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                              BAD DRAINS;
                                  AND
                           HOW TO TEST THEM:
                                  WITH
 NOTES ON THE VENTILATION OF SEWERS, DRAINS, AND SANITARY FITTINGS, AND
            THE ORIGIN AND TRANSMISSION OF ZYMOTIC DISEASE.


                                   BY

                           R. HARRIS REEVES.

[Illustration]

                 E. & F. N. SPON, 125, STRAND, LONDON.

                      NEW YORK: 35, MURRAY STREET.

                                 1885.




                             INTRODUCTION.


The impetus given to improvements in sanitary matters by the conferences
held during last year at the Health Exhibition, as well as the desire
shown by engineers and others to improve the sanitary condition of
towns, has induced me to publish the following system of detecting
defects in drainage and sanitary fittings.

It must be admitted that grave errors have been committed by engineers,
architects, and builders, both in planning the fittings of houses and in
laying drains to the main sewers, during the last twenty years. These
errors have been found to have produced serious effects on the public
health. They have also been the means of establishing throughout the
country a number of Sanitary Protection Societies.

These institutions have been the means of saving many useful lives, but
I trust that the day is not far distant when these societies will cease
to exist, and such terms as “scientific plumbers” and “sanitary
arrangements carried out on the most scientific principles” will be a
thing of the past.

To my mind it is a national disgrace to know that in this nineteenth
century architects and builders fixed fittings to houses, and laid
drains from houses to sewers, which affected the health of the occupants
to such an extent that it was necessary to establish insurance offices
to protect persons from being killed by workmen or their employers. What
a page for future historians!

The work or purpose of drains and sanitary fittings is to carry off by
water the soil and dirt from our houses, and it is lamentable to think
that this cannot be done without injury to life.

What should we say if the same precautions were necessary to test or
examine the work of other professions or trades?

To many the system described in these pages may appear new, but it is by
no means so, as it was discovered and used by me in 1880, and was then
the means of finding out serious defects in a supposed perfect drainage
system.

From that time up to the present it has proved of considerable value in
determining any defect in the construction of drains and fittings. With
the detector and anemometer I have been enabled to discover the cause of
so many failures in sewer ventilation, and to trace the origin and
transmission of many cases of zymotic disease.

The object of this work is to place the same knowledge in the hands of
every person connected with sanitary work.

 _May, 1885._




                               CONTENTS.


                                                         PAGE
          BAD DRAINS, AND HOW TO TEST THEM                  1

          SEWER VENTILATION                                32

          THE ORIGIN AND TRANSMISSION OF ZYMOTIC DISEASE   56




                              BAD DRAINS;
                                  AND
                           HOW TO TEST THEM.


“Bad Drains.” How often has this term been used during the last few
years? By the medical profession alone, thousands of cases have been
attributed to this cause. To the honour and credit of that profession
its members have thought out and worked out the cause of innumerable
cases of disease under their charge, and rightly fixed their origin to
be due to “bad drains.”

In many cases it has been but a fashionable term to describe cases which
had the appearance of gas poisoning, but did not owe their origin to
drains; but rather to the heated and impure atmosphere of rooms, late
hours, and the sudden change from heat to cold. If there have been a few
hundred cases where “bad drains” were supposed to have caused the
illness and such was not the case, there have been thousands of others
where the disease originated from them, but was taken as a matter of
course, or as one of the frailties of the human frame, when undoubtedly
the cause was “bad drains.”

It is a most remarkable thing, that whilst on the one hand we have the
medical profession energetically working to find out defects in the
planning of drains and sanitary fittings, and writing articles on them,
we have on the other hand surveyors and others who have treated the
matter as a doctor’s fad.

During the last five years scarcely a medical conference has been held
without the question of “bad drains” forming one of the principal
subjects discussed. Medical officers of health have made stirring
speeches and reports to Local Boards; but where is the surveyor who has
had the energy to do the same unless it has been actually forced upon
him? It is a curious but noteworthy fact, that nearly the whole of the
evils of badly constructed drains, and the principal improvements in
them, have been forced on surveyors, builders, and plumbers by the
medical profession and the public.

The reticence shown by surveyors in dealing with “bad drains” may be
attributed to their unwillingness to acknowledge the errors and defects
in works already executed. These works were, at the time, executed
according to the theories adopted by the most eminent engineers in the
profession, and it would be considered unprofessional to admit errors.

There is scarcely a district (excepting where drains have been laid
within the last three years) where the branch drains are trapped into
the main sewers with an efficient water-seal. Surveyors feel that to
acknowledge this would be tantamount to acknowledging a want of
professional knowledge or neglect of duty on their part.

Now, strictly speaking, this could not be the case, and a surveyor
(placed in such a position where he knows that there are defects in his
drainage system, and probably these errors were made by himself,) could
say that these now known defects were not previously known by the most
eminent engineers, and especially with regard to sewer-gas, its
treatment, and action on the public health. Boldly facing the matter and
advocating that the drainage under his charge should be so perfected
that no medical man could point to it as being detrimental to health, if
it entailed an unusual expenditure, coming from the surveyor he would
carry the Board with him, and in doing so would make his position at the
Board doubly secure.

To prove this we have only to refer to reports made by engineers during
the last fifteen years on drainage schemes, compare the results of the
theories laid down, and note the instances in which they have failed,
especially those in connection with sewage farms and the ventilation of
sewers.

I will quote a few extracts from these reports:—

“No injury to health can possibly take place from gas issuing from
properly constructed gratings fixed in the middle of the road, and if
one is a nuisance, dig down and put in others until the nuisance is
removed.”

This has certainly not been the case. You may dig as many holes as you
like, and put in as many gratings, yet some will be injurious to health.

In describing sewage farms, they were described as being (if adopted)
the means of securing a large revenue to the Local Board by the
excellent crops grown, one engineer stating that persons could walk
through them with as much pleasure as through a flower or kitchen
garden; but practical experience has proved this to be incorrect: and
although these statements were made in good faith, they have not been
realised.

You may regulate the irrigation of a sewage farm to such a nicety that
no odour from the sewage is perceptible in the district; yet the
atmosphere will contain poisons which will have a very detrimental
effect on the health of those living there.

For a few years after sewage farms have been laid out, they pay, and you
get good crops from them, but after that the ground becomes so soured
that the farm is almost useless.

In face of these facts no surveyor should hesitate to bring forward
known improvements to his Board.

Many owners of property have recognised the importance of adopting the
best sanitary measures for their houses, although in some cases it is
only a plea to let or sell their property. As an instance of this, some
time ago I was in search of a house in the suburbs, and met with one
described as standing on good gravelly soil, with good drainage and
perfect sanitary arrangements. The builder and owner took me over the
house, and on reaching the kitchen pointed out with some degree of pride
that the sink was cut off from the drains, and stated that the drains
were constructed on the most “scientific principles.”

Now although scientific plumbers have done good work in making our
dwellings more healthy, they have in many cases overdone the matter. The
fact of their displaying conspicuously, on signs and billheads,
“Sanitary work executed on the most scientific principles,” is not
always a guarantee that a healthy house can be received from their
hands.

In the house above referred to, everything to the eye appeared sound and
good, but on the house being occupied, a disagreeable odour was noticed
in the kitchen, and in some of the lower rooms. The sink-pipe, which was
pointed out by the builder as being “cut off,” ran from the sink trough
without a trap or water-seal of any kind, and through this pipe, when
the doors were shut, the air was supplied to the building at the rate of
180 feet per minute. The back of the W.C. was ventilated from the
outside to give free ventilation to the space under the seat, and
through the ventilators (which were working as inlets) the air came into
the house, which supplied the bedrooms, passing over the pan, between it
and the seat.

The above is an illustration of a house where the sanitary arrangements
were supposed to be on the most scientific principles! Fresh air being
supplied to bedrooms by passing over the closet-pan, and in the kitchen
and rooms below by passing through a 2-inch sink-pipe. This is one of
the many cases that may be mentioned to show the necessity of testing
any system of drainage and sanitary fittings.

This is not an unusual occurrence, as thousands of similar cases exist,
where the principal air supply passes over sanitary fittings or through
apertures which bring it in contact more or less with decomposed matter.
In a building where a number of fireplaces exist, a constant current of
air is passing in from the outside, which after mixing with the air in
the building escapes up the chimney. An ordinary chimney extracts from
the room from 60 to 120 cubic feet of air per minute, thus in a
ten-roomed house you have going out of the chimneys at least 1000 cubic
feet of air per minute. When the house is closed this large volume of
air is drawn into it through apertures offering the least resistance,
whether it be ventilators in the w.c., kitchen sinks, or drains in the
basement (which traps may have been siphoned), over sanitary pipes or
through doors and windows. Whichever point offers the least resistance,
there the supply to feed the chimneys will come.

The injurious effects on the health of persons who occupy buildings that
take in their air supply through unclean apertures are too well known to
those medical men and others who have had experience in sanitary
matters, and it can be only estimated by results. I could enumerate
cases where the health of the inmates and the death-rate were conclusive
evidence to prove the disastrous effects produced by air being supplied
through such inlets. One case in particular, which consisted of eight
blocks of buildings planned exactly alike. The drains were cut off on
the outside at the foot of all soil-pipes, and a second disconnection
about 50 feet from the building. In one building the basement was
drained into the branch drain with a trap in the inside, and from the
quantity of water and soil which flowed through this branch drain the
basement trap was constantly being siphoned, leaving a 6-inch air supply
into the building through 50 feet of drain. This, combined with 200 feet
per minute through the W.C., had the effect of causing an unusual
depression of spirits in the occupants of this building, and more deaths
occurred in this one block than in the whole of the others.

It does not require a large amount of scientific knowledge to ensure a
healthy building. What is required is sound pipes, the area of them in
proportion to the work they have to do, tight joints, and a knowledge of
ventilation. Nothing must be left to theory. A pipe either leaks and
lets out the soil, or it is sound. If it is sound, sewage matter can be
carried through it anywhere without the slightest injury to health or
unpleasantness of any kind. Pipes can be ventilated without traps being
siphoned, and the gases from sewers and soil-pipes treated so as to
ensure healthy buildings at a moderate cost.

As a rule, the first intimation of any defect in the drainage system of
a town or the sanitary fittings of a building is given by the medical
officer of health or the medical attendant of the family, whose
attention has been forcibly drawn to it by the serious illness of the
inmates.

It is no unusual occurrence, that after the medical officer, surveyor,
and inspector of nuisances have made a minute inspection of a building,
they leave it without discovering defects which exist in pipes carefully
cased over, or in the sanitary fittings.

To detect the manner in which poisons from drains are thrown into a
building and inhaled by the occupants, is oftentimes not an easy matter.
In many cases the drains have been so cut about and additions made to
them, that to trace defects or even the number of drains which are
attached to the branch drains or sewers, a considerable amount of
excavating is necessary.

The system described in these pages is intended to prevent in a measure
this excavating, and to enable a person above the ground to determine
the number, capacity, and state of the drains underneath the surface, as
well as to more readily discover any imperfections in soil-pipes and
sanitary fittings.

When sewers are laid to a town or district, it is the practice of the
authorities to let the work by tender, the lowest tender being
oftentimes accepted; consequently it is in the interest of the
contractor to get the work done as quickly and cheaply as possible.

It is impossible for the engineer, or clerk of works, to see the whole
of the work done, and the result is that a large quantity of bricks
which form the sewer are not properly bedded. Liquid sewage finds its
way through the joints of the brickwork and percolates through the soil,
in some cases to a very considerable distance, contaminating the water
it mixes with on its course, and oftentimes it forms a putrid mass under
the basement of buildings which happen to be of a lower level than the
sewers. To prevent this, a clause should be inserted in the contract
that each length of drain or sewer should be tested by atmospheric
pressure, say 5 lb. to a square inch.

The top of the sewer should be as tight as the bottom to prevent any gas
escaping through the sandy soil or rubble which may be filled in around
the sewers or drains.

Leaky sewers and badly-jointed pipes under the soil should never be
allowed, yet the danger is not so great in them as in those pipes laid
above the ground. Joints to these pipes so often leak that without
testing them thoroughly when laid, one leaky joint would cause an
unpleasant odour in a building for years without its source being
discovered. The reason of this is, that the current of air passes
through buildings in a thousand different ways. I have known a sickly
odour to come from a cupboard on the first floor of the wing of a
building some 60 feet from any soil-pipe or grating; one case in
particular, that of a nursery cupboard. This occurred through a leaky
soil-pipe from the closet in the basement of the building.

From the planning of the building the chimney near the cupboard had the
greatest draught of air in the house, and the air which supplied this
chimney came principally from the basement. The sewer gas from the leaky
joint, being of a heavier gravity than the atmosphere of the house, was
carried along the floor unobserved to this particular room, filling at
night, when the fire was not burning, this cupboard, which contained
linen, and this held the impurities given off from the leaky joint in
the pipe.

Many cases of a similar nature could be mentioned, where families will
never recover the loss sustained by them through similar leaky joints in
the soil-pipes.

Insufficient fall to sewers does not often occur in those laid under the
supervision of engineers, but it is in the branch drains connected to
them where so many blunders are made. Oftentimes one part of a drain is
laid almost level, whilst another part is laid with a steep gradient.
This facilitates the choking of drains, and the siphoning of traps.

Some persons lay drains from houses to the main sewer or to branch
drains which are altogether out of proportion to the work they have to
do.

The smaller the drain is kept the better, but the diameter should be
regulated according to the quantity of water and soil flowing into it,
taking into consideration the possibility of additional inlets being
added.

The best plan is to collect the number of inlets or supplies to the
drain, compare them with the gradient to which they are laid, and put in
a drain which, if all the inlets are supplying water at the same time,
would not fill more than nine-tenths of its area.

In some cases I have seen a 9-inch drain laid from a house having only
two closets, sink and bath outlet attached. If the whole of these were
used at the same time, the area of the flow into the drain would only be
7·696 inches, but in the 9-inch drain the area would be 63·617 inches,
or nearly nine times the size required to carry off the water and soil.

The whole space not occupied by water and soil is filled with gas, which
extracts poisons from sewage and distributes them at outlets according
to the displacement caused by the water and soil entering and flowing
through the drain.

Architects and builders laying drains to houses or buildings should
discard the theories of any persons who do not keep to this rule: that
the smaller the drain is, the better, providing it does not fill; and
the least quantity of gas there is in the drain, the less dangerous will
be the poison in the gas when discharged through openings or gratings.
The reason of this is, that in a small drain only a small quantity of
the sewage is exposed to the action of the gas in transit; whereas in a
large drain the greater portion of the sewage is exposed, thus
increasing its decomposition.

When storm water from houses or land enters drains, great care should be
taken to form openings or inlets near where drains are likely to fill,
as the injurious effects of trap siphoning are of serious consequence to
health.

In many cases the construction of new drains and sewers in a district
have been simply a waste of money as regards improving the health of the
inhabitants, and numerous cases of zymotic disease, and in some cases an
epidemic has occurred where previously such diseases were almost
unknown. This is caused principally by connecting old drains (some of
which are disused ones and connected with old cesspits) to the new
drains leading to the sewers.

In cesspits and old drains the soil and putrid matter have been for
years allowed to accumulate, and the poison from such matter, when
distributed into the open air through gratings in the new sewers or into
houses, is, when inhaled into the system, the cause of these zymotic
outbreaks. In tracing these old drains and in preventing stagnant gases
from remaining in any portion of the drain, the engineer or architect
cannot pay too much attention, as confined gases when charged with
poisons from putrid matter are the principal factors in producing
disease.

