THE METHOD OR METHODS OF FORMING TUNNELS OR DRIFTS UNDER GROUND
Year: 1818

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MARC
ISAMBARD BRUNEL, of Lindsay Row, Chelsea, in the County of Middlesex,
Civil Engineer, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twentieth day of
January, in the fifty-eighth year of His reign, give and grant unto me, the
said Marc Isambard Brunel, my cxors, adññors, and assigns, His special
licence,'full power, sole privilege and authority, that I, the said Marc Isambard
Brunel, my exors, adiiors, and assigns, should and lawfully might, during the
term of years therein mentioned, make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, my Invention of
"THE METHOD OR METHODS OF FORMING TUNNELS OR DRIFTS UNDER GROUND;" in
which said Letters Patent there is contained a proviso that if I, the said
Marc Isambard Brunel, shall not particularly describe and ascertain the
nature of my said Invention, and in what manner the same is to be performed,
by an instrument in writing under my handiand scal, and cause the same to
be inrolled in His Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said Letters Patent, that
then the said Letters Patent, and all liberties and advantages whatsoever
thereby granted, shall utterly cease, determine, and become void, as in and
by the same, relation being thereunto had, may more fully and at large
annear

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Mark Isambard Brunel, do hereby declare that the nature of my said Inven-
tion, and the manner in which the same is to be performed, are particularly
described and ascertained in and by the Drawings hereunto annexed, and the
following description thereof (that is to say):-
I shall premise by observing, that the chief difficulties to be overcome in
the execution of tunnels under the bed of great rivers lies in the insufficiency
of the means of forming the excavation. The great desideratum, therefore,
consists in finding efficacious means of opening the ground in such a manner
that no more earth shall be displaced than is to be filled by the shell or body
of the tunnel, and that the work shall be effected with certainty.
The first method I shall describe for obtaining this desirable result, is
applicable to a tunnel of large dimensions as well as to a simple drift or a
driftway. In the formation of a drift under the bed of a river, too much
attention cannot be paid to the mode of securing the excavation against the
breaking down of the earth. It is on that account that I propose to resort
to the use of a casing or a cell, intended to be forced forward before the
timbering which is generally applied to secure the work. This cell may be
similar to one of those represented in Fig. 1, sce letter C. The workman
thus inclosed and sheltered may work with case and in perfect security. It
is obvious that the smaller the opening of a drift, the easier and the more
secure the operation of making the excavation must be. A drift on dimen-
sions not exceeding three feet in breadth by 6 feet in height, forms an
opening of 18 feet area; whereas the body of a tunnel on dimensions suffi-
ciently capacious to admit of a free passage for two carriages abreast cannot
be less than 22 feet diameter, consequently about 20 times as large as the
opening of a small drift. One of the modes which I propose to follow for
the purpose of forming excavations suitable to tunnels of large dimensions
consists in rendering the operation nearly similar to that of forming a small
drift, as being the most easy and the most secure way of proceeding. The
apparatus represented in the Fig. 1, 2, 3, & 4, is one of the nature above
described, and whereby a large excavation suitable to the dimensions of the
proposed tunnel may be made. This apparatus is intended to precede the
body or shell of the tunnel,and it is represented as if the work had already
been commenced with a part of the tunnel a, a, a, a, Fig. 2 & 4, formed
behind it. Fig. 1 represents a tranversal view of an apparatus composed of
small cells A, B, C, D, E, F, G, H, J, K, lying alongside of and parallel with
cach other. Each cell may be forced forward independently of the contiguous
one, so that each workman is supposed to operate in a small drift indepen-

