Popular Science Monthly/Volume 33/July 1888/Safety in House-Drainage
THE
POPULAR SCIENCE
MONTHLY.
JULY, 1888.
| SAFETY IN HOUSE-DRAINAGE. |
By WILLIAM E. HOYT, S. B.
IT was a little more than five years ago that Dr. Frank Hastings Hamilton wrote for "The Popular Science Monthly" an article on sewer-gas, in which he vigorously arraigned science for its failure to keep pace with civilization in the disposal of household wastes. The effect of Dr. Hamilton's article was quite unprecedented. His forcible presentation of facts and theories so affected the popular mind as to create an almost universal distrust of sanitary science, and, even at the present time, the idea prevails that plumbing fixtures in our houses are always a source of danger. In magazines and newspapers the discussion has been from time to time renewed, and the same pessimistic views are almost invariably held that were first advanced by Dr. Hamilton.
It is a subject of vital interest now to determine if this unfortunate condition of things described as existing five years ago still continues. We should know the truth or falsity of the assertion that there has been in late years a retrograde movement, hygienically considered, in substituting house-drains and sewers for the old earth-vaults and cess-pools. Can we have plumbing fixtures in our houses without danger to health, or must we make great concessions in comfort and convenience for the sake of safety? The question has lost none of its interest since Dr. Hamilton called into question the trustworthiness of sanitary science. Let us examine the evidence upon which the indictments have been made. We shall find, in the first place, that there is a surprising popular ignorance in regard to the literature of the science. How many well-informed persons are there, who know of the work of Pettenkofer, of Carmichael, of Naegeli, and Wernich, and Miquel, and a score of other scientists abroad, whose investigations have added so much to our knowledge of specific dangers to health and the means of overcoming them? And how many have heard of the careful and painstaking sanitary work of able scientific authorities in the United States? The labors of Waring and Putnam and Pumpelly and Smyth have been no less valuable, but the records of their investigations and experiments, although of great popular interest, are not widely known. No one can speak or write intelligently on sanitary topics without familiarity with this literature; but the writers who have arraigned sanitary science so severely are those who are most ignorant of its methods and its principles.
Let us consider the popular notion already alluded to—that we can not safely have plumbing fixtures in our houses. It is evident that the present requirements of comfortable living demand a reasonable number of convenient baths, closets and basins, and all the usual apparatus of this kind which modern civilization has introduced into the houses of the well-to-do. We can hardly consider these as luxuries. They are, in fact, absolute necessities; and to dispense with them would cause great inconvenience and inconceivable loss of comfort, and even of health. In compliance with the demands of a high civilization, sanitary science has been directed persistently toward the perfection of means to obtain all possible conveniences for free and frequent ablutions, as well as for the immediate and complete removal of household wastes. What evidence is there that science has failed in this particular? It is said that costly houses fitted with elaborate and expensive appliances for luxurious living have been often invaded by disease and death, and that the cause of this has been sewer-gas. These facts can not be disputed, but it is absurd to claim that science is at fault in this matter. The unfortunate results of such cases are invariably due to ignorance and empiricism.
In his census reports. Dr. Billings estimates that, in the United States, one hundred thousand deaths occur every year from strictly preventable diseases alone. This is unquestionably a very moderate estimate, and, if there are reckoned also twelve cases of serious illness for every death, we see what a great amount of suffering results from ignorance of sanitary principles.
But how is this ignorance manifested? Are not our architects competent to deal with the problem of household sanitation? It will be said, perhaps, that it is the province of the architect to direct the entire work of house-building, and to arrange every detail of the fittings. But it should be considered that the science of sanitation is broad and comprehensive. Years of study and of experience in sanitary work are necessary for a proper understanding of the subject. It is perhaps unfortunate that there is so little in the severe and unpleasant details of this work to commend it to those whose tastes have led them to the study of the more attractive principles of artistic construction and the science of æsthetics. An architect should have the soul of an artist, but there are few men whose nature is so broad as to combine truly artistic tastes with a love for the details of difficult mechanical work, involving the necessity for undertaking comprehensive and exact scientific research. It is the province of the engineer to engage in an occupation of this kind. His natural inclinations and his rigid training in scientific pursuits fit him especially for the direction of matters relating to drainage and sewage disposal.
