Improvements in Fishways, especially suitable for Eels and the like.
Year: 1891

page_text: Date of Application, 21st Nov., 1891
Complete Specification Left, 14th Jan., 1892-Accepted, 20th Feb., 1892
PROVISIONAL SPECIFICATION.
Improvements in Fishways, especially suitable for Eels and
the like.
I, PAUL GERHARDT of Bayreutherstrasse, Berlin, W., Germany, Royal
Chief Fishmaster, do hereby declare the nature of this invention to be as
follows:-
:-
As is well known eels that grow in rivers return to the sea in the spawning time,
but the weirs or damming-up devices used in such rivers offer obstacles to their
progress. In returning to the sea the large eels travel with the current along
the bottom, and are able to pass weirs which are overflowed by the water or
are provided with slots or channels for them to get through; but they cannot
pass weirs which are closed water-tight at the time of the journeying of the eels
in the summer because at that season all the water is used for the motive
apparatus.
The eels therefore endeavour to pass by the motive apparatus, slipping through
the bars of the protective grating, but they are very frequently carried into the
motive apparatus and are torn to pieces. The yearly increasing number and per-
fection of the motive apparatus, turbines, Poncelet-wheels, and the like, thus lead
to a continually augmenting destruction of eels.
In order to obviate these disadvantages, it has been proposed to employ as an eel
way a sheet metal pipe which would commence at the foot of the inlet, and being
led past the turbine, would open or discharge into the tail water.
But with this arrangement by reason of the great head of water, a considerable
quantity of water is lost to the motive apparatus. For this reason the proprietors
of such apparatus regard an eel way of this kind unfavorably.
Now this invention is designed to provide a way that will permit eels and other
fishes to pass the motive apparatus without entailing a considerable loss of water to
the apparatus.
Figs. 1 and 2 of the accompanying drawings illustrate the way in side elevation
aud in plan respectively and
Figs. 3, 4 and 5 shew details.
A is an upwardly inclined channel (Figs. 1 and 2) which may be of straight,
curved, or irregular contour; it is arranged on the protective grating HE¹ of the
dam of the turbine T in such a manner that the said channel which commences at
the bottom of that part of the river which has the higher level almost reaches the
upper water level (O).
The channel consists either wholly or at its lower portion, of wood or other
material that will not frighten away the fish, and should not be of iron.
The wooden walls may be slotted or perforated (see Fig. 3) so as not to interfere
with the supply of water to the motive apparatus, and so as at the same time to
attract the fish by means of the current. From the top C downwards there leads
a channel B (Figs. 1 and 2) of any desired straight, curved or irregular contour,
into the tail water U. The channel B may be formed as an eel ladder or fish
pass by means of stop pieces or steps, and in conjunction with which sand or
the like may be used as shewn. Small slots or holes may also be provided as
illustrated in Fig. 4.
The inlets and outlets of the channels A and B into the upper and the lower
water are preferably widened (Fig. 2).
A slight discharge of water is rendered possible in the top C of the channels A, B,
Fig. 1, in consequence of the slight head of water. This discharge can at times be
entirely or partially arrested by means of a movable flap, protecting valve or the

page_text: like. Ropes or other materials that take up water readily may be arranged to
pass over the top of the channel A, B, from the upper water into the lower water
or tail water (Fig. 5) and thus effect an almost complete shutting off of water, the
eels being however able to pass. Or the shutting off of the water may be effected
automatically by means of movable devices acting as floats, and made of fibrous
materials, leather, wood, or the like.
Dated this 21st day of November 1891.
PAUL GERHARDT,
By L. W., per F. B.
COMPLETE SPECIFICATION.
Improvements in Fishways, especially suitable for Eels and
the like.
I, PAUL GERHARDT of Bayreutherstrasse, Berlin, W., Germany, Royal
Chief Fishmaster, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
As is well known cels that grow in rivers endeavour to pass to the sea in the
spawning season, but the weirs or damming-up devices frequently used in rivers
obstruct their progress. In passing to the sea the cels travel with the current
along the bottom of the river, and can only pass those weirs which are overflowed
by the water, or are provided with slots or channels for them to get through.
During the summer many weirs are closed watertight in order that all the water
may be passed through a suitable water motor and be utilized for motive power
purposes. The eels endeavour to slip through the protective grating employed to
prevent the entrance of large bodies into the motors, and to pass by the motors into
which however they are very frequently carried and therein torn to pieces. The
yearly increasing number and perfection of the water motors employed, such as
turbines, Poncelet-wheels, and the like, thus lead to a continually augmenting
destruction of cels.
To prevent this destruction it has been proposed to employ as an eel-way a sheet
inetal pipe arranged as a bye pass to the motor and having one end near the inlet
of the motor and its other end opening or discharging into the tail water.
With
this arrangement however, owing to the great head of water, a considerable
quantity of water is lost to the motor. For this reason the proprietors of such
apparatus regard an cel way of this kind unfavourably.
Now this invention is designed to provide a fishway that will permit of eels and
other fishes to pass a motor of the kind referred to without entailing a considerable
loss of water to the motor.
Figs. 1 and 2 of the drawings left with my Provisional Specification illus-
trate a fish-way according to this invention in side elevation and plan respectively,
and
Figs. 3 4 and 5 show details.
A is an upwardly inclined channel (Figs. 1 and 2) which may be of straight,
curved, or irregular contours. It is arranged on the protective grating H E of
the dam of the turbine T in such a manner that its lower end commences at the
bottom of that part of the river which has the higher level and its upper end
reaches almost to the upper water level O.
The channel consists either wholly, or at its lower portion only, of wood or other
material that will not frighten away the fish, and should not be of iron. The
wooden walls may be slotted or perforated (see Fig. 3) so as not to interfere with
the supply of water to the turbine, and so as at the same time to attract the fish
moving along with the water current. From the top C there extends downward
into the tail water U a channel B (Figs. 1 and 2) of any desired straight, curved
or irregular contour. This channel B may be formed as an eel ladder or fish pass

page_text: by means of stop pieces or steps, and in conjunction with which sand or the like
may be used as shewn. Small slots or holes may also be provided as illustrated in
Fig. 4. The inlet and outlet of the channels A and B from the upper and into the
lower water respectively are preferably widened (Fig. 2). With this arrangement
a small discharge of water is rendered possible through the top C of the
channels A, B, Fig. 1, in consequence of the slight head of water. This discharge
can at times be entirely or partially arrested when desired by means of a movable
flap, protective valve or the like. Or rope or other material that will readily
absorb water may be arranged to pass through and over the top of the channels A, B,
from the upper water into the lower or tail water (Fig. 5) and thus effect an almost
complete shutting off of water, but so nevertheless as to allow eels to pass. Or the
shutting off of the water may be effected automatically by means of movable
devices made of fibrous materials, leather, wood or the like and arranged to act as
floats.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:―
For enabling eels and other fish to pass over a dam or weir from the upper
water to the tail water of a river, the improved fishway consisting of an upwardly
inclined channel A and a downwardly inclined channel B, the connecting passage
at the top or crown C of these channels being located approximately at the level
of the upper water of the river, and being either left open or adapted to be closed
or partly closed when necessary by means of mechanically operated or automatically
acting devices or by ineans of materials of an absorbent or capillary nature and
whether or not the channel B be formed as a fish pass or cel ladder, substantially
as hereinbefore described and illustrated in the drawings.
Dated this 14th day of January 1892.
P. GERHARDT,
By L. W., per F. B.