IMPROVEMENTS IN CONSTRUCTING SUB-AQUEOUS.
Year: 1883

page_text: LETTERS PATENT to Walter James Bentley of Leeds in the County of York
for an Invention of IMPROVEMENTS IN CONSTRUCTING SUB-AQUEOUS
.
PROVISIONAL SPECIFICATION left by the said Walter James Bentley 'at
the Office of the Commissioners of Patents on the 14th July 1883.
WALTER JAMES BENTLEY of Leeds in the County of York
"IMPROVEMENTS
IN CONSTRUCTING SUB-AQUEOUS STRUCTURES SUCH AS TUNNELS AND THE LIKE
AND APPARATUS THEREFOR
"
My invention is designed to facilitate and cheapen the construction of sub-
aqueous tunnels and other similar structures such as subaqueous drains and
conduits.
For this purpose I use caissons the lower end portions of which are made removable
or movable after the manner of sliding doors or portcullis bulkheads by which
latter name I will for clearness designate the same hereinafter-In the construction
of a tunnel with such apparatus starting from one shore such a caisson as above
referred to (which for distinction I will call N° 1) having been sunk, and the
length of tunnel constructed within it, a watertight joint of any suitable kind,
such, for example, as a concrete and puddle joint, is formed between the top of the
tunnel and the bottom of the fixed portion of the bulkhead of the caisson. Another
caisson (N° 2) is meanwhile sunk in advance, and on its reaching the required
depth the portcullis bulkhead of N° 1 Caisson is removed or raised, and the tunnel
carried forward to the next bulkhead at the end of N° 2 caisson, where the same.
operation is performed, and so on, the operation being repeated with each succeeding
caisson until the opposite shore or termination of the tunnel or work is reached.
Each caisson as the joint in advance of it is formed can be floated off and resunk
in front. It is to be noted that the water tight joint between the lower part of
the
upper
or fixed end of each bulkhead and the top of the work is constructed in
what is technically called "the dry"; that is, before readmission of water to the
caisson in front of which the joint is made.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Walter James Bentley in the Patent Office on the 14th January
1884.
WALTER JAMES BENTLEY late of Leeds in the County of York, now of Great
George Street in the City of Westminster. IMPROVEMENTS IN CONSTRUCTING
SUB-AQUEOUS STRUCTURES SUCH AS TUNNELS AND THE LIKE AND APPARATUS
THEREFOR
My invention is designed to facilitate and cheapen the construction of sub-
aqueous tunnels and other similar structures such as sub-aqueous drains and
conduits.
For this purpose I use caissons or coffer-dams the lower end portions of which
are made removable or movable after the manner of sliding doors or portcullis
bulkheads by which latter name I will for clearness, designate the same hereinafter.
In the construction of a tunnel with such apparatus starting from one shore such
a caisson as above referred to (which for distinction, I will call N° 1) having been
sunk, and the length of tunnel constructed within it, a water tight joint of any
suitable kind, such, for example, as a concrete and puddle joint, is formed between
the top of the tunnel and the bottom of the fixed portion of the bulkhead of the
caisson. Another caisson (N° 2) is meanwhile sunk in advance, and on its reaching
the required depth a water tight joint is made between N° 1 and 2 and the forward'
portcullis bulkhead of No. 1 caisson is removed, or raised, and the tunnel carried
forward to the next bulkhead at the end of N° 2 caisson, where the same operation
is performed, and so on, the operation being repeated with each succeeding caisson
until the opposite shore or termination of the tunnel or work is reached.
Referring to the accompanying sheet of illustrative drawings; Fig 1 is a longitu-
dinal vertical section shewing a tunnel in course of construction with apparatus
according to my invention, Fig 2 is a transverse section through the same; Fig 3
is a plan, and Fig 4 is an enlarged view of a joint at X on Figs 1 and 3.