If we take the testimony of competent sanitary authorities who are constantly employed in the design and execution of systems of house-drainage, it will be found that there are very few architects who can be trusted to prepare specifications for plumbing. In fact, the work of the average architect, in planning and supervising constructions of this kind, has been found to be almost universally clumsy and unscientific. This has been the experience of the writer in almost every case where his services have been called into requisition to remedy serious defects in household drainage which have sometimes caused inconceivable loss and misery. In this connection there may be quoted some pertinent remarks of one of our best known and most reliable sanitary authorities. Colonel George E. Waring, Jr., who recently wrote: "I have had much experience in connection with plumbing work in houses designed and built by some of the first architects of the country, and I do not hesitate to say that, in my experience, I have not found a single case where the architect has made use of the plainest and best developed knowledge of the day on this subject. I may be mistaken, but I think that no architect with whose work I have had to do either wrote or understood the specifications under which the plumbing was to be done."
Perhaps we shall be able to see now a little more clearly why some of our most costly dwellings are veritable whited sepulchres. But what of the plumbers? How is their status to be defined in this connection? From motives of economy, a plumber is sometimes employed to take charge of an entire scheme of house-drainage, and the employer intrusts everything to his care. The unfortunate results of such confidence are seen continually in the unsanitary condition of innumerable houses of rich and poor alike in all of our large cities. There is hardly a parallel to be found in any other occupation where men handle implements of death with such recklessness and with such disastrous consequences. The plumber is a mechanic, and perhaps a tradesman. His opportunities for study are few, and his inclinations are rarely toward self-improvement or useful learning. He blindly considers it his interest to induce his customers to allow him to use the greatest amount of material possible in his work, and the greater the complication of arrangement of pipes and fixtures with the consequent mystification of his patrons,
the more absolute becomes his power, with largely increased possibilities of extra charges.
Compare the plumber and his "helpers" with the young mechanics in almost any good machine-shop, and decide which occupation engages young men of greater intelligence and skill in manual work. Obstinately following tradition, our plumbers generally regard all improved methods developed by the application of scientific principles as dangerous innovations, interfering with the ancient and time-honored traditions of their unprogressive fraternity.
There is another and a stronger obstacle to scientific progress in
Fig. 2.—The Same Fixtures with the Proper Arrangement of Waste-Pipes.
sanitary matters. This is to be found in the powerful influence of capital. In our large cities are the extensive wholesale establishments of dealers in plumbing fixtures and supplies. The amount of money invested in the stock and patterns for manufacturing certain forms of plumbing appliances is enormous. These articles are, many of them, extremely unsanitary and even dangerous when applied to actual use, but the profits on their sales are large, and the introduction of better and more simple forms of apparatus would seriously disarrange the existing order of things. The abolition of the trap-vent laws, for example, would cut out a thousand pounds or more of useless iron and lead pipes from the plumbing of every good-sized house. Manufacturers and dealers would suffer heavy losses, and so the vast interests involved are carefully guarded by all the resources which money can command in municipal legislation. This influence has extended even to the press; and we see tradesmen's journals persistently ignoring scientific progress and upholding still the old methods which are to enrich unscrupulous manufacturers and their clientage of uneducated mechanics. It is for the interest of invested capital that plumbers be kept as ignorant and as unprogressive as possible.
In this conflict of ignorance and prejudice with science, it is not difficult to trace still further the cause for so much popular distrust. If the most common defects in the apparatus for ordinary house-drainage could be clearly understood, it would be readily seen that the want of confidence in plumbing appliances arises mainly from a general misapprehension regarding their real imperfections. We know, for example, that sewer-air, or sewer-gas, as it is improperly called, finds its way continually into many houses, and frequently causes disease and death. How does this sewer-air gain an entrance? If you consult your plumber, he will deny that there is any possibility of such a defect existing in the drain-pipes and fixtures he has put in. But your physician will tell you that the symptoms of illness of some member of the household show unmistakable evidence that the patient has been poisoned by sewer-air. A thorough examination of the drainpipes shows that they are securely jointed, and that there are no leaks in them. Nevertheless it is certain that sewer-air gains an entrance to the house in considerable quantities, and after a time it is discovered that the poisonous air finds its way in through the traps attached to the basins and sinks and water-closets. A word of explanation may be necessary in regard to these traps. Although of a great variety of forms, they are all essentially a device for allowing waste-water to flow through them from the fixtures to which they are attached into the drains, and to prevent air or gases from passing in the opposite direction into the house. The resisting medium in most cases is a water-seal, consisting of a small body of standing water in the body of the trap. When it is found that sewer-air passes freely through these very traps that have been designed to keep it out, the inference is almost irresistible that the water-seals are at fault, and that water is not a suitable medium to be used for this purpose, since air from the drains apparently forces an entrance through it.
