IMPROVEMENTS IN CONSTRUCTING TUNNELS BELOW WATER, AND IN APPARATUS TO BE USED FOR THIS PURPOSE AND FOR FORMING OTHER WORKS BELOW WATER
Year: 1871

page_text: LETTERS PATENT to John Wright, of Rochester, in the County of
Kent, for the Invention of "IMPROVEMENTS IN CONSTRUCTING TUNNELS
BELOW WATER, AND IN APPARATUS TO BE USED FOR THIS PURPOSE AND FOR
FORMING OTHER WORKS BELOW WATER."
Sealed the 6th February 1872, and dated the 29th August 1871.
PROVISIONAL SPECIFICATION left by the said John Wright at the
Office of the Commissioners of Patents, with his Petition, on the
29th August 1871.
I, JOHN WRIGHT, of Rochester, in the County of Kent, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN CON-
STRUCTING TUNNELS BELOW WATER, AND IN APPARATUS TO BE USED
PURPOSE AND FOR FORMING OTHER WORKS BELOW WATER,” to be as follows :—
FOR THIS
•
The object of this Invention is, firstly, to construct tunnels below
water. For this purpose caissons or bells open at the bottom, and from

page_text: which the water is kept out by air under pressure, are employed, and a
continuous foundation is formed in the manner described in the Specifi-
cation of a former Patent granted to me, dated 25th January 1862
(No. 199), sections of such foundation being first formed in succession at
a short distance from one another, and the spaces between such sections
being subsequently filled in as therein described. Upon this continuous
foundation the tunnel is in a similar manner constructed in two or more
horizontal layers, but in the several sections of the horizontal layers
where the two side walls of the tunnel have to be formed, in addition to
forming such side walls I also build or close in the ends of such sections 1
or completely fill in the space between the walls, so that when the
caisson or bell is subsequently placed over the space between two of
such adjoining sections such space may be formed into a cofferdam by
simply closing its ends. When the water has been pumped from such
cofferdam the building in of the side walls of the tunnel to connect ]
together the sections on each side of such space is readily effected, and
then without moving the caisson or bell the building in of a section of
the next horizontal layer above it is proceeded with. After a length of
tunnel has been thus formed, the temporary ends built in or formed at
the cuds of cach section or the material used for filling in the space a
between the side walls may be removed, and that length of the tunnel
will then be completed. The spaces between the several sections of each
layer may be filled in this manner as the work proceeds, or in the case
of small tunnels several complete sections of a tunnel may be thus
formed and the spaces between them subsequently filled in as before 2
described.
In order to be able readily to raise up from the bells or caissons the
earth removed in forming the foundation or to lower down building
materials into the caissons, I form cach caisson or bell with a shaft
rising up from it in which is an endless chain of buckets. At the
bottom of the shaft and within the bell is a hopper, into which any of
the materials to be raised are thrown and are caught up by tho buckets
and raised by them above the upper end of the shaft. The shaft is kept
filled with water, and the weight of the column of water in the shaft is
balanced by the compressed air within the bell pressing on the surface
of the water within the hopper, and if the mouth of the hopper is above
the bottom of the bell provision is made for filling up the shaft with
water above the surface level of the water below which the tunnel or
work is being constructed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Wright in the Great Seal Patent Office on
the 29th February 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
WRIGHT, of Rochester, in the County of Kent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-ninth day of August, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Wright, Her special license that
I, the said John Wright, my executors, administrators, and assigns, or
such others as I, the said John Wright, my executors, administrators,
and assigns, should at any time agree with, and no others, from time
to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN CONSTRUCTING
TUNNELS BELOW WATER, AND IN APPARATUS TO BE USED FOR THIS PURPOSE AND
FOR FORMING OTHER WORKS BELOW WATER," upon the condition (amongst
others) that I, the said John Wright, my executors or administrators,
by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said John Wright, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say:—
The object of this Invention is, firstly, to provide a means by which
tunnels can be constructed under or on the bed of rivers or other waters

page_text: actually through or in the water, obviating the necessity of having any
thickness of carth between the top of a tunnel and the bottom of the
river, as is now the case, and at the same time making the nature of tho
soil as regards porosity, leakage by fissures, or faults in the bottom of no
consequence, it being only necessary that the bottom should have
sufficient solidity to bear the weight of the tunnel when complete. For
this purpose caissons or bells open at the bottom, and from which the
water is kept out by air under pressure, are employed, and a continuous
foundation is formed in the manner described in the Specification of a
former Patent granted to me, dated 25th January 1862 (No. 199),
sections of such foundation being first formed in succession at a short
distance from one another, and the spaces between such sections being
subsequently filled in as therein described. Upon this continuous system
the tunnel is to be constructed in horizontal courses as therein described,
differing only that as in that blocks are built solid I now form a tunnel
within such blocks, which are made sufficiently wide for the purpose by
employing a bell of suitable size. On the upper part of the first course
of blocks, whilst being separately built within the bell, I form a portion
of the invert or so much of the tunnel as is to be contained in the height
of the block in masonry, brickwork, or other suitable material, the hollow
formed by the invert thus made to be filled in with clay or other material
proper for the purpose to the height of the block. Blocks thus made
may be carried across or to any required distance at the bottom of a river.
or other water, or in a trench excavated for the purpose, the intervals
left between them being kept free from water by stanks or dams at each
end, as described in my former Patent, and the junction of the blocks
mado good in the same way; only in this case the part so made good
shall be formed into a portion of the tunnel corresponding and forming
a part with the blocks which it unites. The clay, as described, is placed
within the hollow of the invert and tunnel as the work proceeds, to
prevent the water passing through and filling the interval between the
stanks, which would prevent them being pumped dry and made good as
before described.
In Figure 1 of the accompanying Drawing I have shewn the method
of proceeding in the construction of a tunnel, in which will be seen the
position of the bell in different stages of the work. In the first course,
Figure 1, the bell is resting on the bottom of the river or trench, and
there has already been built in it a number of blocks, as shewn, and in

