Wellington Philosophical Society. 511 



mere trickle along the invert of the sewer. This state of things resulted 

 in the accumulation of deposit, owing to the velocit}' being insufficient. 

 The outfall-main being under pressure, any leak is easily detected, and 

 quite as easilj' repaired, owing to its being laid but little below the 

 surface of the ground. The cost of applying the system to Wellington 

 had purposely not been dealt with in the paper, as sufficient data from 

 which to frame a reliable detail-estimate were not available. It might, 

 however, be stated that, from such information as could be gathered from 

 Mr. Clark's published report and other sources, and allowing for the re- 

 ticulation of the whole forty-two miles of streets with properly-constructed 

 sewers, laid on a concrete bed, provided with man-holes, lamp-holes, 

 automatic flush-tanks, also for the whole of the necessary machinery, 

 cast-iron mains, &c., the cost would not exceed £80,000, or 32s. per head 

 for the 50,000 persons provided for ; while the cost of Mr. Clark's scheme 

 amounted to £145,000, or 41s. 5d. per head for the 70,000 persons pro- 

 vided for. 



In reply to Mr. Hughes, Mr. Higginson agreed that to a certain 

 extent the " separate " system necessitated duplicate sewers, but con- 

 sidered that over a large area of the suburbs it was possible to carry off 

 the rainfall by the side-channels and short lengths of pipes into the 

 nearest natural watercourses. In many cases the watercourses had been 

 converted into sewers, but it was now proposed to re-convert them to 

 their original use. It should also be remembered that the existing drains 

 and sewers would be devoted to this purpose entirely, and that for th& 

 sewage a complete s^^stem of independent sewers is p^o^•ided for in the 

 estimate quoted. It would be impossible for sewer-gas to become gene- 

 rated between the dwellings and the ejectors, provided the sewers were 

 laid to self-cleansing gradients. The area served by each ejector would 

 contain no sewers more than 20 or 30 chains in length, so that, with a 

 velocity given to the sewage of but 2ft. per second, only from 11 to 16 

 minutes would elapse before it had passed from the dwelling into the 

 ejector, and become a thing of the past. It would therefore be seen that, 

 unless a defect and stoppage existed in the sewers, there would not be 

 time for gas to become generated. The system had been in constant use 

 in Southampton and Warrington since 18S4, where the officers in charge 

 expressed to the author, when visiting the works, their entire approval. 

 The town of Y. istbourne was also drained upon this system in 1834, and^ 

 in a report published for the German Embassy bj^ the Chairman of the 

 Drainage Committee, that gentleman stated that they " have every reason 

 to be satisfied with the works already executed on this system." A Select 

 Committee of the House of Commons adopted the system in 1SS6 for the 

 drainage of the Houses of Parliament, Westminster, where it had com- 

 pletely remedied the evils that previously existed. 



In reply to Mr. Richardson, the author of the paper hoped that 

 before long the system would be adopted on a small scale for the drainage 

 of Pitone, when it would be possible to see the ejectors in action. As 

 explained in the paper, the system could be adapted to suit the present 

 requirements of a town, increasing the number of ejector-stations and 

 main outfall-pipes so soon as the increased population warranted the 

 expenditure. 



In reply to the President, Mr. Higginson stated that he regretted he 

 had omitted to mention that the air made use of in the ejectors was com- 

 pressed by an ordinary air-compressing machine, driven by any suitable 

 power available, and placed in the locality best adapted to meet the 

 requirements of the particular case. This compressed air was conveyed 

 by a line of small pipes to the different ejector-stations. It is usual to 

 have only one compressing-station, the loss by friction in a long length of 

 pipes being insignificant. In the proposed scheme for V/ellington, the 

 air-compressing station would be at the Corporation Yards, where either 

 steam- or water-po\Yer would be available. 



