Fig. 3.-Brick Sewer.

next.

is allowed to settle. The process gives a l'einarkalıly clear effluent; | brickwork. The bricks are laid over a templet made to practically the whole of the insoluble constituents of the sewage the section of the sewer, and are grouted with cement. and a portion of the dissolved impurities

are carried down in the An egg-shaped sewer, made with two thicknesses of brick, precipitate, which, when dried and ground along with some sulphate of magnesia, is sold under the name of native guano. The an invert block, and ABC process has been in successful use for nine years at Aylesbury, a concrete setting, where the " ” finds a sale at 70s. per ton. In 1870° the is illustrated iu fig. Rivers Pollution Commissioners reported unfavourably on the pro- 3. Concrete is now cess, a fact which may have prevented its adoption by other towns, but it has since then received the approval of many specialists

. very largely used A recent protracted investigation by Dr C. M. Tidy and Prof. in the construction Dewar showed that the percentage of oxidizable organic matter of sewers, either in removed by the process ranges from 75 to 86—a result, in their

combination with juilginent, satisfactory. At Leeds, where the process was tried for a time, it was given up because the efluent was purer than the brickwork or alone. ris er into which it ran. and the simple lime-process, which costs For this purpose leza but gives a less clear efluent, was adopted in its place.

the concrete conAluch difference of opinion still exists as to the relative inerits sists of from 5 to of broad irrigation, filtration through land, and chemical treatmnt, as means' of 'disposing of sewage. That either of the two ! 7 parts of sand aud first plans or a combination of them both can be made to yield a' gravel or broken sa isfactory solution of the sewage problem, from a liygienic point stone to l of Portof view, seems unquestionable. That chemical treatment, especiand cement. It cially if supplemented by filtration through land, will also purify will, is generally admitted. No process of effective purification is may be used as a maw expected to yield a profit; but the question of cost, on which cradle for or as a tle choice of a system principally turns, is too extensive to be backing to a brick ti uched in this article.

ring, or as the sole II. THE CONVEYANCE OF SEWAGE.—For small sewers, material of construction by running it into position round circular pipes of glazed earthenware or fire-clay or of a mould which is removed when the concrete is sufficiently Boulded cement are used, from 6 inches to 18 inches set, the inner surface of the sewer being in this case coated nud even 20 inches in diameter. The pipes are made in with a thin layer of cement. skort lengths, and are usually jointed by passing the

In determining the dimensions of sewers, the amount of sewage end or spigot of one into the socket or faucet of the

proper may be taken as equal to the water supply (generally aboul Into the space between the spigot and faucet a 30 gallons per head per díem), and to this must be added an allowring of gasket or tarred hemp should be forced, and the

ance for the surface water lue to rainfall. The latter, which is rest of the space filled up with cement, not clay. The generally by far the larger coustituent, is to be estimated from the

maximuin rate of rainfall for the district and from the area and gasket prevents the cement from entering the pipe, and so

character of the surface. In the sewerage of Berlin, for example, obstructing the flow; at the same time it forms an elastic (one of th- most recent instances of the combined water-carriage packing which serves to keep the successive lengths of system applied on a large scale), the maximum rainfall allowed for pipe concentric, even if the cement should fail

. The

is of an inch per hour, of which one-third is supposed to enter

the sewers. pipes are laid with the spigot ends pointing in the direction rainfall account must of course be taken of the relief provided by

lū any estimate of the size of seirers based on of the flow, with a uniform gradient, and, where practi- storm-overflours, and also of the capacity of the servers to becoirie cable, in straight lines. In special positions, such as simply charged with water during the short time to which very under the bed of a stream, cast-iron pipes are used for heavy showers are invariably limited. Rainfall at the rate of 5 or

6 inches per hour has been known to occur for a few minutes, but the conveyance of sewage. Where the capacity of an

it is altogether unnecessary to provide (even above stormuoverflows) 18-inch circular pipe would be insufficient, built sewers sewers capable of discharging any such amount as this; the time are used in place of earthenware pipes. These are some- taken by sewers of more moderate size to fill would of itself

prevent times circular or oval, but more commonly of an egg and, apart from this, the risk of damage by sach an exceptional

the discharge froin them from reaching & condition of steady flow shaped section, the invert or lower side of the sewer being

fall would t warrant so great an initial expenditure. Engineers a curve of shorter radius than the arch or upper side. differ widely in their estimates of the allowance to be made for The advantage of this form lies in the fact that great the discharge of surface water, and, no rule can be laid down, variations in the volume of flow must be expected, and which would be of general application.