It is at this point that the serious error of a false assumption is so frequently made. The truth is, that sewer-air does not come into our houses in any appreciable quantity through the water seals of traps. On the contrary, it passes through the trap when the seal has been lost—when the water has been accidentally withdrawn or forced out. The broad principle of the efficiency of water-seals is not affected by these apparent failures. The difficulty is in maintaining the seals—in keeping them intact and secure against all the various adverse influences that may affect them. And here the aid of sanitary science must be sought; for the plumber's art has been powerless to devise traps that will protect our houses from the foul air of the sewers. Every failure in this attempt has been from a disregard of principles that have been well established by competent authorities. What are these principles?
For many years, skillful chemists, devoting themselves to sanitary work, have been carrying on careful investigations regarding the possibility of the passage of sewer-air and disease-germs through the water-seals of traps. The definite determination of this question is necessary in order to establish proper means of defense against the dangers we have already considered. It is evident that the form of traps and other apparatus to be used for this purpose will depend upon a conclusive demonstration of the truth or falsity of the views of those who have maintained that water as a resisting medium gives no protection in this particular The evidence which we have upon this point is clear and conclusive.
As long ago as 1877, Naegeli, an eminent scientific authority in Munich, established conclusively that disease-germs can never be given off from a liquid at rest in any ordinary temperature. Later researches by Carmichael, Wernich, and Miquel, chemists and sanitarists of world-wide reputation, corroborated the truth of Naegeli's demonstrations in every respect.
In 1880 the United States National Board of Health, through the efforts of Colonel George E. Waring, Jr., secured an appropriation for the purpose of investigating the same subject. Two able chemists. Prof. Raphael Pumpelly and George A. Smyth, Ph. D., were employed to conduct the investigations. A long series of careful and delicate experiments was made, extending through several months, and the published report of the results forms a valuable contribution to the literature of sanitation. The conclusions in this instance are precisely the same as those of the other authorities above referred to—viz., that disease-germs can not be given off to the air from any quiescent liquid at a normal temperature.
The experiments of Dr. Neil Carmichael, Fellow of the Faculty of Physicians and Surgeons at Glasgow, are particularly interesting. They were conducted, with rare skill and an honest endeavor to ascertain the worst conditions existing ordinarily in houses containing the usual forms of plumbing fixtures. Dr. Carmichael attached his experimental apparatus to the traps of two common water-closets connected with a foul soil-pipe leading into an old sewer. The outlet of this sewer, some three hundred yards away, was submerged at high tide, so that sewer air or gases were forced back toward the houses. The top of the soil-pipe used for the experiments was ventilated by a two-inch pipe passing through the roof to the outer air; and, to impose the most severe conditions possible, some of the experiments were conducted with the soil-pipe tightly closed at the top. The average result of many different experiments by Dr. Carmichael is given in the following table:
Quantitative Determination of Gases which passed through Water-Traps (A and B) in Twenty-four Hours.
| GAS. | Old water-closet trap (A). | Kitchen trap (B). | ||
| Grains. | Grains. | |||
| Soil-pipe open at the top | Carbonic acid | 7·084 | 7·084 | |
| 10·470 | ||||
| Ammonia | 1/217, 1/250, 1/330, 1/400 | 1/100, 1/200 | ||
| Sulphureted hydrogen | 1/200 | 1/200 | ||
| Soil-pipe closed at the top. | Carbonic acid | 32·032 | 17·063 | |
| Ammonia | . . . . . . . . . . . . . | 1/400 | ||
| Sulphureted hydrogen | 1/90 | . . . . . . . . . . . . . | ||
Putrid organic vapors, if present, are included in the ammonia.
With the top of the soil-pipe closed, it will be seen that the amount of gases passing through the water was considerably increased, but was still extremely small. And this represents the worst possible condition that can exist in houses which are properly protected by traps having water-seals.
The deductions of Dr. Carmichael from these experiments are here given in his own words, taken from the "Proceedings of the Philosophical Society" of Glasgow:
"These are the quantities of the only sewage gases existing in the soil-pipe in estimable quantities which pass through an ordinary water-closet trap in twenty-four hours. Diffused into the atmosphere of a house during this time, these quantities are, from a health point of view, quite inconsiderable—perfectly harmless. Thirty-two grains (the largest quantity of carbonic acid) is less than the quantity of the same gas given off when a bottle of lemonade is opened. A man exhales in the same time about four hundred times the amount which passes through the trap from an unventilated soil-pipe."
