Chapter I: Early Life (1)

A.D. 1806--1828.

BIRTH OF MR. BRUNEL, APRIL 9, 1806--SIR MARC ISAMBARD BRUNEL--THE
BLOCK MACHINERY--MR. BRUNEL’S SCHOOL LIFE--THE THAMES
TUNNEL--SINKING OF THE ROTHERHITHE SHAFT--DESCRIPTION OF THE
SHIELD--EXTRACTS FROM SIR ISAMBARD BRUNEL’S JOURNALS FROM THE
COMMENCEMENT OF THE THAMES TUNNEL TO THE DATE OF THE SECOND
IRRUPTION OF THE RIVER, JANUARY 12, 1828--_NOTE A:_ THE BOURBON
SUSPENSION BRIDGES--_NOTE B:_ EXPERIMENTS WITH CARBONIC ACID GAS.

ISAMBARD KINGDOM BRUNEL was born on the ninth day of April, 1806, at Portsmouth, and was the only son of Sir Marc Isambard Brunel.[1]

Most biographies commence with an account of the parentage of the person whose life is about to be written. If this be permitted in any case, no apology can be needed for prefixing to a Life of Mr. Brunel some particulars of his father’s career, since he was indebted to him, not only for the inheritance of many natural gifts, and for a professional education such as few have been able to procure, but also for a bright example of the cultivation of those habits of forethought and perseverance, which alone can ensure the successful accomplishment of great designs.

Sir Marc Isambard Brunel was a native of Hacqueville, a village in Normandy, where his family had been settled for several generations. He was originally intended for the priesthood; but, as he showed no inclination for that calling, and a very decided talent for mechanical pursuits, he was permitted to enter the French Navy; and he served in the West Indies for six years, namely, from 1786 to 1792. On his return home, at the expiration of his term of service, his strong Royalist sympathies made it unsafe for him to remain in France, and with great difficulty he managed to escape to America. He landed at New York in September 1793, and soon obtained employment as a civil engineer. A few years afterwards he was appointed engineer to the State of New York; and, while holding that office, he designed a cannon foundry and other important public works.

In January 1799, when Sir Isambard was in his thirtieth year, he came over to England, and shortly after his arrival married Miss Sophia Kingdom, a lady for whom he had formed an attachment some years before.[2]

The first great work undertaken by him in this country was the machinery for making blocks, which he designed and erected for Government at Portsmouth.

The history of the invention and construction of this system of machinery (for it consisted of _forty-three_ separate machines) need not be given at length; but it may be permitted to extract the following passage from Mr. Beamish’s ‘Life of Sir Isambard Brunel’ (pp. 97, 99, 2nd edition), in which he points out the benefits which have resulted from its introduction, and the position its inventor is entitled to hold among those who have contributed to the progress of mechanical science.

Where fifty men were necessary to complete the shells of blocks
previous to the erection of Brunel’s machinery, four men only are
now required, and to prepare the sheaves, six men can now do the
work which formerly demanded the labours of sixty. So that ten men,
by the aid of this machinery, can accomplish with uniformity,
celerity, and ease, what formerly required the uncertain labour of
one hundred and ten.

When we call to mind that at the time these works were executed,
mechanical engineering was only in its infancy, we are filled with
amazement at the sagacity and skill that should have so far
anticipated the progress of the age, as to leave scarcely any room,
during half a century, for the introduction of any improvement....

Beautiful as are the combinations and contrivances in the block
machinery, and highly deserving as the inventor may be of credit
for originating such labour-saving machines for the production of
ships’ blocks, there is a far higher claim to the admiration and
gratitude of all constructors of machinery, and of all workers in
metal. In this block machinery exist the types and examples of all
the modern self-acting tools, without the aid of which the various
mechanical appliances of the present day could not be produced with
the marvellous accuracy which has been attained. It is true that to
the trades unions or combinations among the artisans, is in a great
measure directly due the introduction of self-acting machines; but
the types of all these tools existed in the machines and
combinations of Brunel’s block machinery. The drilling, the
slotting, and the shaping machines, the eccentric chuck, and the
slide rest, with the worm wheel motion, are all to be found in his
machine.

On the completion of the block machinery Sir Isambard Brunel removed to London, and took a house in Lindsay Row, Chelsea, where he remained until he was obliged to live nearer the works of the Thames Tunnel.