In order that sewers should be self-cleansing, the mean velocity the egg-section presents for the small or dry-weather flow of flow should be not less than 24 feet per second. The gradient a narrower channel than would be presented by a circular necessary to secure this is calculated on principles which have been sewer of the same total capacity. Figs. 1 and 2 show stated in the article HYDROMECHANICS (q.v.). The velocity of flow,

V, is

Vecin, where i is the inclination, or ratio of vertical to horizontal distance ; m is the “hydraulic mean depth,” or the ratio of area of section of the stream to the wetted perimeter; and c is a coefficient depending on the dimensions and the roughness of the channel and the depth of the streain. A table of values of c will be found in 8 90

This velocity multiplied by the area of the stream gives the rate of discharge. Tables to facilitate the determination of velocity and discharge in sewers of various dimensions, forms, and gradients will be found in Mr Latham's

and other practical treatises. Fig. 1.

Fig. 2.

Where the contour of the ground does not admit of a sufficient

gradient from the gathering ground to the place of destination, the two common forms of egg-sections, with dimensions ex- sewage must be pumped to a higher level at one or more points in pressed in terms of the diameter of the arch. Fig. 2 is it is frequently desirable not to gather sewage from the whole arca

its course. To minimize this necessity, and also for other reasons, the more modern form, and has the advantage of a

into a single main, but to collect the sewage of higher portions of sharper invert.

The ratio of width to height is 2 to 3. the town by a separate high-level or interception sewer. Built sewers are most commonly made of bricks, Sewer gas is a term applied to the air, fouled by mixture with, moulded to suit the curved structure of which they are to gases which are formed by the decomposition of sewage, and by form part. Separate invert blocks of glazed earthenware,

the organic germs which it carries in suspension, that fills the

sewer in the variable space above the liquid stream. It is uniterra-cotta. or fire-clay are often used in combination with versally recognized that sewer gas is a medium for the conveyance

XXI.

of the article referred to.

Figs. 1, 2.-Forms of Sewers.

of disease, and in all well-designed systems of sewerage stringent To facilitate inspection and cleaning, sewers are, as far as precautions (which will be presently described) are taken to keep it possible, laid in straight lines of uniform gradient, with a manhole out of houses. It is equally certain that the dangerous character or lampholo at each change of direction or of slope and at each of sewer gas is reduced, if not entirely removed, by free admixture junction of mains with one another or with branches. The sewers with the oxygen of fresh air. Sewers should be liberally venti- may advantageously be stepped here and there at manholes. Sir lated, not only for this reason, but to prevent the air within them R. Rawlinson has pointed out that a disference of level between from ever having its pressure raised (by sudden influx of water) so the entrance and exit pipes tends to prevent continuous flow of considerably as to force the "traps ” which separate it from the sewer gas towards the higher parts of the system, and makes the 'atmosphere of dwellings. The plan of ventilation now most ventilation of each section more independent and thorough. approved is the very simple one of making openings from the sewer When the gradient is slight, and the dry-weather flow very small, to the surface of the street at short distances, -generally shafts built occasional Hushing must be resorted to. Flap valves or sliding of brick and cement, -and covering these with inetallic gratings. penstocks are introduced at manholes ; by closing these for å Under each grating it is usual to hang a box or tray to catch short time sewage (or clean water introduced for the purpose) is any stones or dirt that may fall through from the street, but the dammed up behind the valve either in higher parts of the sewer or passage of air to and from the sewer is left as free as possible. The in a special flushing chamber, and is then allowed to advance with a openings to the street are frequently made large enough to allow a rush. Many self-acting arrangements for flushing have been devised man to go down to examine or clean the sewers, and are then called which act by allowing a continuous stream of comparatively small “inanholes.” Smaller openings, large enough to allow a lamp to volume to accumulate in a tank that discharges itself suddenly be lowered for purposes of inspection, are called “ lampholes," and when ful! A very valuable contrivance

of this kind is lír Rogers are often built up of vertical lengths of drain-pipe.

