How to prevent the contamination of the air by the products of decomposition.

There is no evidence to show that the emanations from fresh house-slops, or the excreta of healthy animals, are injurious to health, but it has been proved that when these matters decompose they become dangerous. The bubbles of gas which rise to the surface of such decomposing matters, when they burst, throw up solid particles of organic matter in the air, which float about for some time before falling to the ground. It is, therefore, essential to health that all such matters shall be removed from the vicinity of human beings promptly, before decomposition sets in, or else so manipulated as to prevent decomposition, or promote rapid oxidation.

The lower animals seem to recognize by instinct that their excreta are dangerous, and they deposit them (except when penned up by men) in places remote from their abodes, or else carefully cover them with fresh earth. Man alone retains his excreta in carefully prepared receptacles near his place of residence, until the accumulation is so large that he is forced to remove it.

The ordinary privy-vault should never be allowed. Its only advantage is its cheapness, while it involves constant danger of contamination of the water of adjoining wells or cisterns. Many an epidemic of typhoid fever has been unmistakably traced to this source. If such a vault is a necessity, it should be made water-tight, be small and frequently emptied, the contents should be frequently disinfected, preferably by being covered with fresh earth, and it should be built in such a spot that the current of ground-water (which furnishes the well-water) shall be from the well toward the vault, and never in the opposite direction. Better still is a movable tank, in which the excreta are received and covered with fresh earth daily. This can be emptied over a garden or field without offense. In villages where sewerage is impossible, pails are sometimes used. They have tight covers, and are removed frequently (once or twice a week, clean ones being substituted at the time of removal by the proper authorities), the contents being converted into poudrette at some place remote from habitations.

A better means of disposing of the excreta, where water-closets can not be had, is the earth-closet, of which there are several varieties. These are so constructed that they resemble a water-closet in appearance, but the excreta are caught in a receptacle beneath the seat, and covered with earth, when the handle beside the seat is raised. Dry earth is an excellent disinfectant,[1] and when excreta are thus mingled with it they are gradually oxidized and disappear, so that after a time the same earth may, with proper precautions, be used again.

The earth for these closets must be dry, and sifted of coarse particles, and enough must be deposited upon the excreta to cover them and to absorb the urine.

Its advantages, as compared with the water-closet, are, that it is cheaper, requires less repair, is not hurt by frost, is not injured when improper substances are thrown down it, and requires no water. Its disadvantages are, the trouble of collecting and drying the earth, the necessity of frequently removing the soil, the dust sometimes caused by its use, and the necessity of providing additional means for the disposal of slops.

A perfect method of disposal of excreta and other house refuse would be one which would insure their prompt and rapid removal in such a way as to prevent the contamination of the air of any inhabited locality during such removal, or after their final deposition. The most convenient and economical means yet invented of accomplishing this object is water-carriage; i. e., the matters referred to are conveyed from the house, with the addition of sufficient water to insure a rapid flow, through a series of pipes and tunnels into a large body of running water, or over the surface of the earth, under conditions which insure their rapid conversion into harmless substances.

The water-carriage system includes bowls or sinks for the deposit of refuse matters, connecting-pipes to remove such matters from the house, and public sewers for their further conveyance away from human abodes. The construction and care of public sewers belong to the local government; we have here only to do with house-drainage.

The essentials of house-drainage are: 1. The primary receptacles (bowls, sinks, water-closets, etc.) should be of such material and so constructed as to be impervious to fluids, and easy to clean and keep clean. 2. The pipes should be of such material as to be as durable as possible, and so laid and connected as to form gas-tight conduits, and to insure the rapid passage of whatever enters them, so as to prevent the formation of deposits or incrustations. 3. The drainage system should be so planned and constructed that neither the atmosphere of the house nor the drinking-water can be polluted by anything escaping from it, and no noxious matters can enter it from any other house.

The following plan of construction is that recommended by the Board of Health of New York city:

1. All materials must be of good quality and free from defects; the work must be executed in a thorough and workmanlike manner.

