How to secure them. 121 



house side of the disconnecting air chamber, but no sewer gas 

 can return. This is absolutely essential, but will not be a 

 protection from carelessness or the want of supervision. 



Referring to the various complicated devices adopted with 

 the view of ventilating the soil pipe, Mr. Gray expressed the 

 opinion that far too much is made of it. It is a survival 

 of the old closed-up system, when the sewer gas had direct 

 access to the soil pipe ; but now no such gas can get to the soil 

 pipe by a disconnecting trapped air chamber. The only pollu- 

 tion now possible in the soil pipe is the local removable 

 pollution of the soil pipe itself. Mr. Gray said that the legiti- 

 mate outcome of our present system of trapping and rendering 

 accessible all apparatus, points to the possibility and the 

 desirability of making our soil pipes removable, and accessible 

 for cleansing directly, thereby avoiding the costly and unsightly 

 vents, so strongly recommended under our point, B. 



In dealing with this matter of sewer gas, Mr. Gray said it is 

 strange that we should go to so much trouble to trap off every 

 possible whiff, an d adopt costly and awkward-looking contrivances 

 to ventilate the limited soil surface of our soil pipes, in which 

 there is no sewer gas, while yet we freely admit the sewer gas 

 itself into our public streets. We trap our side gullies, and for 

 this purpose adopt costly apparatus at each side of our thorough- 

 fares, and yet we carefully place in the centre of our tramway 

 lines, open ventilators that belch forth the blasting and deadly 

 sewer gas without let or hindrance. Something must be 

 seriously wrong with such an arrangement ! Surely, if it is so 

 necessary for us to trap off our house drains, it is equally desir- 

 able to adopt some system by which our main sewers may be 

 ventilated, so as not to poison and pollute the atmosphere of 

 our public thoroughfares ! 



Before we can say that our drainage is passed safely beyond 

 our premises, we must see that the drains carry with- 

 out leaking, and that the ground itself is not saturated by 

 drainage from our own drain or any other source. Mr. Gray 

 described the necessity of having a solid bed for the reception 