Mr. Brunel’s first recollections were of the house at Chelsea; and in 1814, when he was eight years old, he commenced his school life under the Rev. Weeden Butler, who resided in the neighbourhood. Previously to his going to Mr. Butler, he had been taught Euclid by Sir Isambard; and he had also a great talent for drawing, for which he had been remarkable even from four years old. His drawings were beautifully precise and neat, but, when the subject admitted of it, full of vigour and picturesque effect.

After some time he was sent to Dr. Morell’s school at Hove, near Brighton. The following extract is taken from one of his letters home in 1820:--

I have past Sallust some time, but I am sorry to say I did not read
all, as Dr. Morell wished me to get into another class. I am at
present reading Terence and Horace. I like Horace very much, but
not as much as Virgil. As to what I am about, I have been making
half a dozen boats lately, till I have worn my hands to pieces. I
have also taken a plan of Hove, which is a very amusing job. I
should be much obliged to you if you would ask papa (I hope he is
quite well and hearty), whether he would lend me his long measure.
It is a long eighty-foot tape; he will know what I mean. I will
take care of it, for I want to take a more exact plan, though this
is pretty exact, I think. I have also been drawing a little. I
intend to take a view of _all_ (about five) the principal houses in
that great town, Hove. I have already taken one or two.

In the intervals of his classical studies he seems to have employed himself, not only in making a survey of Hove in its existing state, but also in a critical examination of the works in progress for its enlargement. It is told of him that one evening he predicted the fall, before the next morning, of some houses which were building opposite the school, and laid a bet on the subject, which his companions readily accepted. He had noticed the bad way in which the work was done, and that the stormy weather, which appeared to be setting in for the night, would probably blow the walls down. In the morning he claimed the wager, for the buildings had fallen in the night.

Except from November 1820 to August 1822, when he was at the Collége Henri Quatre at Paris,[3] Mr. Brunel was so very little absent from home that he became thoroughly acquainted with all his father’s undertakings. Among these was the veneering machinery at Battersea, remarkable for the great diameter of the saw, the steadiness of its motion, and the mechanical arrangements for clearing the veneer from the saw; also the works at the Government establishments at Woolwich and Chatham, and the machinery for making shoes. They have been fully described by Mr. Beamish; but the mere mention of their names is enough to show how great were the advantages enjoyed by Mr. Brunel in receiving from his father his early professional education.

From the year 1823 Mr. Brunel was regularly employed in his father’s office. It was in the early part of this year that the project of the Thames Tunnel first began to occupy Sir Isambard’s attention; but he was also engaged at that time in other works of great importance, among them the suspension bridges for the Ile de Bourbon, and designs for bridges of the same character over the Serpentine, and over the Thames at Kingston.[4] Some account of the Bourbon bridges, and also of experiments with carbonic acid gas, on which Mr. Brunel was engaged, will be found in the notes to this chapter.

The history of the Thames Tunnel will be told, as far as possible, in Sir Isambard Brunel’s own words, as given in his journals.[5] Although these extracts do not relate to works for which Mr. Brunel was personally responsible, they have been inserted in the belief that they are valuable, not only as showing the nature and extent of his duties as his father’s assistant, but also as displaying, in the most interesting and authentic form, Sir Isambard’s character and genius at a time when his son was brought into hourly contact with him, and under circumstances which would cause the influence of his example to make a deep and lasting impression.

Previously to the year 1823 there had been several plans suggested for the construction of a tunnel under the Thames; and it would seem that a great demand was supposed to exist for some such means of communication between the two sides of the river eastward of London Bridge; for after the failure of the operations undertaken by Mr. Vasie in 1805, and Mr. Trevethick in 1807,[6] a high level suspension bridge was proposed, although it was not intended to be used for heavy traffic.[7]

The first reference to the Tunnel in Sir Isambard’s journals is dated February 12, 1823. ‘Engaged on drawings connected with Tunnel;’ and on the 17th and following days of the same month, ‘Isambard was engaged on Tunnel.’ These entries become more and more frequent in the pages of his diary, until it is evident that Sir Isambard’s whole time and thoughts were absorbed in this work.

The spring of 1823 was occupied in preparing drawings and models of his plans, and in enlisting the sympathy and assistance of various influential persons. By the close of the year the designs were matured sufficiently to enable the promoters of the scheme to commence the task of organising a company for carrying it out; and in January 1824 they resolved to call a general meeting of their friends, and invite public subscriptions.