2. The arrangement of soil and waste pipes must be as direct as possible.

3. The drain, soil, and waste pipes, and the traps, must, if practicable, be exposed to view for ready inspection at all times, and for convenience in repairing. When necessarily placed within partitions or in recesses of walls, soil and waste pipes must be covered with wood-work, so fastened with screws as to be readily removed. In no case shall they be absolutely inaccessible.

4. It is recommended to place the soil and other vertical pipes in a special shaft, between or adjacent to the water-closet and the bath-room, and serving as a ventilating shaft for them. This shaft should be at least two and a half feet square. It should extend from the cellar through the roof, and should be covered by a louvered sky-light. It should be accessible at every story, and should have a very open but strong grating at each floor to stand upon.

Shafts not less than three feet square in area are required in tenement-houses, to ventilate interior water-closets.

5. Every house or building must be separately and independently connected with the street-sewer.

6. Where the ground is made or filled in, the house-sewer—that is to say, the portion of the drain extending from the public sewer to the front wall—must be of cast-iron, with the joints properly calked with lead.

7. Where the soil consists of a natural bed of loam, sand, or rock, the house-sewer may be of hard, salt-glazed, and cylindrical earthenware pipe, laid on a smooth bottom, free from all projections of rock, and with the soil well rammed to prevent any settling of the pipe. Each section must be wetted before applying the cement, and the space between each hub and the small end of the next section must be completely and uniformly filled with the best hydraulic cement. Care must be taken to prevent any cement being forced into the drain to become an obstruction. No tempered-up cement shall be used. A straight-edge must be used inside the pipe, and the different sections must be laid in perfect line on the bottom and sides.

8. Where there is no sewer in the street, and it is necessary to construct a private sewer to connect with a sewer on an adjacent street or avenue, it must be laid under the roadway of the street on which the houses front, and not through the yards or under the houses.

9. The house-drain must be of iron, with a fall of at least one quarter inch to the foot, if possible, and not more than one inch to the foot.

10. Where water-closets or a school-sink discharge into it, the drain must be at least four inches in diameter.

11. It must be hung on the cellar wall or ceiling, unless this is impracticable, in which case it must be laid in a trench cut at a uniform grade, walled upon the sides with brick laid in hydraulic cement, and provided with movable covers, and with a hydraulic concrete base of four inches in thickness, on which the pipe is to rest.

12. It must be laid in a straight line, if possible. All changes in direction must be made with curved pipes, and all connections with Y-branch pipes and one-eighth bends.

13. Any house-drain or house-sewer, put in and covered without due notice to the Health Department, must be uncovered for inspection at the direction of the inspector.

14. A running or half S-trap must be placed on the house-drain at an accessible point near the front of the house. This trap must be furnished with a hand-hole for convenience in cleaning, the cover of which must be properly fitted and made gas and air tight with some proper cement.

15. There must be an inlet for fresh air entering the drain just inside the trap, of at least four inches in diameter, leading to the outer air and opening at or near the street curb, or at a convenient place not less than ten feet from the nearest window. No cold-air box for a furnace shall be so placed that it can by any possibility draw air from this inlet-pipe. The inlet-pipe should never be carried up to the roof inside or outside the house.

16. No brick, sheet-metal, earthenware, or chimney-flue shall be used as a sewer-ventilator, nor to ventilate any trap, drain, soil, or waste pipe.

17. Every vertical soil-pipe and waste-pipe must be of iron, and, where it receives the discharge of fixtures on two or more floors, it must be extended at least two feet above the highest part of the roof or coping, of undiminished size, with a return bend or cowl. It must not open near a window, nor an air-shaft which ventilates livingrooms.

18. Soil, waste, and vent pipes, in an extension, must be extended above the roof of the main building, when otherwise they would open within twenty feet of the windows of the main house or the adjoining house.

19. Horizontal soil and waste pipes are prohibited.

20. The minimum diameter of soil-pipe permitted is four inches. A vertical waste-pipe, into which a line of kitchen-sinks discharge, must be at least two inches in diameter, with one inch and a half branches.

