“Bad Drains.” How often has this term been used during the last few years? By the medical profession alone, thousands of cases have been attributed to this cause. To the honour and credit of that profession its members have thought out and worked out the cause of innumerable cases of disease under their charge, and rightly fixed their origin to be due to “bad drains.”

In many cases it has been but a fashionable term to describe cases which had the appearance of gas poisoning, but did not owe their origin to drains; but rather to the heated and impure atmosphere of rooms, late hours, and the sudden change from heat to cold. If there have been a few hundred cases where “bad drains” were supposed to have caused the illness and such was not the case, there have been thousands of others where the disease originated from them, but was taken as a matter of course, or as one of the frailties of the human frame, when undoubtedly the cause was “bad drains.”

It is a most remarkable thing, that whilst on the one hand we have the medical profession energetically working to find out defects in the planning of drains and sanitary fittings, and writing articles on them, we have on the other hand surveyors and others who have treated the matter as a doctor’s fad.

During the last five years scarcely a medical conference has been held without the question of “bad drains” forming one of the principal subjects discussed. Medical officers of health have made stirring speeches and reports to Local Boards; but where is the surveyor who has had the energy to do the same unless it has been actually forced upon him? It is a curious but noteworthy fact, that nearly the whole of the evils of badly constructed drains, and the principal improvements in them, have been forced on surveyors, builders, and plumbers by the medical profession and the public.

The reticence shown by surveyors in dealing with “bad drains” may be attributed to their unwillingness to acknowledge the errors and defects in works already executed. These works were, at the time, executed according to the theories adopted by the most eminent engineers in the profession, and it would be considered unprofessional to admit errors.

There is scarcely a district (excepting where drains have been laid within the last three years) where the branch drains are trapped into the main sewers with an efficient water-seal. Surveyors feel that to acknowledge this would be tantamount to acknowledging a want of professional knowledge or neglect of duty on their part.

Now, strictly speaking, this could not be the case, and a surveyor (placed in such a position where he knows that there are defects in his drainage system, and probably these errors were made by himself,) could say that these now known defects were not previously known by the most eminent engineers, and especially with regard to sewer-gas, its treatment, and action on the public health. Boldly facing the matter and advocating that the drainage under his charge should be so perfected that no medical man could point to it as being detrimental to health, if it entailed an unusual expenditure, coming from the surveyor he would carry the Board with him, and in doing so would make his position at the Board doubly secure.

To prove this we have only to refer to reports made by engineers during the last fifteen years on drainage schemes, compare the results of the theories laid down, and note the instances in which they have failed, especially those in connection with sewage farms and the ventilation of sewers.

I will quote a few extracts from these reports:—

“No injury to health can possibly take place from gas issuing from properly constructed gratings fixed in the middle of the road, and if one is a nuisance, dig down and put in others until the nuisance is removed.”

This has certainly not been the case. You may dig as many holes as you like, and put in as many gratings, yet some will be injurious to health.

In describing sewage farms, they were described as being (if adopted) the means of securing a large revenue to the Local Board by the excellent crops grown, one engineer stating that persons could walk through them with as much pleasure as through a flower or kitchen garden; but practical experience has proved this to be incorrect: and although these statements were made in good faith, they have not been realised.

You may regulate the irrigation of a sewage farm to such a nicety that no odour from the sewage is perceptible in the district; yet the atmosphere will contain poisons which will have a very detrimental effect on the health of those living there.

For a few years after sewage farms have been laid out, they pay, and you get good crops from them, but after that the ground becomes so soured that the farm is almost useless.

In face of these facts no surveyor should hesitate to bring forward known improvements to his Board.

Many owners of property have recognised the importance of adopting the best sanitary measures for their houses, although in some cases it is only a plea to let or sell their property. As an instance of this, some time ago I was in search of a house in the suburbs, and met with one described as standing on good gravelly soil, with good drainage and perfect sanitary arrangements. The builder and owner took me over the house, and on reaching the kitchen pointed out with some degree of pride that the sink was cut off from the drains, and stated that the drains were constructed on the most “scientific principles.”

Now although scientific plumbers have done good work in making our dwellings more healthy, they have in many cases overdone the matter. The fact of their displaying conspicuously, on signs and billheads, “Sanitary work executed on the most scientific principles,” is not always a guarantee that a healthy house can be received from their hands.

