Chapter II: Introduction (2)

“Make proper provision for the ventilation of sewers and drains in such a manner that there may be a free current of air in them in the direction of the sewage flow.”

It was also recommended “that the stack pipes should be connected with the sewers without the intervention of traps, in order to assist the ventilation, and there should be no trap between the trap at the inlet and the sewer.”

This system was found far worse than the open gulleys or shoots in the City in 1830, as at Croydon (which was one of the first towns to carry out works of sewage under the General Board of Health) no sooner had the sewers been in use before an outbreak of fever took place.

Dr. Niell Arnott and Mr. T. Page, C.E., were appointed by the Home Secretary to report on the outbreak at Croydon, and Mr. Page in his report states—

“Whenever a water-closet even with the best form of siphon trap is introduced into a house, it will be well to provide an escape into the open air. When several soil-pans or sinks from the apartments of a large house are discharged into a common soil-pipe or vertical main, the main should be continued up to the roof and to the open air, and if practicable it should be carried near the chimney. Pipe sewers must also have ample ventilation provided at all available points. If the air is confined it is most dangerous when it breaks forth, which sooner or later it will do, such evils would have been avoided.”

It is quite evident by these remarks that the system of ventilating the City sewers in 1830 was more perfect than at Croydon, and had Mr. Page tested the sewers and sanitary fittings by the compression of gases in them, he would have found that the action of the water in the pipe prevented the gas from being confined.

In 1858, Mr. Goldsworthy Gurney made experiments in the neighbourhood of the House of Commons by connecting a number of the sewers near with the furnace of the clock-tower, and this was reported on by Sir Joseph Bazalgette as follows:—

“I find that the furnace of the clock-tower of the House of Parliament was supposed to have been connected with the adjoining district to the extent of about a quarter of a square mile, and with about 6½ miles of sewers, but that the ventilation had in reality been intercepted by a flap so that the benefit supposed to be derived therefrom was purely imaginary. Having come to that conclusion, the next thing I directed my attention to was, supposing the whole of the air extracted by that furnace was produced from the sewers, and supposing that all the intermediate channels could be stopped, and that it could be directed from the most remote ends of each of the sewers, and distributed over those sewers with the most perfect theoretical accuracy, so as to have uniform currents passing through each of the sewers towards that chimney, still the effect on those sewers would be nothing, and the way in which I prove my statement is this: the total area of the 6½ miles of sewers now connected with the furnace is 713 feet, the total area of the channel through which the air has to be brought from them is 8 feet, that is about the ninetieth part of 713; the air was passing at the rate of 542 feet per minute through the 8 feet area. Therefore, if I could divide that over the whole district, the velocity in all those sewers would be 6 feet per minute or ⅕ of a mile per hour. But we have shown already that there exist in the sewers from other causes velocities amounting to 100 feet per minute and upwards; and 6 feet per minute is practically speaking stagnation and not ventilation.”

This experiment was undoubtedly one that if it had been continued (instead of being abandoned), and the errors corrected, would have led to a more practical result. The area of the air space to the furnace was 8 feet, and the current 542 feet, or equal to 6 miles an hour. If this current had been the same in the sewers as in the channel, the suction produced on the water-traps of the small drains attached would lift the water in each trap a little more than 3 inches. But as the ordinary trap has only an average 2-inch dip, the weakest would have been at once sucked and the experiment a failure. Had the dips of the traps been 4 inches, the drains would have remained sealed except at the intended inlets. The air being supplied at the ends would have gone through the sewers without breaking the water-seal, providing that the air space between the crown of the sewer and the sewage was not in any way blocked. If the current in the sewers had been less than 200 feet per minute, the ordinary trap would have effectually sealed the various inlets.

Had the average area of gas space above the sewage been 8 feet, the whole of the 6½ miles of sewers would have been emptied of its gas and supplied with fresh air in about an hour. The different areas should not have been considered, but the total quantity of gas taken.