21. Where lead pipe is used to connect fixtures with vertical soil or waste pipes, or to connect traps with vertical vent-pipes, it must not be lighter than D-pipe.

22. There shall be no traps on vertical soil-pipes or vertical waste-pipes.

23. All iron pipes must be sound, free from holes, and of a uniform thickness of not less than one eighth of an inch for a diameter of two, three, or four inches, or five thirty-seconds of an inch for a diameter of five or six inches; and, in case the building is over sixty-five feet in height above the curb, the use of what is known as extra heavy pipe, and corresponding fittings, are required, which weigh as follows:

24. Before they are connected they must be thoroughly coated inside and outside with coal-tar pitch, applied hot, or some other equivalent substance.

25. When required by an inspector from the Board of Health, the plumbing must be tested with the peppermint or the water test, by the plumber in the presence of the inspector, and all defective joints made tight, and other openings made impermeable to gases. Defective pipe discovered must be removed and replaced by sound pipe.

26. All joints in the iron drain-pipes, soil-pipes, and waste-pipes must be so calked with oakum and lead, or with cement made of iron filings and sal-ammoniac, as to make them impermeable to gas.

27. All connections of lead with iron pipes must be made with a brass sleeve or ferrule, of the same size as the lead pipe, put in the hub of the branch of the iron pipe, and calked in with lead. The lead pipe must be attached to the ferrule by a wiped joint.

28. All connections of lead pipe should be by wiped joints.

29. Every water-closet, urinal, sink, basin, wash-tray, bath, and every tub or set of tubs, must be separately and effectively trapped, except where a sink and wash-tubs immediately adjoin each other, in which case the waste-pipe from the tubs may be connected with the inlet side of the sink-trap; in such a case the tub waste-pipe is not required to be separately trapped.

30. Traps must be placed as near the fixtures as practicable, and in no case shall a trap be more than two feet from the fixture.

31. All exit-pipes must be provided with strong metallic strainers.

32. In no case shall the waste from a bath-tub or other fixture be connected with a water-closet trap.

33. Traps must be protected from siphonage, and the waste-pipe leading from them ventilated, by a special air-pipe, in no case less than two inches in diameter for water-closet traps, and one inch and a half for other traps. Except in private dwellings, the vertical vent-pipes for traps of water-closets in buildings more than four stories in height must be at least three inches in diameter, with two-inch branches to each trap, and for traps of other fixtures not less than two inches in diameter, with branches one and a half inches in diameter, unless the trap is smaller, in which case the diameter of branch vent-pipe must be at least equal to the diameter of the trap. In all cases vertical vent-pipes must be of cast or wrought iron.

34. These pipes must either extend two feet above the highest part of the roof or coping, the extension to be not less than four inches in diameter to avoid obstruction from frost, or they may be branched into a soil-pipe above the inlet from the highest fixture. They may be combined by branching together those which serve several traps. These air-pipes must always have a continuous slope, to avoid collecting water by condensation.

35. Traps of fixtures near the fresh-air inlet may be ventilated by being connected with it.

36. No trap vent-pipe shall be used as a waste or soil pipe.

37. Overflow-pipes from fixtures must, in each case, be connected on the inlet side of the trap.

38. Every safe under a wash-basin, bath, urinal, water-closet, or other fixture, must be drained by a special pipe not directly connected with any soil-pipe, waste-pipe, drain, or sewer, but discharging into an open sink, upon the cellar-floor, or outside the house.

39. The waste-pipe from a refrigerator shall not be directly connected with the soil or waste pipe, or with the drain or sewer, or discharge into the soil; it should discharge into an open sink. Such waste-pipes should be so arranged as to admit of frequent flushing, and should be as short as possible, and disconnected from the refrigerator.

