matter, and often of chamber-slops, of probably 95 per cent. of the
population of this country, and of Europe as well. It is curious, in
examining the recommendations of public health officers and the
requirements of local boards of health, to observe the uniformity with
which this most important subject is passed over with the prescription
that the vault shall be tight, sometimes that it shall be vaulted
over, and sometimes that it shall not be within a certain small number
of feet of a boundary-line or of a drinking-water well. These
prescriptions are most absurd. It is safe to say, that of the millions
of privy-vaults in this country not more than hundreds are really
tight; that a still smaller number are so vaulted over as to prevent
the free exhalation of the gases of decomposition; that those which
are so vaulted over are in all respects of worse sanitary effect than
those which have freer communication with the air, and that their
possibilities of evil reach many times farther than the limits of
distance usually required to intervene between them and the well or
the neighboring property. In view of the universality of their use and
of the completeness with which modern communities are inured to their
presence, it seems almost hopeless to attempt to secure a proper
realization of their great defects. They are always the seat of the
foulest, and even of the most dangerous, decomposition. They taint not
only the air and the soil, but the water of the soil which goes so
often to feed our sources of drinking-water, and their local stench is
of itself sufficient to sicken all who have not by daily and lifelong
habit become accustomed to it. Taking the country at large--farm
houses and village houses as well as the dwellings of cities--it is
not too much to say that the best sanitary service that {220} can be
rendered by those interested in the removal of causes of ill-health
would be in securing the abolition of these barbarous domestic
appliances. In many ways the cesspool is as bad as the vault, but in
some respects the vault is facile princeps as a public and private
nuisance of the most annoying and dangerous character. Wherever a
public or private sewer is available, wherever disposal by irrigation
is possible, and wherever even the crudest attention can be secured
for an automatic or simpler earth-closet, the strongest effort should
be directed to the absolute inhibition of the common privy-vault.
II. THE REMOVAL OF LIQUID HOUSEHOLD WASTES.--As has been stated above,
the liquid household wastes are of much more serious consequence from
a sanitary point of view, as compared with excrementitious matters,
than the public has been wont to suppose. These, owing to the large
amount of water which they contain, are beyond the reach of any system
of dry conservancy. They consist almost invariably of a flood of water
containing but a small percentage of refuse food, urine, soap, filth
of the laundry, grease--everything, in fact, except fecal matter and
the coarser garbage and ashes--constituting the waste of the
household. Where water-closets are used fecal matter is generally
added to the flow, but its relative quantity is small, and its
presence or absence does not seriously affect the problem of disposal.
In a house provided with abundant, generally superabundant, plumbing
appliances, with a large consumption of water, the whole apparatus is
constructed on the theory that all manner of filth is to be taken up
by running water and carried well without the house. Where this
theoretical end is completely attained there exists a condition of
drainage rarely met with and little to be criticised. Unfortunately,
the theoretical excellence is rarely secured. Running water confined
within a narrow channel, and so compelled to move with force
sufficient to give an energetic scouring to the walls of its conduit,
may be trusted to carry with it or to drive before it pretty nearly
all foreign matter that may have been contributed to it, but the
moment this vigorous current is checked, that moment the tendency to
excessive deposit begins. It is checked in practice in various ways:
First. By too great a diameter of the pipe: a volume of discharge
requiring a velocity of 4 feet per second in a pipe 1 inch in diameter
would have a velocity of only 1 foot per second in a channel 2 inches
in diameter, and of less than 6 inches per second in a channel 3
inches in diameter. Ordinarily, except as the deposits are removed by
decomposition (always objectionable), the deposited matters accumulate
and reduce the original bore to the diameter which will secure a
cleansing flow. It is the part of wisdom to provide only this bore at
the outset or not greatly to exceed it, and it is one of the earliest
recommendations of an experienced sanitary engineer to reduce the size
of too large bores where they exist.
Second. By the use of traps larger than the pipes leading to them and
from them, thus increasing the natural tendency of all traps to
stagnation and deposit.