In the house above referred to, everything to the eye appeared sound and good, but on the house being occupied, a disagreeable odour was noticed in the kitchen, and in some of the lower rooms. The sink-pipe, which was pointed out by the builder as being “cut off,” ran from the sink trough without a trap or water-seal of any kind, and through this pipe, when the doors were shut, the air was supplied to the building at the rate of 180 feet per minute. The back of the W.C. was ventilated from the outside to give free ventilation to the space under the seat, and through the ventilators (which were working as inlets) the air came into the house, which supplied the bedrooms, passing over the pan, between it and the seat.

The above is an illustration of a house where the sanitary arrangements were supposed to be on the most scientific principles! Fresh air being supplied to bedrooms by passing over the closet-pan, and in the kitchen and rooms below by passing through a 2-inch sink-pipe. This is one of the many cases that may be mentioned to show the necessity of testing any system of drainage and sanitary fittings.

This is not an unusual occurrence, as thousands of similar cases exist, where the principal air supply passes over sanitary fittings or through apertures which bring it in contact more or less with decomposed matter. In a building where a number of fireplaces exist, a constant current of air is passing in from the outside, which after mixing with the air in the building escapes up the chimney. An ordinary chimney extracts from the room from 60 to 120 cubic feet of air per minute, thus in a ten-roomed house you have going out of the chimneys at least 1000 cubic feet of air per minute. When the house is closed this large volume of air is drawn into it through apertures offering the least resistance, whether it be ventilators in the w.c., kitchen sinks, or drains in the basement (which traps may have been siphoned), over sanitary pipes or through doors and windows. Whichever point offers the least resistance, there the supply to feed the chimneys will come.

The injurious effects on the health of persons who occupy buildings that take in their air supply through unclean apertures are too well known to those medical men and others who have had experience in sanitary matters, and it can be only estimated by results. I could enumerate cases where the health of the inmates and the death-rate were conclusive evidence to prove the disastrous effects produced by air being supplied through such inlets. One case in particular, which consisted of eight blocks of buildings planned exactly alike. The drains were cut off on the outside at the foot of all soil-pipes, and a second disconnection about 50 feet from the building. In one building the basement was drained into the branch drain with a trap in the inside, and from the quantity of water and soil which flowed through this branch drain the basement trap was constantly being siphoned, leaving a 6-inch air supply into the building through 50 feet of drain. This, combined with 200 feet per minute through the W.C., had the effect of causing an unusual depression of spirits in the occupants of this building, and more deaths occurred in this one block than in the whole of the others.

It does not require a large amount of scientific knowledge to ensure a healthy building. What is required is sound pipes, the area of them in proportion to the work they have to do, tight joints, and a knowledge of ventilation. Nothing must be left to theory. A pipe either leaks and lets out the soil, or it is sound. If it is sound, sewage matter can be carried through it anywhere without the slightest injury to health or unpleasantness of any kind. Pipes can be ventilated without traps being siphoned, and the gases from sewers and soil-pipes treated so as to ensure healthy buildings at a moderate cost.

As a rule, the first intimation of any defect in the drainage system of a town or the sanitary fittings of a building is given by the medical officer of health or the medical attendant of the family, whose attention has been forcibly drawn to it by the serious illness of the inmates.

It is no unusual occurrence, that after the medical officer, surveyor, and inspector of nuisances have made a minute inspection of a building, they leave it without discovering defects which exist in pipes carefully cased over, or in the sanitary fittings.

To detect the manner in which poisons from drains are thrown into a building and inhaled by the occupants, is oftentimes not an easy matter. In many cases the drains have been so cut about and additions made to them, that to trace defects or even the number of drains which are attached to the branch drains or sewers, a considerable amount of excavating is necessary.

The system described in these pages is intended to prevent in a measure this excavating, and to enable a person above the ground to determine the number, capacity, and state of the drains underneath the surface, as well as to more readily discover any imperfections in soil-pipes and sanitary fittings.

When sewers are laid to a town or district, it is the practice of the authorities to let the work by tender, the lowest tender being oftentimes accepted; consequently it is in the interest of the contractor to get the work done as quickly and cheaply as possible.

