A course of lectures on sanitary engineering has been delivered during
the past few weeks before the officers of the Royal Engineers
stationed at Chatham, by Captain Douglas Galton, C.B., D.C.L., F.R.S.
The refuse which has to be dealt with, observed Captain Galton,
whether in towns or in barracks or in camp, falls under the following
five heads: 1, ashes; 2, kitchen refuse; 3, stable manure; 4, solid or
liquid ejections; and 5, rainwater and domestic waste water, including
water from personal ablutions, kitchen washing up, washings of
passages, stables, yards, and pavements. In a camp you have the
simplest form of dealing with these matters. The water supply is
limited. Waste water and liquid ejection are absorbed by the ground;
but a camp unprovided with latrines would always be in a state of
danger from epidemic disease. One of the most frequent causes of an
unhealthy condition of the air of a camp in former times has been
either neglecting to provide latrines, so that the ground outside the
camp becomes covered with filth, or constructing the latrines too
shallow, and exposing too large a surface to rain, sun, and air. The
Quartermaster-General's regulations provide against these
contingencies; but I may as well here recapitulate the general
principles which govern camp latrines. Latrines should be so managed
that no smell from them should ever reach the men's tents. To insure
this very simple precautions only are required:
1. The latrines should be placed to leeward with respect to prevailing
winds, and at as great a distance from the tents as is compatible with
convenience. 2. They should be dug narrow and deep, and their contents
covered over every evening with at least a foot of fresh earth. A
certain bulk and thickness of earth are required to absorb the
putrescent gas, otherwise it will disperse itself and pollute the air
to a considerable distance round. 3. When the latrine is filled to
within 2 ft. 6 in. or 3 ft. of the surface, earth should be thrown
into it, and heaped over it like a grave to mark its site. 4. Great
care should be taken not to place latrines near existing wells, nor to
dig wells near where latrines have been placed. The necessity of these
precautions to prevent wells becoming polluted is obvious. Screens
made out of any available material are, of course, required for
latrines. This arrangement applies to a temporary camp, and is only
admissible under such conditions.
A deep trench saves labor, and places the refuse in the most
immediately safe position, but a buried mass of refuse will take a
long time to decay; it should not be disturbed, and will taint the
adjacent soil for a long time. This is of less consequence in a merely
temporary encampment, while it might entail serious evils in
localities continuously inhabited. The following plan of trench has
been adopted as a more permanent arrangement in Indian villages, with
the object of checking the frightful evil of surface pollution of the
whole country, from the people habitually fouling the fields, roads,
streets, and watercourses. Long trenches are dug, at about one foot or
less in depth, at a spot set apart, about 200 or 300 yards from
dwellings. Matting screens are placed round for decency. Each day the
trench, which has received the excreta of the preceding day, is filled
up, the excreta being covered with fresh earth obtained by digging a
new trench adjoining, which, when it has been used, is treated in the
same manner. Thus the trenches are gradually extended, until
sufficient ground has been utilized, when they are plowed up and the
site used for cultivation. The Indian plow does not penetrate more
than eight inches; consequently, if the trench is too deep, the lower
stratum is left unmixed with earth, forming a permanent cesspool, and
becomes a source of future trouble. It is to be observed, however,
that in the wet season these trenches cannot be used, and in sandy
soil they do not answer. This system, although it is preferable to
what formerly prevailed--viz., the surface defilement of the ground
all round villages and of the adjacent water courses--is fraught with
danger unless subsequent cultivation of the site be strictly enforced,
because it would otherwise retain large and increasing masses of
putrefying matter in the soil, in a condition somewhat unfavorable to
rapid absorption. These arrangements are applicable only to very rough
life or very poor communities.
The question of the removal of kitchen refuse, manure, etc., from
barracks next calls for notice. The great principle to be observed in
removing the solid refuse from barracks is that every decomposable
substance should be taken away at once. This principle applies
especially in warm climates. Even the daily removal of refuse entails
the necessity of places for the deposit of the refuse, and therefore
this principle must be applied in various ways to suit local
convenience. In open situations, exposed to cool winds, there is less
danger of injury to health from decomposing matters than there would
be in hot, moist, or close positions. In the country generally there
is less risk of injury than in close parts of towns. These
considerations show that the same stringency is not necessarily
required everywhere. Position by itself affords a certain degree of
protection from nuisance. The amount of decomposing matter usually
produced is also another point to be considered. A small daily product
is not, of course, so injurious as a large product. Even the manner of
accumulating decomposing substances influences their effect on health.
There is less risk from a dung heap to the leeward than to the
windward of a barrack. The receptacles in which refuse is temporarily
placed, such as ash pits and manure pits, should never be below the
level of the ground. If a deep pit is dug in the ground, into which
the refuse is thrown in the intervals between times of removal, rain
and surface water will mix with the refuse and hasten its
decomposition, and generally the lowest part of the filth will not be
removed, but will be left to fester and produce malaria. In all places
where the occupation is permanent the following conditions should be
attended to:
1. That the places of deposit be sufficiently removed from inhabited
buildings to prevent any smell being perceived by the occupants. 2.
That the places of deposit be above the level of the ground--never dug
out of the ground. The floor of the ash pit or dung pit should be at
least six inches above the surface level. 3. That the floor be paved
with square sets, or flagged and drained. 4. That ash pits be covered.
5. That a space should be paved in front, so as to provide that the
traffic which takes place in depositing the refuse or in removing it
shall not produce a polluted surface.
In towns those parts of the refuse which cannot be utilized for manure
or otherwise are burned. But this is an operation which, if done
unskillfully, without a properly constructed kiln, may give rise to
nuisance. One of the best forms of kiln is one now in operation at
Ealing, which could be easily visited from London.
_The removal of excreta from houses._--The chief object of a perfect
system of house drainage is the immediate and complete removal from
the house of all foul and effete matter directly it is produced. The
first object--viz., removal of foul matter, can be attained either by
the water closet system, when carried out in this integrity; but it
could, of course, be attained without drains if there was labor enough
always available; and the earth closet or the pail system are
modifications of immediate removal which are safe. Cesspools in a
house do not fulfill this condition of immediate removal. They serve
for the retention of excremental and other matters. In a porous soil
it endangers the purity of the wells. The Indian cities afford
numerous examples of subsoil pollution. The Delhi ulcer was traced to
the pollution of the wells from the contaminated subsoil; and the soil
in many cities and villages is loaded with niter and salt, the
chemical results of animal and vegetable refuse left to decay for many
generations, from the presence of which the well water is impure.
There are many factories of saltpeter in India whose supplies are
derived from this source; and during the great French wars, when
England blockaded all the seaports of Europe, the First Napoleon
obtained saltpeter for gunpowder from the cesspits in Paris. Cesspools
are inadmissible where complete removal can be effected. Cesspits may,
however, be a necessity in some special cases, as, for instance, in
detached houses or a small detached barrack. Where they cannot be
avoided, the following conditions as to their use should be enforced:
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.
* * * * *