Third. By the use of vertical waste-pipes, which are almost universal,
and which are very often necessary. The velocity of a current measured
along the axis of the pipe is less if the direction is vertical than
if it is laid on {221} a steep slope, because of the tendency of
liquids flowing through vertical pipes, which they do not fill, to
adhere to the walls and to travel with a rotary movement. I have seen
vertical soil-pipes furred with excrement to a thickness of nearly
three-eighths of an inch; I have never seen a corresponding deposit in
a pipe of good slope where the current was direct. This latter point
is rather one of curious interest than of practical value--certainly
from the physician's point of view. Even in original construction it
is rarely possible to give soil-pipes other than a practically
vertical course as they pass from one story to the next. Indeed, the
physician need not trouble himself to consider the question of the
size or of the direction of this main channel. He will often find
occasion to criticise the use of unduly large waste-pipes from single
vessels; as, for example, two-inch pipes leading from bath-tubs; two
and a half-inch pipes leading from laundry-tubs; and three-inch pipes
leading from kitchen-sinks. Where reconstruction is to be undertaken,
he may with advantage exert himself to secure in these lateral
waste-pipes a diameter never exceeding one and a half inches, and from
kitchen- and pantry-sinks, whose outflow is loaded with grease,
preferably not exceeding the diameter of one and a half inches, with
traps of even a little less size. Where several vessels lead into the
same waste-pipe these small diameters may increase the tendency to the
emptying of the traps by siphonage, but if proper mechanical traps are
used for baths, wash-bowls, and laundry-tubs, and if ample flushing
appliances are connected with kitchen- and pantry-sinks, the temporary
removal of the trapping-water by siphonage may generally be
disregarded. It will seldom happen that the removal of water will be
so complete as to prevent the satisfactory closing of the mechanical
valve by capillarity, even if it fails, in itself, to make a perfectly
tight fit.
A favorite recent requirement of theoretical sanitarians, and one
which has perhaps for business reasons been eagerly accepted by the
plumbing trade, is what is called the "back" ventilation of traps;
that is, the carrying of a vent-pipe from every trap in the house to a
point above the roof. In my judgment, there is more to condemn than
there is to commend this practice, for I believe that the more rapid
emptying of traps by evaporation where they are not constantly
supplied by frequent use, the dangers of accident to lead pipe, which
is generally used for ventilating purposes, and the misapplication of
a large outlay which might better be applied in other directions,
constitute convincing arguments against this favorite new method of
preserving the integrity of the water-seal. There are a number of
traps which are closed by floating balls, or by balls bearing upon the
outlet, which seem to be quite satisfactory and efficient. The worst
waste-pipes, by far, are those of kitchen- and pantry-sinks which pass
a large amount of hot grease. This soon cools sufficiently to congeal,
and it attaches itself to the walls of the pipe, where it does congeal
until the bore is reduced to what is barely sufficient to furnish the
necessary limited water-way. Grease-traps of various forms have been
invented with a view to retaining this obstructing material. After
much experience with all of them that have been in general use, I have
become convinced that the only satisfactory way to avoid the
difficulty in question is to retain the outflow of the sink until a
certain considerable quantity has accumulated, and until its grease
has entirely {222} congealed, then to discharge the whole volume
rapidly through a pipe of small calibre. This may be done with
Carson's grease-trap by throwing in a pail of water to start a siphon
action when the vessel has become filled to its overflow-point. It is
more simply accomplished by a device of my own, wherein the whole
outflow is retained by a plug at the bottom of a large vessel working
after the manner of the plug of a wash-basin, until it is filled to
the level of the sink, and then opening the outlet for its sudden
discharge.
Good workmanship is as important as, if not indeed more important
than, good arrangement. It seems a very simple proposition to say that
all waste-pipes, whose office it is to carry foul liquids out of the
house, should be made tight in material and in joint. It is a
remarkable fact, however, that leaky joints in soil-pipes and in
drains are by no means rare. Probably there are few houses, very few,
in which they do not occur. The soil-pipe is put together by inserting
the small end of each section into the bell at the top of the section
below it, practically like putting the outlet of one funnel into the
larger upper portion of another. There may be abundant space for
leakage at every joint from the top to the bottom of the house,
without there being the least show of the leakage of water. The foul
air within the pipe may escape freely through a dozen openings, while
the heavier liquid flow takes its easiest and most direct course
downward from the point of one pipe through the bell of the one below.
When we come to the horizontal run of the soil-pipe in the basement,
if an imperfection of the joint occurs on the lower side there is an
obvious drip, which continues at least until closed by rust. Similar
imperfections in other parts of the joint would not be so manifested.
It has recently been demonstrated that there is no safety in the
construction of soil-pipes short of that absolute assurance which can
be secured only by an efficient test. Plugging all the outlets of the
soil-pipe and filling it with water, the slightest leak will be
exposed.
However defective may be the condition of an iron soil-pipe, vertical
or horizontal, it is perfection itself compared with the usual state
of a drain laid under the cellar floor; and here is a point where the
least experienced inspector of house drainage cannot be mistaken.