It is impossible for the engineer, or clerk of works, to see the whole of the work done, and the result is that a large quantity of bricks which form the sewer are not properly bedded. Liquid sewage finds its way through the joints of the brickwork and percolates through the soil, in some cases to a very considerable distance, contaminating the water it mixes with on its course, and oftentimes it forms a putrid mass under the basement of buildings which happen to be of a lower level than the sewers. To prevent this, a clause should be inserted in the contract that each length of drain or sewer should be tested by atmospheric pressure, say 5 lb. to a square inch.

The top of the sewer should be as tight as the bottom to prevent any gas escaping through the sandy soil or rubble which may be filled in around the sewers or drains.

Leaky sewers and badly-jointed pipes under the soil should never be allowed, yet the danger is not so great in them as in those pipes laid above the ground. Joints to these pipes so often leak that without testing them thoroughly when laid, one leaky joint would cause an unpleasant odour in a building for years without its source being discovered. The reason of this is, that the current of air passes through buildings in a thousand different ways. I have known a sickly odour to come from a cupboard on the first floor of the wing of a building some 60 feet from any soil-pipe or grating; one case in particular, that of a nursery cupboard. This occurred through a leaky soil-pipe from the closet in the basement of the building.

From the planning of the building the chimney near the cupboard had the greatest draught of air in the house, and the air which supplied this chimney came principally from the basement. The sewer gas from the leaky joint, being of a heavier gravity than the atmosphere of the house, was carried along the floor unobserved to this particular room, filling at night, when the fire was not burning, this cupboard, which contained linen, and this held the impurities given off from the leaky joint in the pipe.

Many cases of a similar nature could be mentioned, where families will never recover the loss sustained by them through similar leaky joints in the soil-pipes.

Insufficient fall to sewers does not often occur in those laid under the supervision of engineers, but it is in the branch drains connected to them where so many blunders are made. Oftentimes one part of a drain is laid almost level, whilst another part is laid with a steep gradient. This facilitates the choking of drains, and the siphoning of traps.

Some persons lay drains from houses to the main sewer or to branch drains which are altogether out of proportion to the work they have to do.

The smaller the drain is kept the better, but the diameter should be regulated according to the quantity of water and soil flowing into it, taking into consideration the possibility of additional inlets being added.

The best plan is to collect the number of inlets or supplies to the drain, compare them with the gradient to which they are laid, and put in a drain which, if all the inlets are supplying water at the same time, would not fill more than nine-tenths of its area.

In some cases I have seen a 9-inch drain laid from a house having only two closets, sink and bath outlet attached. If the whole of these were used at the same time, the area of the flow into the drain would only be 7·696 inches, but in the 9-inch drain the area would be 63·617 inches, or nearly nine times the size required to carry off the water and soil.

The whole space not occupied by water and soil is filled with gas, which extracts poisons from sewage and distributes them at outlets according to the displacement caused by the water and soil entering and flowing through the drain.

Architects and builders laying drains to houses or buildings should discard the theories of any persons who do not keep to this rule: that the smaller the drain is, the better, providing it does not fill; and the least quantity of gas there is in the drain, the less dangerous will be the poison in the gas when discharged through openings or gratings. The reason of this is, that in a small drain only a small quantity of the sewage is exposed to the action of the gas in transit; whereas in a large drain the greater portion of the sewage is exposed, thus increasing its decomposition.

When storm water from houses or land enters drains, great care should be taken to form openings or inlets near where drains are likely to fill, as the injurious effects of trap siphoning are of serious consequence to health.

In many cases the construction of new drains and sewers in a district have been simply a waste of money as regards improving the health of the inhabitants, and numerous cases of zymotic disease, and in some cases an epidemic has occurred where previously such diseases were almost unknown. This is caused principally by connecting old drains (some of which are disused ones and connected with old cesspits) to the new drains leading to the sewers.

In cesspits and old drains the soil and putrid matter have been for years allowed to accumulate, and the poison from such matter, when distributed into the open air through gratings in the new sewers or into houses, is, when inhaled into the system, the cause of these zymotic outbreaks. In tracing these old drains and in preventing stagnant gases from remaining in any portion of the drain, the engineer or architect cannot pay too much attention, as confined gases when charged with poisons from putrid matter are the principal factors in producing disease.

