want of confidence in plumbing appliances 

 arises mainly from a general misapprehension regarding their 

 real imperfections. We know, for example, that sewer-air, or 

 sewer-gas, as it is improperly called, finds its way continually into 

 many houses, and frequently causes disease and death. How does 

 this sewer-air gain an entrance ? If you consult your plumber, 

 he will deny that there is any possibility of such a defect existing 

 in the drain-pipes and fixtures he has put in. But your physician 

 will tell you that the symptoms of illness of some member of the 

 household show unmistakable evidence that the patient has been 

 poisoned by sewer-air. A thorough examination of the drain- 

 pipes shows that they are securely jointed, and that there are no 

 leaks in them. Nevertheless it is certain that sewer-air gains an 

 entrance to the house in considerable quantities, and after a time 

 it is discovered that the poisonous air finds its way in through 

 the traps attached to the basins and sinks and water-closets. A 

 word of explanation may be necessary in regard to these traps. 

 Although of a great variety of forms, they are all essentially a 

 device for allowing waste-water to flow through them from the 

 fixtures to which they are attached into the drains, and to prevent 

 air or gases from passing in the opposite direction into the house. 

 The resisting medium in most cases is a water-seal, consisting of 

 a small body of standing water in the body of the trap. When it 

 is found that sewer-air passes freely through these very traps that 

 have been designed to keep it out, the inference is almost irre- 

 sistible that the water-seals are at fault, and that water is not a 

 suitable medium to be used for this purpose, since air from the 

 drains apparently forces an entrance through it. 