40. The sediment-pipe from kitchen boilers must be connected on the inlet side of the sink-trap.

41. All water-closets within the house must be supplied with water from special tanks or cisterns, the water of which is not used for any other purpose. The closets must never be supplied directly from the Croton supply-pipes. A group of closets may be supplied from one tank; but water-closets on different floors are not permitted to be flushed from one tank.

42. The valves of cisterns must be so fitted and adjusted as to prevent wasting of water, especially where cisterns are supplied from a tank on the roof.

43. The overflow-pipes from water-closet cisterns must discharge into an open sink, or where its discharge will attract attention and indicate that waste of water is occurring, but not into the bowl of the water-closet, not into the soil or waste pipe, nor into the drain or sewer. When the pressure of the Croton is not sufficient to supply these tanks, a pump must be provided.

44. Tanks for drinking-water are objectionable; if indispensable, they must never be lined with lead, galvanized iron, or zinc. They should be constructed of iron, or wood lined with tinned and planished copper. The overflow should discharge upon the roof, or be trapped and discharge into an open sink, never into any soil or waste pipe or water-closet trap, nor into the drain or sewer.

45. Rain-water leaders must never be used as soil, waste, or vent pipes; nor shall any soil, waste, or vent pipe be used as a leader.

46. When within the house, the leader must be of cast-iron, with leaded joints; when outside of the house, and connected with the house-drain, it must be trapped beneath the ground or just inside of the wall, the trap being arranged in either case so as to prevent freezing. In every case where a leader opens near a window or a light-shaft, it must be properly trapped at its base.

47. No steam exhaust or blow-off pipe from a steam-boiler will be allowed to connect with any soil or waste pipe, or directly with the house-drain. They should discharge into a tank or condenser, the waste from which, if to be discharged into the sewer through the house-drain, must be connected on the sewer side of the running trap.

48. Subsoil drains must be provided whenever necessary.

49. Yards and areas should always be properly graded, cemented, flagged, or well paved, and properly drained; when the drain is connected with the house-drain, it must be effectively trapped. Front-area drains must, where practicable, be connected with the house-drain inside of the running trap.

50. Cellar and foundation walls must, where possible, be rendered impervious to dampness, and the use of asphaltum or coal-tar pitch, in addition to hydraulic cement, is recommended for that purpose.

51. No privy-vault or school-sink will be allowed in any cellar or basement; nor shall the general privy accommodation of a tenement or lodging house be allowed to be in the cellar or basement.

52. No privy-vault, or cesspool for sewage, will be permitted in any part of the city where water-closets or a school-sink can be connected with a public sewer in the street.

53. School-sinks must be of cast-iron, not more than two feet in depth, connected at the upper end with the Croton supply, and at the lower end with a drain leading to the street-sewer, and provided with an outlet at the lowest point and on the bottom so as to admit of a complete discharge of the contents whenever the outlet is opened and the sink flushed with water.

54. The sink must be set so that the flange will be at least two feet below the yard surface, to prevent freezing. It must be at least ten feet from any window, or as near that distance as practicable.

55. The waste-pipe from a hydrant-sink in the yard must be properly trapped, especially where it discharges into a school-sink, a privy-vault, or cesspool, or the house-drain.

56. Open light and air courts must be properly drained.

57. When a privy-vault or cesspool must necessarily be used, and the water-supply of the premises is from a well, they must be at least fifty feet from the well; and the privy-vault must be absolutely tight.

Explanatory Remarks.

2. As direct as possible. To insure an uninterrupted flow. When a pipe has to pass an obstruction (a beam or post) an offset is used (Fig. 2).

3. The soil-pipe is that which conveys the contents of water-closets to the house-drain: the waste-pipes are intended to carry other refuse fluids only. The house-drain is the large pipe which receives the contents of the soil and waste pipes and conveys them outside the house.

A trap is a bend (with or without an enlargement) of the pipe, intended to retain a sufficient amount of the fluids that enter it to occlude the pipe and prevent the backward flow of air. The effective water-seal is represented by the total depth of water in the trap, minus the inside diameter of the pipe, and should be at least one inch.