Many persons place a well-constructed trap at the inlet, and another some distance along the drain, say at the end of a building or grounds, without any ventilation between the two traps. In fact this used to be a common occurrence; but it should never be done. If the drain should be a 6-inch one, and the traps 50 feet apart, the amount of gas between the two traps would average 9 cubic feet, and this gas would in the ordinary working of the drain remain for years, getting more poisonous the longer it remained undisturbed. The owner of the house, knowing that he had a good trapped drain connected to sewers, would feel himself safe, and naturally think his house healthy. Far better for him if the house were drained into a ventilated cesspit, as when the gases in the drain became released, which may occur by the siphoning of the traps at the house-connection, the danger would be equal to the emptying of a disused cesspit, and carrying the contents through the house. The more a person tests the working of gas in sewers or drains the more he will find that branch drains from their construction supply the poisons which render the gases in the sewers themselves so noxious.

In 1880, whilst engaged in tracing the course of an outbreak of typhoid, I made a series of experiments with a view to trace the source from which the disease emanated, and every experiment proved that the origin of the disease lay in the gases which were in contact with putrid sewage matter, existing in old drains and cesspits attached to the sewers as well as in the gases which were confined between traps. The distribution of the disease was due to the imperfect construction of the sewers, drains, and sanitary fittings.

The most successful experiment, and the one from which the greatest result was obtained, and which I have ever since most successfully used, was in determining the state, size, and condition of the drains underground, and also that of the house or buildings, by measuring by compression the gas contained in the sewer or sanitary fittings. The principal cause of its distribution was the compression of the gas between the water-traps, the siphoning of house-traps leaving at times a free passage for the gas to enter the house.

The amount of compression or displacement necessary to force the gas in bulk through the traps has been accurately measured, to know what quantity of liquid was required to be thrown into a drain or sewer of any size to force the gas in bulk through the water-trap. The lifting power of the gas on the water by compression was found to be 1
300 part of its bulk. Thus, if a drain perfectly sound, and sealed with a water-seal each end, held 300 feet of gas, 1 cubic foot of water thrown into the drain would force the gas in bulk through the water-seal.

It became evident, that if both ends of any drain were sealed with a water-trap or otherwise for testing, the capacity of the drain or leaks of any kind could be determined without excavating.

As it was inconvenient to watch the working of the drain through the traps, I constructed an instrument called a detector^[1] to observe the working of the atmosphere in the drain. This instrument, or a gas-pressure gauge, when attached to the drain, will denote by the rising of the liquid the amount of compression in the drain. This, when compared with the quantity of water thrown into it, will give the size and capacity of the drain, and will also indicate any siphoning of traps or leaks which exist in any of the sanitary fittings of the house.

The following table will show the amount of gas in every 100 feet of circular pipe or drain, from 4 to 30 inches in diameter, also the amount of water thrown into a trap to produce the necessary pressure of gas to lift the liquid 1 inch in the detector or pressure gauge: the quantity being as near as possible 3? ozs. of water to 1 cubic foot of gas space.

The method of testing drains and fittings by compression of gas is as follows:—When the drainage plan of a building exists, the work of testing by compression of gas in the drain will be a very simple matter.

Plate 1 shows the drains as laid to a semidetached villa, with two inlets from sinks marked 1, one from bath overflow marked 2, and two from the soil-pipes of closets in the basement and first-floor marked 3. The drain from A to B is a 6-inch stoneware pipe, and its length is 100 feet. The amount of gas in it would be 191096
1728 cubic feet. The branch drains from the other inlets are 4 inches in diameter, and the collected lengths are 50 feet, and the quantity of gas in them would be 4627
1728 cubic feet, giving a total in the whole of the drain of nearly 24 cubic feet.

If the indiarubber pipe to the detector or pressure gauge is placed in either of the traps marked 1, and the glass tube filled with liquid up to the data line, 5 pints of water poured into either of the traps marked 1, will produce a rise of 1 inch in the liquid of the detector, that is if all the drains are clear and joints tight, the drains being stopped off for testing at A.

Should a trap be fixed anywhere between A and B a lesser quantity will be required to lift the liquid, and the position of the trap can be determined by comparing the exact quantity of water used with the capacity or quantity of gas in the drain.

If a trap should be fixed or a stoppage formed in any part of the drain A B, the flushing of a closet or sink would, by the compression of the gas, force it in bulk through the weakest trap, or the one having the least dip or seal. The quantity which would pass through would depend on the amount of water used in the flushing and the fall of the drain.

