Chapter 4

1st. A cesspit should never be located under a dwelling. It should be placed outside, and as far removed from the immediate neighborhood of the dwelling as circumstances will allow. There should be a ventilated trap placed on the pipe leading from the watercloset to the cesspit. 2d. It should be formed of impervious material so as to permit of no leakage. 3d. It should be ventilated. 4th. No overflow should be permitted from it. 5th. When full it should be thoroughly emptied and cleaned out; for the matter left at the bottom of a cesspit is liable to be in a highly putrescible condition.

Where a cesspit is unavoidable, perhaps the best and least offensive system for emptying it is the pneumatic system. This is applicable to the water closet refuse alone. The pneumatic system acts as follows: A large air-tight cylinder on wheels, or, what answers equally, a series of air-tight barrels connected together by tubes about 3 in. diameter, placed on a cart, brought as near to the cesspit as is convenient; a tube of about the same diameter is led from them to the cesspit; the air is then exhausted in the barrels or cylinder either by means of an air pump or by means of steam injected into it, which, on condensation, forms a vacuum; and the contents of the cesspit are drawn through the tube by the atmospheric pressure into the cylinder or barrels. A plan which is practically an extension of this system has been introduced by Captain Liernur in Holland. He removes the fæcal matter from water closets and the sedimentary production of kitchen sinks by pneumatic agency. He places large air-tight tanks in a suitable part of the town, to which he leads pipes from all houses. He creates a vacuum in the tanks, and thus sucks into one center the fæcal matter from all the houses. Various substitutes have been tried for the cesspit, which retain the principle of the hand removal of excreta. The first was the combination of the privy with an ashpit above the surface of the ground, the ashes and excreta being mixed together, and both being removed periodically. The next improvement was the provision of a movable receptacle. Of this type the simplest arrangement is a box placed under the seat, which is taken out, the contents emptied into the scavenger's cart, and the box replaced. The difficulty of cleansing the angles of the boxes led to the adoption of oval or round pails. The pail is placed under the seat, and removed at stated intervals, or when full, and replaced by a clean pail. In Marseilles and Nice a somewhat similar system is in use. They employ cylindrical metal vessels furnished with a lid which closes hermetically, each capable of holding 11 gallons. The household is furnished with three or four of these vessels, and when one is full the lid is closed hermetically, the vessel thus remaining in a harmless condition in the house till taken away by the authorities and replaced by a clean one. The contents are converted into manure. In consequence of the offensiveness of the open pail, the next improvement was to throw in some form of deodorizing material daily. In the north of England the arrangement generally is that the ashes shall be passed through a shoot, on which they are sifted--the finer fall into the pail to deodorize it, the coarser pass into a box, whence they can be taken to be again burned--while a separate shoot is provided for kitchen refuse, which falls into another pail adjacent.

Probably the best known contrivance for deodorizing the excreta is the dry earth system as applied in the earth closet, in which advantage is taken of the deodorizing properties of earth. Dry earth is a good deodorizer; 1½ lb. of dry earth of good garden ground or clay will deodorize such excretion. A larger quantity is required of sand or gravel. If the earth after use is dried, it can be applied again, and it is stated that the deodorizing powers of earth are not destroyed until it has been used ten or twelve times. This system requires close attention, or the dry earth closet will get out of order; as compared with water closets, it is cheaper in first construction, and is not liable to injury by frost; and it has this advantage over any form of cesspit--that it necessitates the daily removal of refuse. The cost of the dry earth system per 1,000 persons may be assumed as follows: Cost of closet, say, £500; expense of ovens, carts, horses, etc., £250; total capital, £750, at 6 per cent. £37 10_s._ interest. Wages of two men and a boy per week, £1 12_s._; keep of horses, stables, etc., 18_s._; fuel for drying earth, 1_s._ 6_d._ per ton dried daily, £1 10_s._; cost of earth and repairs, etc., 14_s._; weekly expenses, £4 14_s._ Yearly expenses, £247 (equal to 4_s._ 11_d._ per ton per annum); interest, £37 10_s._--total, £284 10_s._, against which should be put the value of the manure. But the value of the manure is simply a question of carriage. If the manure is highly concentrated, like guano, it can stand a high carriage. If the manuring elements are diffused through a large bulk of passive substances, the cost of the carriage of the extra, or non-manuring, elements absorbs all profit. If a town, therefore, by adding deodorants to the contents of pails produces a large quantity of manure, containing much besides the actual manuring elements--such as is generally the case with dry earth--as soon as the districts immediately around have been fully supplied, a point is soon reached at which it is impossible to continue to find purchasers. The dry earth system is applicable to separate houses, or to institutions where much attention can be given to it, but it is inapplicable to large towns from the practical difficulties connected with procuring, carting, and storing the dry earth.