Many persons place a well-constructed trap at the inlet, and another
some distance along the drain, say at the end of a building or grounds,
without any ventilation between the two traps. In fact this used to be a
common occurrence; but it should never be done. If the drain should be a
6-inch one, and the traps 50 feet apart, the amount of gas between the
two traps would average 9 cubic feet, and this gas would in the ordinary
working of the drain remain for years, getting more poisonous the longer
it remained undisturbed. The owner of the house, knowing that he had a
good trapped drain connected to sewers, would feel himself safe, and
naturally think his house healthy. Far better for him if the house were
drained into a ventilated cesspit, as when the gases in the drain became
released, which may occur by the siphoning of the traps at the
house-connection, the danger would be equal to the emptying of a disused
cesspit, and carrying the contents through the house. The more a person
tests the working of gas in sewers or drains the more he will find that
branch drains from their construction supply the poisons which render
the gases in the sewers themselves so noxious.

In 1880, whilst engaged in tracing the course of an outbreak of typhoid,
I made a series of experiments with a view to trace the source from
which the disease emanated, and every experiment proved that the origin
of the disease lay in the gases which were in contact with putrid sewage
matter, existing in old drains and cesspits attached to the sewers as
well as in the gases which were confined between traps. The distribution
of the disease was due to the imperfect construction of the sewers,
drains, and sanitary fittings.

The most successful experiment, and the one from which the greatest
result was obtained, and which I have ever since most successfully used,
was in determining the state, size, and condition of the drains
underground, and also that of the house or buildings, by measuring by
compression the gas contained in the sewer or sanitary fittings. The
principal cause of its distribution was the compression of the gas
between the water-traps, the siphoning of house-traps leaving at times a
free passage for the gas to enter the house.

The amount of compression or displacement necessary to force the gas in
bulk through the traps has been accurately measured, to know what
quantity of liquid was required to be thrown into a drain or sewer of
any size to force the gas in bulk through the water-trap. The lifting
power of the gas on the water by compression was found to be 1/300 part
of its bulk. Thus, if a drain perfectly sound, and sealed with a
water-seal each end, held 300 feet of gas, 1 cubic foot of water thrown
into the drain would force the gas in bulk through the water-seal.

It became evident, that if both ends of any drain were sealed with a
water-trap or otherwise for testing, the capacity of the drain or leaks
of any kind could be determined without excavating.

As it was inconvenient to watch the working of the drain through the
traps, I constructed an instrument called a detector[1] to observe the
working of the atmosphere in the drain. This instrument, or a
gas-pressure gauge, when attached to the drain, will denote by the
rising of the liquid the amount of compression in the drain. This, when
compared with the quantity of water thrown into it, will give the size
and capacity of the drain, and will also indicate any siphoning of traps
or leaks which exist in any of the sanitary fittings of the house.

Footnote 1:

  This instrument with instructions as to reagents can be obtained from
  E. Cetti, Meteorological Instrument Maker, 36, Brooke Street, Holborn,
  price 12_s._ 8_d._ It is cheaper and more convenient than the
  pressure-gauge, and registers any pressure during the testing of
  drains.

The following table will show the amount of gas in every 100 feet of
circular pipe or drain, from 4 to 30 inches in diameter, also the amount
of water thrown into a trap to produce the necessary pressure of gas to
lift the liquid 1 inch in the detector or pressure gauge: the quantity
being as near as possible 3⅓ ozs. of water to 1 cubic foot of gas space.

[Illustration: Plate 1.]

 ─────────────────┬─────────────────┬─────────────────┬─────────────────
    Diameter of   │Cubic Contents of│ Amount of Water │Area of Pipe 1728
 Circular Pipe or │ Gas in each 100 │to produce 1 inch│ = 1 cubic foot.
      Drain.      │ feet length of  │rise of Liquid in│
                  │  Drain Pipe or  │    Detector.    │
                  │     Sewer.      │                 │
 ─────────────────┼─────────────────┼─────────────────┼─────────────────
       ins.       │    cub. ft.     │gals. pts.  ozs. │
                 4│      8–1255/1728│    0     1     7│           12·566
                 6│     19–1096/1728│    0     4     0│           28·274
                 9│      44–308/1728│    1     1     2│           63·617
                12│      78–932/1728│    2     0     5│          113·097
                15│    122–1242/1728│    3     1     6│          176·715
                18│    176–1234/1728│    4     5     0│          254·469
                19│    196–1546/1728│    5     1     1│          283·529
                20│     218–288/1728│    5     5     7│          314·160
                21│     240–913/1728│    6     2     1│          346·361
                22│    263–1695/1728│    6     7     0│          380·133
                23│     288–917/1728│    7     4     2│          415·476
                24│     314–276/1728│    8     1     6│          452·390
                25│    340–1530/1728│    8     7     0│          490·875
                26│    368–1212/1728│    9     4    13│          530·930
                27│    397–1063/1728│   10     2    14│          572·556
                28│    427–1147/1728│   11     1    12│          615·753
                29│    458–1201/1728│   11     7     8│          660·521
                30│    490–1512/1728│   12     6     9│          706·860
 ─────────────────┴─────────────────┴─────────────────┴─────────────────

The method of testing drains and fittings by compression of gas is as
follows:—When the drainage plan of a building exists, the work of
testing by compression of gas in the drain will be a very simple matter.

Plate 1 shows the drains as laid to a semidetached villa, with two
inlets from sinks marked 1, one from bath overflow marked 2, and two
from the soil-pipes of closets in the basement and first-floor marked 3.
The drain from A to B is a 6-inch stoneware pipe, and its length is 100
feet. The amount of gas in it would be 19–1096/1728 cubic feet. The
branch drains from the other inlets are 4 inches in diameter, and the
collected lengths are 50 feet, and the quantity of gas in them would be
4–627/1728 cubic feet, giving a total in the whole of the drain of
nearly 24 cubic feet.

If the indiarubber pipe to the detector or pressure gauge is placed in
either of the traps marked 1, and the glass tube filled with liquid up
to the data line, 5 pints of water poured into either of the traps
marked 1, will produce a rise of 1 inch in the liquid of the detector,
that is if all the drains are clear and joints tight, the drains being
stopped off for testing at A.

Should a trap be fixed anywhere between A and B a lesser quantity will
be required to lift the liquid, and the position of the trap can be
determined by comparing the exact quantity of water used with the
capacity or quantity of gas in the drain.

If a trap should be fixed or a stoppage formed in any part of the drain
A B, the flushing of a closet or sink would, by the compression of the
gas, force it in bulk through the weakest trap, or the one having the
least dip or seal. The quantity which would pass through would depend on
the amount of water used in the flushing and the fall of the drain.

The drains to the building having been tested, and their defects
ascertained, it will be necessary now to test the soil-pipe.

On this plan it is fixed on the outside of the house, having a trap with
an open grating just beyond the basement closet, and a ventilating pipe
carried above the eaves of the roof. Whether the soil-pipe be fixed
inside or outside of the building it should be perfectly gas-tight, and
in this testing a person cannot be too particular.

In testing the soil-pipe shown on plan, the easiest method is to put the
detector or pressure-gauge at the grating of the trap 3, placing the
indiarubber tube over the grating, and making a tight joint with clay.
Then close the top of the ventilating pipe and pour water in the top
closet, when, if the joints are tight, the liquid in the detector will
rise suddenly, and then lower itself as the water leaves the trap,
indicating that the soil-pipe is tight, but if it is not tight, no
rising of the liquid will take place. Should there be no trap at the
bottom of the soil-pipe, it will be necessary to excavate down to the
drain to take out a length of pipe, to seal the mouth of the drain with
clay for testing. If there should be leaky joints or holes in the
soil-pipe, a little sulphur burnt in the pipe, or a little pungent
essence thrown into it, will clearly denote where the leaks are.

Having tested the soil-pipe and proved it tight, or effectually stopped
all leaks as the case may be, no gas can be given off in these drains or
fittings except through the ventilators (under ordinary circumstances)
as no trap has been siphoned in the testing.

As before stated, the ventilating pipe runs to the top of the building
of the same diameter as the soil-pipe, in fact this is a plan of drains
to a house recently built in the suburbs of London, and the planning of
them would be considered perfect by many sanitary men, but before we
testify them as perfect, let us carefully analyse the working of the
ventilation.

The ventilating pipe being carried above the roof is strictly in
accordance with the bye-laws of the Local Board, although it spoils the
appearance of the house. One reason why it was put there is to prevent
the siphoning of the closet trap, and its height is to carry out the
recommendations of medical writers in the _Lancet_ who have so often
insisted that these tall pipes, carried some feet away from chimneys or
bedroom windows, were necessary.

Let us test this theory.

We will flush the closet by throwing down slops and giving the closet
the regular flush, carefully testing what takes place. The result is
that the soil-pipe, instead of carrying off the odours from the top,
only forms an air inlet, and 2¼ cubic feet of air has been sucked in at
the top of the pipe, and the same quantity of gas discharged through the
grating. As this grating on the plan is only 2 feet from the passage
door which leads into the kitchen, the least that occurs is that a
portion enters the house, and the cook has a slight headache when
preparing the meals for the day.

To be more certain of this let us test the working of the ventilation by
a dozen flushings of the closets, and the same results are obtained by
measurement, 27 cubic feet of air entered the top of the pipe, and has
been driven out at the grating below. This proves that it is unnecessary
to spoil the appearance of our houses by the erection of these pipes, or
of carrying them above the soil-pipe or closet level.

It would not be consistent for me here to state how these unsightly
pipes could be avoided, but I am confident that ere long they will
become obsolete, although they have been erected by thousands in various
parts of the country.

We will now test the working of the ventilation in drains A B, and those
in branch drains to traps marked I. As they are clear, we find that the
gases in them are not so poisonous as in the sewers to which they are
connected.

A manhole grating exists in the sewer some 40 yards from the back of the
building, and through this grating the gas which is driven by the
flushing escapes, and its density depends on the nature of the soil
passing in the sewer. Its density is lessened by diffusion, or the
mixing of the gas which takes place at the grating, but the time it
takes for the gas which is in the drain near the traps I, to mix with
the fresh air at the grating in the street is a problem that I will
leave others to solve. We are certain that no gas in bulk can pass
through the trap under ordinary circumstances.

We can now certify that the drains are tight, well trapped and
ventilated, they are laid strictly in accordance with the bye-laws of
the Local Board, and we can quote that similar plans were exhibited last
year at the Health Exhibition, as models for country architects and
builders to copy; and ninety-nine out of every hundred sanitary
inspectors would sign the certificate that the sanitary arrangements
were carefully tested, and found perfect.

[Illustration: Plate 2.]

Experience in working the detector will not allow me to do this.
Although for months not the slightest particle of sewer gas has entered
the building, until one evening about eight o’clock a sickly smell is
observed in the kitchen, and this is attributed to a change in the
weather, heavy rain having fallen during the day, and no notice was
taken of it before retiring to rest. In the morning the house is
unbearable. The inspector of nuisances is sent for, who cannot detect
anything wrong in the drains. The surveyor to the Local Board visits the
house with the same result, and it is not until the middle of the day
before the nuisance has abated, its cause still a mystery to the
sanitary officials and to the owner of the house, who is a medical man
of great experience in sanitary matters, and a sanitary writer.

Now what really did occur was this. The sewer at the back nearly filled
with water and soil caused by the heavy rains, and when this was rising,
about 2 cubic feet of gas was forced from the drain B through the
grating at the bottom of the soil-pipe. The junction where the drain at
A joined the sewer was made as usual about two-thirds the height of the
sewer, consequently the drain from A to B filled some 20 feet during the
storm. When the storm abated, the water leaving the drain at A sucked
the trap at the bottom of the soil-pipe 3. The seal being gone, the gas
from the sewer at once came through the trap, the current being
estimated at from 80 to 200 feet per minute; so that the quantity of gas
given off at the trap, which is 2 feet from the door, would be about
2000 cubic feet from the time the trap was sucked until it was filled
again by the flushing of the closet.

This is by no means an exceptional occurrence, two similar cases
occurred in the suburbs last year. In one case the owner of the house
was seriously ill for several days, and was for some weeks obliged to
neglect his business and seek a change of air. In the other case the
daughter was taken ill with a zymotic disease which nearly cost her her
life, and it was months before she regained her strength.

The easiest method of preventing this siphoning of the traps is to fix a
small mica valve at the most convenient part of the drain between A and
B, fixing it above the ground. You can also prevent it as well as the
gas coming near the house by putting in a trap at A and having an open
grating between A and B. This would not prevent the 2000 cubic feet of
gas before referred to from escaping from the drains, but would cause it
to be discharged some distance from the house. You would also have about
23 cubic feet of gas in the drain always mixing with the atmosphere of
the garden at this point when the traps are full and tight.

Plate 2 shows the plan and drains of a hospital which I tested by this
system in 1880. As it was an old building the testing was somewhat
different to that described in Plate 1.

[Illustration: Plate 3.]

For years a sickly smell was observed in the ward, and more especially
when the heating apparatus was at work, and it was thought to arise from
the number of bad cases in the ward. A good system of ventilation was
adopted by the introduction of fresh air through flues which ran under
the floor to the whole length of the building, and in winter the air was
warmed by passing over hot-water pipes in the flues, and was distributed
at various parts of the ward through open gratings in the floor, with a
good extraction in the roof, which was open to the ward, but ceiled over
the rafters.

Double the amount of fresh air was admitted, warmed, and extracted, with
a view to improve the atmosphere of the building, but with no better
results. I then decided to test the drains which were shown on the plan
of the building as on Plate 2, the drain marked A B being tested first
by stopping it off and fixing the detector at B. This being a 9-inch
drain pipe and the length 130 feet, gave 57–600/1728 cubic feet as the
contents of gas in it. Adding 6 cubic feet for the branch drain at C,
making a total of 63–600/1728 cubic feet.

The amount of water required to be thrown into the trap A would be 1
gal. 5 pts. 3 ozs. to produce the necessary pressure of gas in the drain
to lift the liquid 1 inch in the detector. Instead of taking 1 gal. 5
pts. 3 ozs., it took 7 gals. 6 pts. 9 ozs., giving an additional 237
cubic feet of gas space to be somewhere attached to the drain. This
could not be leaks, if it had been the liquid in the detector would not
have risen at all.

The ground was opened at D, the drain sealed, and the detector fixed,
and the total quantity of gas in the drain by measurement from the seal
to trap A was found to be 46 cubic feet, and by testing this was found
to be correct, consequently the additional gas space was between B and
D.

I particularly noticed that the gases in these drains were more
poisonous than they should have been, considering the nature of the
sewage flowing through them, and by using a reagent as a liquid in the
detector, its discoloration indicated that the gas was in contact with a
large quantity of putrid matter which was of a different character to
that of the sewage flowing in the drain.

A drain searcher, or pointed rod was used, and after driving it into the
ground a few times, it struck the large cesspit E, and by the sound
given it was clear that a drain was underneath, when, on excavating, the
old cesspit and drains shown on Plate 3 were discovered, containing more
than 60 cubic yards of black putrid sewage.

The junction at F was cut off and the drain made good, when a second
testing by fixing the detector at B gave the quantity of gas in the
drain to be 63–600/1728 cubic feet.

The cleaning out of 60 cubic yards of sewage and the removal of the old
drains did not in the slightest degree diminish the nuisance inside the
building, consequently the 15-inch drain on the opposite side of the
building was stopped off at G and H, and in testing the detector was
placed at G. This length of drain being 140 feet contained 175–1098/1728
cubic feet of gas, and 4 gals. 4 pts. 8 ozs. of water thrown into the
trap H should have lifted the liquid to the usual height in the
detector. This and a similar quantity of water did not indicate any
compression, but the discoloration of the reagent in the detector was
much quicker than on the drain which was first tested.

