DRAINS SEWAGE. 



ordinary supply of the town. As these smaller 

 drains are not sufficient to carry off all the surface 

 and rain water as well as the sewage, overflow 

 weirs are provided at certain points where the 

 excess must go over and pass away into some 

 other channel. This is the system now most 

 generally adopted ; but it is attended with serious 

 disadvantages to be afterwards noted. 



The next point for consideration is the disposal 

 of the filth at the main outfall. Hitherto, it has 

 been the practice to carry the discharge of sewers 

 into the nearest stream. The effect of this practice, 

 taken in conjunction with an increasing popula- 

 tion and the multiplication of manufactures, has 

 been, that most of our streams and rivers, instead 

 of being images of purity and beauty, have become 

 offensive to the senses, and vehicles of poison to 

 men and animals living near them. It is also 

 very objectionable to empty sewage into the sea ; 

 for tide-locked drains are attended with many 

 evils, and sewage mixed with salt water and ex- 

 posed by the retreating tide is more offensive than 

 ever. Various judicial decisions have shewn that 

 this poisoning of the rivers is illegal ; and legisla- 

 tion is daily tending more in the direction of 

 making it obligatory on towns to use every pos- 

 sible means to purify their sewage of its noxious 

 ingredients before allowing it to escape. How 

 to remove from sewage the foul matters held in 

 suspension in the water, is the difficult part of this 

 great problem ; and, inseparably conjoined with 

 it is the further question, of how to utilise these 

 matters. Dirt has been defined to be, ' Valuable 

 matter in the wrong place.' When in its right 

 place, it is riches, and its right place is the soil. 

 As to the value of the ingredients of sewage as 

 manure, there is little dispute ; the real questions 

 concern the method and cost of its application. 



None of the attempts to purify sewage by 

 chemical means deodorising, as it is called have 

 succeeded. The only hopeful plan is the applica- 

 tion, of the liquid portion at least, to irrigation. 



Sewage irrigation, in a rough and imperfect 

 manner, has long been practised with profit in the 

 neighbourhood of Edinburgh. By this means, a 

 tract of several hundred acres of meadow-land 

 between the city and the sea is made to pro- 

 duce crops of grass worth from 20 to ^40 an 

 acre per annum. The effluent water, however, is 

 still very foul At Croydon, again, the sewage has 

 been applie'd to irrigation with profit, and is also 

 so purified as to prevent nuisance. In both these 

 cases, however, the sewage flows upon the land by 

 gravitation ; and in the case of Croydon, a very 

 considerable portion of the sewage which could 

 not be utilised is poured into the metropolitan 

 sewers, throwing on that body the difficulty of deal- 

 ing with it. But in by far the greater number of 

 cases it would have to be elevated by pumping, 

 and it is here that the chief difficulty occurs. The 

 difficulty is mainly occasioned by the uncertainty 

 arising from the rain and surface water being 

 mixed with the sewage ; and hence the proposal 

 to keep the sewage and rainfall separate, by a 

 double system of drainage. The chief advocate, 

 if not the originator, of this plan is Mr William 

 Menzies, C.E. Deputy Surveyor of Windsor Forest 

 and Parks, who laid down the principles in his 

 work on The Sanitary Management and Utilisa- 

 tion of Sewage. The main objection to the plan 

 is its apparent expensiveness at the outset, but 



this is a matter open to much consideration. Its 

 advantages are many and obvious. The advocates 

 of this double system of drainage say that the 

 total separation of the two is the most sanitary 

 method, because the street-gratings and rain-water 

 pipes, which at present let down the rain-water 

 into the sewage-drains, act, in fact, as so many 

 ventilating shafts, and discharge the stench in the 

 midst of the inhabitants ; while, under a separate 

 system, the sewage-pipe would be entirely sealed 

 up, and only ventilated where it could be done 

 with safety; that the rain-water as a flushing- 

 power ought to be entirely discarded, as it fails in 

 dry weather, just when it is most wanted ; that in 

 wet weather, and winter again, the great quantity 

 of water sent down through the drains by the 

 present system is agriculturally a serious injury ; 

 that when pumping has to be employed for lifting 

 the liquid for irrigation, as it is in most cases, all is 

 uncertainty, and that no machinery can be econ- 

 omical and efficient under such circumstances. 

 With regard to the expense, it is further main- 

 tained that, as the rain-water and surface-water 

 can be discharged at the nearest point, all the 

 drains may be much lessened in size ; and further, 

 that the flushing-power of the water in the 

 sewage-drains will be much more efficient, while 

 the corresponding lessening of the expense in 

 carrying out the process of utilisation will com- 

 pletely compensate any additional outlay that may 

 be incurred in laying the drains in towns. If we 

 take the case, which is a common one, of a popu- 

 lation of 10,000 people living upon a square mile, 

 the first-mentioned system, where rain and sewage 

 water go together, would require pumping-ma- 

 chinery, in dry weather, of, say, five horse-power, 

 to lift the liquid ; and it would further be neces- 

 sary, for wet weather, to h'ave in reserve a lifting- 

 power of 150 horses; while, on the separate 

 system, where the sewage alone would have to be 

 dealt with, the five horse-power engine would be 

 regularly and constantly employed, and its work 

 would be almost entirely confined to the daytime, 

 whereas the other must be ready for every emer- 

 gency. 



The system of separating the sewage and rain- 

 water has been carried out in several large asylums 

 and public buildings, and the sanitary results have 

 been thoroughly satisfactory. The principles of 

 the separate system of drainage for towns were 

 fully confirmed in the report by Colonel Ewart, 

 C.B. R.E. appointed in 1866 by the Home Secre- 

 tary to investigate this subject The drainage of 

 Eton has been since then completed from first to 

 last on this principle, and the sewage utilised ; 

 and the system has been in operation in the town 

 of Haddington since 1870. 



In 1873, after five or six years' full considera- 

 tion of every plan and scheme, the drains of 

 Windsor Castle and all the crown buildings 

 at Windsor were reconstructed .on this system, 

 under the charge of Mr Menzies and Captain 

 Gun, R.E. 



Presuming, then, that by this separation we can 

 arrive at a fixed quantity of, say, 20 or 30 gallons 

 of sewage per head of the population, the first step 

 would be to pass the whole through a filter or 

 strainer, so that all matter would be inter- 

 cepted which would be likely to interfere with the 

 pumping, or choke the smaller pipes used for 

 irrigation. This is necessary, also, because in its 