Dr. Carmichael then explains in detail his experiments in regard to the passage of disease-germs through traps, and concludes as follows:
"The liquids in all these tubes and flasks, though kept from two to five months at cultivation temperature, have remained perfectly clear, and even when examined with a lens multiplying nine hundred diameters, exhibited no trace of life. The conditions of these experiments seem to me crucial, and to warrant the conclusion that germs do not pass through a sound water-trap. If no germs pass through, then it is certain that no particles pass through, because the particles in a soil-pipe are putrid, and because the passage of organic particles through water necessarily
Fig. 3—A Pot-Trap, showing how Water escapes by Siphonage. impregnates them with germs. Clearly, therefore, such particles as epithelium from the bowels in typhoid fever, containing the typhoid contagia, are cut off and effectually excluded from the house by a sound water-trap. Water-traps are, therefore, for the purpose for which they are employed—that is, for the exclusion from houses of injurious substances contained in the soil-pipe—perfectly trustworthy. They exclude the soil-pipe atmosphere to such an extent that what escapes through the water is so little in amount and so purified by filtration as to be perfectly harmless; and they exclude entirely all germs and particles, including, without doubt, the specific germs or contagia of disease."
The testimony of these distinguished scientists must be regarded as conclusive in the absence of contradictory evidence. Is there such evidence on record? Let us examine the authorities. It is claimed that different results have been obtained in a few instances by other investigators. Some years ago, Prof. Doremus showed that gases would pass through water from one test-tube to another. But it must be remembered that the gases used in these experiments were in a highly concentrated form. Such conditions as were then imposed are absolutely impossible outside of the chemical laboratory. The atmosphere of sewers, drains, and soil-pipes is in reality ordinary air containing less than one per cent of the gases and particles given off by decomposing sewage. The results of over sixty analyses made by such men as Dr. Letheby, Dr. Miller, of London, and the late Prof. Nichols, of Boston, show an average of only four tenths of one per cent of carbonic acid with mere traces of sulphureted hydrogen, marsh-gas, and ammonia. The putrid organic vapors, and the putrefactive germs, particles, and spores of fungi, were found also in extremely minute quantities. But the important consideration is, that these germs, particles, and spores, the most dangerous elements of sewer-air, can not escape from the water-seal, and that the quantity of carbonic acid, and the accompanying gases arising from sewer-air, which, even under the worst conditions, can pass through water, is minute and utterly harmless. The experiments of Prof. Doremus were therefore irrelevant and valueless as applied to a determination of the efficiency of trap-seals.
It has been said, too, that Mr. Paton, a chemist temporarily in the employ of the health department of the city of Chicago, at one time observed the passage of sewer-gases through the seal of a trap. Since frequent reference has been made to this experiment, it is fortunate that the report of Mr. Paton is still accessible. An examination of the document in question, and of a drawing of the apparatus employed in the experiment, shows at once that the results obtained have no relation whatever to the subject we are considering. Mr. Paton, instead of trying to ascertain if gases would find their way unassisted through a trap-seal, adopted the very original method of forcing them through the water into a vacuum by atmospheric pressure. A more absurd proceeding could hardly be imagined, were it not for the fact that these experiments were in reality conducted to determine the value of a so-called germicide which the health officers had been asked to examine.
There is, then, absolutely nothing in the form of reliable testimony that can be brought forward to contradict in any particular the positive and comprehensive statements of the eminent scientific authorities previously referred to.
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| Fig. 4.—First Step in the Development of an Anti-siphonic Trap. |
It is established beyond question that water may be safely used as a seal for traps. But may there not be a better and more complete medium of resistance against sewer-air? The attempt has been made to substitute mechanical valves of various kinds in place of the water; a seal of mercury has also been employed, and, in some instances, balls of rubber and of metal have been used in conjunction with water; but these substitutes and additions have, in every case, proved extremely objectionable, on account of obstructing the outward flow of waste-water, and so causing accumulations of filth in the traps and water-pipes.
It is not at all probable, then, that any better contrivance than that of a water-seal will ever be devised for the protection of our houses from the poisonous air of drains and sewers. But, having determined this point, we find that there are still serious difficulties to overcome in making traps that will not lose their seal. In our house-drains there are always certain influences that tend to lower the water in the traps, or even to draw it forcibly out, and then, of course, with the seal destroyed, there is no protection against sewer-air. Siphonage, capillary attraction, and evaporation are among the most potent of these hostile agencies. Certain atmospheric disturbances also, such as strong draughts of air, may produce the same effect, and the trouble which has resulted from causes of this kind has, for the most part, been ignorantly attributed to the supposed easy permeability of the water as regards the dangerous gases of decomposition in our sewers.
