Fig. 3 represents a section through a dwelling house, illustrating the essential elements of a system of house drainage.

A is the gravel trap, into which the subsoil drain B discharges, and which serves to prevent the gases from the sewer from entering the drain tiles and permeating the cellar. The drain B for cellar drainage should be of common 1 1/4-2-inch tile drains, laid with open joints, around which tarred paper or cotton rags may be wrapped to prevent any stoppage of the tiles from dirt falling in at the joints.

C is the house drain, which should consist of 4-inch vitrified pipe with well cemented joints to within 10 feet from the cellar wall. D is the running trap on the main drain to disconnect the house from the sewer. Into it the rain leader X discharges. E is a Y branch, closed with a brass trap screw, for cleaning purposes. F is a fresh air pipe, 4 inches in diameter, entering the house drain above the trap, and carried some distance away from the house, its mouth being hidden from view by shrubbery, and covered with a wire basket for protection against obstructions.

G is the 4-inch house drain, of heavy iron pipe, with well caulked lead joints, carried with sufficient fall along the cellar wall to the furthest point, where it receives either a soil pipe or a rain leader.

H H are the 4-inch iron soil pipes, which join the iron drain in cellar by Y branches and eighth bends. They are extended full size through the roof, and their outlets I I are protected by a strong wire basket.

J is a small refrigerator which wastes into a movable pail. K is the large tank in attic which is supplied through a ball-cock from street pressure. Its overflow pipe L is shown trapped by an S-trap with deep seal, and emptying into the gutter of the roof. The blow-off N from tank runs down vertically and delivers over the kitchen sink.

M M are small cisterns for flushing the water closets and slop hopper only.

O O are earthenware wash bowls with 1 1/4-inch waste pipes and overflow pipes of lead, trapped by Cudell's or Bower's traps, and delivering into 4" X 2" Y branches of soil pipes.

P is a pantry sink, of heavy tinned and planished copper, with overflow and 1 1/4" waste pipe of lead trapped by a Bower's trap and entering a Y branch of soil pipe.

Q are cement stone or ceramic wash tubs, with 1 1/2" waste pipe, and trapped by a Bower's trap.

R is an all-earthenware flushing-rim slop hopper, trapped by a vented S-trap, and flushed from a special cistern.

S is the kitchen sink, of galvanized or enamelled iron, or of earthenware, trapped by an 1 1/4" Bower's trap with 1 1/2" lead waste pipe.

T is a bath tub, of enamelled iron, or heavy planished copper or of porcelain. It is provided with a standing waste, and trapped by an 1 1/4" Cudell running trap.

T' is a small hip bath, of copper, provided with overflow and l 1/2" waste pipe, trapped by a vented S-trap.

V is a 2 inch air pipe to prevent the siphonage of traps. It is extended through roof, and enlarged to a 4-inch outlet, which should be left without any other covering than a wire basket. Into this air pipe enter the vent pipes from S-traps under slop hopper, water closet and hip bath.

W W W are water closets, the types shown being the long and short hopper and the washout closets. Each of these is provided with a special flushing cistern M M M.

X X is a rain leader delivering the water into the running trap of the house drain.

Y is the blow-off from the boiler, which wastes into a Y branch of the iron drain in cellar.

The system described and illustrated differs from the methods of house drainage as practiced in England in one essential point. There, it is the rule to keep soil pipes separate from waste pipes, to deliver to the former, in the words of Prof. Fleming Jenkin, "such foul matters as would certainly be tainted when contagious disease occurs in the house," in other words, the waste water from water closets, urinals, slop sinks and probably laundry tubs; a second system "receives all liquids, which may be called dirty, but not foul - the water from baths, kitchen sinks, and wash hand basins." It is, moreover, the rule in England to locate the soil pipe outside of the house walls, and to deliver the waste pipes over an open gully in the yard, from whence the wastes run into the house drain. Both arrangements are entirely impracticable in this country on account of the severity of the climate, and the separation of the two systems by discriminating between foul and dirty waste water leads to unnecessary complications. With well jointed, thoroughly ventilated soil pipes of iron, it seems quite permissible in American plumbing to run into them the wastes from any fixture in the house, if it be near the soil pipe, and where vertical stacks of waste pipes are run for bath tubs and wash basins, these waste pipes, if properly jointed, may with perfect safety deliver into the iron cellar drain, which receives the soil pipes of the house.

If all the given rules are carefully observed, the system of drainage of a dwelling will be as perfectly as possible in accordance with the present knowledge of sanitary science. Time and experience may find out hitherto unknown faults, but will also, it is believed, teach the proper remedy. With pipes of proper material, properly joined, properly laid, and properly and sufficiently often flushed with air and water, the object of a system of house drainage seems to be attained, viz., the instant removal from the house of all liquid and semi-liquid waste matthe and the perfect oxidation and constant dilution of the air contained in the 'pipes.

Says Mr. J. C. Bayles: " The conclusion I have reached is that when sewer gas finds its way into a house through the soil and waste pipes, the fault lies somewhere between the architect, the builder and the plumber. In any case, it is without excuse. I know that houses can be drained into sewers - without bringing sewer gas into them. The existence of foul sewers is in itself a perpetual danger to the public health, but there is no reason why we should bring that danger into our houses by providing channels through which the poisonous air of the sewer can find a means of ingress. I know of houses into which no sewer gas ever comes - unless, possibly, through the windows, borne in with the air of the street - and I have no hesitation in saying that, when the tenants of houses demand immunity from the dangers of unhealthful conditions, architects and builders will find a means of correcting the evils now complained of as practically irremediable. Sanitary reform in cities only waits until those to be benefited by it shall demand it."