160 president's address — SECTION H. 



a pumping station, a sewag-e farm, or situated in the estuary 

 of a river, or the ocean. The district is divided up into 

 sections, in wliicli ])ipe sewers are laid at the most suitable 

 gradient to ensure sufficient velocity to render them always 

 self-cleansing. This is readily done by sinking, in a central 

 or some other convenient position within the various sections, 

 pneumatic ejector stations. To these, as to a steam pumping 

 station, the sewage would flow quickly through the gravita- 

 tion sewers, which, behig of comparatively short length, the 

 sewage from the house furthest away from the ejector 

 station could not fail to reach it in a fresh and undecomposed 

 condition. These sewers are flushed daily by automatic 

 flush tanks. The ejectors raise the sewage delivered to them 

 up to the level of the main outfall sewer, which may 

 discharge by gravitation, or with the assistance of the air 

 pressure. The ejectors are sap])lied with compressed air 

 from central pumping stations, arranged in the most con- 

 venient manner to suit the district under consideration, and 

 they receive and eject the sewage as fast as it is dehvered to 

 them, working automatically. 



It frequently happens that certain low-lying districts 

 cannot be conveniently included in the general scheme of 

 main drainage for a city or town, in which case Shone's 

 System enables the engineer to deal with the low-lying 

 districts, and raise the sewage up to the level of the main 

 gravitation sewers ; but when applied in this way it is com- 

 parable with the following metliods of raising sewage : — 

 a. By means of Cornish, Worthington, or other 



Pumping Engines. 

 h. Mr. Baldwin Latham's Hydraulic Pumping System. 

 c. Mr, Waring's System of Syphonage, such as used 

 successfully at Schiedam, Holland. 



The drainage of the subsoil is most important, and sub- 

 soil drains may be conveniently laid in the same trench as the 

 sewer proper, but they should be made to discharge into the 

 natural creeks and water-courses in preference to the sewers. 



The success of the water-carriage system will not be 

 complete unless both the main sewers and house drains are 

 efficiently ventilated ; foi- while it is necessary to remove 

 decomposable matter as rapidly as possible it is also imjiortant 

 to provide means for modifying decomposition and diluting 

 and removing the gaseous products. This is attained, where 

 the house drains discharge into pipe sewers, by making the 

 soil pipe itself a ventilator, reaching above the roof and 



