SEWAGE 



343 



which is actuated from the movement of the seat 

 of the closet, and in which the earth after admix- 

 ture with the faecal matter is retained in a tank on 

 wheels which can readily be removed and replaced 

 with another tank when required. The objection 

 to the earth-closet is that it necessitates heavy 

 double carriage of the materials, and that it only 

 deals with part of the refuse produced. From a 

 sanitary point of view, however, it is clearly 

 superior to any other method of dry conservancy. 



Pneumatic Systems of Sewerage. The Liernur 

 system, the oldest pneumatic system of sewerage, 

 is the invention of Captain C. T. Liernur, and is 

 in operation in some continental towns, especially 

 in Holland ; but there is no town at present in 

 which the entire sewage of the whole town is 

 treated on this system. The Liernur system con- 

 sists in aiding the withdrawal of the fecal matters 

 from the habitation with the assistance of air- 

 pressure. Under this system, at some convenient 

 central place, works are erected, and steam or 

 other power is provided which gives motion to an 

 air-pump which keeps certain air-tight receivers 

 exhausted or partially exhausted of air, and these 

 receivers communicate by means of air-tight iron 

 pipes with various convenient stations throughout 

 the district that is to be served by this system. 

 From these latter stations other iron pipes branch 

 off into the streets, and with these pipes the 

 imliviilii.il houses are connected by means of iron 

 pipes witli a valve on each house-drain, which 

 is controlled from outside the house by the persons 

 in charge of the system. The closet within the 

 house is a truncated conical vessel with a bent 

 pipe at the bottom, looking like a trap, but which 

 is used for receiving and storing the faecal and 

 other matters deposited in the closet. A partial 

 vacuum being maintained in the pipes of the 

 system, it is obvious that if the valve at the 

 street front of the houses is suddenly opened the 

 atmospheric pressure acting on the matters collected 

 in the bent tube at the bottom of the closet and in 

 the pipes between this point and the valve will be 

 withdrawn and a large volume of air will be carried 

 into the pipes, which will continue so long as the 

 valve is open and a partial vacuum is maintained. 

 The Liernur system, from a sanitary point of view, 

 is little better than the pail system ; and, in spite 

 of the value put on the manure, it is, when com- 

 pared with a proper system of sewers and water- 

 carriage, very expensive. All the pipes and fit- 

 tings must be constructed of iron, and it does 

 not deal with the whole of the sewage, so that a 

 system of sewers is requisite for dealing with the 

 greater part of the waste waters. In all the pneu- 

 matic systems the large volume of foul air ex- 

 hausted from foul pipes, and again liberated into 

 the atmosphere, is a source of very considerable 

 danger to health. 



The Berlier system, which has been partially 

 adopted in Paris, is similar to the Liernur system, 

 except that the discharge from the house into the 

 vacuum-pipes in the street is automatic in its 

 action. The same objections apply to this as to 

 the Liernnr system. 



The Shone system is another pneumatic system, 

 used simply for raising sewage from one level to 

 another higher level. In this system, instead 

 of a vacuum being used, air above atmospheric 

 pressure is directly applied to the liquid sewage 

 contained in an iron vessel called an ejector, 

 and the direct pressure of the air forces the 

 sewage out of the ejector to the required alti- 

 tude. Under this system the town is usually 

 drained on the separate system of water-carriage 

 to a number of convenient points at which there 

 are ejectors. The air used for transmitting the 

 tequisite power is compressed at some convenient 



point, and is distributed through iron pipes to the 

 various ejector stations to be used as required. 

 The Shone system is ingenious, but very expen- 

 sive, both in first cost and to maintain at work, 

 and it has the sanitary disadvantages, in common 

 with other pneumatic systems, of liberating foul 

 air into the atmosphere. It has, however, been 

 adopted by the authorities of several small English 

 towns, and is in operation at the Houses of Parlia- 

 ment. 



The Hydraulic Sewage System. This is a system 

 that has for its object the focal pumping of sewage 

 at several points within a district, and raising it to 

 a higher level. In this case the district may be 

 divided into a number of separate areas, and atsome 

 convenient central position in each area an auto- 

 matic hydraulic pumping-station is established, to 

 which the sewers of the district gravitate. In this 

 system a power-station is provided just as in the 

 various pneumatic systems, and at this station steam 

 or other power is employed, this power being trans- 

 mitted throughout the district to the various auto- 

 matic stations by water at high pressure. At the 

 power-station the water is pumped into an accumu- 

 lator, which is a cylinder weighted to the requisite 

 pressure, riding on a ram, through the centre of 

 which the water enters the cylinder, and the cylin- 

 der rises and falls as it is more or less filled with 

 water. From this accumulator pipes are carried 

 to the various automatic pumping-stations through- 

 out the district. The automatic hydraulic engines 

 at the various local stations are simply direct-act- 

 ing pumping-engines, in which the high-pressure 

 water gives motion to a piston within a cylinder, 

 and this in turn works a pump directly attached 

 to it. The automatic engines are controlled by a 

 float in such a way that when there is sewage to 

 pump it is pumped just as fast as it flows from the 

 sewers, and when the flow of the sewage declines 

 the hydraulic engine stops until the supply of sew- 

 age is replenished. In the transmission of the 

 power, water under a pressure of 700 Ib. per square 

 inch or more is used ; and the great advantage of 

 the system over any pneumatic system arises from 

 the fact that a large amount of power can- be dis- 

 tributed with little loss. For the friction of water, 

 unlike air, in passing through pipes does not in- 

 crease with the pressure ; there is just as much loss 

 in transmitting water at 10 Ib. pressure per square 

 inch as at 1000 Ib. per square inch through a pipe 

 of the same size, and consequently the actual per- 

 centage of loss at the higher pressure is very small. 

 Another great advantage of water over air is that 

 there may be any number of variable altitudes to 

 which the sewage is raised without loss of power, 

 as it is only a question of grading the size of the 

 cylinders of the automatic hydraulic engines to 

 adapt them to any lift. High-pressure water can 

 also be stored in an accumulator ready for urgent 

 work without increase of pressure, and without 

 the loss that arises when it is attempted to store 

 air in a receiver for use. Again, the water that 

 has been used for transmitting the power is used 

 for the purpose of flushing the sewers, as it may be 

 distributed to automatic flush-tanks. This saves 

 the cost of buying water for the purpose of flush- 

 ing the sewers ; generally the water so applied, if 

 it had to be purchased, would involve a greater 

 expenditure than the whole cost of transmission of 

 the power. The water used for transmitting power 

 may be the purified sewage or subsoil water, and 

 if the latter source is adopted the result of taking 

 it from the ground and so reducing the water-level 

 is a further great gain from a sanitary point of 

 view. 



The hydraulic system of pumping is more 

 economical at work than any other system, and 

 it occupies less space than any other apparatus. 



