SAFETY IN HOUSE-DRAINAGE. 309 



soil surrounding the foundations is drawn freely into our dwell- 

 ings, and any pollution of this soil-atmosphere must occasion se- 

 rious danger. 



In a like manner, rain-water conductors are to be cut off from 

 a direct connection with the house drain or sewer. The upper 

 end of conductor-pipes opening near windows may readily convey 

 sewer-air into the house, unless special precautions are taken to 

 guard against it. 



It is usual to place a large trap in the main house-drain a short 

 distance outside of the cellar-wall. The object of this is to keep 

 the air of the street-sewer from entering the drain-pipes within 

 the house. But a trap in the main drain obstructs the outward 

 flow of sewage to such an extent as to cause accumulations of 

 filth to collect, which may produce a condition of affairs in the 

 house-drain considerably worse than that existing in the sewer. 

 In ordinary cases it will be safer to omit the trap, and allow the 

 air of the sewer to flow through the main soil-pipe and out at the 

 top above the roof. But there are important exceptions to this 

 general rule. A trap should always be used between a cess-pool 

 and the house draining into it. And when sewers have a slight 

 inclination, with a sluggish flow through them, so that they are 

 unusually foul, it will be better to have traps put into the connect- 

 ing house-drains. Whenever these traps are used, there must be 

 an inlet provided for the admission of a copious supply of fresh 

 air to the drain-pipes between the trap and the house, and as near 

 to the former as possible. This will cause an almost constant up- 

 ward flow of air through the main channel of the house drainage 

 system, giving free ventilation to places where impurities may 

 collect. 



Space will not allow a more extended consideration of matters 

 of detail. The design and execution of our systems of house- 

 drainage should always be intrusted to some competent sanitary 

 authority, in place of being left to the hap-hazard direction of 

 careless architects and ignorant plumbers. The importance of 

 obtaining absolute security where so much inherent danger exists 

 can not be overestimated. With all the advantages derived from 

 a constant and sure development of the science of sanitation, our 

 houses may be made safe against the entrance of sewer-air. The 

 perils arising from ignorance and neglect are easily eliminated. 

 And, above all, a determined effort should be made to arouse 

 public opinion, so that it shall demand the repeal of objectionable 

 municipal ordinances framed in the interest of corrupt politicians 

 and mercenary tradesmen. 