The velocities of 100 feet here mentioned, is accounted for as follows. Should the sewage in any part of the sewers lower itself, causing an additional gas space in that part of the sewer, the rush of gas in the sewer to fill the space would cause this 100 feet per minute current.

These hitherto unaccountable currents in sewers and drains are produced by the variation of the gas space above the sewage, the result of water being thrown in at the various inlets.

The gases of a sewer may be passing backward and forward in currents varying from 100 to 300 feet per minute, and not any ventilation would take place except at the gratings, and this would be very little indeed when the gas in the sewer was of a heavier gravity than the atmosphere.

Speaking on the same subject, Colonel Haywood says, “a down draught so complete as to be superior to the diffusive power of the gases, you cannot start with a velocity of less than 2 miles an hour, and suppose the whole district has been so arranged as to have a sufficient exhaustive power, the mere opening of a water-closet, or the enlarging or the putting in of a new drain into a sewer, or the making of a hole a foot square, or a servant taking up a bell trap in a sink, or a sewer-man lifting a side entrance covering, would very much destroy the power of the furnace, and unless you had a gigantic power sufficient to guard against these casualties the system could only be a failure.”

What is here meant is, suppose that if the whole of the 6½ miles of sewers were emptied of their gas at a velocity of 2 miles an hour, the poisons from the sewage would not be noticeable or injurious in the atmosphere of the drain. If each inlet to the sewer was trapped, the opening of a water-closet or the opening of a bell trap in the sink would not have affected the 2 miles an hour current in the sewers.

Had the currents in the sewers near the furnace of the clock-tower been kept at 2 miles an hour, the traps being tight, and attention been paid to the compression of the gases in the sewers by the water entering them, the experiment would have been in a measure a successful one.

From 1855 to 1872, Sir R. Rawlinson, C.B., Dr. A. Miller, and Sir Joseph Bazalgette were carrying out experiments with charcoal trays and screens, and a committee of the Metropolitan Board of Works in their report, say:—

“The results were sufficiently favourable to warrant the use of charcoal ventilators in connection with such air-shafts as were sources of annoyance and complaint, but their adoption had also the effect of diminishing the upward current of foul air through the shafts and of confining it to the sewers, thereby endangering the safety of the men working in them, so that it is necessary that such ventilators should be cautiously and not generally applied.”

These experiments in sewer ventilation were the most valuable of any yet made to solve the question, but their failure could be attributed to the following results.

The working of charcoal in the extraction of poisons given off from sewage in its transit through the sewers, and which poisons become mixed with the gas, and the placing of charcoal in layers or baskets so that the gas should pass through the interstices of the charcoal, is without a doubt the best method of dealing with charcoal as an agent in arresting or picking up the poisons from putrid matter which is contained in the gas. But the obstacle this gives to the supply or exhaust of air to the sewer is greater than the power of the water-trap: consequently traps are sucked or forced, and the inlet of fresh air takes place through them into the sewers.

The gas from the sewer escapes through the weakest trap into the house, thus nullifying the effects of the charcoal trays and rendering them almost useless. The passing of the gas over the tray would prevent this, but experiments prove that charcoal has not the power to attract and retain the poisons from the sewage, and which is retained in the gas. Thus these poisons pass over the charcoal through the grating into the street.

These experiments prove that if the poisons from the gas are extracted at the outlets, and the drains into sewers trapped with a water-seal, and the siphoning or forcing of traps are prevented, sewers can be ventilated without being a nuisance or prejudicial to health. But it must be borne in mind that the instant the current of air in sewers, drains, soil-pipes, or sanitary fittings exceeds a velocity of 3 miles an hour, even if they have open ends, no trap with a 2-inch seal is safe from being siphoned.

Many surveyors state that sewer gas is uncontrollable. This is an error. The gases of a sewer are as controllable as the atmosphere of a room. It is the compression of the gas caused by an increase of water in the drain, and the temperature of the atmosphere on the surface of the ground at the various points where the gratings are fixed, which makes the currents of gas in drains so uncertain. The sudden lowering of the sewage in a drain will stop the nearest gratings or shaft from working as inlets.