Various means have been devised to prevent siphonage of traps. One of the most common is that of trap-ventilation or back venting, so called. In its most common form, it consists of a system of air-tubes connected with the crown of each trap, and running by one or several lines of larger pipes to the outer air above the roof of the building. It was expected that this device would prevent entirely the siphonage of traps, and in several cities plumbing laws have been framed requiring all traps to be vented in this manner. But in hundreds of houses to-day, where this method of protection has been adopted, we find sewer-air entering freely through traps that continually lose their seal. And it will be easily seen, after a little reflection, that this fallacious remedy causes quite as serious evils as those it is designed to obviate. In the first place, if the ventilation of the trap by this method is effective, a current of air is introduced close to the water-seal, and this circulation must induce evaporation of the water in the trap, rapid in proportion to its efficiency as a ventilator, so that the seal is soon destroyed. This frequently happens to the traps of basins and other plumbing fixtures that are not in every-day use. Again, it is found that the friction of the air in the vent-pipes is sometimes so great as to prevent them from performing their proper function. In this case, where there is the slightest retardation in the passage of air through the vent, siphonage takes place and the seal of the trap is destroyed as readily as if the vent-pipes had not been used. Again, the lower orifice of the air-pipe is frequently obstructed by filth thrown up to the crown of the trap as the waste-water passes rapidly out. In time, this obstruction increases to such an extent that the vent pipes can not give a free passage for the air, and there is consequently no relief for the seal when siphonage occurs. It should be observed, also, that in modern houses, where trap-ventilation is considered to be most perfect, there is still another set of air-tubes, running from the inside of every trap-seal to the larger air-pipes extending through the roof of the building. With this double ventilation, the deleterious effect of air-currents on trap-seals is, of course, greatly increased.
Some idea of the complication and enormous expense of this system may be formed from an illustration of its application to a group of four plumbing fixtures in adjoining rooms on one floor of an elegant residence recently built in New York city (Fig. 1). It will be seen that the air-pipes require an almost complete duplication of the waste and soil pipes. This, of course, adds greatly to the cost of the plumbing, and increases the danger from imperfections in the largely augmented number and length of pipes with their multifarious joints.
Fig. 2 shows the same number of fixtures in the same relative position, but the plumbing is arranged in accordance with the requirements of modern methods as developed by the application of scientific principles.
Not long after the adoption of the fallacious device of back-venting, it became evident that more efficient means of guarding against the dangers of sewer-air were necessary, and persistent
Fig. 5.—Second Step in the Development or an Anti-siphonic Trap.
effort was directed toward devising better methods of house-drainage. The result has been the attainment of a new order of things by the recognition of scientific principles previously ignored.
For the development of this science, credit must be given mainly to an accomplished sanitarist of Massachusetts, Mr. J. Pickering Putnam, whose experiments and investigations on subjects relating to household sanitation are unquestionably the most thorough and complete that have ever been put on record. The first of this series of experiments was made for the Board of Health of Boston, in 1883. Subsequently, special demonstrations were shown before the Suffolk District Medical Society of Massachusetts, the Boston Society of Architects, and others. The results have been published in the "Boston Medical and Surgical Journal," the "American Architect," the "Sanitary Record" of London, and other periodicals.
Without referring now directly to the experiments and investigations, we may consider briefly certain principles which have been established by them. The first and cardinal principle of science as applied to house-drainage is simplicity. In the place of a wilderness of pipes tangled in hopeless confusion about every fixture, modern science demands that there shall be only a simple and positive system which shall act with directness and certainty in every case. The old air-pipes from traps are discarded. There are fewer joints, and the danger from leakage is lessened. Instead of traps that easily lose their seal, notwithstanding the relief-pipes attached, traps are now used that in themselves will resist the hostile influences of evaporation and siphonage. The new system demands that basins, sinks, baths, and water-closets shall be so constructed as to act after the manner of flush-tanks, and scour the whole system of waste-pipes at each discharge. It requires that there shall be no hidden and inaccessible recesses in 
Fig. 6—Showing the Principle of an Anti-siphoning Trap. plumbing fixtures, where filth •may collect and putrefy, so as to become offensive and dangerous. The absolute prevention of serious evils is considered of far greater importance than means to palliate them.