The drain was then opened at I, dividing it into two sections, that from
G to I containing 93 cubic feet. Testing this by 2 gals. 3 pts. 6 ozs.
of water gave the exact rise in the detector, consequently the leaks and
bad gas must be in the section from I to H. This was tested by a fresh
reagent in the detector, when the speedy discoloration of the liquid
indicated that the source of the poison was very near.

By a few piercings of the ground at K, by the iron rod or searcher, the
drain was found, and by following the old drain the two cesspits and
additional drains shown in Plate 3 were discovered, and about 150 loads
of old putrid sewage had to be excavated and cleared away. The leaks
which prevented the rise of the liquid in the detector were in the crown
of the old sewage tank M, and the hot-water pipes of the heating
apparatus running in an air-shaft just over it, the heat extracted the
poisons from the sewage and distributed them into the ward.

The connections at K and N having been stopped up, the drain from I H
was again tested, when it gave 36 cubic feet more gas space than there
should have been in the drain. A few piercings of the soil at O led to
the excavating of those old drains which are shown attached, and these
being excavated and cleared away, and the connections to drains K, N,
and O being stopped, the drain was again tested from I to H, when
compression in the detector took place in comparison to the exact
quantity of gas that should be by measurement in the drain.

In describing the method of testing drains as shown on Plates 1, 2, and
3, nothing has been mentioned as to the level to which branch drains to
houses should be laid, or the method of testing them to ascertain their
fall.

The fall given to branch drains should not be less than 1 in 100, but 1
in 80 is far preferable, and if the drains are laid to this level, water
will flow easily through them, but should any part be laid out of a
level the water would lay in them and thus give a less quantity of gas.
Then when tested by compression to the capacity of the drain the lesser
quantity would denote the nature of the dip.

When a plan of drains exists, as in the two cases shown on Plates 1, 2,
and 3, the difficulty of testing them and proving their defects will not
be as great as when no plan has been made. If no plan has been made or
no record kept of them, it is best to make a rough plan of the building,
fixing the positions of all inlets, their sizes and lengths, of branches
to the drains on the premises, and also to lay down on the plan the
length and size of this drain to where it reaches the extent of the
property or joins the main sewer, opening the ground for testing in a
similar manner to that described in Plate 1.

In testing pipes or sanitary fittings of any kind, leaks can be easily
found by attaching the detector or pressure gauge to the most convenient
part of the pipe or fitting, and when everything is sound care should be
taken to flush all inlets at the same time, to ascertain whether the
rush of water has any effect on the traps or water-seal. If the
vibration in the detector or pressure gauge exceeds 2/10ths of an inch,
a freer gas space must be provided, or the action of the water checked
in some manner. Pipes, whether sanitary or otherwise, can be tested as
to tightness in a similar manner.

Some modification may be necessary in testing large sewers or the drains
of a district, but if the testing is performed in a similar manner to
that adopted in the above case the condition of the drains and fittings
can be accurately ascertained. The least pressure or suction on the
traps of drains or fittings will be shown by the vibration of the liquid
in the detector or pressure gauge when the water passes through the
pipes with flushing.

The term “bad drains” is not exclusively confined to those drains that
have leaky joints, or have an insufficient fall, or traps which siphon
during the passage of the water, but may also be applied to systems of
sewers in general. There are two points in almost every system of
drainage that call for some improvement. The first is having the inlets
at junctions where small drains join sewers at the side of the sewers.
Thousands of traps are being continually siphoned by this cause as soon
as the water fills the sewer above the inlet of the branch drain, as
this, when filled with water only a short distance, forces gas through
the weakest trap, and on the water and soil lowering itself in the
sewer, this water acts exactly as the plunger of a pump and draws the
water out of the weakest trap. This is often the one in the area or
basement of the building, and to avoid this all inlets at junctions
should enter the top of the sewers, not for the soil to drop down so as
to cause the sewers to silt, but in an oblique direction with the sewage
flow. The second point is in the ventilation of sewers, which is not an
easy subject to handle.




                           SEWER VENTILATION.


The question of ventilation is a very difficult one, whether it is in
connection with sewers or buildings.

The ventilation of buildings has received more attention than that of
sewers, excepting within the last three years.

In the ventilation of buildings we have the work and experience of Mr.
Haden, Captain Galton, Dr. Parkes, Messrs. Howarth, Tobin, Boyle,
Banner, and others, who have not only made the ventilation of buildings
their principal study, but have also spent large sums of money in
carrying out experiments with a view of getting a system of ventilation
applicable to any building. I have no doubt that each of the above
authorities in house ventilation would candidly admit that some of the
most favourable experiments they had made, and from which at the time
they expected the greatest results, had, when they had been practically
applied in different localities and under different circumstances,
proved their worst failures in providing a regular supply of fresh air
to and the extraction of foul air from any building.

If in the ventilation of buildings so many failures to get a perfect and
universal system can be recorded, it is quite natural that the same will
be the case in the ventilation of sewers.

The most eminent engineers of the present day will admit that vast
improvements must be made in sewer ventilation before they can say of a
district where a quantity of drains are laid and a large bulk of sewage
matter is carried through them, that the atmosphere of that district is
as pure as that of one where no drains are laid or where no sewage
matter can be found.

It was not until 1840 that the question of sewer ventilation received
very much attention, and it is in the reports to the City Commissioners
of Sewers and to the Metropolitan Board of Works that the earliest
results are recorded.

The report of Colonel Hayward to the City Commissioners of Sewers, dated
18th March, 1858, contains some of the earliest and most valuable
information as to sewer ventilation.

In that report it is stated that, previous to 1830, “the sewers were
ventilated by the gulleys, which were large open shafts or shoots
connected with the sewers without traps of any description: they were
connected with gratings of large size, the bars of which were farther
apart than those at present in use; there were no ventilating shafts
rising to the centre of carriageways, nor were there any side entrances
by which access to the sewers could be had. Whatever ventilation took
place therefore was effected by the gulleys, and if a sewer required to
be cleansed or examined the mode adopted was to open holes in the centre
of carriageways down to what are technically called manholes, or working
shafts, and perform these operations from these apertures, the shafts
being left open a sufficient length of time to ensure ventilation before
the men descended, and if there was fear of an accumulation of gas or
mephitic vapour, which sometimes was the case near the heads of sewers,
but at few other points in them.”

Complaints of the effluvium from these gulleys were made before the year
1830, and are stated to have grown louder and stronger after that date.

Here we have the first experience and results of free and open
ventilation to sewers. As regards the number of these gulleys in
proportion to the sewers we have no evidence in these reports, but
judging from their being specified as large open shafts, the area for
the inlet and outlet of air to the sewers would be if anything greater
than that of the present day. Yet this report states that the ill odours
which escaped from the gulleys, although they might not be pestilential,
became more repulsively offensive, and the attention of the
Commissioners of Sewers was drawn to the evil, and it was felt that some
remedy or palliative ought to be devised.

The means taken to obviate this evil may be termed the first experiment
in sewer ventilation.

“A gulley trap was devised and fixed in the Pavement, Finsbury, in 1834,
and in 1840 nine hundred of the gulleys had been trapped with a view to
remedy the evil, with the following results.

“It became apparent even before that number was fixed, that the sewers
were becoming dangerous to workmen to enter, and the gases generated
found vent by the house drains (then generally untrapped) into
dwellings.”

[It is quite evident that the compression of gases which takes place in
the sewers by the rising and falling of the liquid and sewage flowing in
them was not then known, or this experiment by closing the gulleys and
ventilating the sewers through the house traps would not have been
attempted.

At any rate the first experiment in sewer ventilation in the City cannot
be said to have been a successful one, as it left matters worse than
before.]

“To obviate this, ventilating shafts connecting directly with small iron
gratings in the centre of the carriageways were formed: this mode of
ventilating was also first adopted in the City, and the system of
trapping (with numerous modifications in manner) and ventilating the
sewers in the centre of the carriageways spread through the length of
the metropolis.”

Can it be said that this alteration was an improvement in sewer
ventilation?

The noxious or pestilential vapours that were so repulsive in 1840 when
escaping through the gulleys were not rendered less poisonous by being
given off in the middle of the road or carriageways, but the constant
passing of carriages over the gratings had the effect of mixing the
gases of the sewer more quickly with the atmosphere of the street. Thus
their noxious qualities were not so much observed, but the effect of
these gases on the public health by this arrangement has not been as
satisfactory as many imagine.

When the carriage traffic is suspended during the night, the effluvium
from these gratings is now similar to that experienced from the shoots
or gulley shafts in 1830. This opinion is formed by comparing the report
with testings taken at the gratings last year.

The last improvement suggested to give a better system of sewer
ventilation in the City is the erection of shafts at the sides of the
buildings where possible. A resolution was passed last year by the City
Commissioners of Sewers to erect these shafts where practicable. The
effect of this alteration will be to remove the nuisance from the street
and carry it to a higher level. If it is intended to work these shafts
in conjunction with the open gratings, the effect will be that in some
streets the whole of the gas from the sewers adjoining will be pouring
out of one shaft. In the summer time its density will be increased by
the friction in the shafts, and the high temperature of the atmosphere
will cause a more rapid decomposition in the sewage.

In low buildings or warehouses there is nothing to prevent the poisons
from the sewers from being conveyed down the chimneys into the
buildings, and the employés taking a zymotic disease whilst engaged in
their work and at night taking it to various parts of the suburbs.

It is better to let the gas escape at a low level, where it could be
purified when it is a nuisance, and especially in the case of an
epidemic, than discharge gas with a greater density at a higher level.

The General Board of Health in 1848 issued the following minutes of
information with reference to sewers and house drains—

“Make proper provision for the ventilation of sewers and drains in such
a manner that there may be a free current of air in them in the
direction of the sewage flow.”

It was also recommended “that the stack pipes should be connected with
the sewers without the intervention of traps, in order to assist the
ventilation, and there should be no trap between the trap at the inlet
and the sewer.”

This system was found far worse than the open gulleys or shoots in the
City in 1830, as at Croydon (which was one of the first towns to carry
out works of sewage under the General Board of Health) no sooner had the
sewers been in use before an outbreak of fever took place.

Dr. Niell Arnott and Mr. T. Page, C.E., were appointed by the Home
Secretary to report on the outbreak at Croydon, and Mr. Page in his
report states—

“Whenever a water-closet even with the best form of siphon trap is
introduced into a house, it will be well to provide an escape into the
open air. When several soil-pans or sinks from the apartments of a large
house are discharged into a common soil-pipe or vertical main, the main
should be continued up to the roof and to the open air, and if
practicable it should be carried near the chimney. Pipe sewers must also
have ample ventilation provided at all available points. If the air is
confined it is most dangerous when it breaks forth, which sooner or
later it will do, such evils would have been avoided.”

It is quite evident by these remarks that the system of ventilating the
City sewers in 1830 was more perfect than at Croydon, and had Mr. Page
tested the sewers and sanitary fittings by the compression of gases in
them, he would have found that the action of the water in the pipe
prevented the gas from being confined.

In 1858, Mr. Goldsworthy Gurney made experiments in the neighbourhood of
the House of Commons by connecting a number of the sewers near with the
furnace of the clock-tower, and this was reported on by Sir Joseph
Bazalgette as follows:—

“I find that the furnace of the clock-tower of the House of Parliament
was supposed to have been connected with the adjoining district to the
extent of about a quarter of a square mile, and with about 6½ miles of
sewers, but that the ventilation had in reality been intercepted by a
flap so that the benefit supposed to be derived therefrom was purely
imaginary. Having come to that conclusion, the next thing I directed my
attention to was, supposing the whole of the air extracted by that
furnace was produced from the sewers, and supposing that all the
intermediate channels could be stopped, and that it could be directed
from the most remote ends of each of the sewers, and distributed over
those sewers with the most perfect theoretical accuracy, so as to have
uniform currents passing through each of the sewers towards that
chimney, still the effect on those sewers would be nothing, and the way
in which I prove my statement is this: the total area of the 6½ miles of
sewers now connected with the furnace is 713 feet, the total area of the
channel through which the air has to be brought from them is 8 feet,
that is about the ninetieth part of 713; the air was passing at the rate
of 542 feet per minute through the 8 feet area. Therefore, if I could
divide that over the whole district, the velocity in all those sewers
would be 6 feet per minute or ⅕ of a mile per hour. But we have shown
already that there exist in the sewers from other causes velocities
amounting to 100 feet per minute and upwards; and 6 feet per minute is
practically speaking stagnation and not ventilation.”

This experiment was undoubtedly one that if it had been continued
(instead of being abandoned), and the errors corrected, would have led
to a more practical result. The area of the air space to the furnace was
8 feet, and the current 542 feet, or equal to 6 miles an hour. If this
current had been the same in the sewers as in the channel, the suction
produced on the water-traps of the small drains attached would lift the
water in each trap a little more than 3 inches. But as the ordinary trap
has only an average 2-inch dip, the weakest would have been at once
sucked and the experiment a failure. Had the dips of the traps been 4
inches, the drains would have remained sealed except at the intended
inlets. The air being supplied at the ends would have gone through the
sewers without breaking the water-seal, providing that the air space
between the crown of the sewer and the sewage was not in any way
blocked. If the current in the sewers had been less than 200 feet per
minute, the ordinary trap would have effectually sealed the various
inlets.

Had the average area of gas space above the sewage been 8 feet, the
whole of the 6½ miles of sewers would have been emptied of its gas and
supplied with fresh air in about an hour. The different areas should not
have been considered, but the total quantity of gas taken.

The velocities of 100 feet here mentioned, is accounted for as follows.
Should the sewage in any part of the sewers lower itself, causing an
additional gas space in that part of the sewer, the rush of gas in the
sewer to fill the space would cause this 100 feet per minute current.

These hitherto unaccountable currents in sewers and drains are produced
by the variation of the gas space above the sewage, the result of water
being thrown in at the various inlets.

The gases of a sewer may be passing backward and forward in currents
varying from 100 to 300 feet per minute, and not any ventilation would
take place except at the gratings, and this would be very little indeed
when the gas in the sewer was of a heavier gravity than the atmosphere.

Speaking on the same subject, Colonel Haywood says, “a down draught so
complete as to be superior to the diffusive power of the gases, you
cannot start with a velocity of less than 2 miles an hour, and suppose
the whole district has been so arranged as to have a sufficient
exhaustive power, the mere opening of a water-closet, or the enlarging
or the putting in of a new drain into a sewer, or the making of a hole a
foot square, or a servant taking up a bell trap in a sink, or a
sewer-man lifting a side entrance covering, would very much destroy the
power of the furnace, and unless you had a gigantic power sufficient to
guard against these casualties the system could only be a failure.”

What is here meant is, suppose that if the whole of the 6½ miles of
sewers were emptied of their gas at a velocity of 2 miles an hour, the
poisons from the sewage would not be noticeable or injurious in the
atmosphere of the drain. If each inlet to the sewer was trapped, the
opening of a water-closet or the opening of a bell trap in the sink
would not have affected the 2 miles an hour current in the sewers.

Had the currents in the sewers near the furnace of the clock-tower been
kept at 2 miles an hour, the traps being tight, and attention been paid
to the compression of the gases in the sewers by the water entering
them, the experiment would have been in a measure a successful one.

From 1855 to 1872, Sir R. Rawlinson, C.B., Dr. A. Miller, and Sir Joseph
Bazalgette were carrying out experiments with charcoal trays and
screens, and a committee of the Metropolitan Board of Works in their
report, say:—

“The results were sufficiently favourable to warrant the use of charcoal
ventilators in connection with such air-shafts as were sources of
annoyance and complaint, but their adoption had also the effect of
diminishing the upward current of foul air through the shafts and of
confining it to the sewers, thereby endangering the safety of the men
working in them, so that it is necessary that such ventilators should be
cautiously and not generally applied.”