What led engineers to form this opinion was the failure of experiments with motive power to get certain results in ventilating sewers, the same as in a building. It is impossible to get ventilation to sewers through open gratings except the inlets from the house drains are sealed with a water-seal.

The unsatisfactory results obtained from many experiments in sewer ventilation have not been the fault of the plan or the appliances used, but arose from the wretched manner in which house drains have been connected to the sewers.

I shall never forget the testing of some sewers with a view of improving the ventilation of them. They were public sewers and almost new ones, and as far as the sewers themselves were concerned you could not have had better, both as regards a good fall and tight joints. But the manner in which the connections were made to them was something astonishing. Untrapped gulleys at the sides of the streets, drains from the sewers into the kitchens of houses without a single trap. In some cases two or more traps were fixed according to the whim of the owner of the house. Rain-water pipes from the flats of windows on the ground floor were connected to sewers without traps, closets with no ventilating pipes, and a dozen other imperfections were found on the branch drains and fittings.

Before completing the tests of these drains and fittings, I suggested that all faults and errors found in connection with the branch drains should at once be remedied, and each drain be connected to the sewer with a trap, or else it would be of little use to improve the ventilation of the sewers. I was quietly informed that this could not for one moment be entertained, as where these evils were the worst was on property belonging to members of the Local Board, and any attempt to pass a resolution to compel this to be done would be futile, and the necessity of doing it attributed to the zeal of local sanitarians.

I am glad to say that cases like this are exceptional, but there are many towns where similar evils will remain until an epidemic breaks out and the authorities are compelled to have them remedied. The amount of air passing through the sewer is no indication of the ventilation or the amount of air that is being admitted, or the quantity of gas charged with poisons that is given off. I have tested the gas in a sewer and at the ventilating shafts, and have repeatedly found the gas in the sewer flowing at a high velocity whilst the air in the open ventilating shaft was perfectly stagnant.

I have not been able to make experiments to know how long gas will remain in a sewer, but from observations of its gravity and working in different localities I believe that the poisons from sewage matter are retained in the lower strata of the air of sewers in some cases for months, and when open gratings are only 50 yards apart. The quantity of air taken in at the gratings at this time is a little more than the displacement caused by the water, and when gases are released to any extent it is through atmospheric influences.

If you measure the amount of air going in and out of say twenty open gratings in the same locality, the small quantity would astonish those who had not previously tested it.

Repeatedly has it been written and said that if you put a shaft or grating at the top of a hill, or sewer, it will take off the impure gas of a district, but I have had men working for days at the top of a sewer 150 and 200 feet higher than the lowest grating, and no trap intervening, yet during this time not a particle of gas left the drain at this the highest opening, but at times a good inlet current would take place down the drain.

I find that one of the most fatal mistakes to make in sewer ventilation is to introduce a large quantity of fresh air into a sewer at a high temperature. An atmosphere at from 90° to 100° thrown into a sewer will rapidly decompose sewage matter and produce results exactly opposite to that intended. It is when the hot atmosphere of a summer’s day comes in contact with the sewage in the sewers that the worst poisons are generated and given off, and the gases which come from the gratings are the most noxious. This rapid decomposition is more particularly felt in the suburbs, where the drains are of stoneware and the sewage has to be carried through them for a considerable distance.

Common sense teaches us that all matter of a nature like that passing through sewers will decompose more rapidly and reach a higher state of putrefaction in an atmosphere of a high temperature, even above ground, than in any other condition. Experiments confirm this to be the case whether it be applied to matter in sewers, vaults, or tanks. The best experiments that I have made in sewer ventilation is in keeping the temperature as low as possible, admitting into the sewer sufficient air to prevent any action taking place on the water-seal, and what gas came out of the sewer by compression to purify it at the gratings, extracting the poisons that it had taken up from the sewage.