Such, in brief, are the leading principles of the new method which are directly opposed to those of the old. We may look a little more closely into the details of their execution. Simplicity has been secured, as already stated, by the rejection of complicated vent-pipes, and by the adoption of traps secure against siphonage or evaporation. The gradual development of one form of such a trap is an interesting study, but there is space only to outline the principles upon which it is constructed.
The experiments of Mr. Putnam on trap-siphonage showed in what manner the water is withdrawn from traps by siphonic action. It was seen that air, rushing through the seal to fill a vacuum beyond, threw the water upward and outward through the orifice of the trap into the waste-pipe, as shown by arrows in the sketch of a pot-trap (Fig. 3). It was observed, too, that a part of the water struck the top of the trap and was reflected back in the form of spray. This suggested the possibility of retaining the water in the trap under siphonic disturbance by repeated deflections from reflecting surfaces. Various experimental patterns of traps were made by Mr. Putnam, as shown in Figs. 4 and 5; and, finally, the form shown in Fig. 6 was found to be anti-siphonic and self-cleansing under all conditions that exist in good plumbing practice. It has four reflecting surfaces to deflect the water from the outlet, and the seal is so deep and the construction such as to enable it to resist both evaporation and capillary attraction.
The general principle that all plumbing fixtures shall act as flush-pots, so that the waste-pipes shall be automatically cleansed, is of great importance. A strong flushing action is secured by making the outlets of the fixtures as large as the waste-pipes
themselves, and by the use of traps having a free water-way, with no balls or mechanical valves to obstruct the flow of waste-water. Aeration is effected by the admission of a free admixture of air into the waste-pipes, automatically forced in by the water escaping from the fixtures above.
The abolition of inaccessible filth-collecting recesses in modern plumbing has necessitated a complete change in the construction of the old forms of appliances with which we have been familiar. Our basins, baths, and pantry-sinks have been made with over-flow openings connecting with pipes concealed from view and entirely inaccessible for cleaning. These overflow-pipes invariably become receptacles for filth, and the emanations from them are always offensive and dangerous. The new patterns of basins, sinks, and baths have the overflows in the form of a short, movable stand-pipe set in a recess at the back or end of the fixtures. This stand-pipe serves also as an outlet-plug. When raised from its seat by a simple lifting device, it permits the escape of waste-water, and by a single movement it is readily detached from its place for cleaning (Fig. 7).
The overflow-pipe of our common set-basins forms a receptacle for the accumulation of a thick deposit of filthy slime in its interior, which, by putrefying, pollutes the air of houses to a dangerous
Fig. 8.—Set-Basin, with Common Overflow-Pipe and "Fore" and "Back" Vents. degree (Fig. 8). Since the interior of this pipe is quite inaccessible for purposes of cleansing, there is no remedy for the evil except by abandoning the use of this old form of fixture, which has also other equally objectionable features. The chain attached to the outlet-plug invariably collects a great quantity of filth in its numerous well-protected recesses and on the entire irregular surface of the links. It is almost impossible to remove this filthy accumulation by any ordinary means, and the continued use of a household fixture of this kind by different persons is offensive to good taste, and violates the generally accepted standards of personal cleanliness established by ordinary hygienic principles.
Our common water-closets in general use have so many serious faults of design and construction as to demand especial consideration in this connection. Some of the most costly and elaborate patterns recently designed and put upon the market are dangerous and unfit for use. Delicately tinted and fancifully molded shapes of porcelain or earthenware are no guarantees of safety. Sanitary requirements in the construction of water-closets are so clearly defined that the essential features can be readily understood from a brief enumeration.
First of all, the water-seal must be deep—never less than four inches—and this seal must be exposed to view for reasons which will be hereafter given. Again, there must be a considerable depth of standing water in the bowl of the closet, to deodorize fecal matter and to secure cleanliness. The outlet of the bowl must also be completely submerged, to prevent its becoming foul and offensive from use. The closet should invariably have some device for maintaining the water-seal against loss from evaporation.
The traps of water-closets are especially exposed to the danger of losing their seal. This happens frequently from the effect of wind and other atmospheric disturbances. An open fire in an adjoining room, or a ventilator near by, may cause this loss of seal from sudden draughts of air, and sewer-air frequently has free entrance into houses for hours and even days at a time when the danger is not suspected by the occupants, since the water-seal of the trap, in badly constructed fixtures, is wholly concealed from view.