Field's siphon flush tank, shown in fig. 4. When the liquid in

Domes. tic sewer age.

sites.

Fig. 4.-Field's Siphon Flush Tank. the tank accumulates so that it reaches the top of the annular | the trap, is greater than that of the air above the trap by an amount siphon, and begins to flow over the lip, it carries with it enough exceeding the pressure due to a column of water equal in height to air to produce a partial vacuum in the tube. The siphon then the seal, the trap will be forced and air will bubble through. This bursts into action, and a rapid discharge takes place, which con- is one way in which a trap may fail, but this may be prevented by tinues till the water level sinks to the foot of the bell-shaped cover. sufficient ventilation of the pipe below the trap. Other

possibilities of failure are, however, only too numerous.

the
III. DOMESTIC SEWERAGE.-In water-carriage | If the pipe is disused for some time, the water

may eva-
system each house has its own network of drain-pipes, porate so considerably as to break the scal. The pipe,
soil-pipes, and waste-pipes, which lead from the basins, if of lead, may bend out of shape, or it may even be só
sinks, closets, and gullies within and about the house badly set in the first instance as to make the trap in-

The seal may be

operative. Primary to the common sewer. These must be planned to

broken by the capillary action of requi. remove sewage from the house and its precincts quickly a thread or strip of cloth, hang

and without leakage or deposit by the way; the air ing over the lip of the trap and
within them must be kept out of the dwelling, by causing the water to drain away.

A rush of water down the pipe,
placing a water-trap at every opening through which

suddenly arrested, may pass the
sewage is to enter the pipes, and by making all internal trap with such momentum as to
pipes gas-tight; the pipes must be freely ventilated by a leave it wholly or partly empty.

6
current of fresh air, in order to oxidize any deposited filth Another and a common cause of
and to dilute any noxious gas they niay contain ; finally-

failure can be explained by re

ference to fig. 5. . Let a column Fig. 5.—Common Water-
and this is of prime importance—the air of the common of water rush down the soil-pipe
sewer must be rigorously shut out from all drains and pipes c from a closet or sink which
within the house. To disconnect the pipes of each indi discharges into it at some higher point. As the water
vidual house from the atmosphere of the common sewer

passes the junction with the branch d it will produce a
is the first principle of sound domestic sanitation. When partial vacuum in the branch, and so tend to suck over the contents

of the trap. This process, which is sometimes called the siphonage this is done the house is safe from contagion from without, of traps, can be guarded against by ventilating the branch, either so far as contagion can come through sewer gas; and, how- hy a separate ventilating pipe leading to the open air or by a pipe & ever faulty in other respects the internal fittings may be, (shown by dotted lines) connecting the top of the branch'd with a the house can suffer no other risk than that which arises point sufficiently far up on the soil-pipe to be above the column of

water which is passing the junction. One more imperfection in traps from its own sewage.

may be named. The experiments of Dr Fergus have shown that Protection against the passage of gas through open- the water in traps will allow gases to pass through by absorbing the ings which admit of the entry of water is secured by the gas on one surface and giving it off at the other. It is improb

able that this action occurs to such an extent as to be dangerous familiar device known as the water-trap.

by permitting the transfer of disease germs from one to the other The simplest and in many respects the best form of trap is a side. Apart from any risk of this kind, however, it is clear that a bent pipe or inverted siphon (fig. 5) which is sealed by water lying trap is open to so many possibilities of failure as to forni a very inin the bend. The amount of the seal (measured by the vertical sufficient barrier between the air of a room and the foul air of a sewer. distance between the lines a and b) varies in practice from about Nevertheless the practice was until very lately alınost universal, an inch to 3 inches. If the pressure of air within the pipe, below and is still far from uncommon, of connecting closets, sinks, and

Trap.