Many gases which are found in sewers have an affinity to water, and will make their way to the water-seal and become absorbed in the water of the trap to some extent, but not to the extent many persons imagine, or to become detrimental to health.

When a disinfectant having a greater attractive power than the water is used in connection with the ventilation, this attraction to the water-seal will not take place.

If necessary, in hot weather or in large sewers, or those of an easy gradient, cold air of a very low temperature could be introduced, which would prevent decomposition taking place to any extent during the transit of the sewage. If the whole area of a system of sewers was charged four times a day with air at a temperature of 30° we should have no complaints of sewer gas.

The details of such plans would be out of place here as they are the subject matter of several patents, but sewage can be carried through districts without its gases being injurious to health or without sewage being subjected to rapid decomposition almost as easily as meat is now transmitted from New Zealand to England without any decomposition taking place during its transit.

Before leaving the question of sewer ventilation it will be well to note the results obtained by the valuable experiments I have quoted, and which have been made from time to time by the City Commissioners and the Metropolitan Board of Works. One cause of the failure of these experiments has been conclusively proved to be due to the wretched condition of branch drains and house connections attached to the sewers on which the experiments were made, and these are in a measure out of the control of the officers of these Boards; and until a proper survey of branch drains and house connections has been made, and traps placed in proper positions, the ventilation of these sewers will be almost as imperfect as in 1830.

The sanitary survey which is now being made in this country by the Local Government Board will fail in one of its most important objects unless it insists on every surveyor knowing the condition of drains under the surface of the ground. A cursory glance at the plans of a district, or a surface sanitary survey will not do very much in arresting zymotic disease, and the staff stated to be employed on this survey is totally inadequate for the work.

To successfully deal with sewer ventilation it should be divided into two sections: (_a_) That of the sewers and branch drains which are directly under the control of the officers of the various Boards, (_b_) Those drains immediately attached to houses, including the soil-pipes.

The necessity for ventilating a sewer is, that in an unventilated sewer or drain the instant a compression of the air in a sewer, between the sewage and crown of the sewer, takes place to 1/300 part of its bulk, gas is forced through the weakest trap according to the displacement of water, and as the water is lowering in the drain fresh air will be admitted into the drain through this trap. Thus if a drain or sewer is not ventilated it will ventilate itself.

Should a sewer be ventilated with open gratings in the centre of the roads, the placing of gratings at a moderate distance apart would diffuse the gas equally in a flat district if the temperature on the surface of the ground at each grating were the same, but the variation of the temperature in streets is such that the heat of the street at one grating will be a sufficient motive power to extract the gas from many sewers through this one grating, the others only forming inlets while the increased heat lasts.

In hilly districts, where the drains are of necessity of a steep gradient, the quick flow of the sewage will cause the gas to pass more rapidly when much sewage is flowing in the drain, the worst gas coming out at the lowest grating, generally a grating before a junction, or where two drains meet of different gradients: but when scarcely any sewage is flowing, the gas will flow to the highest grating. Thus, in putting gratings on steep gradients (if no method of purifying the gas is used), the gratings should not be placed in regular distances apart, but where the gas can be discharged in the most open space.

In hot weather, although ten times the amount of air passes through sewers of steep gradient than in a flat district, the gases from sewers on a steep gradient are far the most noxious. If open gratings only are used on a system of sewers, the gas but not the sewage should be trapped off into districts, not only as the means of preventing the gas rushing in volumes to certain points, but for preventing germs of disease travelling in the gas of a sewer from an unhealthy to a healthy district, which is the case under the present system, by leaving sewers for miles without any gas check.

We have in sewers and drains a power created by the influx of the sewage which is greater than any mechanical means that can be used in the ventilation of them, and it is to get the best method of applying this power that sanitary engineers must direct their attention.