With the idea that if the solid part of the excreta could be separated from the liquid and kept comparatively dry the offensiveness would be much diminished, and deodorization be unnecessary, a method for getting rid of the liquid portion by what is termed the Goux system has been in use at Halifax. This system consists in lining the pail with a composition formed from the ashes and all the dry refuse which can be conveniently collected, together with some clay to give it adhesion. The lining is adjusted and kept in position by a means of a core or mould, which is allowed to remain in the pails until just before they are about to be placed under the seat; the core is then withdrawn, and the pail is left ready for use. The liquid which passes into the pail soaks into this lining, which thus forms the deodorizing medium. The proportion of absorbents in a lining 3 in. thick to the central space in a tub of the above dimensions would be about two to one; but unless the absorbents are dry, this proportion would be insufficient to produce a dry mass in the tubs when used for a week, and experience has shown that after being in use for several days the absorbing power of the lining is already exceeded, and the whole contents have remained liquid. There would appear to be little gain by the use of the Goux lining as regards freedom from nuisance, and though it removes the risk of splashing and does away with much of the unsightliness of the contents, the absorbent, inasmuch as it adds extra weight which has to be carried to and from the houses, is rather a disadvantage than otherwise from the manurial point of view.

The simple pail system, which is in use in various ways in the northern towns of England, and in the permanent camps to some extent at least, and of which the French "tinette" is an improved form, is more economically convenient than the dry earth system or the Goux or other deodorizing system, where a large amount of removal of refuse has to be accomplished, because by the pail system the liquid and solid ejections may be collected with a very small, or even without any, admixture of foreign substances; and, according to theory, the manurial value of dejections per head per annum ought to be from 8_s._ to 10_s._ The great superiority, in a sanitary point of view, of all the pail or pan systems over the best forms over the old cesspits or even the middens is due to the fact that the interval of collection is reduced to a minimum, the changing or emptying of the receptacles being sometimes effected daily, and the period never exceeding a week. The excrementitious matter is removed without soaking in the ground or putrefying in the midst of a population.

These plans for the removal of excreta do not deal with the equally important refuse liquid--viz., the waste water from washing and stables, etc. As it is necessary to have drains for the purpose of removing the waste water, it is more economical to allow this waste water to carry away the excreta. In any case, you must have drains for removing the fouled water. Down these drains it is evident that much of the liquid excreta will be poured, and thus you must take precautions to prevent the gases of decomposition which the drains are liable to contain from passing into your houses.

There is a method which you might find useful on a small scale to which I will now draw your attention, as it is applicable to detached houses or small barracks--viz., the plan of applying the domestic water to land through underground drains, or what is called subsoil irrigation. This system affords peculiar facilities for disposing of sewage matter without nuisance. There are many cases where open irrigation in close contiguity to mansions or dwellings might be exceedingly objectionable, and in such cases subsoil irrigation supplies a means of dealing with a very difficult question. This system was applied some years ago by Mr. Waring in Newport, in the United States. It has recently been introduced into this country.

The system is briefly as follows: The water from the house is carried through a water-tight drain to the ground where the irrigation is to be applied. It is there passed through ordinary drain pipes, placed 1 ft. below the surface, with open joints, by means of which it percolates into the soil. Land drains, 4 ft. deep, should be laid intermediately between the subsoil drains to remove the water from the soil. The difficulty of subsoil irrigation is to prevent deposit, which chokes the drains; and if the foul domestic water is allowed to trickle through the drains as it passes away from the house it soon chokes the drains. It is, therefore, necessary to pass it in flushes through the drains, and this can be best managed by running the water from the house into one of Field's automatic flush tanks, which runs off in a body when full.