GRATING

END OPEN FOA
VENTILATION

STONE COVER

TO SEWER

WC

even bedroom basins with common sewers by a continuous system of An arrangement of double disconnecting trap is illustrated in tig piping, in which the only safeguard against the entry of sewer gas is 8. Any sewer gas forcing the trap next the sewer is still kept bach a single trap close to each sink or basin. This means that sewer gas, } by the upper trap and will charged with the infection of a whole community, is brought within escape by a grating or open a few inches of the atmosphere of the dwelling, ready to contamin- | ventilating, shaft which ate it whenever the trap fails from any of the causes which have enters at A, while air to been named, or whenever, by a flow of water through it, the seal is ventilate the house-drain sufficiently disturbed to allow bubbles of gas to escape into the room. enters the upper trap from The remedy for this lies in having, at any convenient point on

the manhole. This arrangeeach house-drain, a disconnecting trap which separates the house ment no doubt gives more system from the sewer, and so establishes what

absolute protection than a may be called an outer line of defence. Any

single trap of the kind alaccidental leakage of sewer gas througlı it then

ready described, but it is does no more than cause a comparatively slight

probable that (except in pollution of the air within the house-drains,

cases where the sewers are and if these are well ventilated the effects of

very foul and liable to this are insensible. At each individual basin

frequent excess of

min TO HOUSSR or other fitting a trap is still required, but its

pressure) the ad

A function is now merely to shut out the air of

vantage is so slight the house-drains from the rooms, and, as the

as to be more than air of the house-drains is no longer nolluted

counterbalanced by by connexion with the sewers, the occasional

the greater liabil

FIG. 8.--Double Disconnecting Trap. failure of this function is a matter of com

ity to accidental paratively small moment. Further, the dis

stoppage and greater complexity which this arrangement entails. connecting trap on the house-drain furnishes

The extent to which it is permissible or advisable in practice to a convenient place of access for fresh air; and

allow several fittings to discharge into a single waste-pipe the ventilation is completed by carrying the

soil-pipe will vary in different cases. We can recognize a broad highest point of each soil-pipe or waste-pipe

distinction between sewage from closets and urinals, liable to the up to the level of the roof and leaving it open

most dangerous taint should disease occur within the house, and there. This arrangement will be understood

the comparatively innocuous sewage that comes from basins, baths, by reference to fig. 6, which shows a soil-pipe,

and sinks. Some sanitarians go so far as to advise that these two open at its upper end, discharging into a

classes of sewage should be kept absolutely apart within the house, house-drain in which there is a disconnecting

by the use of a complete double system of house drain-pipes. This, trap provided with an open grating for the

however, is an extreme measure ; no reasonable objection can be entry of air. The soil-pipe is ventilated by a

urged against the discharge into a water-closet soil-pipe of water current of air which (usually if not always)

from a bath or wash hand basin in the same room, except perhaps flows upwards. This not only dilutes any

that if the soil-pipe is of lead its corrosion is hastened by hot gases that are produced in the pipe, but

water; and the additional flushing which the soil-pipe so receives quickly oxidizes any foul matter that may

is a distinct advantage. But to connect a water-closet soil-pipe adhere to the sides. Care must be taken to

with winks and basins in other apartments is to multiply possibilities avoid having the upper end of the pipe open

for the spread of disease within the house, and it is strongly advisnear windows or under eaves. In the figure

able to convey the waste from them by a separate pipe, protected the branch leading to a

from the sewer by a disconnecting trap of its own with a grating water-closet is ventilated by

open to the air. This applies with special force to the washhand a pipe carried into an upper

basins that are often fixed in bedrooms and dressing-rooms. part of the soil-pipe ; this

Nothing could be more dangerous than the usage--of which many is scarcely necessary if the

good houses still furnish instances of multiplying these convenbranch be short. Another

iences without regard to the risk they involve, and making this construction is to carry a

risk as great as possible by placing each in direct communication distinct ventilating pipe up FIG. 6.-House-Drain properly disconnected

through an ordinary trap with the soil-pipe, itself perhaps unvenfrom the top of the branch

from sewer, and ventilated.