The difficulties that are met with in ventilating sewers with open gratings are so great, that I am convinced that as soon as engineers study the question more fully, the system will be abandoned.

The method of carrying off the soil by water through sewers has proved a good and convenient one, and scarcely any defect can be found in any drainage scheme except that of the ventilation, which is at present one that is condemned by the inhabitants of most towns as a nuisance, especially in hot weather, and by the medical profession as being most prejudicial to health.

As a remedy for this, we must profit by the experience of the early experiments I have quoted, which points conclusively to the fact that if we extract from the gas (which by compression must of necessity leave the sewers at openings) the noxious and disease-producing poisons contained in it, at the gratings, and by those means prevent a rapid decomposition of the sewage taking place, and without putting any undue pressure on the water-seals to houses, we have overcome the greatest difficulty in the work.

In old drains or sewers it will be the work of some time for the surveyor to know that each drain from the house to the main sewer is trapped with a good water-seal, yet this is the most important factor in providing good ventilation.

Some persons have hastily condemned the water-trap, having found out that they have been siphoned by the transit of the sewage. This is a mistake. A properly constructed water-seal or trap that clears itself at each flushing is the best seal for sewer gas. It will not keep out gas if it is forced in bulk by excessive pressure, any more than coal gas can be kept out of houses if a greater pressure is put on at the works than the resistance of the trap in the chandelier. In manufacturing gas, either experimentally or otherwise, water is the seal always used, but we do not attach anything to break that seal when dealing with gas for illuminating purposes, the same as is done in many cases with sewers.

Where new drains are laid, no difficulty in getting a good seal to branch drains need be experienced, and no drain from the house to sewers should be laid without its being completely disconnected or cut off as near the soil-pipe as possible.

In dealing with the ventilation of soil-pipes or vertical drains, many improvements can in future be made. The idea of carrying tall ventilating pipes to the tops of houses was to carry off gas that was forced in bulk through the trap at the bottom of the soil-pipe from the sewer, but in well-laid drains this should never occur. If the drain be disconnected it would leave at the point of disconnection.

The velocity of the water rushing down the pipe, as proved in the previous chapter on drain testing, carries the gas out at the bottom of the pipe, the top of the pipe forming the inlet when odours are given off from the passing soil, but as soon as the flushing is over a return current takes place and fresh air ascends the pipe.

If you do not use any method of purifying the gas which escapes through the pipe, the best plan is to have the pipe as open as possible at the top and bottom, and at all bends, for ventilation. These openings need only be just above the level of the water flow to prevent splashing, and by following this rule those unsightly pipes (which give buildings more the appearance of a distillery or chemical works rather than a dwelling-house or home) can be avoided and erected so as to form one of the ornaments in the architecture of the building.

There is at present too much theory in sewer ventilation, without paying any attention to results gained, or to the laws which control the atmosphere and its action on sewage matter.

THE ORIGIN AND TRANSMISSION OF ZYMOTIC DISEASE.

Whilst making experiments and taking observations five years ago, to trace the origin and transmission of some cases of zymotic disease, I formed an opinion that the theory as regards the transmission of zymotic disease by contagion was to a certain extent an erroneous one.

I mentioned this to some of my medical acquaintances at the time, but as it was so opposite to the prevailing ideas, I was advised not to publish or hold out such opinions, as they were contrary to the theories accepted by the medical profession.

Now that these theories have been severely shaken, and in many cases reversed by medical men themselves, during the past year, I shall plead no excuse, but insert them for the guidance of those engaged in sanitary work.

The source of zymotic diseases may be traced to persons inhaling or taking into the system poisons from putrid sewage matter, and those poisons are conveyed into the body, either in the food they eat, the water they drink, or the air they breathe. Whether they are organic or inorganic, they poison the blood, which becomes more or less diseased, according to their density or vitality, or whether each of the zymotic diseases is produced by distinct organic germs grown and developed from putrid matter under different atmospheric influences, it matters not to my mind in proving the true method by which zymotic diseases are transmitted.

