[Footnote 1: Abstract from the presidential address delivered
before the Association of Municipal and Sanitary Engineers and
Surveyors, at the annual meeting in Leicester, July 18, 1887.]
By Mr. J. GORDON, C.E.
The average mortality for England and Wales was 22.4 in 1838, and in
1886 19.3, which shows a saving on last year's population of England
and Wales of 86,400 lives annually, and a saving in suffering from an
estimated number of about 1,728,000 cases of sickness. To accomplish
all this, vast sums of money have been expended, probably not always
wisely, inasmuch as there have been mistakes made in this direction,
as in all new developments of science when applied in practice, and
evils have arisen which, if foreseen at all at the outset, were
underrated.
The great object of the public health act, 1848, was to enable local
authorities by its adoption to properly sewer, drain, and cleanse
their towns, and to provide efficient supplies of water, free from
contamination and impurities dangerous to health. The raising of money
by loans repayable in a series of years, which the act empowered,
enabled all these objects to be accomplished, and, while the first
duty of local authorities was undoubtedly the provision of a good
supply of water and proper sewerage for the removal of liquid filth
from the immediate vicinity of inhabited dwellings, the carrying out
of proper works for the latter object has been of much slower growth
than the former. Private companies led the way, in fact, in providing
supplies of water, inasmuch as there was a prospect of the works
becoming remunerative to shareholders investing their money in them;
and in nearly every instance where local authorities have eventually
found it to be in the interests of the inhabitants of their districts
to purchase the work, they have had to pay high prices for the
undertaking. This has generally led to a great deal of dissatisfaction
with companies holding such works, but it must not be forgotten that
the companies would, in most instances, never have had any existence
if the local authorities had taken the initiative, and that but for
the companies this great boon of a pure supply of water would most
probably have been long delayed to many large as well as small
communities.
The evils which have arisen from the sewering and draining of towns
have been of a twofold character. First, in the increased pollution of
rivers and streams into which the sewage, in the earlier stages of
these works, was poured without any previous treatment; and secondly,
in the production of sewer gas, which up to the present moment seems
so difficult to deal with. These concomitant evils and difficulties
attending the execution of sanitary works are in no way to be
underrated, but it still remains the first duty of town authorities to
remove, as quickly as possible, all liquid and other refuse from the
midst and immediate vicinity of large populations, before putrefaction
has had time to take place.
There are some minds whose course of reasoning seems to lead them to
the conclusion that the evils attending the introduction of modern
systems of sewerage are greater than those of the old methods of
dealing with town sewage and refuse, but the facts are against them to
such an extent that it would be difficult to point to a responsible
medical officer in the kingdom who would be courageous enough to
advocate a return to the old regime of cesspools, privy ashpits, open
ditches, and flat bottomed culverts. The introduction of earth closets
as one of the safeguards against sewer gas has made no headway for
large populations, and is beset with practical difficulties.
In the Midland and Lancashire towns the system known as the pail or
tub system has been much more largely introduced as a substitute for
the water closet, and it has, from a landlord's point of view, many
attractions. In the first place, the first cost, as compared with that
of a water closet, is very small, and the landlord is relieved for
ever afterward I believe, in most towns, of all future costs and
maintenance; whereas, in the case of water closets, there is
undoubtedly great difficulty in cottage property in keeping them in
good working order, especially during the frosts of winter. There are,
however, many objections to the pail system, which it is not proposed
to touch upon in this address, beyond this, that it appears to be a
costly appendage to the water carriage system, without the expected
corresponding advantage of relieving the municipal authorities of any
of the difficulties of river pollution, inasmuch as the remaining
liquid refuse of the town has still to be dealt with by the modern
systems of precipitation or irrigation, at practically the same cost
as would have been the case if the water carriage system had been
adopted in its entirety.
The rivers pollution act gave an impetus to works for the treatment of
sewage, although much had been done prior to that, and Leicester was
one of those towns which led the way so early as 1854 in precipitating
the solids of the sewage before allowing it to enter the river. The
innumerable methods which have since then been tried, and after large
expenditures of money have proved to be failures, show the
difficulties of the question.
On the whole, however, sewage farms, or a combination of the chemical
system with irrigation or intermittent filtration, have been the most
successful, so that the first evil to which the cleansing of towns by
the increased pollution of rivers gave rise may now be said to be
capable of satisfactory solution, notwithstanding that the old battle
of the systems of precipitation versus application of sewage to land
still wages whenever opportunity occurs.