In a series of careful experiments, conducted by the writer, it was observed that even in well-ventilated soil-pipes, strong air-currents prevail to such an extent as to cause the water-seal of 
Fig. 9—"Wash-out" Water-Closet, showing how Accidental Obstructions may remain undetected in the Trap which is concealed from View. traps to fluctuate with a quick rise and fall, so that enough water is soon spilled over the outlet of traps to unseal them entirely. The results of these experiments have recently been fully confirmed by other investigators.
Of course, the more shallow the seal, the greater is the danger of its being destroyed from any cause; and for this reason a considerable depth of water is required in the trap of every water-closet, it is necessary, also, that this seal should be plainly exposed to view, in order that any loss of water from the causes just mentioned, or by leakage, may be readily noticed.
But it will be observed that the water-closets in most common use have an extremely shallow seal. The reason of this is that, with the imperfect means employed for flushing them, a greater depth of water in the trap can not be allowed, since it would seriously retard the outward flow of waste-water. The common "wash-out" closets, so called, with the allied forms of "short hoppers" and "long hoppers," and the complicated and dangerous "plunger," "valve," and "pan closets," all depend on the 
Fig. 10.—"Short-Hopper" Water-Closet, showing Accumulations of Filth in the Bowl. weight of a stream or body of water falling from above to force out the waste matter from the bowl of the closet through the trap below. This force is rarely sufficient to give proper flushing action, even with a shallow trap-seal. A deeper trap would oppose too much resistance to the discharge of waste matters from closets of the kind just referred to. Cleanliness and safety can be secured only by a greatly modified form of construction, and by the employment of totally different means for flushing. The principles of the siphon and of the water-jet have been applied successfully to this purpose, so that deep and safe water-seals can be used which are in full view at all times.
The illustration, Fig. 11, shows a form of siphon closet devised by Colonel Waring. The flushing is effected by opening a valve in 
Fig. 11.—A Siphon Closet, with Deep Water-Seal. a tank above, which produces a quick rush of water into the bowl. This fills the longer arm of the siphon and the weir-chamber below by the overflow through the neck or short arm. As soon as this takes place, the contents of the bowl are forcibly drawn out by siphonic action and discharged into the waste-pipe, after which the normal level of the water in the bowl is re-established by an after-fill from the tank.
There are, however, certain so-called pneumatic or siphon closets which should be carefully avoided on account of their having a double trap. This principle of construction is directly opposed to sanitary requirements. Double traps are not permissible in any case for a single plumbing fixture, since their use greatly retards the outflow of water and waste matter, thereby causing accumulations of filth that are dangerous and offensive. It should be observed, too, that in these closets the second trap gives no additional protection against sewer-air, since a relief-pipe from the air-space between the traps opens directly into the apartment in which the closet is placed through a concealed orifice above the flushing-tank. The main trap is also completely hidden from view in a part of the closet entirely inaccessible.
Figs. 12 and 13 show a trap-jet closet devised by Mr. J. Pickering 
Fig. 12.—Showing the Principle of a Trap-Jet Water-Closet. For convenience of illustration the inlet and outlet are here represented on opposite sides of the bowl. Putnam to conform to the requirements of the essential principles already stated. Its construction is extremely simple. It has a deep and perfectly protected trap-seal exposed to plain view in the bowl of the closet. The flushing-pipe stands always full of water, equilibrium being maintained by atmospheric pressure. Should the water in the bowl be lowered by evaporation or siphonage, air will enter the flushing-pipe through one of the opening* at the lower end, and water immediately descends to restore the loss to the trap-seal.
Fig. 14 shows a simple illustration of this principle in the sketch of an inverted bottle with the mouth submerged in a basin of water. The contents of the bottle remain undisturbed so long as the level of the surface of the fluid in the basin is constant; but if this be lowered, so that air enters the mouth of the bottle, a corresponding volume of water escapes from the bottle into the basin to restore equilibrium. The application of this principle of protection to houses which are closed and left untenanted during several months of the year is manifestly of great importance. Our city residents, after a summer passed at the sea-shore, or in the fresh, pure air of the mountains, often return to houses which have upholstered furniture, carpets, curtains, and heavy draperies saturated with the foul and poisonous air of sewers and drains which has had unrestricted entrance to the deserted houses for months at a time.