These experiments in sewer ventilation were the most valuable of any yet
made to solve the question, but their failure could be attributed to the
following results.

The working of charcoal in the extraction of poisons given off from
sewage in its transit through the sewers, and which poisons become mixed
with the gas, and the placing of charcoal in layers or baskets so that
the gas should pass through the interstices of the charcoal, is without
a doubt the best method of dealing with charcoal as an agent in
arresting or picking up the poisons from putrid matter which is
contained in the gas. But the obstacle this gives to the supply or
exhaust of air to the sewer is greater than the power of the water-trap:
consequently traps are sucked or forced, and the inlet of fresh air
takes place through them into the sewers.

The gas from the sewer escapes through the weakest trap into the house,
thus nullifying the effects of the charcoal trays and rendering them
almost useless. The passing of the gas over the tray would prevent this,
but experiments prove that charcoal has not the power to attract and
retain the poisons from the sewage, and which is retained in the gas.
Thus these poisons pass over the charcoal through the grating into the
street.

These experiments prove that if the poisons from the gas are extracted
at the outlets, and the drains into sewers trapped with a water-seal,
and the siphoning or forcing of traps are prevented, sewers can be
ventilated without being a nuisance or prejudicial to health. But it
must be borne in mind that the instant the current of air in sewers,
drains, soil-pipes, or sanitary fittings exceeds a velocity of 3 miles
an hour, even if they have open ends, no trap with a 2-inch seal is safe
from being siphoned.

Many surveyors state that sewer gas is uncontrollable. This is an error.
The gases of a sewer are as controllable as the atmosphere of a room. It
is the compression of the gas caused by an increase of water in the
drain, and the temperature of the atmosphere on the surface of the
ground at the various points where the gratings are fixed, which makes
the currents of gas in drains so uncertain. The sudden lowering of the
sewage in a drain will stop the nearest gratings or shaft from working
as inlets.

What led engineers to form this opinion was the failure of experiments
with motive power to get certain results in ventilating sewers, the same
as in a building. It is impossible to get ventilation to sewers through
open gratings except the inlets from the house drains are sealed with a
water-seal.

The unsatisfactory results obtained from many experiments in sewer
ventilation have not been the fault of the plan or the appliances used,
but arose from the wretched manner in which house drains have been
connected to the sewers.

I shall never forget the testing of some sewers with a view of improving
the ventilation of them. They were public sewers and almost new ones,
and as far as the sewers themselves were concerned you could not have
had better, both as regards a good fall and tight joints. But the manner
in which the connections were made to them was something astonishing.
Untrapped gulleys at the sides of the streets, drains from the sewers
into the kitchens of houses without a single trap. In some cases two or
more traps were fixed according to the whim of the owner of the house.
Rain-water pipes from the flats of windows on the ground floor were
connected to sewers without traps, closets with no ventilating pipes,
and a dozen other imperfections were found on the branch drains and
fittings.

Before completing the tests of these drains and fittings, I suggested
that all faults and errors found in connection with the branch drains
should at once be remedied, and each drain be connected to the sewer
with a trap, or else it would be of little use to improve the
ventilation of the sewers. I was quietly informed that this could not
for one moment be entertained, as where these evils were the worst was
on property belonging to members of the Local Board, and any attempt to
pass a resolution to compel this to be done would be futile, and the
necessity of doing it attributed to the zeal of local sanitarians.

I am glad to say that cases like this are exceptional, but there are
many towns where similar evils will remain until an epidemic breaks out
and the authorities are compelled to have them remedied. The amount of
air passing through the sewer is no indication of the ventilation or the
amount of air that is being admitted, or the quantity of gas charged
with poisons that is given off. I have tested the gas in a sewer and at
the ventilating shafts, and have repeatedly found the gas in the sewer
flowing at a high velocity whilst the air in the open ventilating shaft
was perfectly stagnant.

I have not been able to make experiments to know how long gas will
remain in a sewer, but from observations of its gravity and working in
different localities I believe that the poisons from sewage matter are
retained in the lower strata of the air of sewers in some cases for
months, and when open gratings are only 50 yards apart. The quantity of
air taken in at the gratings at this time is a little more than the
displacement caused by the water, and when gases are released to any
extent it is through atmospheric influences.

If you measure the amount of air going in and out of say twenty open
gratings in the same locality, the small quantity would astonish those
who had not previously tested it.

Repeatedly has it been written and said that if you put a shaft or
grating at the top of a hill, or sewer, it will take off the impure gas
of a district, but I have had men working for days at the top of a sewer
150 and 200 feet higher than the lowest grating, and no trap
intervening, yet during this time not a particle of gas left the drain
at this the highest opening, but at times a good inlet current would
take place down the drain.

I find that one of the most fatal mistakes to make in sewer ventilation
is to introduce a large quantity of fresh air into a sewer at a high
temperature. An atmosphere at from 90° to 100° thrown into a sewer will
rapidly decompose sewage matter and produce results exactly opposite to
that intended. It is when the hot atmosphere of a summer’s day comes in
contact with the sewage in the sewers that the worst poisons are
generated and given off, and the gases which come from the gratings are
the most noxious. This rapid decomposition is more particularly felt in
the suburbs, where the drains are of stoneware and the sewage has to be
carried through them for a considerable distance.

Common sense teaches us that all matter of a nature like that passing
through sewers will decompose more rapidly and reach a higher state of
putrefaction in an atmosphere of a high temperature, even above ground,
than in any other condition. Experiments confirm this to be the case
whether it be applied to matter in sewers, vaults, or tanks. The best
experiments that I have made in sewer ventilation is in keeping the
temperature as low as possible, admitting into the sewer sufficient air
to prevent any action taking place on the water-seal, and what gas came
out of the sewer by compression to purify it at the gratings, extracting
the poisons that it had taken up from the sewage.

Many gases which are found in sewers have an affinity to water, and will
make their way to the water-seal and become absorbed in the water of the
trap to some extent, but not to the extent many persons imagine, or to
become detrimental to health.

When a disinfectant having a greater attractive power than the water is
used in connection with the ventilation, this attraction to the
water-seal will not take place.

If necessary, in hot weather or in large sewers, or those of an easy
gradient, cold air of a very low temperature could be introduced, which
would prevent decomposition taking place to any extent during the
transit of the sewage. If the whole area of a system of sewers was
charged four times a day with air at a temperature of 30° we should have
no complaints of sewer gas.

The details of such plans would be out of place here as they are the
subject matter of several patents, but sewage can be carried through
districts without its gases being injurious to health or without sewage
being subjected to rapid decomposition almost as easily as meat is now
transmitted from New Zealand to England without any decomposition taking
place during its transit.

Before leaving the question of sewer ventilation it will be well to note
the results obtained by the valuable experiments I have quoted, and
which have been made from time to time by the City Commissioners and the
Metropolitan Board of Works. One cause of the failure of these
experiments has been conclusively proved to be due to the wretched
condition of branch drains and house connections attached to the sewers
on which the experiments were made, and these are in a measure out of
the control of the officers of these Boards; and until a proper survey
of branch drains and house connections has been made, and traps placed
in proper positions, the ventilation of these sewers will be almost as
imperfect as in 1830.

The sanitary survey which is now being made in this country by the Local
Government Board will fail in one of its most important objects unless
it insists on every surveyor knowing the condition of drains under the
surface of the ground. A cursory glance at the plans of a district, or a
surface sanitary survey will not do very much in arresting zymotic
disease, and the staff stated to be employed on this survey is totally
inadequate for the work.

To successfully deal with sewer ventilation it should be divided into
two sections: (_a_) That of the sewers and branch drains which are
directly under the control of the officers of the various Boards, (_b_)
Those drains immediately attached to houses, including the soil-pipes.

The necessity for ventilating a sewer is, that in an unventilated sewer
or drain the instant a compression of the air in a sewer, between the
sewage and crown of the sewer, takes place to 1/300 part of its bulk,
gas is forced through the weakest trap according to the displacement of
water, and as the water is lowering in the drain fresh air will be
admitted into the drain through this trap. Thus if a drain or sewer is
not ventilated it will ventilate itself.

Should a sewer be ventilated with open gratings in the centre of the
roads, the placing of gratings at a moderate distance apart would
diffuse the gas equally in a flat district if the temperature on the
surface of the ground at each grating were the same, but the variation
of the temperature in streets is such that the heat of the street at one
grating will be a sufficient motive power to extract the gas from many
sewers through this one grating, the others only forming inlets while
the increased heat lasts.

In hilly districts, where the drains are of necessity of a steep
gradient, the quick flow of the sewage will cause the gas to pass more
rapidly when much sewage is flowing in the drain, the worst gas coming
out at the lowest grating, generally a grating before a junction, or
where two drains meet of different gradients: but when scarcely any
sewage is flowing, the gas will flow to the highest grating. Thus, in
putting gratings on steep gradients (if no method of purifying the gas
is used), the gratings should not be placed in regular distances apart,
but where the gas can be discharged in the most open space.

In hot weather, although ten times the amount of air passes through
sewers of steep gradient than in a flat district, the gases from sewers
on a steep gradient are far the most noxious. If open gratings only are
used on a system of sewers, the gas but not the sewage should be trapped
off into districts, not only as the means of preventing the gas rushing
in volumes to certain points, but for preventing germs of disease
travelling in the gas of a sewer from an unhealthy to a healthy
district, which is the case under the present system, by leaving sewers
for miles without any gas check.

We have in sewers and drains a power created by the influx of the sewage
which is greater than any mechanical means that can be used in the
ventilation of them, and it is to get the best method of applying this
power that sanitary engineers must direct their attention.

The difficulties that are met with in ventilating sewers with open
gratings are so great, that I am convinced that as soon as engineers
study the question more fully, the system will be abandoned.

The method of carrying off the soil by water through sewers has proved a
good and convenient one, and scarcely any defect can be found in any
drainage scheme except that of the ventilation, which is at present one
that is condemned by the inhabitants of most towns as a nuisance,
especially in hot weather, and by the medical profession as being most
prejudicial to health.

As a remedy for this, we must profit by the experience of the early
experiments I have quoted, which points conclusively to the fact that if
we extract from the gas (which by compression must of necessity leave
the sewers at openings) the noxious and disease-producing poisons
contained in it, at the gratings, and by those means prevent a rapid
decomposition of the sewage taking place, and without putting any undue
pressure on the water-seals to houses, we have overcome the greatest
difficulty in the work.

In old drains or sewers it will be the work of some time for the
surveyor to know that each drain from the house to the main sewer is
trapped with a good water-seal, yet this is the most important factor in
providing good ventilation.

Some persons have hastily condemned the water-trap, having found out
that they have been siphoned by the transit of the sewage. This is a
mistake. A properly constructed water-seal or trap that clears itself at
each flushing is the best seal for sewer gas. It will not keep out gas
if it is forced in bulk by excessive pressure, any more than coal gas
can be kept out of houses if a greater pressure is put on at the works
than the resistance of the trap in the chandelier. In manufacturing gas,
either experimentally or otherwise, water is the seal always used, but
we do not attach anything to break that seal when dealing with gas for
illuminating purposes, the same as is done in many cases with sewers.

Where new drains are laid, no difficulty in getting a good seal to
branch drains need be experienced, and no drain from the house to sewers
should be laid without its being completely disconnected or cut off as
near the soil-pipe as possible.

In dealing with the ventilation of soil-pipes or vertical drains, many
improvements can in future be made. The idea of carrying tall
ventilating pipes to the tops of houses was to carry off gas that was
forced in bulk through the trap at the bottom of the soil-pipe from the
sewer, but in well-laid drains this should never occur. If the drain be
disconnected it would leave at the point of disconnection.

The velocity of the water rushing down the pipe, as proved in the
previous chapter on drain testing, carries the gas out at the bottom of
the pipe, the top of the pipe forming the inlet when odours are given
off from the passing soil, but as soon as the flushing is over a return
current takes place and fresh air ascends the pipe.

If you do not use any method of purifying the gas which escapes through
the pipe, the best plan is to have the pipe as open as possible at the
top and bottom, and at all bends, for ventilation. These openings need
only be just above the level of the water flow to prevent splashing, and
by following this rule those unsightly pipes (which give buildings more
the appearance of a distillery or chemical works rather than a
dwelling-house or home) can be avoided and erected so as to form one of
the ornaments in the architecture of the building.

There is at present too much theory in sewer ventilation, without paying
any attention to results gained, or to the laws which control the
atmosphere and its action on sewage matter.




            THE ORIGIN AND TRANSMISSION OF ZYMOTIC DISEASE.


Whilst making experiments and taking observations five years ago, to
trace the origin and transmission of some cases of zymotic disease, I
formed an opinion that the theory as regards the transmission of zymotic
disease by contagion was to a certain extent an erroneous one.

I mentioned this to some of my medical acquaintances at the time, but as
it was so opposite to the prevailing ideas, I was advised not to publish
or hold out such opinions, as they were contrary to the theories
accepted by the medical profession.

Now that these theories have been severely shaken, and in many cases
reversed by medical men themselves, during the past year, I shall plead
no excuse, but insert them for the guidance of those engaged in sanitary
work.

The source of zymotic diseases may be traced to persons inhaling or
taking into the system poisons from putrid sewage matter, and those
poisons are conveyed into the body, either in the food they eat, the
water they drink, or the air they breathe. Whether they are organic or
inorganic, they poison the blood, which becomes more or less diseased,
according to their density or vitality, or whether each of the zymotic
diseases is produced by distinct organic germs grown and developed from
putrid matter under different atmospheric influences, it matters not to
my mind in proving the true method by which zymotic diseases are
transmitted.

On the origin or source from which these diseases are produced, I do not
think there are two opinions, viz. that of poisons from putrid matter,
and the question to be solved is in what manner these poisons are
conveyed into the system. To do this it will be necessary to quote some
cases of zymotic disease and the circumstances which surrounded them.

In a small district, a girl thirteen years of age was taken with
diphtheria, and in two days after the younger brother was taken and the
other children appeared sickly. From investigation it was certain that
the poison had not been conveyed into the system by food or water. The
children generally took their meals in the kitchen, the door of which
opened into the yard, which was about 10 feet long by 8 feet wide, in
the corner of which was the W.C. I tested the atmosphere entering the
room at the bottom of the doorway, and found that it contained poisonous
matter, and on testing the closet and drains I found a hole 3 inches by
¼ inch in the closet trap. Here was the source of poison which produced
the disease. The gas in the drain was confined between two traps and in
contact with putrid sewage matter, and when it was removed no poison
from any other source could be detected. The first child that was taken
ill died, but the other recovered.

Now it is quite evident that the second child did not take the disease
from the first, as it had not time to develop. The atmosphere of the
room and the breath of the child were not as poisonous as the atmosphere
of the kitchen in a line between the kitchen fire and the door, and it
was on this line both children sat at their meals, and thus inhaled the
poison with their food. Had the gases in the other drains of the
district been of the same density as in this one, and similar leaks
existed in the sanitary fittings, diphtheria would have spread, and by
the popular theory its transmission would have been attributed to
contagion from this family, which in face of the above facts would have
been incorrect.