The second evil to which I have made reference, viz., that of sewer
ventilation, seems still unsolved, and I would earnestly entreat
members, all of whom have more or less opportunities of experimenting
and making observations of the behavior of sewer gas under certain
conditions, to direct their attention to this subject. It is admitted
on all hands that the sewers must be ventilated--that is, that there
must be a means of escape for the polluted air of the sewers; for it
is well known that the conditions prevailing within the sewers during
the twenty-four hours of the day are very varying, and on this subject
the early observations of the late medical officer for the City of
London (Dr. Letheby), and the present engineer for the City of London
(Lieutenant-Colonel Heywood), and the still more recent investigations
of Professor Pettenkofer, of Munich, Professor Soyka, of Prague, and
our own members, Mr. McKie, of Carlisle, Mr. Read, of Gloucester, and
others, are worthy of attention. It does not, however, seem to be so
readily or universally conceded that a plentiful supply of fresh air
is of equal importance, and that the great aim and object of sewer
ventilation should be the introduction of atmospheric air for the
purpose of diluting and oxidizing the air of the sewers, and the
creation of a current to some exit, which shall, if possible, either
be above the roofs of the houses, or, still better, to some point
where the sewer gas can be cremated. The most recent contribution to
this subject, in direct opposition to these views, is to be found in
the address of Professor Attfield to the Hertfordshire Natural History
Society and Field Club, in which it is laid down that all that is
necessary is a vent at an elevation above the ground, and that,
therefore, the surface ventilators, or other openings for the
introduction of fresh air, are not only not necessary, but are, on the
contrary, injurious, even when acting as downcast shafts.
These aims and objects are beset with difficulties, and the most
scientific minds of the country have failed so far to devise a method
of ventilation which shall at the same time be within the range of
practical application as regards cost and universally satisfactory.
The report of last year of a committee of the metropolitan board of
works is worth attention, as showing the opinion of metropolitan
surveyors. Out of forty districts, the opinions of whose surveyors
were taken, thirty-five were in favor of open ventilation, two were
doubtful, two against, and one had no experience in this matter. The
average distances of the ventilators were from 30 to 200 yards, and
the committee came to the conclusion that "pipe ventilators of large
section can be used with great advantage in addition to, and not in
substitution for, surface ventilators." To supplement the street
openings as much as possible with vertical cast iron or other shafts
up the house sides would seem to be the first thing to do, for there
can be no doubt that the more this is done, the more perfect will be
the ventilation of the sewers. It must also not be forgotten that the
anxiety, of late years, of English sanitarians to protect each house
from the possible dangers of sewer gas from the street sewer has led
to a system of so-called disconnection of the house drains by a water
seal or siphon trap, and that, consequently, the soil pipes of the
houses, which, when carried through the roofs, acted as ventilators to
the public sewers, have been lost for this purpose, and thus the
difficulty of sewer ventilation has been greatly increased.
In Leicester we have been fortunate enough to secure the co-operation
of factory owners, who have allowed us to connect no fewer than
fifty-two chimneys; while we have already carried out, at a cost of
about £1,250, 146 special shafts up the house sides, with a locked
opening upon a large number of them, by means of which we can test the
velocity of the current as well as the temperature of the outflowing
air. The connections with the high factory chimneys are all of too
small a caliber to be of great use, being generally only six inches,
with a few exceptionally of nine inches in diameter.
The radius of effect of specially erected chimneys, as shown by the
experiments of Sir Joseph Bazalgette, and as experienced with the
special ventilating towers erected at Frankfurt, is disappointing and
discouraging when the cost is taken into consideration. It can not be
expected, however, that manufacturers will admit larger connections to
be made with their chimney; otherwise, of course, much more
satisfactory results would be obtained. To fall back upon special
shafts up the house sides means, in my opinion, that there should be
probably as many in number as are represented by the soil pipes of the
houses, for in this we have a tested example at Frankfurt, which, so
far as I know, has up to the present moment proved eminently
satisfactory.
The distance apart of such shafts would largely depend on the size of
them, but as a rule it will be found that house owners object to large
pipes, in which case the number must be increased, and if we take a
distance of about 30 yards, we should require about 5,000 such shafts
in Leicester. Whether some artificial means of inducing currents in
sewers by drawing down fresh air from shafts above the eaves of the
houses, and sending forth the diluted sewer gas to still higher
levels, or burning it in an outcast shaft, will take the place of
natural ventilation, and prove to be less costly and more certain in
its action, remains to be seen. But it is quite certain that
notwithstanding the patents which have already been taken out and
failed, and those now before the public, there is still a wide field
of research before this question is satisfactorily solved, so that no
cause whatever shall remain of complaint on the part of the most
fastidious.