When you have water closet and drainage, the great object to be attained in house drainage is to prevent the sewer gas from passing from the main sewer into the house drain. It was the custom to place a flap at the junction of the house drain with the sewer; but this flap is useless for preventing sewer gas from passing up the house drain. The plan was therefore adopted of placing a water trap under the water closet basin or the sink, etc., in direct communication with the drain. The capacity of water to absorb sewer gas is very great, consequently the water in the trap would absorb this gas. When the water became warm from increase of temperature, it would give out the gas into the house; when it cooled down at night, it would again absorb more gas from the soil pipe, and frequent change of temperature would cause it to give out and reabsorb the gas continually.

These objections have led to the present recognized system--viz., 1st, to place a water trap on the drain to cut off the sewer gases from the foot of the soil pipe; and, next, to place an opening to the outer air on the soil pipe between the trap and the house to secure efficient disconnection between the sewer and the house. It is, moreover, necessary to produce a movement of air and ventilation in the house drain pipes to aerate the pipe and to oxidize any putrescible products which may be in it. To do this, we must insure that a current of air shall be continually passing through the drains; both an inlet and an outlet for fresh air must be provided in the portions of the house drain which are cut off from the main sewer, for without an inlet and outlet there can be no efficient ventilation. This outlet and inlet can be obtained in the following manner: In the first place, an outlet may be formed by prolonging the soil pipe at its full diameter, and with an open top to above the roof, in a position away from the windows, skylights, or chimneys. And, secondly, an inlet may be obtained by an opening into the house drain, on the dwelling side of and close to the trap, by means of the disconnecting manhole or branch-pipe before mentioned, or where necessary by carrying up the inlet by means of a ventilating pipe to above the roof. The inlet should be equal in area to the drain pipe, and not in any case less than 4 in. in diameter. If it were not for appearance and the difficulty of conveying the excreta without lodgments, an open gutter would be preferable to a closed pipe in the house. This arrangement is based on the principle that there should be no deposit in the house drains. Therefore the utmost care should be taken to lay the house drains in straight lines, both in plan and gradient, and to give the adequate inclination.

The following are desirable conditions to observe in house drains: 1. As to material of pipes. House drains should be made either of glazed stoneware pipes or fireclay pipes with cement joints, or preferably of cast iron pipes jointed with carefully-made lead joints, or with turned joints and bored sockets. I say preferably of cast iron. In New York the iron soilpipe, with joints made with lead, is now required by the municipal regulations. It is a stronger pipe than a rainwater pipe. The latter will often be found to have holes. A lead joint cannot be made properly in a weak pipe, therefore the lead joint is to some extent a guarantee of soundness. Lead pipes will be eaten away by water containing free oxygen without carbonic acid, therefore pure rainwater injures lead pipes. An excess of carbonic acid in water will also eat away lead. You will find that in many cases pinholes appear in a soilpipe, and when inside a house that allows sewer gas to pass into the house. Moreover, lead is a soft material; it is subject to indentations, to injury from nails, to sagging. A cast-iron pipe, when coated with sewage matter, does not appear to be subject to decay; and if of sufficient substance it is not liable to injury. When once well fixed, it has no tendency to move. I would, therefore, advocate cast iron in lieu of lead soilpipes. In fixing the soilpipe which is to receive a water-closet, the trap should form part of the fixed pipe; so that if there is any sinking the down pipe will not sink away from the trap. It is, however, not sufficient to provide good material. There is nothing which is more important in a sanitary point of view than good workmanship in house drainage. In this matter, it is on details that all depends. Just consider; the drain pipes under the best conditions of aeration contain elements of danger, and those pipes are composed of a number of parts, at the point of junction of any one of which the poison may escape into the house. You thus perceive how necessary it is first to reduce the poison to a minimum by cutting off the sewer gas which might otherwise pass from the street sewer to the house drain, and in the next place being most careful in the workmanship of every part of your house drains and soilpipes. Reduce your danger where you can by putting your pipes outside. But you cannot always do that--for instance, at New York and in Canada they would freeze.