It will be noticed that the lower end of the flushing-pipe shown in Fig, 12 is divided, one orifice being connected with the flushing-rim and the other with a small opening at the bottom of the
Fig. 13.—Trap-Jet Closet, showing the Actual Shape.
bowl. When the valve in the tank is raised, the lower opening allows a strong jet of water to be thrown upward toward the outlet. This forcibly expels a portion of the contents of the bowl and lowers the water and waste matters into the neck, whence they are ejected by the combined action of the upper and lower flushing-streams. A strong wash descending from the flushing-rim cleanses the bowl thoroughly and afterward refills it to the level of the trap-outlet. The discharge of the closet is almost noiseless, since the lower orifices of the flushing-pipe are submerged.
Considerable space has been given to a description of the most common defects of plumbing fixtures, for the reason that these imperfections are usually the unsuspected source of danger to life and health in houses where the plumbing is most elaborate and costly. Poor material in the drain-pipes and leaky joints are readily recognized perils that may be easier avoided because they are better understood. It may be well, in conclusion, to note a few important points that should be observed in every well-designed system of house-drainage.
The plumbing should be concentrated as much as possible, so that the various fixtures shall be near one vertical line of soil-pipe extending through the house from basement to roof. This soil-pipe should not be less than four inches in diameter, with an extension above the roof of a size two inches larger, to prevent obstruction by frost. The upper end of this extension should be open, without an attachment of hood, or cowl, or bend, and should not open near a window or ventilator.
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| Fig. 14—Inverted Bottle. To illustrate the principle of an automatic supply to a water-closet trap affected by evaporation or other causes. |
The soil-pipe should never be connected in any way with a chimney-flue, since downward draughts, when the flue is cold, or when strong winds are blowing, will, in such cases, circulate sewer-air freely through the house.
The soil-pipe, if of cast-iron, should be of the greatest thickness made for this purpose, as a safeguard against hidden defects in the iron and the danger of splitting at the joints. Soil-pipes and water-pipes should have in all cases as few joints as possible, and these should be made with the greatest care. The well-known Durham system, which employs screw-joints for the connections of long sections of wrought-iron pipes, undoubtedly gives much greater security against leakage than the more common methods of plumbing, which require all joints to be made by calking with lead.
No drain-tiles or earthenware pipes of any kind should be used in the house or under the foundations to convey sewage. Certain local conditions may sometimes require that drains for subsoil water shall be laid within the cellar-walls, and in such cases it is best to have a separate line of drainage entirely independent of the sewer, but, if it is necessary to deliver this water into the main house-drain, the connection must be made at some distance from the house, in such a way as to have a freely ventilated air-space between the two systems of drains, so that there is no opportunity for the foul air from the sewer to enter and circulate through the open-jointed line of earthen tiles beneath the cellar bottom. Almost equal care is necessary when drains for soil-water are laid just without the cellar-walls, since air from the soil surrounding the foundations is drawn freely into our dwellings, and any pollution of this soil-atmosphere must occasion serious danger.
In a like manner, rain-water conductors are to be cut off from a direct connection with the house drain or sewer. The upper end of conductor-pipes opening near windows may readily convey sewer-air into the house, unless special precautions are taken to guard against it.
It is usual to place a large trap in the main house-drain a short distance outside of the cellar-wall. The object of this is to keep the air of the street-sewer from entering the drain-pipes within the house. But a trap in the main drain obstructs the outward flow of sewage to such an extent as to cause accumulations of filth to collect, which may produce a condition of affairs in the house-drain considerably worse than that existing in the sewer. In ordinary cases it will be safer to omit the trap, and allow the air of the sewer to flow through the main soil-pipe and out at the top above the roof. But there are important exceptions to this general rule. A trap should always be used between a cess-pool and the house draining into it. And when sewers have a slight inclination, with a sluggish flow through them, so that they are unusually foul, it will be better to have traps put into the connecting house-drains. Whenever these traps are used, there must be an inlet provided for the admission of a copious supply of fresh air to the drain-pipes between the trap and the house, and as near to the former as possible. This will cause an almost constant upward flow of air through the main channel of the house drainage system, giving free ventilation to places where impurities may collect.
Space will not allow a more extended consideration of matters of detail. The design and execution of our systems of house drainage should always be intrusted to some competent sanitary authority, in place of being left to the hap-hazard direction of careless architects and ignorant plumbers. The importance of obtaining absolute security where so much inherent danger exists can not be overestimated. With all the advantages derived from a constant and sure development of the science of sanitation, our houses may be made safe against the entrance of sewer-air. The perils arising from ignorance and neglect are easily eliminated. And, above all, a determined effort should be made to arouse public opinion, so that it shall demand the repeal of objectionable municipal ordinances framed in the interest of corrupt politicians and mercenary tradesmen.