page_text: dently of the adjacent one. The front of the work is protected by small
boards L, L, L, L, which the workman applies as he finds most convenient.
Several men may work at the same time with perfect security and without
being liable to any obstruction from each other.
Fig. 2 represents a longitudinal section of the apparatus, wherein a work
man is seen at work. Each cell is to be moved or forced forward by any
mechanical aid suitable to the purpose, but I give the preference to hydraulic
presses M, M, Fig. 2, which are made to abut against a strong framing
N, N, N, fixed within the body or shell of the tunuel. When the ground.
has been removed and the several cells have been forced forward to a suffi-
cient distance, then a space P, P, corresponding with that distance, is left
between the ends of the cell and the shell of the tunnel a, a, a, a. But in
order to prevent the breaking down of the earth, or the cruption of a large
body of water to each of the cells, and on that side of each which is exposed
to the pressure of the earth, I apply strong iron plates extending beyond the
cell, so as to overlap the shell of the tunnel previously made, thus protecting
the space already cleared. The body or shell of the tunnel may be made of
brick or masonry, but I prefer to make it of cast iron, which I propose to line
afterwards with brickwork or masonry.
Fig. 3 represents a transvers sectional view of the tunnel at the line b, b,
Fig. 4, shewing the framing which is to form the abatement for the hydraulic
presses.
Fig. 4 is a plan exhibiting the internal arrangements of the cells, the
hydraulic presses M, M, M, M, and the framework N, N, N, forming the
abatement of those presses. Each cell in the longitudinal direction thereof is
formed into a prismatic figure such as adapts itself to the situation which it
respectively occupies in the area which is intended to be excavated. In order
to facilitate the progressive movement of the cells I introduce friction rollers
between the opposite sides of all the cells, one row of which, for the sake of
As the construction of the
exemplification, is represented at P, Fig. 2.
hydraulic presses is well understood by mechanics in general, and as the appli-
cation and use of the said presses and framework forming the abatement to
the same must be sufficiently apparent from the preceding description thereof
and the various Figures in the annexed Drawings, they require no further
explanation; I have only to add, that after so much of the earth, as before
described, has been removed by the workman, and after the cells have been
forced forward by the aid of the presses into the position as represented in
Fig. 2 and 4, and also after another portion of the shells of the tunnel has
been added so as to occupy or fill up the space p, p, it then becomes necessary

page_text: that the framework or abatement N,N,N, should be moved forward througha
space equal to that through which the cells had previously been moved. The
said frame having been so moved, it must again be firmly fixed in its now
situation, so as to resist the reaction of the presses as the repetition of their
aid becomes necessary to press or force forward the cells on the removal of
fresh portions of earth. As no competent workman would be at a loss to find
adequate means to secure the abutment in its place, so as that it should
not recede or give way by the opposed action of the presses in pushing
forward the cells, I need not here point them out; I would, however, explain
the method which I employ for advancing or moving the abatement forward
whenever that becomes necessary. It is obvious that the pision rods of the
presses must extend to and be in immediate contact with the abatement, but
I also make them fast to the said abatement, and by making the said presses
double-acting, or, in other words, in such a manner as that the force of the
water may be employed as occasion requires on either side of the pistons of
the said presses, I obtain, from the agency of the said presses when so con-
structed, not only the means of pushing forward the cells, but also of drawing
forward the said abatement.
Before I proceed to describe my other method of forming tunnels or
drifts, I would premise that the leading features of this other method consists
in rendering the operation nearly similar to that of forming one or more small
drifts or driftways; the combination of mechanical expedients by means of
which I perform the same, I denominate a teredo or auger, from its great
analogy to that instrument and also the vermes, known under the name of
Teredo Navalis. This insect is capable of perforating the toughest timber
by the power and organization of its augur-like head worked by the motion of
the body inclosed within its tubular cell, which cell may be supposed to repre-
sent a tunnel. The head, which forms part of the mechanical combination
alluded to before, has not, however, received the confirmation of an anger
for the purpose of cutting into and through the ground, but the protruding
lip forms the orifice through which the earth is to be removed by manual aid.
This head forms likewise a shield that is to protect the work against the
breaking down of the earth. In this instance the shell of the tunnel is
formed by a systematic combination of hollow pieces of cast iron which, when
united togetherby boltsorscrews, presents externally somewhat the appearance g
of a riband wound edge to edge round a cylinder throughout its whole length,
as seen in Fig. 9 from A to B, when it is evident the riband would take a
direction similar to that of the thread of a screw.
Fig. 9 is a representation of the exterior of a part of the tunnel already