Traps are of various kinds, and many are patented. The accompanying figures represent the principal types.

Fig. 3 is the S-trap. Fig. 4 is the half S-trap. There is also a three-quarter S-trap. Fig. 5 is a D-trap, formerly much used, but now mostly out of date, because it retains dirt. Fig. 6 is a bag-trap. It has no advantage over the S-trap, and uses more material. Fig. 7 is a bottle-trap, much used in Boston. This also retains dirt. There are varieties of it, the distinguishing feature of all being that the fluids enter them at the bottom and flow out at the top.

Fig. 8 is the bell-trap, so called from its shape. Much used for the drains of paved areas, yards, and cellars; liable to retain dirt, and needs frequent cleaning; not a good trap. Fig. 9 is a running-trap, used in house-drains and other pipes that are nearly horizontal. Fig. 10 represents a mason’s trap. Is built of brick or stone and cement. Used in brick-drains and sewers, in receiving-basins at street corners, etc. Requires frequent cleaning, and should never be used inside a building. Fig. 11 represents the method of trapping a cesspool. The same plan is also used for grease-traps, the outlet-pipe dipping below the surface of the contents so that it is never obstructed by the grease, which floats on top.

A few patent traps are shown as samples:

Fig. 12 is the Adee trap, a modification of the D-trap. Fig. 13 is the Bower trap, claimed to be secured against siphonage or back pressure by a rubber ball which floats up against the entering-pipe. Modification of the bottle-trap. Fig. 14 is Bedell’s trap, with a metallic flap or valve, and an opening on the sewer side of the valve, to relieve pressure. Fig. 15 is Stewart’s trap, intelligible from the diagram. Traps are also made of iron or glass, with a mercury seal, which, it is claimed, are proof against siphoning, pressure, or evaporation.

4. A louvered sky-light is one with slats at the sides inclining outward, so that air can escape but rain can not enter.

6. Calked with lead. (See 26.)

7. Tempered-up cement. Cement which has been used once, and has been broken up and ground, for using a second time.

9. House-drain, of iron. (See “Bad Odors, 2, a.”)

10. Water-closets. Four principal classes, with innumerable varieties, mostly patented.

1. The pan-closet (Fig. 16). Its chief advantage is its cheapness and the ease with which it can be repaired. Its disadvantage is the odor that usually attends its use. When the handle (a) is raised, the contents of the pan (b) are thrown against the side of the iron container (c), and some filth adheres there and decomposes, filling the container with a noisome stench, which escapes into the room every time the closet is used. An abundant flush, an enameled container, and proper ventilation of the container, reduce this nuisance materially. Generally condemned by sanitarians.

2. Hopper-closets (Fig. 17). Rather unsightly, because the water and floating matter in the trap are visible, and matters often cling to the sides, but, with an abundant flush suddenly discharged, are very inoffensive.

3. Plunger-closets, of which the Jennings closet (Fig. 18) may be taken as a type. The handle lifts a plug, which allows the contents of the bowl to run out, and, when the plug is dropped in place, the bowl is filled again from a ball-cock. These closets are liable to get out of order; the plungers or plugs lose their rubber flanges and leak, and the plunger-chamber is apt to retain filth.

4. It is evident that if the hopper-closet could have its trap bent to one side out of sight, and its hopper enlarged toward the bottom, so that nothing would strike and cling to its sides, it would be an excellent one. Of such a type are the Tidal-Wave and National closets (Fig. 19), a being the water-pipe, which discharges into a flushing rim, and b a vent-pipe to relieve pressure between the two bodies of water during a discharge, and prevent siphoning.

A water-closet, to be well flushed, should have a discharge of three gallons of water in five seconds, sent directly downward all around the rim.

School-sink (also called trough-sink or privy-sink). An iron trough, having a sewer-connected opening with a movable iron plug in the bottom at one end, for the discharge of its contents, and a pipe at the other end, from which it is filled with water. It is practically an elongated water-closet. (See 53.)