On the origin or source from which these diseases are produced, I do not think there are two opinions, viz. that of poisons from putrid matter, and the question to be solved is in what manner these poisons are conveyed into the system. To do this it will be necessary to quote some cases of zymotic disease and the circumstances which surrounded them.

In a small district, a girl thirteen years of age was taken with diphtheria, and in two days after the younger brother was taken and the other children appeared sickly. From investigation it was certain that the poison had not been conveyed into the system by food or water. The children generally took their meals in the kitchen, the door of which opened into the yard, which was about 10 feet long by 8 feet wide, in the corner of which was the W.C. I tested the atmosphere entering the room at the bottom of the doorway, and found that it contained poisonous matter, and on testing the closet and drains I found a hole 3 inches by ¼ inch in the closet trap. Here was the source of poison which produced the disease. The gas in the drain was confined between two traps and in contact with putrid sewage matter, and when it was removed no poison from any other source could be detected. The first child that was taken ill died, but the other recovered.

Now it is quite evident that the second child did not take the disease from the first, as it had not time to develop. The atmosphere of the room and the breath of the child were not as poisonous as the atmosphere of the kitchen in a line between the kitchen fire and the door, and it was on this line both children sat at their meals, and thus inhaled the poison with their food. Had the gases in the other drains of the district been of the same density as in this one, and similar leaks existed in the sanitary fittings, diphtheria would have spread, and by the popular theory its transmission would have been attributed to contagion from this family, which in face of the above facts would have been incorrect.

Another case. In a large town diphtheria broke out, and some hundreds were attacked and over two hundred died. The source of the disease was not in the food or water, and the only disease-producing poison that could be found was in the gas issuing from the sewer gratings and sanitary fittings. Schools were closed and the usual remedies used to prevent contagion, but all to no purpose. The sewers being of an easy gradient had silted, forming at intervals masses of putrid matter, and in the best houses, where the disease was most prevalent, poisons from the sewers were laid on to them by the badly-constructed drains and sanitary fittings. The authorities at last took the matter vigorously in hand, cleansed and sweetened the sewers as much as possible, and then the disease abated and died out. Had contagion been the means by which the disease was transmitted, it would have continued as it existed in the town under almost every kind of atmospheric temperature.

Here we have evidence showing that putrid matter did exist from which poisons were given off and their mode of transit into the body, but not the slightest evidence to prove the poison passed direct from one person to another.

These poisons in the gas can be destroyed by washing the gas in a chemical solution on leaving the grating, and since this has been done medical men have cured the disease by washing the throat in a similar solution.

Numbers of typhoid cases could be mentioned where poisons from putrid matter were conveyed into the system by water, milk, and impure food, but I have never heard of a case where the poison was detected leaving one person for another.

If in 1883 a person had stated that cholera was not contagious, they would have been ridiculed, yet the principal physician and those in charge of the cholera hospitals of Paris last year, certified to the representative of one of our daily papers that cholera was not contagious. The cholera epidemic of last year proves that cholera poisons are produced by heat and atmospheric influences on putrid matter, and circumstances favour the theory that they are inorganic, and when inhaled into the system poison the organisms of the blood to such an extent as to produce the disease. Cases of cholera broke out in different parts of the Continent at the same date, clearly showing that contagion had nothing to do with producing or transmitting the disease. In England our ports were jealously watched to prevent any case from being landed. Had a case been landed, the excreta from that one case might, when mixed with the sewage of a large town, have been the means of spreading the disease through the whole district, as miles of sewers are so laid that poisons in the gases can be effectually distributed through the district in a very short time. Open ventilation to sewers would greatly assist this, and especially when the gases in the drains and the fresh air admitted into them were of a high temperature. It is very improbable that cases if imported would break out in two towns at the same time, or that the poison could be conveyed in the atmosphere which divides us from the Continent.