The drains to the building having been tested, and their defects ascertained, it will be necessary now to test the soil-pipe.

On this plan it is fixed on the outside of the house, having a trap with an open grating just beyond the basement closet, and a ventilating pipe carried above the eaves of the roof. Whether the soil-pipe be fixed inside or outside of the building it should be perfectly gas-tight, and in this testing a person cannot be too particular.

In testing the soil-pipe shown on plan, the easiest method is to put the detector or pressure-gauge at the grating of the trap 3, placing the indiarubber tube over the grating, and making a tight joint with clay. Then close the top of the ventilating pipe and pour water in the top closet, when, if the joints are tight, the liquid in the detector will rise suddenly, and then lower itself as the water leaves the trap, indicating that the soil-pipe is tight, but if it is not tight, no rising of the liquid will take place. Should there be no trap at the bottom of the soil-pipe, it will be necessary to excavate down to the drain to take out a length of pipe, to seal the mouth of the drain with clay for testing. If there should be leaky joints or holes in the soil-pipe, a little sulphur burnt in the pipe, or a little pungent essence thrown into it, will clearly denote where the leaks are.

Having tested the soil-pipe and proved it tight, or effectually stopped all leaks as the case may be, no gas can be given off in these drains or fittings except through the ventilators (under ordinary circumstances) as no trap has been siphoned in the testing.

As before stated, the ventilating pipe runs to the top of the building of the same diameter as the soil-pipe, in fact this is a plan of drains to a house recently built in the suburbs of London, and the planning of them would be considered perfect by many sanitary men, but before we testify them as perfect, let us carefully analyse the working of the ventilation.

The ventilating pipe being carried above the roof is strictly in accordance with the bye-laws of the Local Board, although it spoils the appearance of the house. One reason why it was put there is to prevent the siphoning of the closet trap, and its height is to carry out the recommendations of medical writers in the Lancet who have so often insisted that these tall pipes, carried some feet away from chimneys or bedroom windows, were necessary.

Let us test this theory.

We will flush the closet by throwing down slops and giving the closet the regular flush, carefully testing what takes place. The result is that the soil-pipe, instead of carrying off the odours from the top, only forms an air inlet, and 2¼ cubic feet of air has been sucked in at the top of the pipe, and the same quantity of gas discharged through the grating. As this grating on the plan is only 2 feet from the passage door which leads into the kitchen, the least that occurs is that a portion enters the house, and the cook has a slight headache when preparing the meals for the day.

To be more certain of this let us test the working of the ventilation by a dozen flushings of the closets, and the same results are obtained by measurement, 27 cubic feet of air entered the top of the pipe, and has been driven out at the grating below. This proves that it is unnecessary to spoil the appearance of our houses by the erection of these pipes, or of carrying them above the soil-pipe or closet level.

It would not be consistent for me here to state how these unsightly pipes could be avoided, but I am confident that ere long they will become obsolete, although they have been erected by thousands in various parts of the country.

We will now test the working of the ventilation in drains A B, and those in branch drains to traps marked I. As they are clear, we find that the gases in them are not so poisonous as in the sewers to which they are connected.

A manhole grating exists in the sewer some 40 yards from the back of the building, and through this grating the gas which is driven by the flushing escapes, and its density depends on the nature of the soil passing in the sewer. Its density is lessened by diffusion, or the mixing of the gas which takes place at the grating, but the time it takes for the gas which is in the drain near the traps I, to mix with the fresh air at the grating in the street is a problem that I will leave others to solve. We are certain that no gas in bulk can pass through the trap under ordinary circumstances.

We can now certify that the drains are tight, well trapped and ventilated, they are laid strictly in accordance with the bye-laws of the Local Board, and we can quote that similar plans were exhibited last year at the Health Exhibition, as models for country architects and builders to copy; and ninety-nine out of every hundred sanitary inspectors would sign the certificate that the sanitary arrangements were carefully tested, and found perfect.

Experience in working the detector will not allow me to do this. Although for months not the slightest particle of sewer gas has entered the building, until one evening about eight o’clock a sickly smell is observed in the kitchen, and this is attributed to a change in the weather, heavy rain having fallen during the day, and no notice was taken of it before retiring to rest. In the morning the house is unbearable. The inspector of nuisances is sent for, who cannot detect anything wrong in the drains. The surveyor to the Local Board visits the house with the same result, and it is not until the middle of the day before the nuisance has abated, its cause still a mystery to the sanitary officials and to the owner of the house, who is a medical man of great experience in sanitary matters, and a sanitary writer.