12. Y-branch (Fig. 20), so named from its shape. There are also half Y-branches.

Eighth bends. There are also quarter bends (Fig. 21), sixth bends, and sixteenth bends. These are used in pipe-connections in order to discharge the contents of the branch pipes in the same general direction with the current in the main pipes, for, if the discharge enters at a right angle, a deposit is apt to form opposite the point of connection.

14. Trap in house-drain. Intended to cut off all communication between the house and the street sewer. If a contagious disease occurs in one’s own house, he can be sure that the excreta are disinfected, and that disease-germs can not escape into the air, even if the pipes happen to be defective; but he can not be sure that such excreta are properly disinfected in other houses. The only safe way, therefore, is for each house to be cut off from all others by the means described. The objections to the trap on the house-drain are, that it forms a slight obstruction to the flow of drainage, and is liable to be obstructed by deposits, and that it favors “cushioning,” i. e., the forcing of smaller traps, when the air in the drain is compressed between this trap and a down-coming mass of water. (See “Bad Odors,” 1, d.) The first of these objections is met by making the trap a half S one, so that the fluids fall down one limb with sufficient force to wash out the bottom of the trap thoroughly with each discharge, and the second by the fresh-air inlet, which relieves the pressure that otherwise might force the traps.

15. The fresh-air inlet affords free entrance for air, and, as the main lines of pipe are open above the roof, the difference in length of the pipes will give rise to a constant current of fresh air through them, in one direction or the other. (See “Bad Odors,” 1 c.) This results in the oxidation of whatever filth may cling to the pipes, and dilutes offensive gases so that they are rendered harmless. It has also been shown that the various microscopic organisms, which are believed to be the specific cause of certain diseases, increase in virulence, when they propagate in the absence or with a deficient supply of oxygen, while the intensity of their action is diminished if they grow where oxygen is plentiful.

16. Ventilation in chimney-flues. (See “Bad Odors,” 1, c.)

17. Vertical pipes of iron. Iron resists corrosion and the assaults of rats better than lead, and lead pipes are sometimes occluded by pressure and settling. Branch wastes are generally of lead because it is easily cut and bent, so as to be used in difficult situations.

Return-bend or cowl. To prevent senseless persons from throwing things down the pipe, and thus obstructing it.

20. Diameter of pipes. The inside diameter is always meant.

21. D-pipe. (See Appendix B.)

22. No traps on vertical pipes,i. e., at the foot of such pipes, because they would prevent the free circulation of air, and thus render the fresh-air inlet practically useless. Also to prevent “cushioning.”

23. Cast-iron pipes are made in five-foot lengths, with an enlargement at one end, called the hub or bell, and a bead around the edge of the other end (the spigot-end). The spigot-end of one pipe fits loosely into the hub of another, sufficient room being left for calking. (See 26.)

24. Pipes are tarred by being heated to 500° Fahr. and then dipped perpendicularly into a hot bath of coal-tar pitch mixed with a small proportion of heavy coal-oil. This coating prevents corrosion, or at least greatly retards it.

25. Wrought-iron pipes, with screw joints, are used by the Durham House Drainage Company, the joints being gas-tight. They have the advantage of being very durable and impervious to gases, but the disadvantage of being too permanent. If it is desired to change the position of a fixture, or to connect a new one, it is easy to break a hole in a cast-iron pipe, or to remove a portion of it, but where wrought-iron pipe is used this is almost impossible. The Durham system also costs about twenty-five per cent more than the common one, and it is not strictly correct to say that its use renders a house absolutely secure against leakage of sewer-air, because it does not do away with lead branch-pipes, in which frequent leakages occur, and all irregular portions of pipe, with branches, etc., in this system are made of cast-iron with calked joints, as in the ordinary system.

The water-test is applied by plugging the pipe carefully, and closing all openings below a certain point, and then filling it with water to that level. If there is any leakage, the water-level will gradually sink. If the pipes are tight, it will remain the same.

Peppermint-test. (See hereafter.)