page_text: formed, as from A to B and B to C; itrepresents the exterior of the apparatus
which I employ in forming the excavation. Fig. 10 is an end view of the head
of the apparatus, in which two orifices are brought to sight, one at D and
the other at E. These orifices may be considered as the mouths of two teredos
through each of which the earth is to be removed; Fig. 8 is an internal view
of the same. In both views 8 & 10 the end of the larger teredo is represented
as being formed of a number of radiant pieces extending from the circumfe-
rence of the tunnel to the cylinderforming the body of the lesser teredo. The
cylindricel body of the larger teredo is composed of a number of pieces
resembling externally staves. To the end of each of these staves is affixed
one of the radiant pieces a, a, a, a, &c. These staves with the radiant pieces
attached to them are capable of being moved forward in the longitudinal
direction of the tunnel one at a time. In order to overcome the friction of the
staves.sliding against the earth and against each other, I employ of hydraulic
presses one press to each stave, attached in the manner represented at 6, b,
Fig. 6. Fig. 5 & 11 represent sectional views of the body of the greater
teredo, and illustrate the form, disposition, and union of the staves. Fig. 6
represents a longitudinal section of Fig. 9, explaining the internal construction
of the apparatus. This apparatus may be divided into three separate heads,
namely, the body of the larger teredo already described, the body of the
lesser teredo with its shaft and the internal drum K, Fig. 5, 6, and 11. This
drum first serves to give and preserve the cylindrical form of the body of
the toredo, next it supports the staves forming that body, and to the said
drum the hydraulic presses marked b, b, are fixed. In Fig. 11, the internal
edges of the staves are seen in contact with and bearing upon the friction
wheels c, c.
Having already said that the staves and radiant pieces attached to them are
moveable, and the means by which they are moved, I now proceed to explain
the object for which they are moveable, and the order in which they are to be
moved. It is evident from the nature of the thing that the orifice or mouth
of the teredo should always be presented to the earth that is to be removed;
but as the whole apparatus does not move round so as to produce this
effect, it is necessary that the staves with the radiant pieces should be made
subserviant to that end, this is rendered practicable by the order in which
they can move so as to preserve at all times the character of the teredo, not by
turning the teredo itself, but by giving a progressive motion to the protruding
lip of the teredo, which remains to be described. This lip is composed of an
iron plate sufficiently strengthened and of the shape seen at d, e, D, & f,
Fig. 10, and also of the portion of a cylinder extending beyond and over

page_text: lapping the end of the opposite staves. This lip is capable of being moved
round the body of the lesser teredo, and may be forced forwards as the work
proceeds. When this lip has been moved through a space equal to the width
of a stave, the stave next in succession must be forced forward in the order
already described and contained in the operation to the end of the work.
Other expedients might be pointed out which the nature of the ground might
render necessary so as to reduce the aperture of the orifice or closing itentirely.
The lesser teredo, so much resembling the common auger or a boring bit,
requires no further description, as its application is too obvious. When
the lesser teredo is in action, the workman stands in the body of the toredo,
and applies through the orifice the tools or instruments necessary to displace
the earth.
Fig. 7 is a representation of a tunnel when completed, having a small
drain O, as seen in Fig. 6 & 7, underneath it.
Lastly, I declare that I do not claim any of the mechanical implements I
make use of in their detached character as forming any part of my Inven-
tion, but my Invention consists in the combination and application of the
expedients already described.
In witness whereof, 1, the said Marc Isambard Brunel, have hereunto
set my hand and seal, this Twentieth day of July, in the year of 2
our Lord One thousand eight hundred and eighteen.
M° J. BRUNEL. (L.S.)
AND BE IT REMEMBERED that on the Twentieth day of July in