Another case. In a large town diphtheria broke out, and some hundreds
were attacked and over two hundred died. The source of the disease was
not in the food or water, and the only disease-producing poison that
could be found was in the gas issuing from the sewer gratings and
sanitary fittings. Schools were closed and the usual remedies used to
prevent contagion, but all to no purpose. The sewers being of an easy
gradient had silted, forming at intervals masses of putrid matter, and
in the best houses, where the disease was most prevalent, poisons from
the sewers were laid on to them by the badly-constructed drains and
sanitary fittings. The authorities at last took the matter vigorously in
hand, cleansed and sweetened the sewers as much as possible, and then
the disease abated and died out. Had contagion been the means by which
the disease was transmitted, it would have continued as it existed in
the town under almost every kind of atmospheric temperature.

Here we have evidence showing that putrid matter did exist from which
poisons were given off and their mode of transit into the body, but not
the slightest evidence to prove the poison passed direct from one person
to another.

These poisons in the gas can be destroyed by washing the gas in a
chemical solution on leaving the grating, and since this has been done
medical men have cured the disease by washing the throat in a similar
solution.

Numbers of typhoid cases could be mentioned where poisons from putrid
matter were conveyed into the system by water, milk, and impure food,
but I have never heard of a case where the poison was detected leaving
one person for another.

If in 1883 a person had stated that cholera was not contagious, they
would have been ridiculed, yet the principal physician and those in
charge of the cholera hospitals of Paris last year, certified to the
representative of one of our daily papers that cholera was not
contagious. The cholera epidemic of last year proves that cholera
poisons are produced by heat and atmospheric influences on putrid
matter, and circumstances favour the theory that they are inorganic, and
when inhaled into the system poison the organisms of the blood to such
an extent as to produce the disease. Cases of cholera broke out in
different parts of the Continent at the same date, clearly showing that
contagion had nothing to do with producing or transmitting the disease.
In England our ports were jealously watched to prevent any case from
being landed. Had a case been landed, the excreta from that one case
might, when mixed with the sewage of a large town, have been the means
of spreading the disease through the whole district, as miles of sewers
are so laid that poisons in the gases can be effectually distributed
through the district in a very short time. Open ventilation to sewers
would greatly assist this, and especially when the gases in the drains
and the fresh air admitted into them were of a high temperature. It is
very improbable that cases if imported would break out in two towns at
the same time, or that the poison could be conveyed in the atmosphere
which divides us from the Continent.

Fortunately, when the continental outbreak was known, the authorities in
the metropolis and other towns used disinfectants on all known putrid
matter, and especially at the sewer gratings. This was an expensive
process, but it had the effect of preventing the atmospheric influences
(which were similar to those on the Continent) from developing the
poison to a vitality necessary to give the disease.

It would be an excellent preventive if the authorities of towns would
thoroughly examine every part of their districts, and know for a
certainty whether in their sewers, cesspits, vaults, or dust-bins there
existed putrid matter, or gases from them similar to those which
produced the disease on the Continent. The expense of such an
examination and for remedying the evils cannot be an excuse for not
doing this work, as the monetary loss experienced by the residents of
those continental towns and cities by the outbreak was enormous. What
the loss would be to the residents of the metropolis if a cholera
epidemic were to occur, it is difficult to imagine, and yet in many of
the districts cholera-producing elements exist from which in all
probability the heat and atmospheric influences experienced during
several weeks of excessive dry weather during the summer months will
produce poisons of a similar vitality to those produced on the Continent
during the past year.

Previous to the cholera epidemic, small-pox was very prevalent in
London, and I very carefully noted the cases as they were reported, and
visited the districts where the disease was most prevalent, for the
purpose of testing the nature of the gases in the sewers, and observing
how the sewers and sanitary fittings were constructed.

In many of these districts, and especially those of Homerton, Hackney,
Bow, and Bromley, the drains are so laid and the fittings so constructed
that a supply of sewer gas is pumped into the houses, and it is
impossible for persons to live in the houses of these districts without
inhaling gases that have been for a long time in contact with sewage
matter.

Whether the small-pox poison is an organic one (which I believe it is),
and is produced from a collection of matter in a high state of
decomposition, with or without being mixed with the excreta of persons
suffering from the disease, or whether it is of an inorganic nature, the
poison is derived from this source rather than from the impurities
thrown off through the skin of persons suffering from the disease. As a
proof of this, as soon as the cholera broke out last year on the
Continent, almost every gulley and grating in the metropolis where sewer
gas passes was charged more or less with a disinfectant, which minimised
the poison in the gas. The result was that small-pox abated in an
epidemic form although the temperature of the atmosphere increased.

The disinfectants so placed could not, naturally, affect the gas in
branch drains to houses, or putrid matter in various parts of the
sewers, or if it had, judging from its beneficial effects at the
outlets, small-pox would have disappeared.

If contagion were the means by which this disease was distributed,
disinfectants at sewer gratings would not have prevented the disease
continuing in an epidemic form.

Take the adjoining districts of Fulham and Putney. During the epidemic,
the gases from the sewer gratings in the Fulham district were more dense
than those at Putney. Fulham had many cases of small-pox, but Putney
none, although persons from each district were in daily contact with
each other; but the houses were not connected by the same system of
sewers.

It must not be thought that I wish to advance the theories of the
anti-vaccinationist. I have had my children vaccinated because it is the
law, and in the opinion of medical men a preventive against the disease,
but viewing the change of medical opinion with reference to cholera
during last year, and comparing tests and observations that have been
made, they will soon be convinced that vaccination is a futile remedy to
use with a view of stamping out the disease.

At present the question is (with medical men) one of theory, but ere
long I am certain that they will take a more practical view of the case
and definitely fix the origin of this disease and its distribution.

Previous to vaccination being introduced, putrid matter in vaults,
cesspits, and drains was allowed to reach a higher state of
putrefaction, and thus the poisons from them became more virulent and
produced the disease of a more virulent type.

If modern systems of drainage and sanitary arrangements were the means
of preventing this high state of putrefaction, and of reducing the
disease to a milder form, perfecting these arrangements should be the
means of stamping it out altogether and rendering vaccination useless.

Unless it can be proved that poisons given off through the skin and from
the lungs of persons suffering from the disease are as virulent as those
from putrid matter alone, or from the excreta from those suffering from
the disease, the theory of contagion[2] cannot be entertained.

Footnote 2:

  The word contagion as here used is not intended to apply to cases
  where persons not affected sleep in the same bed, or wear the same
  clothes, or handle things from, or persons suffering from this
  disease, as this would be inoculation.

Many medical men will say that the facts to prove that small-pox is
transmitted by contagion are so positive that there is no chance of
disputing them.

Let us examine two cases to support this theory.

Small-pox is prevalent, say, in the north of London; a man is in
business there from seven to eight hours each day, but his home is in
the S.W. district. He is taken ill, and remains at home, calling in his
medical attendant, who on his second visit pronounces it a case of
small-pox, and orders his removal to the hospital. In a few days other
members of the family are taken and removed, and similar cases occur in
the neighbourhood.

The theory of the medical man would be that his first patient had
contracted his disease in his place of business in the N.W. district and
had conveyed it to the S.W. district, distributing it in the
neighbourhood in which he lived. This is only theory, and the only thing
the medical man has to rely on to prove his case is, that the man first
taken was engaged three-fourths of each day where small-pox was
prevalent. Against this theory, assume that the disease originated by
the whole of these persons inhaling poisons from putrid matter in their
own locality or at their own doors, or in their homes, but that the
atmospheric influences to develop the poison was a few days longer
completing its work in the S.W. district than in the north. Then test
the sanitary conditions of both localities, and you will find similar
matter producing poisons. These are facts that will support this view of
the case, as well as the following evidence which cannot be
contradicted. When sewage matter is allowed to remain in bulk
undisturbed, and in connection with a system of sewers, it forms retorts
for the generation of these poisons, and they are conveyed for miles in
drains by atmospheric and other influences; and where these people lived
the gases would probably be discharged with a greater facility than at
any other point.

Take another case. A man leaves London for the country, and a day or two
after his arrival he is taken ill with small-pox. There is no system of
drains to the house in which he is located. People living in this and
other houses are affected with the disease, and the medical officer of
health in his report states that the disease was conveyed from London to
the district by this man. He was certainly the first one affected, and
at first sight this case appears to be conclusive in favour of
contagion, for if he did not contract the disease in London and bring it
into the country how was it that he was first affected?

It is certain that putrid matter from which the poisons are derived
exists in villages similar to that in towns, consequently the poisons
are there, and medical men agree that when a person leaves one locality
for another, for what is commonly called a change of air, the system
undergoes a change. This change had such an effect on the system of this
man that the poison from the putrid matter of the village had a greater
effect on him and poisoned the blood more quickly, than on those who
were inhaling the poison during its various stages of development: but
when it was fully developed by atmospheric influences the disease
appeared in those other persons who were in contact with the poison.

The action of sewer poison on the system is similar to that experienced
by persons taking cold. Persons occupied in rooms which have an equal
temperature, or are not subjected to cold chilly winds, take colds and
contract all sorts of complaints on being exposed to currents of cold
air even for a short time. The draught from a window only, when a cold
stream of air is playing upon it, will do this: the blood is chilled,
hence the cold, fever, or one of the many complaints follow; but on
persons used to exposure it has no effect. In the same way sewer poisons
act on those who suddenly inhale them, only the blood becomes poisoned
instead of chilled; but on those who are in constant contact with them
they have not such an effect, yet on these persons the effect of them
can be traced.

The medical profession have hitherto placed too much reliance on
isolation as the sole means of stamping out this disease.

The Metropolitan Asylums Board have had ample means at their disposal
since 1867 to test the soundness of this theory, yet after spending
something like 480,000_l._ per annum, small-pox has increased 100 per
cent. since that date! This fact alone is sufficient evidence to prove
that other means than those of isolation must be used to effectually
stamp out this disease.

It is of little use to have elaborate arrangements in hospitals and
camps to minimise the effects on persons who have taken the disease, and
at the same time allow the source from which it emanates to remain
undisturbed. I admit that it is a question too complicated to be
exhaustively dealt with in a work on the testing of drains and sanitary
fittings, but it is inserted to show what a power those who are engaged
in designing or executing sanitary works hold for good or evil in
affecting the health of the community.

Experience proves that ninety-nine zymotic cases out of every hundred
are caused through imperfect sanitary works and appliances.


 LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD STREET AND
                              CHARING CROSS.




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 Taking Off after the Old Method.

 Northern Practice.

 The General Statement of the Methods recommended by the Manchester
    Society of Architects for taking Quantities.

 Examples of Collections.

 Examples of “Taking Off” in each Trade.

 Remarks on the Past and Present Methods of Estimating.

  _A Practical Treatise on Heat, as applied to the Useful Arts_; for the
    Use of Engineers, Architects, &c. By THOMAS BOX. With 14 plates.
    Third edition, crown 8vo, cloth, 12_s._ 6_d._

  _A Descriptive Treatise on Mathematical Drawing Instruments_: their
    construction, uses, qualities, selection, preservation, and
    suggestions for improvements, with hints upon Drawing and Colouring.
    By W. F. STANLEY, M.R.I. Fifth edition, _with numerous
    illustrations_, crown 8vo, cloth, 5_s._

  _Spons’ Architects’ and Builders’ Pocket-Book of Prices and
    Memoranda._ Edited by W. YOUNG, Architect. Royal 32mo, roan, 4_s._
    6_d._; or cloth, red edges, 3_s._ 6_d._ _Published annually._
    Eleventh edition. _Now ready._

  _Long-Span Railway Bridges_, comprising Investigations of the
    Comparative Theoretical and Practical Advantages of the various
    adopted or proposed Type Systems of Construction, with numerous
    Formulæ and Tables giving the weight of Iron or Steel required in
    Bridges from 300 feet to the limiting Spans; to which are added
    similar Investigations and Tables relating to Short-span Railway
    Bridges. Second and revised edition. By B. BAKER, Assoc. Inst. C.E.
    _Plates_, crown 8vo, cloth, 5_s._

  _Elementary Theory and Calculation of Iron Bridges and Roofs._ By
    AUGUST RITTER, Ph.D., Professor at the Polytechnic School at
    Aix-la-Chapelle. Translated from the third German edition, by H. R.
    SANKEY, Capt. R.E. With 500 _illustrations_, 8vo, cloth, 15_s._

  _The Builders Clerk_: a Guide to the Management of a Builder’s
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  _The Elementary Principles of Carpentry._ By THOMAS TREDGOLD. Revised
    from the original edition, and partly rewritten, by JOHN THOMAS
    HURST. Contained in 517 pages of letter-press, and _illustrated with
    48 plates and 150 wood engravings_. Third edition, crown 8vo, cloth,
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  Section I. On the Equality and Distribution of Forces—Section II.
  Resistance of Timber—Section III. Construction of Floors—Section IV.
  Construction of Roofs—Section V. Construction of Domes and
  Cupolas—Section VI. Construction of Partitions—Section VII.
  Scaffolds, Staging, and Gantries—Section VIII. Construction of
  Centres for Bridges—Section IX. Coffer-dams, Shoring, and
  Strutting—Section X. Wooden Bridges and Viaducts—Section XI. Joints,
  Straps, and other Fastenings—Section XII. Timber.

  _Our Factories, Workshops, and Warehouses_: their Sanitary and
    Fire-Resisting Arrangements. By B. H. THWAITE, Assoc. Mem. Inst.
    C.E. _With 183 wood engravings_, crown 8vo, cloth, 9_s._

  _Gold_: Its Occurrence and Extraction, embracing the Geographical and
    Geological Distribution and the Mineralogical Characters of
    Gold-bearing rocks; the peculiar features and modes of working
    Shallow Placers, Rivers, and Deep Leads; Hydraulicking; the
    Reduction and Separation of Auriferous Quartz; the treatment of
    complex Auriferous ores containing other metals; a Bibliography of
    the subject and a Glossary of Technical and Foreign Terms. By ALFRED
    G. LOCK, F.R.G.S. _With numerous illustrations and maps_, 1250 pp.,
    super-royal 8vo, cloth, 2_l._ 12_s._ 6_d._

  _A Practical Treatise on Coal Mining._ By GEORGE G. ANDRÉ, F.G.S.,
    Assoc. Inst. C.E., Member of the Society of Engineers. _With 82
    lithographic plates._ 2 vols., royal 4to, cloth, 3_l._ 12_s._

  _Iron Roofs_: Examples of Design, Description. _Illustrated with 64
    Working Drawings of Executed Roofs._ By ARTHUR T. WALMISLEY, Assoc.
    Mem. Inst. C.E. Imp. 4to, half-morocco, £2 12_s._ 6_d._

  _A History of Electric Telegraphy_, to the Year 1837. Chiefly compiled
    from Original Sources, and hitherto Unpublished Documents, by J. J.
    FAHIE, Mem. Soc. of Tel. Engineers, and of the International Society
    of Electricians, Paris. Crown 8vo, cloth, 9_s._

  _Spons’ Information for Colonial Engineers._ Edited by J. T. HURST.
    Demy 8vo, sewed.

      No. 1, Ceylon. By ABRAHAM DEANE, C.E. 2_s._ 6_d._

                               CONTENTS:

  Introductory Remarks—Natural Productions—Architecture and
  Engineering—Topography, Trade, and Natural History—Principal
  Stations—Weights and Measures, etc., etc.

      No. 2. Southern Africa, including the Cape Colony, Natal, and the
        Dutch Republics. By HENRY HALL, F.R.G.S., F.R.C.I. With Map.
        3_s._ 6_d._

                               CONTENTS:

  General Description of South Africa—Physical Geography with
  reference to Engineering Operations—Notes on Labour and Material in
  Cape Colony—Geological Notes on Rock Formation in South
  Africa—Engineering Instruments for Use in South Africa—Principal
  Public Works in Cape Colony: Railways, Mountain Roads and Passes,
  Harbour Works, Bridges, Gas Works, Irrigation and Water Supply,
  Lighthouses, Drainage and Sanitary Engineering, Public Buildings,
  Mines—Table of Woods in South Africa—Animals used for Draught
  Purposes—Statistical Notes—Table of Distances—Rates of Carriage,
  etc.