page_text: the position it now occupies, as shewn, the earth from within has been
excavated, and a block of concrete or masonry has been constructed, in
which a portion of a tunnel in cast iron segments is shewn in the corre-
sponding cross section, which also shows the hollow filled in with clay.
Between this block and the next the interval is shewn full of water
before the stanks at each end have been applied and the water pumped
out, which cannot be until the bell is placed over it for the next
course.
The cross section of the second course is shewn with an additional
height of segments fixed and filled in with clay, as in the first course,
and it will be understood that in constructing this second course the bell
will always be placed over the intervals left in the first. The compressed
air will force and keep out the water to the level of the top of the first
course and the surface of the water in the interval, which when the
stanks at each end are applied can be pumped out, and the water will
flow into that of the river by the action of the compressed air within the
bell notwithstanding the superior head of water in the river. As soon
as the water is thus pumped out the concrete or brickwork completing
the block of the lower course can be put in, and the cast-iron segments
connecting those of the adjoining blocks fixed in place and the first
course finished, when before removing the bell the block for the second
course can be built, as shewn in the section; the bell will then .be
moved forward over the next interval in the first course, which will be
made good, another block of the second course constructed, and an
interval left over the centre of a block in the first course to be pumped
out and made good, as just described for the first course when the third
course is being constructed, and so on until the whole is completed, as
shewn in the different sections in the Drawing, the last of which shows
the tunnel completed surrounded by a square of concrete and filled with
clay, which can be removed as the work proceeds provided there is a
sufficient amount left to prevent the water flowing through tɔ fill in the
intervals before they are are made good. Of course when the clay is
removed a clear open tunnel will be completed. In place of construct-
ing the tunnel of concrete with an interior lining of cast iron, the tunnel
may be of concrete alone, or concrete lined with moulded blocks of
artificial stone. Blocks of Ransome's artificial stone would be very
suitable for the purpose, or the tunnel might be formed of brickwork
or other suitable material.

page_text: The caisson or bell can readily be raised and shifted from place to
place by a traveller running upon rails on a shafting supported on piles,
as shewn at Figure 1, the traveller being fitted up with a suitable engine
and travelling and hoisting gear.
In the caissons or hells described in the Specification of my former
Patent before mentioned all the earth excavated and materials supplied
to the interior of the bell had to be passed through the air locks at the
top of the shaft, which passed up from the bell to above the water line,
thereby causing considerable loss of time and air. To obviate this I fix
inside the bell a tank or hopper, as shown in the sections, Figure 2.
From the hopper a shaft rises through the top of the bell to above the
surface of the water; this shaft is open at each end and dips a short
distance below the mouth of the hopper. The shaft and hopper aro.
always kept filled with water, a stream of water being supplied con-
tinually to the shaft by pumps or other supply for the purpose. By this
means the escape of air from the bell will be prevented, although in
excess of the pressure corresponding to the height of the water between
the surfaces of the water in the hopper and that of the river, because if
the hopper is by the extra supply always kept full, the water in it can
never be depressed below the bottom of the shaft, and by that means air
cannot escape through it; therefore the water in the bell by a superior
pressure of air can be forced and kept down to the bottom of the bell,
and the water in the shaft will rise to such height above the surface of
the river as the bottom of the bell is below that contained in the hopper.
Within this shaft is contained a set of revolving buckets, as also shewn,
by which all earth excavated from the bottom of the bell and cast into
the hopper can be drawn up, and consequently excavation can be carried
on as rapidly as by ordinarily digging and throwing out. The endless
chain of buckets is driven continuously, as shown, by gearing and an
endless driving belt from the engine carried by the traveller. By means
also of the shaft before mentioned, or an additional shaft and hopper,
materials may be lowered into the bell through the water perfectly dry
in buckets having a flap box lid so hinged that when shut the edges of
the lid shall overlap those of the bucket so far that the air contained in
the lid may prevent the water rising up to the edge of the bucket. Caro
will only be requisite to lower the bucket through the shaft and take it
out vertically. By this means no particular care is required in fitting
the lid. The caisson or bell is also provided with another shaft rising

page_text: up
from it to above the water level, and which at its upper end carries a
chamber fitted up with air locks, as heretofore. This shaft and chamber
are shewn roughly in the sections of caissons or bells at Figure 1.
Having thus described the nature of my Invention, and the manner of
performing the same, I would have it understood that I do not confine
myself to tho precise details herein-before given, but what I claim is,-
1. The construction of tunnels below water, substantially in the
manner herein described.
2. The construction of a diving bell with a shaft rising up from an
open hopper within the bell; to above, the water line, substantially as
herein described, such shaft and hopper being kept filled with water to
balance the pressure of air within the bell, and thereby prevent the
escape of air from the bell up through the shaft.
In witness whereof, I, the said John Wright, have hereunto set my
hand and scal, this Twenty-eighth day of February, in the year of
our Lord One thousand cight hundred and seventy-two.
T.
JOHN WRICH