All drain pipes should be proved to be watertight by plugging up the lower end of the drain pipe and filling it with water. In no case should a soilpipe be built inside a wall. It should be so placed as to be always accessible. 2. The pipes should be generally 4 in. diameter. In no instance need a drain pipe inside a house exceed 6 in. in diameter. 3. Every drain of a house or building should be laid with true gradients, in no case less than 1/100, but much steeper would be preferable. When from circumstances the drain is laid at a smaller inclination, a flush tank should be provided. They should be laid in straight lines from point to point. At every change of direction there should be reserved a means of access to the drain. 4. No drain should be constructed so as to pass under a dwelling house, except in particular cases when absolutely necessary. In such cases the pipe should be of cast iron, and the length of drain laid under the house should be laid perfectly straight--a means of access should be provided at each end; it should have a free air current passing through it from end to end, and a flush tank should be placed at the upper end. 5. Every house drain should be arranged so as to be flushed, and kept at all times free from deposit. 6. Every house drain should be ventilated by at least two suitable openings, one at each end, so as to afford a current of air through the drain, and no pipe or opening should be used for ventilation unless the same be carried upward without angles or horizontal lengths, and with tight joints. The size of such pipes or openings should be fully equal to that of the drain pipe ventilated. 7. The upper extremities of ventilating pipes should be at a distance from any windows or openings, so that there will be no danger of the escape of the foul air into the interior of the house from such pipes. The soilpipe should terminate at its lower end in a properly ventilating disconnecting trap, so that a current of air would be constantly maintained through the pipe. 8. No rainwater pipe and no overflow or waste pipe from any cistern or rainwater tank, or from any sink (other than a slop sink for urine), or from any bath or lavatory, should pass directly to the soilpipe; but every such pipe should be disconnected therefrom by passing through the wall to the outside of the house, and discharging with an end open to the air. I may mention here that the drainage arrangements of this Parkes Museum in which we are assembled were very defective when the building was first taken. Mr. Rogers Field, one of the committee, was requested to drain it properly, and it has been very successfully accomplished.

I would now draw your attention to some points of detail in the fittings for carrying away waste water.

First, with regard to lavatories. As already mentioned, every waste pipe from the sink should deliver in the open air, but it should have an opening at its upper end as well as at its lower end, to permit a current of air to pass through it; and it should be trapped close to the sink, so as to prevent the air being drawn through it into the house; otherwise you will have an offensive smell from it. I will give you an instance: At the University College Hospital there are some fire tanks on the several landings. The water flows in every day, and some flows away through the waste pipes; these pipes, which carry away nothing but fresh London water to empty in the yard, got most offensive simply from the decomposition of the sediment left in them by the London water passing through them day after day. A small waste pipe from a bath or a basin is a great inconvenience. It should be of a size to empty rapidly--for a bath 2 inches, a basin 1½, inches. There are other points connected with fittings to which I would call your attention. The great inventive powers which have been applied to the w.c. pan are an evidence of how unsatisfactory they all are. Many kinds of water-closet apparatus and of so-called "traps" have a tendency to retain foul matter in the house, and therefore, in reality, partake more or less of the nature of small cesspools, and nuisances are frequently attributed to the ingress of "sewer gas" which have nothing whatever to do with the sewers, but arise from foul air generated in the house drains and internal fittings. The old form was always made with what is called a D-trap. Avoid the D-trap. It is simply a small cesspool which cannot be cleaned out. Any trap in which refuse remains is an objectionable cesspool. It is a receptacle for putrescrible matter. In a lead pipe your trap should always be smooth and without corners. The depth of dip of a trap should depend on the frequency of use of the trap. It varies from ½ inch to 3½ inches. When a trap is rarely used, the dip should be deeper than when frequently used, to allow of evaporation. In the section of a w.c. pan, the object to be attained is to take that form in which all the parts of the trap can be easily examined and cleaned, in which both the pan and the trap will be washed clean by the water at each discharge, and in which the lever movement of the handle will not allow of the passage of sewer gas.

And now just a few personal remarks in conclusion. I have had much pleasure in giving to my old brother officers in these lectures the result of my experience in sanitary science. In doing so, I desired especially to impress on you who are just entering your profession the importance of giving effect to those principles of sanitary science which were left very much in abeyance until after the Crimean war. I have not desired to fetter you with dogmatic rules, but I have sought, by general illustrations, to show you the principles on which sanitary science rests. That science is embodied in the words, pure earth, pure air, pure water. In nature that purity is insured by increasing movement. Neither ought we to stagnate. In the application of these principles your goal of to-day should be your starting-post for to-morrow. If I have fulfilled my object, I shall have interested you sufficiently to induce some of you at least to seize and carry forward to a more advanced position the torch of sanitary science.

* * * * *

PASTEUR'S NEW METHOD OF ATTENUATION.