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THE POPULAR SCIENCE MONTHLY. 



lated directly througli the soil-pipes to the tops of the houses ? 

 The reply to this is, that where there are properly constructed self- 

 cleansing sewers, having no cess-pool connections, and the house 

 connections of which are made under the control of the engineer 

 having charge of the sewers, it is well to omit the trap between 

 house and sewer, and let the latter ventilate directly through the 

 soil-pipes ; but exception should be made to this where the top of 

 a soil-pipe would be on a level with or below the windows of in- 

 habited rooms in a neighboring house. When the house-drains 

 are connected with a cess-pool, or with a sewer presenting the 

 characters of a cess-pool, it is safer to insert the trap ; in which 

 case there should always be a fresh-air opening between the 

 trap and the house. If the pipes and fixtures in a house are 

 properly arranged, and the joints are all tight, there is very 

 little risk to the inhabitants of the house itself in having a 

 direct connection with an ordinary sewer without a trap; the 

 danger really being to the inhabitants of neighboring houses. 

 On the other hand, if the trap between the sewer and the house 

 be properly inserted, it creates no risk of danger or nuisance in 

 the house to which it is applied, and costs little. The argument 

 that it checks discharges from the house and tends to produce 

 deposit in the horizontal part of the soil-pipes next to it on the 



CLEANING HAND'HDLHu, 



TRAP 



Fig. 3. 



house side, is unsound if this part of the pipe has a proper fall and 

 the top of the trap is six inches below the pipe ; for I have exam- 

 ined pipes which had been twelve years in use under such cir- 

 cumstances, and found no deposit worth speaking of. A proper 

 form of trap between house and sewer, with fresh-air inlet, is 

 shown in Fig 3. The question is of more importance taken in 

 connection with the ventilation of sewers by street openings as 