Under all circumstances, at least in all work hitherto executed, he
should demand as absolutely necessary that the drains under the cellar
floor be removed, that the earth which has been fouled by the leakage
of its joints and its breaks shall be taken out to the clean untainted
soil below, and refilled with well-rammed pure earth or with concrete,
the drainage being carried through a properly-jointed iron pipe above
the pavement, and preferably with a fall from the ceiling of the
cellar to near the floor at the point of outlet--in full sight for the
whole distance. It sometimes happens that the necessity for using
laundry-tubs or other vessels in the cellar makes the retention of an
underground course imperative. When retained, the drain should be of
heavy cast iron with most securely leaded joints tested under a head
of several feet. When found to be tight and secure, it should not be,
as ordinarily recommended, left in an open channel covered with boards
or flags and surrounded by a vermin-breeding, unventilated and
uninspected space, but closely and completely imbedded in the best
hydraulic cement mortar. Its careful testing before this {223}
enclosure is of course the only condition under which the work can be
permitted.
Tightness of all waste-pipes being secured, the next point in order is
their proper ventilation. A good deal has been said, and little has
been proved, about the different effects on the human system of the
gases of decomposition which have been produced in the absence of a
sufficient circulation of air, and those produced where the
ventilation and dilution are more complete. The probabilities of the
case are, of course, entirely in favor of the latter condition, and it
is accepted by all sanitarians as an axiom that all water-ways and all
vessels in which organic decomposition, even the decomposition of
adhering slime, takes place, should be ventilated as thoroughly as
possible. Until about ten years ago nearly all waste-pipes were
tightly closed at the top, and were shut from the sewer by a trap at
the foot, allowing absolutely no communication between the outer air
and the atmosphere of the pipe except as fresh air might be carried in
through the water-seals of the traps at each end. At about that time
it was becoming the general custom in the better class of work to
carry a small vent-pipe, often only one inch in diameter, rarely more
than two inches in diameter, through the roof of the house, closing it
at the top and perforating it with a few inefficient holes. This had
undoubtedly the effect of relieving the pressure on the atmosphere of
the pipe caused by the filling of unventilated sewers with tide-water
or storm-water, or by a sudden increase of temperature from the
admission of hot water. Later, it was accepted as a universal rule,
and it became a quite general practice, to carry the soil-pipe above
the roof with its full diameter, providing its summit with some form
of ventilating cowl. All this constituted not ventilation, but
venting. Real ventilation was introduced only with the very recent
improvement of admitting fresh air at the foot of the soil-pipe, so as
to make a complete circulation from one end to the other--a
circulation sufficient to produce, by the diffusion of gases, a very
fair ventilation of lateral waste-pipes of moderate length. It is now
coming to be understood that ventilating cowls, of whatever form, are
an obstruction to the movement of air in the absence of wind, and
that, as what is needed is never a vigorous current, but always a
living one, these cowls had better be dispensed with. We have learned,
too, that the most efficient means for increasing the flow of air
through the top is to increase its diameter at the top, enlarging the
highest length of a four-inch pipe, for example, to a diameter of six
inches. With this arrangement, and with a foot-ventilation four inches
in diameter opening at a point where it can never be obstructed by
rubbish or by snow, there will be secured a condition perhaps more
efficient in improving the condition of an imperfectly drained house
than any other one thing that may be done.
I have sketched above, in a very hurried manner, the main outline of a
system of house-drainage which may be accepted or which may be
recommended by a physician with confidence of securing a good result.
To go more into detail in technical matters would be out of place in a
paper of this character. Before leaving this subject, however, it is
important to call attention to the fact that what is recognized in our
houses as sewer gas is in far greater degree the product of
decomposition taking place within the house-drains themselves than the
product {224} of decomposition in the distant sewer forced into the
house through its connecting drain. It is emphatically a case of the
beam in our own eye as compared with the mote in the eye of our
neighbor. It is a rule which has exceptions, but they are few, that
the contained air of the house-pipes is far worse than the contained
air of the sewer; and the conviction is growing that the use of a trap
to the main drain between the house and the public sewer is more often
objectionable than advantageous. Such a trap always tends to check the
flow of the drain and to induce deposits whose decomposition is
objectionable. Wherever the abandonment of the trap is anything like
universal the considerable ventilation of the sewer thereby secured
brings its atmosphere to a condition which makes it not objectionable,
and generally useful, as a source of movement in the air of the
interior drain- and soil-pipe.
(_a_) Public sewers are more or less good or bad entirely according to
their character and condition. As a rule, a well-flushed sewer which
is used for no other purpose than the removal of foul waste, built on
what is called the separate system, and automatically flushed at least
daily, may be considered to be, if well laid and tightly jointed,
absolutely safe. A public sewer of large size and of irregular
construction, receiving not only household wastes, but the wash of
streets as well, may be regarded at least as an object of grave
suspicion. These general statements may be so far qualified by the
character of the sewers of each class as to run very nearly together;
that is to say, separate sewers, with leaky joints, irregular grades,
defective alignment, insufficient flushing, and inadequate restriction
as to the matters they are to receive, will be an intolerable and
dangerous nuisance; on the other hand, a large brick sewer built in
the best manner and of the best material, with sufficient fall and
sufficient supply to maintain itself in a cleanly condition, is free
from the serious drawbacks which usually attach to sewers of this
class.