Now what really did occur was this. The sewer at the back nearly filled with water and soil caused by the heavy rains, and when this was rising, about 2 cubic feet of gas was forced from the drain B through the grating at the bottom of the soil-pipe. The junction where the drain at A joined the sewer was made as usual about two-thirds the height of the sewer, consequently the drain from A to B filled some 20 feet during the storm. When the storm abated, the water leaving the drain at A sucked the trap at the bottom of the soil-pipe 3. The seal being gone, the gas from the sewer at once came through the trap, the current being estimated at from 80 to 200 feet per minute; so that the quantity of gas given off at the trap, which is 2 feet from the door, would be about 2000 cubic feet from the time the trap was sucked until it was filled again by the flushing of the closet.

This is by no means an exceptional occurrence, two similar cases occurred in the suburbs last year. In one case the owner of the house was seriously ill for several days, and was for some weeks obliged to neglect his business and seek a change of air. In the other case the daughter was taken ill with a zymotic disease which nearly cost her her life, and it was months before she regained her strength.

The easiest method of preventing this siphoning of the traps is to fix a small mica valve at the most convenient part of the drain between A and B, fixing it above the ground. You can also prevent it as well as the gas coming near the house by putting in a trap at A and having an open grating between A and B. This would not prevent the 2000 cubic feet of gas before referred to from escaping from the drains, but would cause it to be discharged some distance from the house. You would also have about 23 cubic feet of gas in the drain always mixing with the atmosphere of the garden at this point when the traps are full and tight.

Plate 2 shows the plan and drains of a hospital which I tested by this system in 1880. As it was an old building the testing was somewhat different to that described in Plate 1.

For years a sickly smell was observed in the ward, and more especially when the heating apparatus was at work, and it was thought to arise from the number of bad cases in the ward. A good system of ventilation was adopted by the introduction of fresh air through flues which ran under the floor to the whole length of the building, and in winter the air was warmed by passing over hot-water pipes in the flues, and was distributed at various parts of the ward through open gratings in the floor, with a good extraction in the roof, which was open to the ward, but ceiled over the rafters.

Double the amount of fresh air was admitted, warmed, and extracted, with a view to improve the atmosphere of the building, but with no better results. I then decided to test the drains which were shown on the plan of the building as on Plate 2, the drain marked A B being tested first by stopping it off and fixing the detector at B. This being a 9-inch drain pipe and the length 130 feet, gave 57600
1728 cubic feet as the contents of gas in it. Adding 6 cubic feet for the branch drain at C, making a total of 63600
1728 cubic feet.

The amount of water required to be thrown into the trap A would be 1 gal. 5 pts. 3 ozs. to produce the necessary pressure of gas in the drain to lift the liquid 1 inch in the detector. Instead of taking 1 gal. 5 pts. 3 ozs., it took 7 gals. 6 pts. 9 ozs., giving an additional 237 cubic feet of gas space to be somewhere attached to the drain. This could not be leaks, if it had been the liquid in the detector would not have risen at all.

The ground was opened at D, the drain sealed, and the detector fixed, and the total quantity of gas in the drain by measurement from the seal to trap A was found to be 46 cubic feet, and by testing this was found to be correct, consequently the additional gas space was between B and D.

I particularly noticed that the gases in these drains were more poisonous than they should have been, considering the nature of the sewage flowing through them, and by using a reagent as a liquid in the detector, its discoloration indicated that the gas was in contact with a large quantity of putrid matter which was of a different character to that of the sewage flowing in the drain.

A drain searcher, or pointed rod was used, and after driving it into the ground a few times, it struck the large cesspit E, and by the sound given it was clear that a drain was underneath, when, on excavating, the old cesspit and drains shown on Plate 3 were discovered, containing more than 60 cubic yards of black putrid sewage.

The junction at F was cut off and the drain made good, when a second testing by fixing the detector at B gave the quantity of gas in the drain to be 63600
1728 cubic feet.