Fortunately, when the continental outbreak was known, the authorities in the metropolis and other towns used disinfectants on all known putrid matter, and especially at the sewer gratings. This was an expensive process, but it had the effect of preventing the atmospheric influences (which were similar to those on the Continent) from developing the poison to a vitality necessary to give the disease.

It would be an excellent preventive if the authorities of towns would thoroughly examine every part of their districts, and know for a certainty whether in their sewers, cesspits, vaults, or dust-bins there existed putrid matter, or gases from them similar to those which produced the disease on the Continent. The expense of such an examination and for remedying the evils cannot be an excuse for not doing this work, as the monetary loss experienced by the residents of those continental towns and cities by the outbreak was enormous. What the loss would be to the residents of the metropolis if a cholera epidemic were to occur, it is difficult to imagine, and yet in many of the districts cholera-producing elements exist from which in all probability the heat and atmospheric influences experienced during several weeks of excessive dry weather during the summer months will produce poisons of a similar vitality to those produced on the Continent during the past year.

Previous to the cholera epidemic, small-pox was very prevalent in London, and I very carefully noted the cases as they were reported, and visited the districts where the disease was most prevalent, for the purpose of testing the nature of the gases in the sewers, and observing how the sewers and sanitary fittings were constructed.

In many of these districts, and especially those of Homerton, Hackney, Bow, and Bromley, the drains are so laid and the fittings so constructed that a supply of sewer gas is pumped into the houses, and it is impossible for persons to live in the houses of these districts without inhaling gases that have been for a long time in contact with sewage matter.

Whether the small-pox poison is an organic one (which I believe it is), and is produced from a collection of matter in a high state of decomposition, with or without being mixed with the excreta of persons suffering from the disease, or whether it is of an inorganic nature, the poison is derived from this source rather than from the impurities thrown off through the skin of persons suffering from the disease. As a proof of this, as soon as the cholera broke out last year on the Continent, almost every gulley and grating in the metropolis where sewer gas passes was charged more or less with a disinfectant, which minimised the poison in the gas. The result was that small-pox abated in an epidemic form although the temperature of the atmosphere increased.

The disinfectants so placed could not, naturally, affect the gas in branch drains to houses, or putrid matter in various parts of the sewers, or if it had, judging from its beneficial effects at the outlets, small-pox would have disappeared.

If contagion were the means by which this disease was distributed, disinfectants at sewer gratings would not have prevented the disease continuing in an epidemic form.

Take the adjoining districts of Fulham and Putney. During the epidemic, the gases from the sewer gratings in the Fulham district were more dense than those at Putney. Fulham had many cases of small-pox, but Putney none, although persons from each district were in daily contact with each other; but the houses were not connected by the same system of sewers.

It must not be thought that I wish to advance the theories of the anti-vaccinationist. I have had my children vaccinated because it is the law, and in the opinion of medical men a preventive against the disease, but viewing the change of medical opinion with reference to cholera during last year, and comparing tests and observations that have been made, they will soon be convinced that vaccination is a futile remedy to use with a view of stamping out the disease.

At present the question is (with medical men) one of theory, but ere long I am certain that they will take a more practical view of the case and definitely fix the origin of this disease and its distribution.

Previous to vaccination being introduced, putrid matter in vaults, cesspits, and drains was allowed to reach a higher state of putrefaction, and thus the poisons from them became more virulent and produced the disease of a more virulent type.

If modern systems of drainage and sanitary arrangements were the means of preventing this high state of putrefaction, and of reducing the disease to a milder form, perfecting these arrangements should be the means of stamping it out altogether and rendering vaccination useless.

Unless it can be proved that poisons given off through the skin and from the lungs of persons suffering from the disease are as virulent as those from putrid matter alone, or from the excreta from those suffering from the disease, the theory of contagion[2] cannot be entertained.

Footnote 2:

The word contagion as here used is not intended to apply to cases
where persons not affected sleep in the same bed, or wear the same
clothes, or handle things from, or persons suffering from this
disease, as this would be inoculation.