The caissons are constructed of wrought iron, or other suitable material such as
steel, and each comprises two main portions; The first or central portion consists
of two long sides a firmly braced to one another by means of bulkheads or bracing
(which bracing may be such as indicated at b on Fig 3, but which for the sake
of clearness, is not shewn elsewhere in the drawings). Each of the sides'a is itself
a caisson composed of two skins about four feet apart, and two ends; the lower
edge all round being made a cutting edge to facilitate sinking as is well understood.
At a suitable height-which may be about six feet from the lower edge a water-and
air-tight deck c with suitable doors and air locks to give access is formed to enable
the sinking to be performed by pneumatic apparatus where necessary. The second
or end portion of each caisson comprises two short sides a¹ an upper fixed bulk-
head d, and a portcullis bulkhead e which it will be understood constitutes an
essential feature of the apparatus. This portcullis bulkhead and the two short
sides have all cutting edges at the bottom and an air-tight deck c similar to those
of the long sides. When this portcullis bulkhead is down in readiness for the
apparatus to be sunk it is firmly bolted to the bottom of the fixed bulkhead and to
angle irons projecting from the two sides, and the joint is made water-tight by
means of india-rubber or other, packing. From the portcullis bulkhead shafts.are,
as shewn in the drawing, carried up to above water level, to allow access to the
interior for the purpose of sinking. In the drawings Figs 1, 2 and 3 I have repre-
sented a tunnel in course of construction. I have already described in outline the
method of using the apparatus. But in order to a clear understanding of the same,

page_text: I now proceed to explain it more particularly with reference to the drawings.
Starting from any point a caisson formed of two long sides such as a a and two ends
portions such as a' al de so as to enclose a rectangular space in plan is first floated
into position and sunk by the addition of weight as well understood to the required
depth; the water is then pumped out, the material in the interior is excavated and
the length of work within constructed. A watertight joint of any suitable kind,
as for instance a concrete and puddle joint, such as shewn in Fig 1 is formed
between the top of the work and the bottom of the fixed bulkhead of the forward
end. Another caisson consisting of two long sides and one end portion is mean-
while sunk as near as possible to the first and the joint between the two made
temporarily watertight by some of the usual methods such as wood piles between
iron cheeks (as used on the cast iron coffer dam of the Thames Victoria Embank
ment, London) or outside piles lined with felt and drawn together by bolts or
otherwise. When this joint has been made good the water is pumped out and the
material enclosed by. this second caisson is excavated, the portcullis bulkhead at the
forward end of the first caisson is raised, and the construction of the work continued
to the forward end of the second caisson where a similar concrete and puddle.
watertight joint is formed; the end portion and the side caissons behind the first
watertight joint are meanwhile floated off and. prepared for sinking in advance, as
indicated to the right in Figs 1 and 3 and this process is repeated until the end of
the work is reached.
It is to be noted that all the watertight joints between the work and the caissons
are constructed in what is technically called "the dry," that is before re-admission
of water to the caisson in which the joint is made.
A single skin may be used for the sides and bulkheads instead of the double
skin; in which case it will probably be more economical to leave the lower portions
-up to the top of the work constructed-in the ground, only floating off and
re-using the upper portions. It will be evident apparatus constructed and arranged
according to my invention may be used for various sub-aqueous building operations
including the construction of piers and walls. Having described the nature of my
said invention and the manner of carrying it into practical effect I hereby declare
that what I consider to be novel and original and therefore claim as secured to me
under the Letters Patent hereinbefore first in part recited is :-
1. In constructing sub-aqueous structures such as tunnels and the like, the use
as above set forth of caissons the end portions of which are made with an upper
fixed part and a lower part movable or removable substantially as described.
2. The apparatus constructed and arranged as hereinabove described and illus-
trated in the drawings with end portions each comprising an upper fixed part and
a lower moveable or removable part for use in sub-aqueous building operations.
In Witness whereof I the said Walter James Bentley have hereunto set my
hand and seal this fourteenth day of January in the year of our Lord 1884.
WATTER TAMES DENT EV