26. Oakum is packed into the space between the spigot-end of one pipe and the hub of the other, and driven against the bead above mentioned. This packing is called a gasket. Melted lead is poured in on top of the oakum, and, when it has cooled, is driven in tight with a calking iron and mallet. When ordinary pipe is used, the calking will sometimes split the hub, and this furnishes an argument for the general use of extra-heavy pipe.

Iron-filings, etc., making what is called a rust-joint.

27. Ferrules, or sleeves, are used because lead pipes are too soft and yielding to withstand the calking. Lead can not be soldered to iron, and therefore brass or copper has to be used. If iron ferrules are used, the lead pipe must be turned up on the outside far enough so that its edge shall be covered by the melted lead used in calking, so as to prevent leakage of gas, as hereafter described. (See “Bad Odors,” 1, b.)

28. Wiped-joints are those always used for lead pipe, and are indicated by a raised ring of solder surrounding the pipe.

29. A trap, with a good water-seal, is an effective barrier against the passage of sewer-air or particles of organic matter. The experiments of Carmichael, confirmed by Wernich and Pumpelly, have amply demonstrated that sewer-air passes through the water-seal in such minute quantities that it can not possibly harm any one, and that solid particles of matter can not pass at all.

Separate traps, except, etc. (See “Bad Odors,” 1, d.)

33. Siphonage. (See “Bad Odors,” 1, d 37.)

37. Overflow-pipes from fixtures. It is better to connect them with the trap below the water-level. (See “Bad Odors,” 1, d.)

38. Safes are sheets of metal (generally lead) with turned-up edges, placed beneath basins, sinks, water-closets, etc., to protect the floor in case of leakage. The waste-pipes of safes are common sources of nuisance. (See “Bad Odors,” 1, c.)

39. To prevent contamination of the contents of the refrigerator.

41. When water-closets are flushed directly from the common supply-pipe of the house, as in the different kinds of valve-closets, the water in the pipes, under certain circumstances, will be contaminated: e. g., if a person opens a faucet on one floor at the same moment that the valve is opened to flush a water-closet on a higher floor, water will be sucked back from the valve, and the air of the closet will follow it. Check-valves have been used to prevent this, but they should not be depended on.

Various forms of tanks or cisterns for water-closets are here shown. Fig. 22 represents a tank, b, which discharges water as long as the handle (attached to the chain a) is raised. It gives a flush also of the entire contents of the service-box c, after the handle is lowered. Fig. 23 shows a waste-preventing tank, which is divided into two compartments, b and d. It will be seen that this allows only the contents of d to be discharged, with an after-flush from c. Fig. 24 shows a tank, in which the chain a is attached to the seat, and is pulled down when the seat is depressed. It will be seen that no water can flow while the closet is in use, but, when the seat is released, the contents of c are discharged with great force. In all these figures, e is a ball-cock. This cock is controlled by a hollow copper ball, which floats on water, and is attached to the end of a lever. When the water falls, the ball falls with it, and opens the cock. When it is floated up to a certain point, it closes the cock and stops the flow.

45. Leaders should not be used as soil-pipes, because, during a rain, the ventilation of the pipes is interfered with by the downward flow of water, which will also empty unventilated traps by siphoning. The necessity of having leaders open flush with the roof also interferes with proper ventilation.

47. If steam enters a soil-pipe, it heats the water in the traps, injures joints on account of the extreme changes of temperature induced, and hastens corrosion of the pipes.

Fig. 25 shows a system of house-drainage for a city house planned in accordance with the above rules.

In country houses, where there are no sewers, the best method of disposing of the house-slops is subsoil drainage. The house system may be the same as that already explained for city houses. The fluids are conducted by a pipe with tight joints to a flush-tank (Fig. 26) near the house. This tank is so constructed that it empties itself, by a siphon action, whenever it gets full, discharging all its contents in a very short time, and thus washing out thoroughly the pipes into which it empties. “The outlet-pipe from this tank is continued by a cemented vitrified pipe to a point about twenty-five feet farther away. Here it connects with a system of open-jointed drain-tiles, consisting of one main, fifty feet long, and ten lateral drains, six feet apart, and each about twenty feet long. These drains underlie a part of the lawn, and are only about ten inches below the surface” (Waring). It will be understood that the purpose of this method of drainage is to have the organic matter contained in the house-refuse appropriated by vegetation, and it must therefore be distributed within reach of the grass-roots.