One other important question common to all towns is that of the
collection and disposal of the ashes and refuse of the households. It
is one which is becoming daily more difficult to deal with, especially
in those large communities where the old privy and ashpit system has
not been entirely abolished. The removal of such ashes is at all times
a source of nuisance, and if they cannot be disposed of to the
agriculturists of the district, they become a source of difficulty. In
purely water-closeted towns the so-called dry ashpits cannot be kept
in such a condition as to be entirely free from nuisance, especially
in the summer months, inasmuch as the refuse of vegetable and animal
matter finds its way into them, and they are, in close and inhabited
districts, necessarily too close to the living apartments of the
dwellings. The tendency therefore now is rather to discourage the
establishment of ashpits by the substitution of ashbins, to be
collected daily or weekly as the case may be, and I think there can be
no doubt that from a sanitary point of view this is by far the best
system, harmonizing as it does with the general principle applicable
to town sanitation of removing all refuse, likely by decomposition to
become dangerous to health, as quickly as possible from the precincts
of human habitations.
The difficulty of disposing of the ashes, mixed as they must
necessarily be with animal and vegetable matter, is one that is
forcing itself upon the attention of all town authorities, and the
days of the rich dust contractors of the metropolis are practically
numbered. Destruction by fire seems to be the ultimate end to be aimed
at, and in this respect several towns have led the way. But as this is
a subject which will be fully dealt with by a paper to be read during
the meeting, I will not anticipate the information which will be
brought before you, further than to say that the great end to be aimed
at in this method of disposing of the ashes and refuse of towns is
greater economy in cost of construction of destructors, as well as in
cost of working them.
The progress in sanitation on the Continent, America, and the colonies
has not been coincident with the progress in England, but these
countries have largely benefited by the experience of the United
Kingdom, and in some respects their specialists take more extreme
views than those of this country in matters of detail. This is,
perhaps, more particularly the case with the Americans, who have
devised all sorts of exceptional details in connection with private
drainage, in order to protect the interior of the houses from sewer
gas, and to perfect its ventilation. In plumbing matters they seem
also to be very advanced, and to have established examinations for
plumbers and far-reaching regulations for house drainage.
Time will not permit me to examine into the works of a sanitary
character which have been undertaken in the several countries after
the example of England, but they have been attended with similar
beneficial results and saving in life and sickness as in this country,
although the Continental towns which have led the way with such works
cannot as yet point to the low rates of mortality for large towns
which have been attained in England, with the exception of the German
towns of Carlsruhe, Frankfurt, Wiesbaden, and Stuttgart, which show
death rates of 20.55, 20.64, 22, and 21.4 respectively. The greatest
reduction of the mortality by the execution of proper sewerage and
water works took place in Danzig, on the Baltic, and Linz, on the
Danube, where after the execution of the works the mortality was
reduced by 7.85 and 10.17 per 1,000 respectively, and in the case of
Danzig this reduction is almost exclusively in zymotic diseases.
Berlin is also a remarkable example of the enterprise of German
sanitarians, for there they are demonstrating to the world the
practicability of dealing with the sewage from a population of over 1¼
million upon 16,000 acres of land, of which about 10,000 acres are
already under irrigation.
In taking this chair, it has been usual, when meetings have been held
out of London, for your president to give some account of the works of
his own town. In the present instance I feel that I can dispense with
this course, in so far as that I need not do more than generally
indicate what has been the course of events since I read to a largely
attended district meeting in May, 1884, a paper on "The Public Works
of Leicester." At that time large flood prevention works were in
course of construction, under an act obtained in 1881, for continuing
the river improvement works executed under previous acts. The works
then under contract extended from the North Mill Lock and the North
Bridge on the north to the West Bridge and Bramstone Gate Bridge on
the south, along the river and canal, and included bridges, weirs,
retaining walls, and some heavy underpinning works in connection with
the widening and deepening of the river and canal. These works were
duly completed, as well as a further length of works on the River Soar
up to what is known as the old grass weir, including the Braunstone
Gate Bridge, added to one of the then running contracts, at a total
cost, excluding land and compensation, of £77,000. At this point a
halt was made in consequence of the incompleteness of the negotiations
with the land owners on the upper reach of the river, and this,
together with various other circumstances, has contributed to greater
delay in again resuming the works. In the interval, a question of
whether there should be only one channel for both river and canal
instead of two, as authorized by the act, has necessarily added
considerably to the delay. But as that has now been settled in favor
of the original parliamentary scheme, the authority of the council has
been given to proceed with the whole of the works.
One contract, now in progress, which members will have an opportunity
of inspecting, was let to Mr. Evans, of Birmingham, in March last, for
about £18,000. It consists of a stone and concrete weir, 500 feet in
length, with a lock of 7 feet 6 inches lift and large flood basins,
retaining and towing path walls, including a sunk weir parallel with
the Midland Railway viaduct. This contract is to be completed by March
next. The remainder of the works about to be entered upon include a
new canal and flood channel about 1,447 yards long, and the deepening
and widening of the River Soar for a length of about 920 yards, with
two or three bridges.
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