      No. 3. India. By F. C. DANVERS, Assoc. Inst. C.E. With Map. 4_s._
        6_d._

                               CONTENTS:

  Physical Geography of India—Building
  Materials—Roads—Railways—Bridges—Irrigation—River
  Works—Harbours—Lighthouse Buildings—Native Labour—The Principal
  Trees of India—Money—Weights and Measures—Glossary of Indian Terms,
  etc.

  _A Practical Treatise on Casting and Founding_, including descriptions
    of the modern machinery employed in the art. By N. E. SPRETSON,
    Engineer. Third edition, with 82 _plates_ drawn to scale, 412 pp.,
    demy 8vo, cloth, 18_s._

  _Steam Heating for Buildings_; or, Hints to Steam Fitters, being a
    description of Steam Heating Apparatus for Warming and Ventilating
    Private Houses and Large Buildings, with remarks on Steam, Water,
    and Air in their relation to Heating. By W. J. BALDWIN. _With many
    illustrations._ Fourth edition, crown 8vo, cloth, 10_s._ 6_d._

  _The Depreciation of Factories and their Valuation._ By EWING
    MATHESON, M. Inst. C.E. 8vo, cloth, 6_s._

  _A Handbook of Electrical Testing._ By H. R. KEMPE, M.S.T.E. Third
    edition, revised and enlarged, crown 8vo, cloth, 15_s._

  _Gas Works_: their Arrangement, Construction, Plant, and Machinery. By
    F. COLYER, M. Inst. C.E. _With 31 folding plates_, 8vo, cloth,
    24_s._

  _The Clerk of Works_: a Vade-Mecum for all engaged in the
    Superintendence of Building Operations. By G. G. HOSKINS, F.R.I.B.A.
    Third edition, fcap. 8vo, cloth, 1_s._ 6_d._

  _American Foundry Practice_: Treating of Loam, Dry Sand, and Green
    Sand Moulding, and containing a Practical Treatise upon the
    Management of Cupolas, and the Melting of Iron. By T. D. WEST,
    Practical Iron Moulder and Foundry Foreman. Second edition, _with
    numerous illustrations_, crown 8vo, cloth, 10_s._ 6_d._

  _The Maintenance of Macadamised Roads._ By T. CODRINGTON, M.I.C.E,
    F.G.S., General Superintendent of County Roads for South Wales. 8vo,
    cloth, 6_s._

  _Hydraulic Steam and Hand Power Lifting and Pressing Machinery._ By
    FREDERICK COLYER, M. Inst. C.E., M. Inst. M.E. _With 73 plates_,
    8vo, cloth, 18_s._

  _Pumps and Pumping Machinery._ By F. COLYER, M.I.C.E., M.I.M.E. _With
    23 folding plates_, 8vo, cloth, 12_s._ 6_d._

  _The Municipal and Sanitary Engineer’s Handbook._ By H. PERCY
    BOULNOIS, Mem. Inst. C.E., Borough Engineer, Portsmouth. _With
    numerous illustrations_, demy 8vo, cloth, 12_s._ 6_d._

                               CONTENTS:

  The Appointment and Duties of the Town Surveyor—Traffic—Macadamised
    Roadways—Steam Rolling—Road Metal and Breaking—Pitched
    Pavements—Asphalte—Wood Pavements—Footpaths—Kerbs and Gutters—Street
    Naming and Numbering—Street Lighting—Sewerage—Ventilation of
    Sewers—Disposal of Sewage—House Drainage—Disinfection—Gas and Water
    Companies, &c., Breaking up Streets—Improvement of Private
    Streets—Borrowing Powers—Artizans’ and Labourers’ Dwellings—Public
    Conveniences—Scavenging, including Street Cleansing—Watering and the
    Removing of Snow—Planting Street Trees—Deposit of Plans—Dangerous
    Buildings—Hoardings—Obstructions—Improving Street Lines—Cellar
    Openings—Public Pleasure Grounds—Cemeteries—Mortuaries—Cattle and
    Ordinary Markets—Public Slaughter-houses, etc.—Giving numerous Forms
    of Notices, Specifications, and General Information upon these and
    other subjects of great importance to Municipal Engineers and others
    engaged in Sanitary Work.

  _Tables of the Principal Speeds occurring in Mechanical Engineering_,
    expressed in metres in a second. By P. KEERAYEFF, Chief Mechanic of
    the Obouchoff Steel Works, St. Petersburg; translated by SERGIUS
    KERN, M.E. Fcap. 8vo, sewed, 6_d._

  _A Treatise on the Origin, Progress, Prevention, and Cure of Dry Rot
    in Timber_; with Remarks on the Means of Preserving Wood from
    Destruction by Sea-Worms, Beetles, Ants, etc. By THOMAS ALLEN
    BRITTON, late Surveyor to the Metropolitan Board of Works, etc.,
    etc. _With 10 plates_, crown 8vo, cloth, 7_s._ 6_d._

  _Metrical Tables._ By G. L. MOLESWORTH, M.I.C.E. 32mo, cloth, 1_s._
    6_d._

                               CONTENTS:

  General—Linear Measures—Square Measures—Cubic Measures—Measures of
  Capacity—Weights—Combinations—Thermometers.

  _Elements of Construction for Electro-Magnets._ By Count TH. DU
    MONCEL, Mem. de l’Institut de France. Translated from the French by
    C. J. WHARTON. Crown 8vo, cloth, 4_s._ 6_d._

  _Electro-Telegraphy._ By FREDERICK S. BEECHEY, Telegraph Engineer. A
    Book for Beginners. _Illustrated._ Fcap. 8vo, sewed, 6_d._

  _Handrailing: by the Square Cut._ By JOHN JONES, Staircase Builder.
    Fourth edition, _with seven plates_, 8vo, cloth, 3_s._ 6_d._

  _Handrailing: by the Square Cut._ By JOHN JONES, Staircase Builder.
    Part Second, _with eight plates_, 8vo, cloth, 3_s._ 6_d._

  _Practical Electrical Units Popularly Explained_, with _numerous
    illustrations_ and Remarks. By JAMES SWINBURNE, late of J. W. Swan
    and Co., Paris, late of Brush-Swan Electric Light Company, U.S.A.
    18mo, cloth, 1_s._ 6_d._

  _Philipp Reis, Inventor of the Telephone_: A Biographical Sketch. With
    Documentary Testimony, Translations of the Original Papers of the
    Inventor, &c. By SILVANUS P. THOMPSON, B.A., Dr. Sc., Professor of
    Experimental Physics in University College, Bristol. _With
    illustrations_, 8vo, cloth, 7_s._ 6_d._

  _A Treatise on the Use of Belting for the Transmission of Power._ By
    J. H. COOPER. Second edition, _illustrated_, 8vo, cloth, 15_s._

  _A Pocket-Book of Useful Formulæ and Memoranda for Civil and
    Mechanical Engineers._ By GUILFORD L. MOLESWORTH, Mem. Inst. C.E.,
    Consulting Engineer to the Government of India for State Railways.
    _With numerous illustrations_, 744 pp., Twenty-first edition,
    revised and enlarged, 32mo, roan, 6_s._

                         SYNOPSIS OF CONTENTS:

  Surveying, Levelling, etc.—Strength and Weight of
  Materials—Earthwork, Brickwork, Masonry, Arches, etc.—Struts,
  Columns, Beams, and Trusses—Flooring, Roofing, and Roof
  Trusses—Girders, Bridges, etc.—Railways and Roads—Hydraulic
  Formulæ—Canals, Sewers, Waterworks, Docks—Irrigation and
  Breakwaters—Gas, Ventilation, and Warming—Heat, Light, Colour,
  and Sound—Gravity: Centres, Forces, and Powers—Millwork, Teeth
  of Wheels, Shafting, etc.—Workshop Recipes—Sundry
  Machinery—Animal Power—Steam and the Steam Engine—Water-power,
  Water-wheels, Turbines, etc.—Wind and Windmills—Steam
  Navigation, Ship Building, Tonnage, etc.—Gunnery, Projectiles,
  etc.—Weights, Measures, and Money—Trigonometry, Conic Sections,
  and Curves—Telegraphy—Mensuration—Tables of Areas and
  Circumference, and Arcs of Circles—Logarithms, Square and Cube
  Roots, Powers—Reciprocals, etc.—Useful Numbers—Differential and
  Integral Calculus—Algebraic Signs—Telegraphic Construction and
  Formulæ.

  _Spons’ Tables and Memoranda for Engineers_; selected and arranged by
    J. T. HURST, C.E., Author of ‘Architectural Surveyors’ Handbook,’
    ‘Hurst’s Tredgold’s Carpentry,’ etc. Fifth edition, 64mo, roan, gilt
    edges, 1_s._; or in cloth case, 1_s._ 6_d._

  This work is printed in a pearl type, and is so small, measuring
  only 2½ in. by 1¾ in. by ¼ in. thick, that it may be easily carried
  in the waistcoat pocket.

  “It is certainly an extremely rare thing for a reviewer to be called
  upon to notice a volume measuring but 2½ in. by 1¾ in., yet these
  dimensions faithfully represent the size of the handy little book
  before us. The volume—which contains 118 printed pages, besides a
  few blank pages for memoranda—is, in fact, a true pocket-book,
  adapted for being carried in the waistcoat pocket, and containing a
  far greater amount and variety of information than most people would
  imagine could be compressed into so small a space.... The little
  volume has been compiled with considerable care and judgment, and we
  can cordially recommend it to our readers as a useful little pocket
  companion.”—_Engineering._

  _A Practical Treatise on Natural and Artificial Concrete, its
    Varieties and Constructive Adaptations._ By HENRY REID, Author of
    the ‘Science and Art of the Manufacture of Portland Cement.’ New
    Edition, _with 59 woodcuts and 5 plates_, 8vo, cloth, 15_s._

  _Hydrodynamics_: Treatise relative to the Testing of Water-Wheels and
    Machinery, with various other matters pertaining to Hydrodynamics.
    By JAMES EMERSON. _With numerous illustrations_, 360 pp. Third
    edition, crown 8vo, cloth, 4_s._ 6_d._

  _Electricity as a Motive Power._ By Count TH. DU MONCEL, Membre de
    l’Institut de France, and FRANK GERALDY, Ingénieur des Ponts et
    Chaussées. Translated and Edited, with Additions, by C. J. WHARTON,
    Assoc. Soc. Tel. Eng. and Elec. _With 113 engravings and diagrams_,
    crown 8vo, cloth, 7_s._ 6_d._

  _Hints on Architectural Draughtsmanship._ By G. W. TUXFORD HALLATT.
    Fcap. 8vo, cloth, 1_s._ 6_d._

  _Treatise on Valve-Gears_, with special consideration of the
    Link-Motions of Locomotive Engines. By Dr. GUSTAV ZEUNER, Professor
    of Applied Mechanics at the Confederated Polytechnikum of Zurich.
    Translated from the Fourth German Edition, by Professor J. F. KLEIN,
    Lehigh University, Bethlehem, Pa. _Illustrated_, 8vo, cloth, 12_s._
    6_d._

  _The French-Polisher’s Manual._ By a French-Polisher; containing
    Timber Staining, Washing, Matching, Improving, Painting, Imitations,
    Directions for Staining, Sizing, Embodying, Smoothing, Spirit
    Varnishing, French-Polishing, Directions for Repolishing. Third
    edition, royal 32mo, sewed, 6_d._

  _Hops, their Cultivation, Commerce, and Uses in various Countries._ By
    P. L. SIMMONDS. Crown 8vo, cloth, 4_s._ 6_d._

  _A Practical Treatise on the Manufacture and Distribution of Coal
    Gas._ By WILLIAM RICHARDS. Demy 4to, with _numerous wood engravings
    and 29 plates_, cloth, 28_s._

                         SYNOPSIS OF CONTENTS:

  Introduction—History of Gas Lighting—Chemistry of Gas Manufacture,
  by Lewis Thompson, Esq., M.R.C.S.—Coal, with Analyses, by J.
  Paterson, Lewis Thompson, and G. R. Hislop, Esqrs.—Retorts, Iron and
  Clay—Retort Setting—Hydraulic Main—Condensers—Exhausters—Washers and
  Scrubbers—Purifiers—Purification—History of Gas Holder—Tanks,
  Brick and Stone, Composite, Concrete, Cast-iron, Compound
  Annular Wrought-iron—Specifications—Gas Holders—Station
  Meter—Governor—Distribution—Mains—Gas Mathematics, or Formulæ for
  the Distribution of Gas, by Lewis Thompson, Esq.—Services—Consumers’
  Meters—Regulators—Burners—Fittings—Photometer—Carburization of
  Gas—Air Gas and Water Gas—Composition of Coal Gas, by Lewis
  Thompson, Esq.—Analyses of Gas—Influence of Atmospheric Pressure and
  Temperature on Gas—Residual Products—Appendix—Description of Retort
  Settings, Buildings, etc., etc.

  _Practical Geometry, Perspective, and Engineering Drawing_; a Course
    of Descriptive Geometry adapted to the Requirements of the
    Engineering Draughtsman, including the determination of cast shadows
    and Isometric Projection, each chapter being followed by numerous
    examples; to which are added rules for Shading, Shade-lining, etc.,
    together with practical instructions as to the Lining, Colouring,
    Printing, and general treatment of Engineering Drawings, with a
    chapter on drawing Instruments. By GEORGE S. CLARKE, Capt. R.E.
    Second edition, _with 21 plates_. 2 vols., cloth, 10_s._ 6_d._

  _The Elements of Graphic Statics._ By Professor KARL VON OTT,
    translated from the German by G. S. CLARKE, Capt. R.E., Instructor
    in Mechanical Drawing, Royal Indian Engineering College. _With 93
    illustrations_, crown 8vo, cloth, 5_s._

  _The Principles of Graphic Statics._ By GEORGE SYDENHAM CLARKE, Capt.
    Royal Engineers. _With 112 illustrations._ 4to, cloth, 12_s._ 6_d._

  _Dynamo-Electric Machinery_: A Manual for Students of
    Electro-technics. By SILVANUS P. THOMPSON, B.A., D.Sc., Professor of
    Experimental Physics in University College, Bristol, etc., etc.
    _Illustrated_, 8vo, cloth, 12_s._ 6_d._

  _The New Formula for Mean Velocity of Discharge of Rivers and Canals._
    By W. R. KUTTER. Translated from articles in the ‘Cultur-Ingénieur,’
    by LOWIS D’A. JACKSON, Assoc. Inst. C.E. 8vo, cloth, 12_s._ 6_d._

  _Practical Hydraulics_; a Series of Rules and Tables for the use of
    Engineers, etc., etc. By THOMAS BOX. Fifth edition, _numerous
    plates_, post 8vo, cloth, 5_s._

  _A Practical Treatise on the Construction of Horizontal and Vertical
    Waterwheels_, specially designed for the use of operative mechanics.
    By WILLIAM CULLEN, Millwright and Engineer. _With 11 plates._ Second
    edition, revised and enlarged, small 4to, cloth, 12_s._ 6_d._

  _Tin_: Describing the Chief Methods of Mining, Dressing and Smelting
    it abroad; with Notes upon Arsenic, Bismuth and Wolfram. By ARTHUR
    G. CHARLETON, Mem. American Inst. of Mining Engineers. _With
    plates_, 8vo, cloth, 12_s._ 6_d._

  _Perspective, Explained and Illustrated._ By G. S. CLARKE, Capt. R.E.
    _With illustrations_, 8vo, cloth, 3_s._ 6_d._

  _The Essential Elements of Practical Mechanics; based on the Principle
    of Work_, designed for Engineering Students. By OLIVER BYRNE,
    formerly Professor of Mathematics, College for Civil Engineers.
    Third edition, _with 148 wood engravings_, post 8vo, cloth, 7_s._
    6_d._

                               CONTENTS:

  Chap. 1. How Work is Measured by a Unit, both with and without
  reference to a Unit of Time—Chap. 2. The Work of Living Agents, the
  Influence of Friction, and introduces one of the most beautiful Laws
  of Motion—Chap. 3. The principles expounded in the first and second
  chapters are applied to the Motion of Bodies—Chap. 4. The
  Transmission of Work by simple Machines—Chap. 5. Useful Propositions
  and Rules.