Many medical men will say that the facts to prove that small-pox is transmitted by contagion are so positive that there is no chance of disputing them.

Let us examine two cases to support this theory.

Small-pox is prevalent, say, in the north of London; a man is in business there from seven to eight hours each day, but his home is in the S.W. district. He is taken ill, and remains at home, calling in his medical attendant, who on his second visit pronounces it a case of small-pox, and orders his removal to the hospital. In a few days other members of the family are taken and removed, and similar cases occur in the neighbourhood.

The theory of the medical man would be that his first patient had contracted his disease in his place of business in the N.W. district and had conveyed it to the S.W. district, distributing it in the neighbourhood in which he lived. This is only theory, and the only thing the medical man has to rely on to prove his case is, that the man first taken was engaged three-fourths of each day where small-pox was prevalent. Against this theory, assume that the disease originated by the whole of these persons inhaling poisons from putrid matter in their own locality or at their own doors, or in their homes, but that the atmospheric influences to develop the poison was a few days longer completing its work in the S.W. district than in the north. Then test the sanitary conditions of both localities, and you will find similar matter producing poisons. These are facts that will support this view of the case, as well as the following evidence which cannot be contradicted. When sewage matter is allowed to remain in bulk undisturbed, and in connection with a system of sewers, it forms retorts for the generation of these poisons, and they are conveyed for miles in drains by atmospheric and other influences; and where these people lived the gases would probably be discharged with a greater facility than at any other point.

Take another case. A man leaves London for the country, and a day or two after his arrival he is taken ill with small-pox. There is no system of drains to the house in which he is located. People living in this and other houses are affected with the disease, and the medical officer of health in his report states that the disease was conveyed from London to the district by this man. He was certainly the first one affected, and at first sight this case appears to be conclusive in favour of contagion, for if he did not contract the disease in London and bring it into the country how was it that he was first affected?

It is certain that putrid matter from which the poisons are derived exists in villages similar to that in towns, consequently the poisons are there, and medical men agree that when a person leaves one locality for another, for what is commonly called a change of air, the system undergoes a change. This change had such an effect on the system of this man that the poison from the putrid matter of the village had a greater effect on him and poisoned the blood more quickly, than on those who were inhaling the poison during its various stages of development: but when it was fully developed by atmospheric influences the disease appeared in those other persons who were in contact with the poison.

The action of sewer poison on the system is similar to that experienced by persons taking cold. Persons occupied in rooms which have an equal temperature, or are not subjected to cold chilly winds, take colds and contract all sorts of complaints on being exposed to currents of cold air even for a short time. The draught from a window only, when a cold stream of air is playing upon it, will do this: the blood is chilled, hence the cold, fever, or one of the many complaints follow; but on persons used to exposure it has no effect. In the same way sewer poisons act on those who suddenly inhale them, only the blood becomes poisoned instead of chilled; but on those who are in constant contact with them they have not such an effect, yet on these persons the effect of them can be traced.

The medical profession have hitherto placed too much reliance on isolation as the sole means of stamping out this disease.

The Metropolitan Asylums Board have had ample means at their disposal since 1867 to test the soundness of this theory, yet after spending something like 480,000_l._ per annum, small-pox has increased 100 per cent. since that date! This fact alone is sufficient evidence to prove that other means than those of isolation must be used to effectually stamp out this disease.

It is of little use to have elaborate arrangements in hospitals and camps to minimise the effects on persons who have taken the disease, and at the same time allow the source from which it emanates to remain undisturbed. I admit that it is a question too complicated to be exhaustively dealt with in a work on the testing of drains and sanitary fittings, but it is inserted to show what a power those who are engaged in designing or executing sanitary works hold for good or evil in affecting the health of the community.

Experience proves that ninety-nine zymotic cases out of every hundred are caused through imperfect sanitary works and appliances.

LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD STREET AND
CHARING CROSS.

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