tilated and provided with no disconnexion from the sewer. Even to a point above the roof;

when the drain or soil-pipe is ventilated and disconnected from and where several fittings discharge into one soil-pipe, the same the sewer, no bedroom basin should, under any circumstances, be ventilating pipe may be made to serve for all. An example of the allowed to discharge into it without first passing a separate open latterarrangement

trap. On the other hand, a bedroom basin may be made perfectly is shown in fig. 10.

safe by leading its The form of dis

waste - pipe (trapped

BRATING connecting trap

under the basin in the shown in fig. 6 GRATING

usual way) into an is that of Mr

open-air channel which W. P. Buchan of

communicates with the Glasgow, who has

sewer by a surface-trap done excellent ser

or gully outside the

TG SEWER vice to the cause

house (fig. 9). Similar of sanitary re

treatment should be form by practising

adopted in the case of and advocating

pantry and scullery the disconnexion

sinks. | Under most

Fig. 9.-Open Trap. and ventilation of

plumbing fixtures it is house-drains and

usual to place a safe-tray to receive any water accidentally spilt. soil-pipes. The same trap is

The discharge pipes from these trays are sometimes, but very obo shown to a larger scale in fig.

jectionably, led into the waste-pipe or soil-pipe below the fixture. 7, where it appears imbedded

The proper method of providing for the discharge of water spilt into in concrete and covered by a

the safe-tray is to lead a pipe from it through the wall and allow built manhole, which gives ac

it to end in the open air (fig. 10, where each of the safe-tray drains cess to the trap in case of its

is marked "waste-pipe"); a flap valve fixed on the end will serve TO SEWER becoming choked. The man

if need be, to keep out draught. hole may have an open grating

Overflow-pipes from cisterns used for dietetic purposes should be at the top; or the top may be

led, in the same way, into the open air and not into soil-pipes or closed by a solid plate (if a FIG. 7.-Buchan Trap and Manhole, with

waste-pipes (fig. 10). Traps on them cannot be depended on to grating there be for any reason ventilating grating in wall.

remain sealed, and any connexion of an overflow-pipe with a soil. inadinissible), in which case a

pipe would result in allowing foul air from the pipe to diffuse ventilating shaft is carried from the manhole to some other open. itself over the surface of water in the cistern-a state of things ing. Fig. 7 shows such a shaft leading to a grating which is placed peculiarly likely to cause pollution of the water. When a cistern vertically in a neighbouring wall. Among other good forms of is used only for water-closet service, its overflow-pipe may properly disconnecting trap, more or less like Buchan’s, mention may be be led into the basin of the closet. made of Weaver's, Potts's, and Hellyer's.

Rain-pipes, extending as they do to the roof, are sometimes used

FRESH AIR INLET

DISCONNEGTING

TRAP

WASTE PIP

OVERILON OPEN TO OUTSIDE
CISTERN FOR SUPPLY OF KITCHEN

NI NISVO NIVO ONV V11101

WASN HAND BASM

IN DEDROOM
(SUPPUED FROM MAIN)

22 ON D.INCN AIR PIPE
CITATO LATINO PIPO

MONJWAO! 801813 3M

uin

BATU ROOM

WASTE
PIPE

OVERFLOW

TO SINK

RAIN PIPE

W.C.

BUCHAN TRAP WITH RANHOLE
AND FRESH AIR INLET

(SUPPLIED FRON MAIN)

RANGE OF TUBS

WASTE
PIPE

8CULLERY SINK
(SUPPUCO FRON NIIN)

CAST IRON WOIL PIPET

4.JNCH FIRECLAY DRNN

to serve as ventilating continuations of soil-pipes and waste-pipes. merely, by diffusion, but by an actual in-draught, for generally the The practice is open to serious objection, for it discharges the drain air of the house has its pressure reduced by chimney draughts to air just under the eaves, at a place where air is generally being a value slightly lower than that of the air outside. The house, in drawn into the house. The ventilating end of a soil-pipe should fact, ventilates itself by drawing in air from the pipe at any hole, be carried to a higher level, as in fig. 6, clear of the lower.edge of a fact which may easily be demonstrated by holding the flame of the roof. It is better to restrict rain. -pes to their legitimate a taper near the hole. function of taking surface water from the roof, or at most to allow Various experimental methods are used of detecting such leaks them to receive slop-water from sinks and basins, and to inake as would admit foul air to the dwelling. Of these the best is the them terminate in or over open traps from which a connexion is “smoke test.” It consists of filling the house-drain, soil-pipes, taken to the house-drain or sewer (fig. 9).