The cleaning out of 60 cubic yards of sewage and the removal of the old drains did not in the slightest degree diminish the nuisance inside the building, consequently the 15-inch drain on the opposite side of the building was stopped off at G and H, and in testing the detector was placed at G. This length of drain being 140 feet contained 1751098
1728 cubic feet of gas, and 4 gals. 4 pts. 8 ozs. of water thrown into the trap H should have lifted the liquid to the usual height in the detector. This and a similar quantity of water did not indicate any compression, but the discoloration of the reagent in the detector was much quicker than on the drain which was first tested.

The drain was then opened at I, dividing it into two sections, that from G to I containing 93 cubic feet. Testing this by 2 gals. 3 pts. 6 ozs. of water gave the exact rise in the detector, consequently the leaks and bad gas must be in the section from I to H. This was tested by a fresh reagent in the detector, when the speedy discoloration of the liquid indicated that the source of the poison was very near.

By a few piercings of the ground at K, by the iron rod or searcher, the drain was found, and by following the old drain the two cesspits and additional drains shown in Plate 3 were discovered, and about 150 loads of old putrid sewage had to be excavated and cleared away. The leaks which prevented the rise of the liquid in the detector were in the crown of the old sewage tank M, and the hot-water pipes of the heating apparatus running in an air-shaft just over it, the heat extracted the poisons from the sewage and distributed them into the ward.

The connections at K and N having been stopped up, the drain from I H was again tested, when it gave 36 cubic feet more gas space than there should have been in the drain. A few piercings of the soil at O led to the excavating of those old drains which are shown attached, and these being excavated and cleared away, and the connections to drains K, N, and O being stopped, the drain was again tested from I to H, when compression in the detector took place in comparison to the exact quantity of gas that should be by measurement in the drain.

In describing the method of testing drains as shown on Plates 1, 2, and 3, nothing has been mentioned as to the level to which branch drains to houses should be laid, or the method of testing them to ascertain their fall.

The fall given to branch drains should not be less than 1 in 100, but 1 in 80 is far preferable, and if the drains are laid to this level, water will flow easily through them, but should any part be laid out of a level the water would lay in them and thus give a less quantity of gas. Then when tested by compression to the capacity of the drain the lesser quantity would denote the nature of the dip.

When a plan of drains exists, as in the two cases shown on Plates 1, 2, and 3, the difficulty of testing them and proving their defects will not be as great as when no plan has been made. If no plan has been made or no record kept of them, it is best to make a rough plan of the building, fixing the positions of all inlets, their sizes and lengths, of branches to the drains on the premises, and also to lay down on the plan the length and size of this drain to where it reaches the extent of the property or joins the main sewer, opening the ground for testing in a similar manner to that described in Plate 1.

In testing pipes or sanitary fittings of any kind, leaks can be easily found by attaching the detector or pressure gauge to the most convenient part of the pipe or fitting, and when everything is sound care should be taken to flush all inlets at the same time, to ascertain whether the rush of water has any effect on the traps or water-seal. If the vibration in the detector or pressure gauge exceeds 2/10ths of an inch, a freer gas space must be provided, or the action of the water checked in some manner. Pipes, whether sanitary or otherwise, can be tested as to tightness in a similar manner.

Some modification may be necessary in testing large sewers or the drains of a district, but if the testing is performed in a similar manner to that adopted in the above case the condition of the drains and fittings can be accurately ascertained. The least pressure or suction on the traps of drains or fittings will be shown by the vibration of the liquid in the detector or pressure gauge when the water passes through the pipes with flushing.

The term “bad drains” is not exclusively confined to those drains that have leaky joints, or have an insufficient fall, or traps which siphon during the passage of the water, but may also be applied to systems of sewers in general. There are two points in almost every system of drainage that call for some improvement. The first is having the inlets at junctions where small drains join sewers at the side of the sewers. Thousands of traps are being continually siphoned by this cause as soon as the water fills the sewer above the inlet of the branch drain, as this, when filled with water only a short distance, forces gas through the weakest trap, and on the water and soil lowering itself in the sewer, this water acts exactly as the plunger of a pump and draws the water out of the weakest trap. This is often the one in the area or basement of the building, and to avoid this all inlets at junctions should enter the top of the sewers, not for the soil to drop down so as to cause the sewers to silt, but in an oblique direction with the sewage flow. The second point is in the ventilation of sewers, which is not an easy subject to handle.