  _The Practical Millwright and Engineer’s Ready Reckoner_; or Tables
    for finding the diameter and power of cog-wheels, diameter, weight,
    and power of shafts, diameter and strength of bolts, etc. By THOMAS
    DIXON. Fourth edition, 12mo, cloth, 3_s._

  _Breweries and Maltings_: their Arrangement, Construction, Machinery,
    and Plant. By G. SCAMELL, F.R.I.B.A. Second edition, revised,
    enlarged, and partly rewritten. By F. COLYER, M.I.C.E., M.I.M.E.
    _With 20 plates_, 8vo, cloth, 18_s._

  _A Practical Treatise on the Manufacture of Starch, Glucose,
    Starch-Sugar, and Dextrine_, based on the German of L. Von Wagner,
    Professor in the Royal Technical School, Buda Pesth, and other
    authorities. By JULIUS FRANKEL; edited by ROBERT HUTTER, proprietor
    of the Philadelphia Starch Works. _With 58 illustrations_, 344 pp.,
    8vo, cloth, 18_s._

  _A Practical Treatise on Mill-gearing, Wheels, Shafts, Riggers, etc._;
    for the use of Engineers. By THOMAS BOX. Third edition, _with 11
    plates_. Crown 8vo, cloth, 7_s._ 6_d._

  _Mining Machinery_: a Descriptive Treatise on the Machinery, Tools,
    and other Appliances used in Mining. By G. G. ANDRÉ, F.G.S., Assoc.
    Inst. C.E., Mem. of the Society of Engineers. Royal 4to, uniform
    with the Author’s Treatise on Coal Mining, containing _182 plates_,
    accurately drawn to scale, with descriptive text, in 2 vols., cloth,
    3_l._ 12_s._

                               CONTENTS:

  Machinery for Prospecting, Excavating, Hauling, and
  Hoisting—Ventilation—Pumping—Treatment of Mineral Products,
  including Gold and Silver, Copper, Tin, and Lead, Iron, Coal,
  Sulphur, China Clay, Brick Earth, etc.

  _Tables for Setting out Curves for Railways, Canals, Roads, etc._,
    varying from a radius of five chains to three miles. By A. KENNEDY
    and R. W. HACKWOOD. _Illustrated_, 32mo, cloth, 2_s._ 6_d._

  _The Science and Art of the Manufacture of Portland Cement_, with
    observations on some of its constructive applications. _With 66
    illustrations._ By HENRY REID, C.E., Author of ‘A Practical Treatise
    on Concrete,’ etc., etc. 8vo, cloth, 18_s._

  _The Draughtsman’s Handbook of Plan and Map Drawing_; including
    instructions for the preparation of Engineering, Architectural, and
    Mechanical Drawings. _With numerous illustrations in the text, and
    33 plates (15 printed in colours)._ By G. G. ANDRÉ, F.G.S., Assoc.
    Inst. C.E. 4to, cloth, 9_s._

                               CONTENTS:

  The Drawing Office and its Furnishings—Geometrical Problems—Lines,
  Dots, and their Combinations—Colours, Shading, Lettering, Bordering,
  and North Points—Scales—Plotting—Civil Engineers’ and Surveyors’
  Plans—Map Drawing—Mechanical and Architectural Drawing—Copying and
  Reducing Trigonometrical Formulæ, etc., etc.

  _The Boiler-maker’s and Iron Ship-builder’s Companion_, comprising a
    series of original and carefully calculated tables, of the utmost
    utility to persons interested in the iron trades. By JAMES FODEN,
    author of ‘Mechanical Tables,’ etc. Second edition revised, _with
    illustrations_, crown 8vo, cloth, 5_s._

  _Rock Blasting_: a Practical Treatise on the means employed in
    Blasting Rocks for Industrial Purposes. By G. G. ANDRÉ, F.G.S.,
    Assoc. Inst. C.E. _With 56 illustrations and 12 plates_, 8vo, cloth,
    10_s._ 6_d._

  _Painting and Painters’ Manual_: a Book of Facts for Painters and
    those who Use or Deal in Paint Materials. By C. L. CONDIT and J.
    SCHELLER. _Illustrated_, 8vo, cloth, 10_s._ 6_d._

  _A Treatise on Ropemaking as practised in public and private
    Rope-yards_, with a Description of the Manufacture, Rules, Tables of
    Weights, etc., adapted to the Trade, Shipping, Mining, Railways,
    Builders, etc. By R. CHAPMAN, formerly foreman to Messrs. Huddart
    and Co., Limehouse, and late Master Ropemaker to H.M. Dockyard,
    Deptford. Second edition, 12mo, cloth, 3_s._

  _Laxton’s Builders’ and Contractors Tables_; for the use of Engineers,
    Architects, Surveyors, Builders, Land Agents, and others.
    Bricklayer, containing 22 tables, with nearly 30,000 calculations.
    4to, cloth, 5_s._

  _Laxton’s Builders’ and Contractors’ Tables._ Excavator, Earth, Land,
    Water, and Gas, containing 53 tables, with nearly 24,000
    calculations. 4to, cloth, 5_s._

  _Sanitary Engineering_: a Guide to the Construction of Works of
    Sewerage and House Drainage, with Tables for facilitating the
    calculations of the Engineer. By BALDWIN LATHAM, C.E., M. Inst.
    C.E., F.G.S., F.M.S., Past-President of the Society of Engineers.
    Second edition, _with numerous plates and woodcuts_, 8vo, cloth,
    1_l._ 10_s._

  _Screw Cutting Tables for Engineers and Machinists_, giving the values
    of the different trains of Wheels required to produce Screws of any
    pitch, calculated by Lord Lindsay, M.P., F.R.S., F.R.A.S., etc.
    Cloth, oblong, 2_s._

  _Screw Cutting Tables_, for the use of Mechanical Engineers, showing
    the proper arrangement of Wheels for cutting the Threads of Screws
    of any required pitch, with a Table for making the Universal
    Gas-pipe Threads and Taps. By W. A. MARTIN, Engineer. Second
    edition, oblong, cloth, 1_s._, or sewed, 6_d._

  _A Treatise on a Practical Method of Designing Slide-Valve Gears by
    Simple Geometrical Construction_, based upon the principles
    enunciated in Euclid’s Elements, and comprising the various forms of
    Plain Slide-Valve and Expansion Gearing; together with Stephenson’s,
    Gooch’s, and Allan’s Link-Motions, as applied either to reversing or
    to variable expansion combinations. By EDWARD J. COWLING WELCH.
    Memb. Inst. Mechanical Engineers. Crown 8vo, cloth, 6_s._

  _Cleaning and Scouring_: a Manual for Dyers, Laundresses, and for
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  _A Handbook of House Sanitation_; for the use of all persons seeking a
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    revised by his Son, E. F. BAILEY-DENTON, C.E., B.A. _With 140
    illustrations_, 8vo, cloth, 8_s._ 6_d._

  _A Glossary of Terms used in Coal Mining._ By WILLIAM STUKELEY
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    woodcuts and diagrams_, crown 8vo, cloth, 5_s._

  _A Pocket-Book for Boiler Makers and Steam Users_, comprising a
    variety of useful information for Employer and Workman, Government
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    Public. By MAURICE JOHN SEXTON. Second edition, royal 32mo, roan,
    gilt edges, 5_s._

  _The Strains upon Bridge Girders and Roof Trusses_, including the
    Warren, Lattice, Trellis, Bowstring, and other Forms of Girders, the
    Curved Roof, and Simple and Compound Trusses. By THOS. CARGILL,
    C.E.B.A.T., C.D., Assoc. Inst. C.E., Member of the Society of
    Engineers. _With 64 illustrations, drawn and worked out to scale_,
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  _A Practical Treatise on the Steam Engine_, containing Plans and
    Arrangements of Details for Fixed Steam Engines, with Essays on the
    Principles involved in Design and Construction. By ARTHUR RIGG,
    Engineer, Member of the Society of Engineers and of the Royal
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  This work is not, in any sense, an elementary treatise, or history
  of the steam engine, but is intended to describe examples of Fixed
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  recent arrangements of Horizontal, Vertical, Beam, Pumping, Winding,
  Portable, Semi-portable, Corliss, Allen, Compound, and other similar
  Engines, by the most eminent Firms in Great Britain and America. The
  laws relating to the action and precautions to be observed in the
  construction of the various details, such as Cylinders, Pistons,
  Piston-rods, Connecting-rods, Cross-heads, Motion-blocks,
  Eccentrics, Simple, Expansion, Balanced, and Equilibrium
  Slide-valves, and Valve-gearing will be minutely dealt with. In this
  connection will be found articles upon the Velocity of Reciprocating
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  Steam Governors, and the like. It is the writer’s desire to draw
  illustrations from every possible source, and give only those rules
  that present practice deems correct.

  _Barlow’s Tables of Squares, Cubes, Square Roots, Cube Roots,
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  _Camus (M.) Treatise on the Teeth of Wheels_, demonstrating the best
    forms which can be given to them for the purposes of Machinery, such
    as Mill-work and Clock-work, and the art of finding their numbers.
    Translated from the French, with details of the present practice of
    Millwrights, Engine Makers, and other Machinists, by ISAAC HAWKINS.
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  _A Practical Treatise on the Science of Land and Engineering
    Surveying, Levelling, Estimating Quantities, etc._, with a general
    description of the several Instruments required for Surveying,
    Levelling, Plotting, etc. By H. S. MERRETT. Third edition, _41
    plates with illustrations and tables_, royal 8vo, cloth, 12_s._
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                          PRINCIPAL CONTENTS:

  Part 1. Introduction and the Principles of Geometry. Part
  2. Land Surveying; comprising General Observations—The
  Chain—Offsets Surveying by the Chain only—Surveying Hilly
  Ground—To Survey an Estate or Parish by the Chain only—Surveying
  with the Theodolite—Mining and Town Surveying—Railroad
  Surveying—Mapping—Division and Laying out of Land—Observations
  on Enclosures—Plane Trigonometry. Part 3. Levelling—Simple
  and Compound Levelling—The Level Book—Parliamentary Plan
  and Section—Levelling with a Theodolite—Gradients—Wooden
  Curves—To Lay out a Railway Curve—Setting out Widths.
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  and Embankments—Tunnels—Brickwork—Ironwork—Timber Measuring.
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  and Plotting—The Improved Dumpy Level—Troughton’s Level—The
  Prismatic Compass—Proportional Compass—Box
  Sextant—Vernier—Pantagraph—Merrett’s Improved Quadrant—Improved
  Computation Scale—The Diagonal Scale—Straight Edge and Sector. Part
  6. Logarithms of Numbers—Logarithmic Sines and Co-Sines, Tangents
  and Co-Tangents—Natural Sines and Co-Sines—Tables for Earthwork, for
  Setting out Curves, and for various Calculations, etc., etc., etc.

  _Saws: the History, Development, Action, Classification, and
    Comparison of Saws of all kinds._ By ROBERT GRIMSHAW. _With 220
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  _A Supplement to the above_; containing additional practical matter,
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    particular conditions. _With 120 illustrations_, cloth, 9_s._

  _A Guide for the Electric Testing of Telegraph Cables._ By Capt. V.
    HOSKIŒR, Royal Danish Engineers. _With illustrations_, second
    edition, crown 8vo, cloth, 4_s._ 6_d._

  _Laying and Repairing Electric Telegraph Cables._ By Capt. V. HOSKIŒR,
    Royal Danish Engineers. Crown 8vo, cloth, 3_s._ 6_d._

  _A Pocket-Book of Practical Rules for the Proportions of Modern
    Engines and Boilers for Land and Marine purposes._ By N. P. BURGH.
    Seventh edition, royal 32mo, roan, 4_s._ 6_d._

  _The Assayer’s Manual_: an Abridged Treatise on the Docimastic
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    BRUNO KERL. Translated by W. T. BRANNT. _With 65 illustrations_,
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  _The Steam Engine considered as a Heat Engine_: a Treatise on the
    Theory of the Steam Engine, illustrated by Diagrams, Tables, and
    Examples from Practice. By JAS. H. COTTERILL, M.A., F.R.S.,
    Professor of Applied Mechanics in the Royal Naval College. 8vo,
    cloth, 12_s._ 6_d._

  _Electricity_: its Theory, Sources, and Applications. By J. T.
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  _The Practice of Hand Turning in Wood, Ivory, Shell, etc._, with
    Instructions for Turning such Work in Metal as may be required in
    the Practice of Turning in Wood, Ivory, etc.; also an Appendix on
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    edition, _with wood engravings_, crown 8vo, cloth, 6_s._

                               CONTENTS:

  On Lathes—Turning Tools—Turning Wood—Drilling—Screw
  Cutting—Miscellaneous Apparatus and Processes—Turning Particular
  Forms—Staining—Polishing—Spinning Metals—Materials—Ornamental
  Turning, etc.

  _Health and Comfort in House Building, or Ventilation with Warm Air by
    Self-Acting Suction Power_, with Review of the mode of Calculating
    the Draught in Hot-Air Flues, and with some actual Experiments. By
    J. DRYSDALE, M.D., and J. W. HAYWARD, M.D. Second edition, with
    Supplement, _with plates_, demy 8vo, cloth, 7_s._ 6_d._

  _Treatise on Watchwork, Past and Present._ By the Rev. H. L.
    NELTHROPP, M.A., F.S.A. _With 32 illustrations_, crown 8vo, cloth,
    6_s._ 6_d._

                               CONTENTS:

  Definitions of Words and Terms used in
  Watchwork—Tools—Time—Historical Summary—On Calculations of the
  Numbers for Wheels and Pinions; their Proportional Sizes, Trains,
  etc.—Of Dial Wheels, or Motion Work—Length of Time of Going without
  Winding up—The Verge—The Horizontal—The Duplex—The Lever—The
  Chronometer—Repeating Watches—Keyless Watches—The Pendulum, or
  Spiral Spring—Compensation—Jewelling of Pivot
  Holes—Clerkenwell—Fallacies of the Trade—Incapacity of Workmen—How
  to Choose and Use a Watch, etc.

  _Notes in Mechanical Engineering._ Compiled principally for the use of
    the Students attending the Classes on this subject at the City of
    London College. By HENRY ADAMS, Mem. Inst. M.E., Mem. Inst. C.E.,
    Mem. Soc. of Engineers. Crown 8vo, cloth, 2_s._ 6_d._

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    Inst. C.E., Author of ‘A Handbook of the Differential Calculus,’
    etc. Second edition, crown 8vo, cloth, 2_s._ 6_d._

                               CONTENTS:

  Symbols and the Signs of Operation—The Equation and the
  Unknown Quantity—Positive and Negative
  Quantities—Multiplication—Involution—Exponents—Negative
  Exponents—Roots, and the Use of Exponents as
  Logarithms—Logarithms—Tables of Logarithms and Proportionate
  Parts—Transformation of System of Logarithms—Common Uses of
  Common Logarithms—Compound Multiplication and the Binomial
  Theorem—Division, Fractions, and Ratio—Continued
  Proportion—The Series and the Summation of the Series—Limit of
  Series—Square and Cube Roots—Equations—List of Formulæ, etc.

