In 1882, M. Bacle published in _Le Génie Civil_ a study of the sewer
systems in some of the large foreign cities. There may be found there a
description of the Liernur system at Amsterdam, Leyden, and Dordrecht, in
Holland, and in certain cities of Germany and the United States.
[Illustration: IMPROVED CATCH BASIN.]
This system consists in the employment of two distinct systems of ducts,
one for the discharges from water-closets and the other for household
wastes, rain water, and the discharges from factories when sufficiently
purified. This arrangement allows the employment of sewers of small
section, provided that it shall be unnecessary to enter them for the
purpose of cleansing them. It has been necessary, therefore, to provide
inlets with a separating apparatus called "gully" or "catch basin," which
retains as completely as possible all solid matter, mud, excrement, and
_debris_ of every kind which maybe floated in by street washing or by
rain-water, and which may be capable of causing stoppages in the sewers,
the choking up being followed by fermentation and the emanation of noxious
vapors.
M.C. Pieper of Berlin suggests a device for a catch basin, which appears
to meet the requirements. It is in the form of a cylindrical metal box,
enlarged in its upper section to receive a filtering cylinder of
perforated sheet iron, which occupies almost the upper half of the device
and rests upon the smaller lower part. The entire apparatus is covered by
a movable funnel, through which enter water and any rubbish which it may
carry with it. From one side a tube allows the liquid to be discharged,
while a siphon placed on the opposite side serves the same purpose under
certain circumstances, as will be explained.
Figure 1 represents the apparatus discharging under normal conditions. The
heavy matter, sand, stones, etc., falls to the bottom into a receptacle
which can be lifted out from time to time and emptied. The lighter buoyant
matters, straw, vegetable _debris_, paper, etc., remain at the surface,
and are retained by the filter; the water passing through the holes in the
sheet iron rushes in a filtered condition through the annular space which
exists in the upper part between the two cylinders, and escapes by the
waste-pipe when the water reaches a proper level. If at a given moment the
quantity of water flowing in is too much to be discharged through this
waste-pipe, the level of the water mounts in the cylinder until it reaches
the top of the siphon. Immediately the siphon comes into play and empties
the upper part of the apparatus, and the filtered water contained in the
annular space already mentioned quickly re-enters the cylinder through the
perforated sheet iron, and in so doing cleans out the perforations with
considerable energy. This second period is represented in the second
figure.
The mouth of the siphon being placed above the movable basket, the heavy
matters contained in the latter are not in the least disturbed, and the
metallic screen placed over the mouth prevents the entrance of any
floating matters. When siphonic action ceases, the water in the short arm
of the siphon empties itself into the main receptacle, and by so doing
cleanses the screen. During a rain or the washing of the streets, the
siphon can work in concurrence with the ordinary discharge-pipe. It is
evident of course that these two--pipes can be placed on the same side of
the apparatus, if this prove the most convenient arrangement.
We will add that this apparatus can be applied not only to the Liernur
system, but also can be used for preventing the entrance of obstructions
into sewers of the ordinary type, where the grade is small or where the
quantity of water is insufficient; and if we adopt the system of
"everything to the sewer," can we not find in the employment of this
apparatus an element for the realization of the famous formula, "Always in
circulation, and never in stagnation?"--_Le Génie Civil._
* * * * *
[Concluded from SUPPLEMENT No. 454, page 7249.]