If water-closets are used, the following system is recommended in “The Sanitary Engineer”: Collect all the sewage of the house in a small and perfectly tight tank or cesspool, in which the paper and fecal matter soon become macerated by fermentation and reduced to a pulp. This tank should overflow into the flush-tank, the overflow-pipe dipping at least a foot below the point of discharge, to avoid the scum. The siphon of the flush-tank should be accessible by a man-hole, so as to be readily cleaned. If thus arranged, and if no roots of trees are in the soil, the distribution-pipes will not clog for a year or more, sometimes not for ten years.

Pipes should be laid at a depth of eight inches, with a slight and uniform descent of not over six or eight inches in one hundred feet. Branches from a four-inch main to the two-inch distribution-pipes should lead from the bottom of the former, instead of from the side, as in ordinary drain connections.

There should be a grease-trap (see “Explanatory Remarks,” 3) attached to the kitchen waste-pipes, in order to prevent clogging of the tanks and pipes by the congelation of fat.

Bad Odors.

When bad odors in a house are traceable to the drainage, they will usually be found to be due to one or more of the following causes:

1. To faulty construction. (a.) Drains.—These may be made of brick or stone and cement. Such materials are pervious to gases, even when sound, and are peculiarly liable to be channeled by rats, especially where an iron or lead pipe enters them. Such a drain should be replaced by an iron one.

(b.) Joints.—Cement-joints are pervious to gases. Putty-joints crack and so become pervious. A lead pipe is sometimes connected with an iron one by means of an iron ferrule, the lead pipe passing inside the ferrule and being turned over its lower edge, extending up on the outside, the ferrule then being calked into the hub. When paper is used for the gasket or packing, it rots away in time, and a passage is left through which gas can escape as follows: up between the hub and the turned-over lead pipe, over its edge, between it and the calking, down between the lead pipe and the ferrule, across the lower edge of the ferrule, and out between the inner surface of the ferrule and the outer surface of the lead pipe. (See Fig. 27.) Sometimes a connection of lead with iron is made by means of a lead flange fastened around the iron pipe with wire, and sometimes the lead pipe is simply stuck into a hole in the iron pipe and fastened with cement or putty. Such work should be replaced by properly made joints as described in the above regulations. (Or in “Bad Odors,” 2, c.)

(c.) Pipes.—If the leaders are not trapped at the bottom, offensive gases from them may enter the nearest windows. A leader is never of the same length as the soil-pipe, and, if there is direct communication between them through the house-drain, there will always be a current of air through them in one direction or the other. If the external air is colder than that inside the pipes, then the heavier column of air will be over the shorter pipe, and the current will be down that one and up the other. If the external air is warmer than that in the pipes, the heavier column will be that which includes the longer pipe, and the current will be down that one and up the shorter. So, as a rule, the current in winter is down the short pipe and up the long one, while in summer it is reversed, and, as the short pipe often ends near windows, the nuisance is greatest when these windows are open. Of course, in such cases, the leader must be trapped.

Ventilating-pipes sometimes end in chimney-flues. This is a bad plan, for, if the flue is in use, the open end of the pipe will become choked with soot and finally be rendered useless. If the flue is not used, there will often be a down draught in it, and the offensive gases may be conveyed through stove-pipes or fireplaces into the rooms of the house. Such gases may even penetrate the walls of the flue and so enter the house. If such a pipe is ever run into a flue, it should be extended at least two feet above the chimney-top.

Ventilating-pipes are sometimes badly arranged, so that they actually neutralize a trap and render it useless. (See Fig. 28.) In this figure a is the soil-pipe and b the ventilating-pipe.