Democratic Northwest. [volume] (Napoleon, Ohio) 1869-1894, 1886-01-28


some more complicated and expen-
sive method Of riding ourselves OF the
inevitable filth. The next best meth
cd Is a system Of sewers and water
works. This, however, does not pre-
vent the necessity of system OF porous
underdrains for the purpose OF remov-
ing the ground-water and @rating the
soil.
The plan of carrying the filth Of a
city by sewers 10 very ancient. The tenn
pie at Jerusalem had very elaborate
system of sewers excavated in the solid
rock. which Is yet In good condition.
Alexandria, Carthage, Herculancum,
Nineveh, and Rome had complete sys-
TENS of sewers and water-works. The
latter seem to be q necessary acom-
paniment to an efficient sewer system.
There are five fundamental rules for
the construction of sewers, to make
them answer fully the purpose for
which they were intended:
/. The sewer should be laid to true
grade, from its place Of beginning to Its
outlet. 1t Is not necessary that the
same rate of fall should extend through
out the whole length Of the sewer. The
grade should be perfectly stright until
il Is changed for another, and so on
until the outlet is reached.
2. The descending grade should be
so suited to the size of the sewer and
the amount of sewage that will be like
ly to flow through II, that 1t will be
self-cleaning.
3. The size of the sewer should be
proportioned to the grade, and the
amount of sewage 1t will be expected
to carry.
4. 1t must be made Of impervious
material and smooth inside.
8. Itmust be ventilated.
We believe that no good and efficient
sewer can be constructed that ignores
any one Of these rules. If the grade is
not true line, the sewage will halt at
the depressions and decomposition take
place with the productions of large
quantities of offensive and dangerous
gases, and it will also in short time
Obstruct the flow, until the sewer be-
comes filed up, and thus rendened
worse than useless. The sewage should
be kept constantly in motion until it
has passed the outlet, so that there will
be no time for fermentation and decom-
position. To make this sure at all times,
the sewer should be of such size and
shane that the sewage whether large or
small in quantity should be concentra-
ted in the bottom. Experience has
shown that the round, or the oval, or
egg shaped sewer is the most efficient.
Sewers are almost invariably too large;
the water is spread over too much sur
face and has not force enough to keep
the solid matter in constant motion.
Large sewers therefore become sewers
of deposit, mere elongated cess-pools,
which require to be cleaned out by
manual labor at frequent intervals, and
increase rather than diminish the dam
gers that arise from the presence of
sewage. A sewer that runs half full
will be much more likely to be self
cleaning than one that is only filled to
one-fitieth part of its capacity; as the
fuller the sewer the more rapidly its
contents will flow. 1t the contents of a
sewer fill it to One-fourth of its capacity
it will be self-cleasing, If it has a proper
grade. A sewer 6 inches in diameter,
with fall of in 292 will flow at the
rate of two feet per second. Ifthe fall
is in 1877, the flow will be three feet
per second, and with fall of in 80; it
will flow four feet per second.
The size of the sewer should be pro-
portioned to the grade and also to the
work it may be called upon todo. If it
is too large, it will fail for want of force
to carry along it contents, as they will
be distributed over too much surface.
If too small, it will necessarily fail
from want of room in which to carry
the sewage brought to it. The opinion
prevails very generally that sewers
should be very large, indeed, it is
thought they can hardly be to large.
The demand is that they be large
enough, forgetting that sewer too
large is as bad, if not worse, than one
too small.
The earlier sewers of Europe were
called "sewers of deposit" because it
was recognized as fact that they
would become obstructed and fill up.
1t was necessary then that they should
be large enough for man to enter;
six feet was supposed to be the necessa-
ry height TO afford facilities for clean
ing. -,
Modern science has demonstrated
that they be made self-cleaning by
making them of size proportioned to
their work and giving them proper
grade. In order to do this the stream
must have depth to float and velocity
sufficient to carry along its solid con-
tents. Suppose the stream to be three
feet wide and one inch deep, it would
not have depth enough to float the solid
matter from house drains, and it could
not have velocity enough to prevent
deposition and its consequences, OBJ
struction, fermentation and decompo-
sition. Contract the channel to one
foot, the flow be increased to three
inches, the friction would be reduced
two-thirds, the velocity increased and
the solid matter kept moving. Contract
lit again to six inches; the friction
would again be very much reduced, and
and the velocity so increased as to
speedily deliver its contents at the out
let.
Before constructing sewer it will be
necessary to ascertain the amount OF
fall that can be obtained, then the
probable maximum of sewage it will
need to carry at one time. First, there
is the sewage proper, that which flows
from the colset, sink and house drain,
to this we add water in various quanti-
ties, according to the supply from wa
ter works. or otherwise.
For 12O towns of England, Mr.. La
trop found that the average amount OF
sewage and water was 25 gallons pei
day for each person. Varying all the
way from to SO per persons, Mr.. War
ing says that it will be q safe rule tc