  _Spons’ Dictionary of Engineering, Civil, Mechanical, Military, and
    Naval_; with technical terms in French, German, Italian, and
    Spanish, 3100 pp., and _nearly 8000 engravings_, in super-royal 8vo,
    in 8 divisions, 5_l._ 8_s._ Complete in 3 vols., cloth, 5_l._ 5_s._
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 In super-royal 8vo, 1168 pp., _with 2400 illustrations_, in 3 Divisions,
       cloth, price 13_s._ 6_d._ each; or 1 vol., cloth, 2_l._; or
                        half-morocco, 2_l._ 8_s._




                              A SUPPLEMENT

                                   TO

                   SPONS’ DICTIONARY OF ENGINEERING.


              EDITED BY ERNEST SPON, MEMB. SOC. ENGINEERS.

 Abacus, Counters, Speed Indicators, and Slide Rule.

 Agricultural Implements and Machinery.

 Air Compressors.

 Animal Charcoal Machinery.

 Antimony.

 Axles and Axle-boxes.

 Barn Machinery.

 Belts and Belting.

 Blasting. Boilers.

 Brakes.

 Brick Machinery.

 Bridges.

 Cages for Mines.

 Calculus, Differential and Integral.

 Canals.

 Carpentry.

 Cast Iron.

 Cement, Concrete, Limes, and Mortar.

 Chimney Shafts.

 Coal Cleansing and Washing.

 Coal Mining.

 Coal Cutting Machines.

 Coke Ovens. Copper.

 Docks. Drainage.

 Dredging Machinery.

 Dynamo-Electric and Magneto-Electric Machines.

 Dynamometers.

 Electrical Engineering, Telegraphy, Electric Lighting and its practical
    details, Telephones

 Engines, Varieties of.

 Explosives. Fans.

 Founding, Moulding and the practical work of the Foundry.

 Gas, Manufacture of.

 Hammers, Steam and other Power.

 Heat. Horse Power.

 Hydraulics.

 Hydro-geology.

 Indicators. Iron.

 Lifts, Hoists, and Elevators.

 Lighthouses, Buoys, and Beacons.

 Machine Tools.

 Materials of Construction.

 Meters.

 Ores, Machinery and Processes employed to Dress.

 Piers.

 Pile Driving.

 Pneumatic Transmission.

 Pumps.

 Pyrometers.

 Road Locomotives.

 Rock Drills.

 Rolling Stock.

 Sanitary Engineering.

 Shafting.

 Steel.

 Steam Navvy.

 Stone Machinery.

 Tramways.

 Well Sinking.


                             NOW COMPLETE.

 _With nearly 1500 illustrations_, in super-royal 8vo, in 5 Divisions,
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 Divisions 1 to 4, 13_s._ 6_d._ each; Division 5, 17_s._ 6_d._; or 2
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                          SPONS’ ENCYCLOPÆDIA

                                 OF THE

        INDUSTRIAL ARTS, MANUFACTURES, AND COMMERCIAL PRODUCTS.


                 EDITED BY C. G. WARNFORD LOCK, F.L.S.

Among the more important of the subjects treated of, are the following:—

 Acids, 207 pp. 220 figs.
 Alcohol, 23 pp. 16 figs.
 Alcoholic Liquors, 13 pp.
 Alkalies, 89 pp. 78 figs.
 Alloys. Alum.
 Asphalt. Assaying.

 Beverages, 89 pp. 29 figs.
 Blacks.
 Bleaching Powder, 15 pp.
 Bleaching, 51 pp. 48 figs.

 Candles, 18 pp. 9 figs.
 Carbon Bisulphide.
 Celluloid, 9 pp.
 Cements. Clay.
 Coal-tar Products, 44 pp. 14 figs.
 Cocoa, 8 pp.
 Coffee, 32 pp. 13 figs.
 Cork, 8 pp. 17 figs.
 Cotton Manufactures, 62 pp. 57 figs.

 Drugs, 38 pp.
 Dyeing and Calico Printing, 28 pp. 9 figs.
 Dyestuffs, 16 pp.

 Electro-Metallurgy, 13 pp.
 Explosives, 22 pp. 33 figs.

 Feathers.
 Fibrous Substances, 92 pp. 79 figs.
 Floor-cloth, 16 pp. 21 figs.
 Food Preservation, 8 pp.
 Fruit, 8 pp.
 Fur, 5 pp.

 Gas, Coal, 8 pp.
 Gems.
 Glass, 45 pp. 77 figs.
 Graphite, 7 pp.

 Hair, 7 pp.
 Hair Manufactures.
 Hats, 26 pp. 26 figs.
 Honey. Hops.
 Horn.

 Ice, 10 pp. 14 figs.
 Indiarubber Manufactures, 23 pp. 17 figs.
 Ink, 17 pp.
 Ivory.

 Jute Manufactures, 11 pp., 11 figs.

 Knitted Fabrics—Hosiery, 15 pp. 13 figs.

 Lace, 13 pp. 9 figs.
 Leather, 28 pp. 31 figs.
 Linen Manufactures, 16 pp. 6 figs.

 Manures, 21 pp. 30 figs.
 Matches, 17 pp. 38 figs.
 Mordants, 13 pp.

 Narcotics, 47 pp.
 Nuts, 10 pp.

 Oils and Fatty Substances, 125 pp.

 Paint.
 Paper, 26 pp. 23 figs.
 Paraffin, 8 pp. 6 figs.
 Pearl and Coral, 8 pp.
 Perfumes, 10 pp.
 Photography, 13 pp. 20 figs.
 Pigments, 9 pp. 6 figs.
 Pottery, 46 pp. 57 figs.
 Printing and Engraving, 20 pp. 8 figs.

 Rags.
 Resinous and Gummy Substances, 75 pp. 16 figs.
 Rope, 16 pp. 17 figs.

 Salt, 31 pp. 23 figs.
 Silk, 8 pp.
 Silk Manufactures, 9 pp. 11 figs.
 Skins, 5 pp.
 Small Wares, 4 pp.
 Soap and Glycerine, 39 pp. 45 figs.
 Spices, 16 pp.
 Sponge, 5 pp.
 Starch, 9 pp. 10 figs.
 Sugar, 155 pp. 134 figs.
 Sulphur.

 Tannin, 18 pp.
 Tea, 12 pp.
 Timber, 13 pp.

 Varnish, 15 pp.
 Vinegar, 5 pp.

 Wax, 5 pp.
 Wool, 2 pp.
 Woollen Manufactures, 58 pp. 39 figs.


              Crown 8vo, cloth, with illustrations, 5_s._




                           WORKSHOP RECEIPTS,

                             FIRST SERIES.


                            BY ERNEST SPON.

                         SYNOPSIS OF CONTENTS.

 Bookbinding.
 Bronzes and Bronzing.

 Candles.
 Cement.
 Cleaning.
 Colourwashing.
 Concretes.

 Dipping Acids.
 Drawing Office Details.
 Drying Oils.
 Dynamite.

 Electro-Metallurgy—(Cleaning, Dipping, Scratch-brushing, Batteries,
    Baths, and Deposits of every description).
 Enamels.
 Engraving on Wood, Copper, Gold, Silver, Steel, and Stone.
 Etching and Aqua Tint.

 Firework Making—(Rockets, Stars, Rains, Gerbes, Jets, Tourbillons,
    Candles, Fires, Lances, Lights, Wheels, Fire-balloons, and minor
    Fireworks).
 Fluxes.
 Foundry Mixtures.
 Freezing.
 Fulminates.
 Furniture Creams, Oils, Polishes, Lacquers, and Pastes.

 Gilding.
 Glass Cutting, Cleaning, Frosting, Drilling, Darkening, Bending,
    Staining, and Painting.
 Glass Making.
 Glues.
 Gold.
 Graining.
 Gums.
 Gun Cotton.
 Gunpowder.

 Horn Working.

 Indiarubber.

 Japans, Japanning, and kindred processes.

 Lacquers.
 Lathing.
 Lubricants.

 Marble Working.
 Matches.
 Mortars.

 Nitro-Glycerine.

 Oils.

 Paper.
 Paper Hanging.
 Painting in Oils, in Water Colours, as well as Fresco, House,
    Transparency, Sign, and Carriage Painting.
 Photography.
 Plastering.
 Polishes.
 Pottery—(Clays, Bodies, Glazes, Colours, Oils, Stains, Fluxes, Enamels,
    and Lustres).

 Scouring.
 Silvering.
 Soap.
 Solders.

 Tanning.
 Taxidermy.
 Tempering Metals.
 Treating Horn, Mother-o’-Pearl, and like substances.

 Varnishes, Manufacture and Use of.
 Veneering.

 Washing.
 Waterproofing.
 Welding.

Besides Receipts relating to the lesser Technological matters and
processes such as the manufacture and use of Stencil Plates, Blacking,
Crayons, Paste Putty, Wax, Size, Alloys, Catgut, Tunbridge Ware, Picture
Frame and Architectural Mouldings, Compos, Cameos, and others too
numerous to mention.


         Crown 8vo, cloth, 485 pages, with illustrations, 5_s._




                           WORKSHOP RECEIPTS,

                             SECOND SERIES.


                           BY ROBERT HALDANE.

                         SYNOPSIS OF CONTENTS.

 Acidimetry and Alkalimetry.
 Albumen.
 Alcohol.
 Alkaloids.
 Baking-powders.
 Bitters.
 Bleaching.
 Boiler Incrustations.
 Cements and Lutes.
 Cleansing.
 Confectionery.
 Copying.
 Disinfectants.
 Dyeing, Staining, and Colouring.
 Essences.
 Extracts.
 Fireproofing.
 Gelatine, Glue, and Size.
 Glycerine.
 Gut.
 Hydrogen peroxide.
 Ink.
 Iodine.
 Iodoform.
 Isinglass.
 Ivory substitutes.
 Leather.
 Luminous bodies.
 Magnesia.
 Matches.
 Paper.
 Parchment.
 Perchloric acid.
 Potassium oxalate.
 Preserving.

=Pigments, Paint, and Painting=: embracing the preparation of
_Pigments_, including alumina lakes, blacks (animal, bone, Frankfort,
ivory, lamp, sight, soot), blues (antimony, Antwerp, cobalt, cœruleum,
Egyptian, manganate, Paris, Péligot, Prussian, smalt, ultramarine),
browns (bistre, hinau, sepia, sienna, umber, Vandyke), greens (baryta,
Brighton, Brunswick, chrome, cobalt, Douglas, emerald, manganese, mitis,
mountain, Prussian, sap, Scheele’s, Schweinfurth, titanium, verdigris,
zinc), reds (Brazilwood lake, carminated lake, carmine, Cassius purple,
cobalt pink, cochineal lake, colcothar, Indian red, madder lake, red
chalk, red lead, vermilion), whites (alum, baryta, Chinese, lead
sulphate, white lead—by American, Dutch, French, German, Kremnitz, and
Pattinson processes, precautions in making, and composition of
commercial samples—whiting, Wilkinson’s white, zinc white), yellows
(chrome, gamboge, Naples, orpiment, realgar, yellow lakes); _Paint_
(vehicles, testing oils, driers, grinding, storing, applying, priming,
drying, filling, coats, brushes, surface, water-colours, removing smell,
discoloration; miscellaneous paints—cement paint for carton-pierre,
copper paint, gold paint, iron paint, lime paints, silicated paints,
steatite paint, transparent paints, tungsten paints, window paint, zinc
paints); _Painting_ (general instructions, proportions of ingredients,
measuring paint work; carriage painting—priming paint, best putty,
finishing colour, cause of cracking, mixing the paints, oils, driers,
and colours, varnishing, importance of washing vehicles, re-varnishing,
how to dry paint; woodwork painting).


                            JUST PUBLISHED.


       Crown 8vo, cloth, 480 pages, with 183 illustrations, 5_s._




                           WORKSHOP RECEIPTS,

                             THIRD SERIES.


                        BY C. G. WARNFORD LOCK.

               Uniform with the First and Second Series.


                         SYNOPSIS OF CONTENTS.

 Alloys.
 Aluminium.
 Antimony.
 Barium.
 Beryllium.
 Bismuth.
 Cadmium.
 Cæsium.
 Calcium.
 Cerium.
 Chromium.
 Cobalt.
 Copper.
 Didymium.
 Electrics.
 Enamels and Glazes.
 Erbium.
 Gallium.
 Glass.
 Gold.
 Indium.
 Iridium.
 Iron and Steel.
 Lacquers and Lacquering.
 Lanthanum.
 Lead.
 Lithium.
 Lubricants.
 Magnesium.
 Manganese.
 Mercury.
 Mica.
 Molybdenum.
 Nickel.
 Niobium.
 Osmium.
 Palladium.
 Platinum.
 Potassium.
 Rhodium.
 Rubidium.
 Ruthenium.
 Selenium.
 Silver.
 Slag.
 Sodium.
 Strontium.
 Tantalum.
 Terbium.
 Thallium.
 Thorium.
 Tin.
 Titanium.
 Tungsten.
 Uranium.
 Vanadium.
 Yttrium.
 Zinc.
 Zirconium.
 Aluminium.


                            JUST PUBLISHED.


      In demy 8vo, cloth, 600 pages, and 1420 Illustrations, 6_s._




                                 SPONS’

                          MECHANIC’S OWN BOOK;

               A MANUAL FOR HANDICRAFTSMEN AND AMATEURS.


                               CONTENTS.

Mechanical Drawing—Casting and Founding in Iron, Brass, Bronze, and
other Alloys—Forging and Finishing Iron—Sheet-metal Working—Soldering,
Brazing, and Burning—Carpentry and Joinery, embracing descriptions of
some 400 Woods, over 200 Illustrations of Tools and their uses,
Explanations (with Diagrams) of 116 joints and hinges, and Details of
Construction of Workshop appliances, rough furniture. Garden and Yard
Erections, and House Building—Cabinet-Making and Veneering—Carving and
Fretcutting—Upholstery—Painting, Graining, and Marbling—Staining
Furniture, Woods, Floors, and Fittings—Gilding, dead and bright, on
various grounds—Polishing Marble, Metals, and Wood—Varnishing—Mechanical
movements, illustrating contrivances for transmitting motion—Turning in
Wood and Metals—Masonry, embracing Stonework, Brickwork, Terracotta, and
Concrete—Roofing with Thatch, Tiles, Slates, Felt, Zinc, &c.—Glazing
with and without putty, and lead glazing—Plastering and
Whitewashing—Paper-hanging—Gas-fitting—Bell-hanging, ordinary and
electric Systems—Lighting—Warming—Ventilating—Roads, Pavements, and
Bridges—Hedges, Ditches, and Drains—Water Supply and Sanitation—Hints on
House Construction suited to new countries.


                 London: E. & F. N. SPON, 125, Strand.
                      New York: 35, Murray Street.

------------------------------------------------------------------------




                          TRANSCRIBER’S NOTES


 1. Silently corrected typographical errors and variations in spelling.
 2. Anachronistic, non-standard, and uncertain spellings retained as
      printed.
 3. Footnotes have been re-indexed using numbers.
 4. Enclosed italics font in _underscores_.
 5. Enclosed bold font in =equals=.