and waste-pipes with a dense and pungent smoke, any escape of In figs. 10 and 11 the sanitary fittings of a small house are shown which into the house is readily observed by eye and nose. A by diagrams, which should be carefully studied

quantity of cotton-waste soaked in oil is lighted, and its fumes as exemplifying a well-arranged system. Two

are blown into the house-drain by a revolving fan, at the ventilatclosets, and a bath and basin in the closet apart

ing cover of the disconnecting trap, or at any other convenient ment, (lischarge into a soil-pipe on the right, and

opening. Smoke soon fills the pipes, and begins to escape at the the branches (except that of the basin) are venti

roof. The upper ends of the pipes are then closed, and the house lated by pipes leading to a sepa

is searched for smoke. Another test, especially applicable to rate air pipe, which, like the

those parts of .drains that are laid under houses, is the hydraulic soil-pipe, is carried above the

test, which consists in stopping up the lower end of the pipe. roof. The overflow of a cistern

filling it with water so as to produce a moderate pressure, and which supplies bath, basin, and

then observing whether the level of the water falls. This test, boiler is carried out to the open

however, is too severe for anv but new and very well constructe air, and so are the waste-pipes of

drains. the leaden safe-trays. A sepa

Every basin, sink, or other fitting should be separately trappe rate cistern supplies each water

oy a bend on the waste

CRATING closet, and its overflow opens

pipe or some other form into the closet basin. A rain.

of trap. A brass cap,

MOEN BASE TRAP pipe (in the middle of the figure)

screwed on a ferule which
is let into the pipe on the
bend, facilitates cleaning
(fig. 5). The warm waste-
water from pantry and

TO SEWER
scullery. sinks contains
much grease, and should
be discharged into a
grease box (fig. 12) where
the water becomes cool
and deposits its grease

Fig. 12.-Grease Trap. before overflowing into the drain. To collect surface water from laundry floors, areas, court-yards, &c., an open trap or gully is used. Fig. 9 shows a simple and good form of open

trap; but if the water is liable Fig. 10.-Diagram Section of the Drains and Fittings of a Small Housc. to carry down sand or earth

a gully (fig. 13) is moro suitreceives a bedroom basin waste, and

able. Even in this simple leads by a 4-inch drainoto a venti

fittinga remarkable ingenuity

ITO SEWER lated grease-box, into which, the

of error has been displayed. scullery sink

Many of the forms favoured by and : wash- BUCHAREST MAIN DRAIN

builders are bad either because of tubs and an

an insecure seal, a narrow outlet, other rain-pipe WITHUANIAN SPAIR PODE

or a tendency to gather filth. One also discharge.

in particular, the well-known Finally, the

“Bell” trap, is an example of whole system Fig. 11.–Plan of the Drains in fig. 10.

nearly everything a trap should is protected by

not be. a Buchan trap in a built manhole, which is covered with a Water-closets used to be almost grating.

invariably of the "pan" type, but Fig. 13.-Gully-Trap. House-drains, that is to say, those parts of tho domestic system wherever sanitary reform has been. of drainage which extend from the soil-pipes and waste-pipes to preached to any purpose the pan closet is giving place to cleane the sewer, are made of glazed fireclay pipes, generally 6 inches and wholesomer patterns. The evils of the pan closet will be ev but sometimes only 4 inches in diameter. A larger size than 6

dent from an inspection of fig. inches is rarely if ever desirable. The pipes are spigot-and-faucet. 14. , At each use of the closet jointed, and the joints should be made with cement in the manner the hinged pan a is tilted down already described for sewers. When, as is often unavoidable, the so that it discharges its contents house-drain has to pass under a part of the house, or to come