With sewerage as with house-drainage it is not worth while to attempt
here to give anything like detailed directions for inspection and for
reformation. It will suffice to call attention to this one broad and
general rule: Every sewer or drain having for its object the removal
of putrescible organic matters must be so arranged as to maintain
itself in a condition of practically absolute cleanliness, without, as
in the case of storm-water sewers, waiting for the flushing effect of
storms, which often come only at long intervals, during which the
worst condition of decomposition may be established. Whether the sewer
be intended for drainage only or for both drainage- and storm-water,
if it contains at any time deposits of any kind, it is defective--more
or less so, of course, according to the extent and duration of the
accumulation.
Although it should be rigidly insisted upon in every case that the
sewer should maintain itself free from deposits, there will still be,
unavoidably, a certain amount of foul gas produced by the
decomposition of the matters coating its walls, and in order to dilute
and to remove this, and perhaps in order to modify their original
character, the most thorough ventilation is necessary.
Any sewer or other drain which at any time gives forth the odor of
putrid decomposition is in bad condition and should be at once
rendered inoffensive. So far as I know, there is no exception to this
rule. I have met no conditions in towns of any size where absolute
self-cleansing may {225} not be secured. It is worth while, however,
to repeat here the statement made above, that sewer gas, in so far as
it is a serious factor in connection with the drainage of houses, is
the product of the interior pipes of the house much more frequently
than of the public sewer in the street.
(_b_) The disposal of liquid wastes by irrigation, so far as this
method is applied to the outflow of public sewers, is not of especial
interest here, but an important modification has been made of the
system of irrigation which is of the greatest consequence in
considering the sanitary improvement of isolated country-houses, of
hospitals, prisons, etc., and of houses in towns about which there is
a small amount of available land. The process which has been found
best suited to the purpose is the invention of the Rev. Henry Moule,
the inventor of the earth-closet. He found it a serious drawback to
the dry-earth system that it was incapable of taking care of the
liquid wastes of the house. He devised a method of conducting the
liquid into very shallow drains made with open-jointed agricultural
drain-tiles, so porous in their character as to allow the liquid
carried by them to escape at the joints into the soil, and thus get
the benefit of its purifying qualities without the unsightly and often
offensive process of allowing the liquid to flow over the surface. The
first use made of this system was about 1866. Since that time its use
has extended very considerably both here and in England, and many
improvements have been made in its details, so that it may now be
accepted as entirely satisfactory.
The process in its best development, as applied to the drainage of
single houses, may be thus described, many of the appliances used
being the subject of patents: The outflow from the house is delivered
into a settling-basin or grease-trap of sufficient size to still the
flow, to cause solids to settle to the bottom, and grease and other
light matters to float at the top. The outlet from this basin is
through a pipe having its inlet at some distance below its
overflow-point; that is, at the level of the comparatively clarified
liquid, below the grease and above the sediment. The outflow passes
into another vessel known as a flush-tank, where it accumulates until
it reaches the summit of a self-acting siphon. This height being
reached, any considerable addition to the flow sets the siphon in
action, and the whole contents of the flush-tank are discharged with
rapidity into the drain beyond. The discharge completed, air is
automatically admitted to the siphon, and no further flow can take
place until the flush-tank has again been filled. The drain, of iron
or vitrified pipes tightly joined, is continued to the edge of the
ground prepared for purification. It here delivers into a series of
open-jointed agricultural tiles, laid with their bottoms not more than
ten inches below the surface of the ground. The total length of these
tile-drains is regulated according to the discharging capacity of the
flush-tank, with a view to their becoming entirely filled at each
discharge. Within a short time after the flow has ceased the liquid
has all left the pipes and entered the soil, its impurities being
retained and its filtered water settling away into the porous or
artificially drained ground below. During the interval between the
discharges of the flush-tank, a day or more, the process of
purification (oxidation) of the retained impurities goes on in the
soil, and its thorough aëration prepares it to purify the next
discharge. This method of {226} disposal is now employed in connection
with hundreds of houses, and its use, which has in some cases
continued for a dozen years, is constantly increasing. Its application
implies a certain amount of fall, but this amount need not be great.
The discharging height of the tank need not be more than twelve
inches. The main outlet need not fall more rapidly than at the rate of
1 to 300, and the absorption-drains ought not to fall more rapidly
than at the rate of 1 to 600. If the tank can be built on the top of
the ground, an average surface fall of 1 to 400 can usually be made to
meet all the requirements. Where waste matters are to be removed from
cellars and basements below the level of the ground, a greater fall is
necessary, or the wastes which are there collected must be thrown to
the tank by pumping or otherwise.