into the container b.. The sides from back to front, iron pipes jointed with lead and coated with of the container are inaccessible an anti-corrosive compound are preferred to fireclay pipes, as for cleaning, and their upper giving a better security against the production of leaks by the portions are out of reach of the settling of the soil and other causes. Soil-pipes, when carried flushing action of the pan. They down inside the house, are of either lead or iron; when outside the gradually become coated with a house they are usually of iron. An outside soil-pipe is obviously foul deposit. A gust of tainted preferable to an inside one ; if the arrangement of the building air escapes at every use of the makes an inside soil-pipe necessary, care must be taken that it shall closet ; and it rarely happens that the be easily accessible for inspection at all parts of its length. The container is air-tight, and that the filth it usual diameter is 4 inches. For the sake of good ventilation it is has gathered does not cause a smell even desirable to continue the soil-pipe to a point above the roof without in intervals of disuse. To make matters reduction of diameter rather than apply a smaller ventilating pipe. worse, many of the older pan closets are Amongst reasons for ventilation one remains to be mentioned, provided with the kind of trap shown in that, owing to the corrosive action of sewer gas, the life of the soil the sketch, called the D trap, which is pipe is greatly shortened if provision for the free circulation of air also liable to become a gathering place for filth. Even with an be wanting or insufficient. A closed soil-pipe becomes in time ordinary trap, however, the pan closet remains so bad that its use pitted with holes, especially in the upper parts of its length. is to be strongly condemned. Defective joints in soil-pipes and waste-pipes, particularly where

A much better closet is the valve or Bramah closet, an excellent they connect with drains, closet-basins, sinks, &c., are another frequent cause of leakage. Any want 05 xir-tightness in drains

WATER

LINE

ashout Oset.

example of which by Frew of Perth is shown in fig. 15. The and the siphon ceases to act. The air-pipe c is cut to give the basin is kept partly full of water by a ground gun-metal valve desired volume. tightly pressed up

As regards house-drainage generally, the points of chief against a conical seat at the basin's foot.

importance may be briefly summed up as follows :-(1) the The chamber below is

use of one or more disconnecting traps to shut off sewer only large enough to

gas. from the whole system of house-drains and pipes ; allow the valve to

(2) the thorough ventilation of house-drains, soil-pipes, turn down; it cannot collect much foul mat

and branches, by providing openings through which air ter and may be venti

can enter at the foot and escape at the top; (3) the dislated by a separate

charge of all sinks, basins, &c., other than water-closet pipe. A trapped over

fittings, and especially of fixed bedroom basins, into open how prevents the basin from being overfilled.

traps in the open air; (4) the direct discharge of cistern The whole closet is

overflows and safe-trays into the open air ; (5) the use of trapped by an ordinary

cleanly and well-designed closets, basins, &c., each sealed bend on the soil-pipe,

by an ordinary bent trap; (6) the use of separate service which is not shown in

cisterns for water-closets. the figure. The volume of water in the basin is

It may seem superfluous to add that the system of much greater than in

pipes must provide a rapid and effective carriage of all pan closets, where the Fig. 15.-Bramah Water-Closet.

sewage to the sewer, and must be water-tight and airheight is limited by the overflow which occurs round the lip of the pan. In some closets

tight. During the last five years, however, it has been of this kind the valve is placed at the side, and, when closed, lies proved, by examination of the best houses in London, nearly: vertical. In another type of valve closet (Jennings's) the that it is no uncommon case for a house to be so completely valve is a conical plug, prossed vertically down on a seat at the side. without effective connexion with the sewer that all its own

Valve closets can be made fairly effective and satisfactory from a sanitary point of view; bụt a much cheaper and certainly not sewage sinks into the soil under the basement; and about less excellent type of closet is the “washout,” an example of 75 per cent. of the houses inspected have failed to pass which (the “National") is shown in fig. 16. (Another wash the “smoke test." out closet, by Doulton, appears in fig. 6.) These are now made In this connexion mention should be made of the in a great variety of good forms, sometimes of a single

piece of system of co-operative house-inspection originated by the white stoneware. They combine cheapness and simplicity with a degree of sanitary perfection that is probably not reached by | late Prof. Fleeming Jenkin. The Edinburgh Sanitary the most expensive closets of the kinds already named. They Protection Association was founded by him in 1878 to have no working parts; the closet is cleansed after use simply by carry out the idea that the sanitary fittings of a house the flush of water, which sweeps everything before it. The flush should be periodically submitted to examination by an must of course be good : a ij-inch service pipe from a cistern not less than 5 feet above the closet will do well. In some recent expert, and that householders should combine to secure designs the cistern is a box at the back of the seat with a wide for this purpose the continuous service of an engineer

able to detect flaws, to advise improvements, and to superintend alterations. The Edinburgh association soon justified its existence by discovering, in the houses of its members, a state of things even worse than students of sanitary science had imagined possible. Similar associations are now doing excellent work in London, Glasgow, and many other large towns.

Space admits of only a very brief mention of those systems of

sewerage in which excreta are not removed by the aid of water. The FIG. 17.-Hopper Closet.

dry-earth system, introduced by the Rev. H. Moule, takes advanoval mouth leading from it to the flushing rim of the pan : this tage of the oxidizing effect which a porous substance such as dry gives a good flush although the cistern is low. A feature of con- earth exerts by bringing any sewage with which it is mixed into struction which may be strongly recommended is to leave the intimate contact with the air contained in its pores. A discharge closet entirely open for inspection and cleaning, instead of con- of urine and fæces is quickly and completely deodorized and absorbed cealing it in a wooden case. "The seat then generally rests on iron when covered with a small quantity of dry.earth ; and the same brackets projecting from the wall, and can be raised on hinges at soil, if exposed to the air and allowed to dry, may be used over and the back, so that the pan may be used as a urinal or slop-sink over again for the same purpose. Even after soil has been several without the risk of fouling. Another good type of closet, sharing times used, however, its value as manure is not so great as to pay with the washout the advantage of having no mechanical parts, is for its transport to any considerable distance ; and for this reason, the “hopper,” illustrated in fig. 17 (Dodd's Hopper). In all these as well as from the fact that it leaves other constituents of sewage closets the horn marked V is for attaching a ventilating pipe. to be dealt with by other means, the system is of rather limited

For the supply of water to a closet a separate cistern is desirable, application. So far as it goes it is excellent, and where there is especially when water for dietetic purposes is liable to be drawn no general system of water-carriage sewerage, or where the waterfrom the main cistern (instead of being taken direct from the water supply is small or uncertain, an earth-closet will, in careful hands, service pipe, which is better). It would seem needless to add, givo perfect satisfaction. Numerous forms of earth-closet are sold in were it not that such faults are

which a suitable quantity of earth is automatically thrown into the common, that no cistern-unless

pan at each time of use. Arrangements of this kind are, however. it be exclusively used for water

not necessary to the success of the system ; a box filled with dry closet supply-should be placed in

earth and a hand scoop will answer the purpose not less effectively. the same room with or just under

Ashes are sometimes substituted for or mixed with the dry earth a water-closet, and that the room

and powdered charcoal is also used. itself should be well lighted, well

The most primitive method of dealing systematically with ventilated, and well shut off from

excreta is to collect the discharges directly in a vessel which is bedrooms. To prevent flushing

either itself carried to the country, and its contents applied to the of closets from being imperfect

land, or is emptied into a more portable vessel for that purpose. through carelessness, many plans

In Japan, for example, in spite of the difficulty of transport over bad have been devised for ensuring that

roads and by human labour, the latter plan is universally followed : once the flow of water is started it

the land and the people have in fact performed for centuries what will continue until a given volume has been discharged. One of may be called a complete cycle of operations. The agricultural the best of these is the arrangement of siphon flush sketched in return is so good that farmers pay for leave to remove excrement, fig. 18 : when the valve a is opened the downrush of water starts and householders look to their discharges as a source of income. the siphon b into action, and even should a be then closed the The plan, although carried out in the roughest manner, appears flow continues until the water-level falls to c, when air is admitted I to involve fewer sanitary drawbacks than might be expected; but

总

Fig. 16.-Washout Water-Closet.

AIR PIPE

CISTERN

FIG. 18.-Water-Closet Cister

with Siphon Flush.