On February 17, Sir Isambard explained his plans at the Institution of Civil Engineers, and on the next day a meeting was held at the City of London Tavern, under the presidency of Mr. William Smith, M.P., more than a hundred persons being present. Resolutions authorising the formation of a company were passed unanimously, and the share list was opened. In the course of an hour one-third of the subscriptions was filled up, namely, 1250 shares; and before the end of the day the number of shares taken was 1381.

Borings were then commenced in order to ascertain the nature of the strata through which the Tunnel would pass. A bed of gravel was found over the clay, which gave Sir Isambard great anxiety. A large pipe or shaft was sunk on the side of the river, and in it the water rose to within three feet of the surface of the ground, and fell about eighteen inches with the tide. ‘It is manifest (Sir Isambard writes) from this that unless the Tunnel is enclosed in the stratum of clay, it would be unsafe to drive through the bed of gravel. The Tunnel must, therefore, begin with the substantial clay.’

However, the result of thirty-nine borings in two parallel lines across the river, to the depth of from 23 to 37½ feet, seemed to prove that there was below the gravel a stratum of strong blue clay of sufficient depth to ensure the safety of the Tunnel.[8]

A report to this effect was made to the shareholders at their first general meeting in July, and it was also stated that the works would be completed in three years.

The first operation connected with the works, was the constriction of a shaft; and for this purpose land was bought on the Rotherhithe bank, about fifty yards from the river. On March 2, 1825, the ceremony of laying the first stone of the shaft was performed.

Mr. Smith, our chairman, attended by most of the members of the
Court of Directors, and a very numerous cortége of friends invited
on the occasion, proceeded from the Tunnel Wharf to the ground,
where they were received among the cheers of a great concourse of
people. Mr. Smith addressed the assembly in a very eloquent speech
suitable to the occasion, and performed the ceremony of laying the
first stone. From this day dates the beginning of the work.[9]

The mode in which Sir Isambard decided to construct the shaft was one not uncommonly adopted in the construction of wells; but to apply it to sinking a shaft fifty feet in diameter was a novel and bold undertaking. The brickwork intended to form the lining of the shaft was built on the surface of the ground, and the earth being excavated from within and underneath the structure, it sank gradually down to its final position.

The brickwork was 3 feet thick, bound together by iron and timber ties, and there were built into it 48 perpendicular iron rods, one inch in diameter, fastened to a wooden curb at the bottom, and to another curb at the top of the wall, by nuts and screws.

When the shaft or tower of brickwork was completed up to the top, 42 feet in height, the next step was to remove the blockings on which it rested, and this being done the gravel was excavated and hoisted up, and the shaft descended by its own weight.

The Rotherhithe shaft was only sunk forty feet in this manner; the remaining twenty feet, in order to leave the opening for the Tunnel, was constructed by under-pinning, or underlaying, as it was then termed. The underlaying was commenced in the beginning of June.[10]

By July 4 they had got down to the level of the intended foundation of the shaft, having passed into a stratum of gravel, black pebbles embedded in greenish sand, with little or no water; from which circumstance Sir Isambard was of opinion that it was unconnected with the stratum of gravel above.

_July 12._--Engaged on a general drawing for the great shield, and
in preparing some instructions for moving the same (a very
intricate operation!)

_July 22._--Underlaying is a very laborious mode of proceeding. The
sinking of a wall well bound as the first, would evidently be the
best and cheapest mode for making another tower of 50 feet
diameter.

On the 28th Sir Isambard enters in his journal the following additional observations upon the success of his plans for sinking the shaft:--

Considering the great labour necessary for securing the ground for
the underlaying, the waste of planking, and of shores, and the time
necessarily taken up in moving about, in securing and in baling
out the water, and the many causes of interruption, and the
imperfect way that things are done in underlaying, it is quite
conclusive that the original plan of making a shaft, by sinking the
structure, is the safest and the most economical. What is done is
sound, and when once in place, may be secured with foundations in a
very easy manner. The brickwork of the shaft is remarkably hard.
Had it been made with brick facings and rubble stone, it would
certainly be water-tight, and almost impenetrable by ordinary ways.
The _vertical ties_ and the _circular wall bands_ are not to be
dispensed with in a structure destined to be moved as the present
has been.

On August 11 the underlaying was completed, and preparations were made for constructing a reservoir in the bottom of the shaft for receiving the permanent pumps. This was finished on October 11, with great difficulty, owing to the nature of the ground, which consisted of loose sand containing a large quantity of water.

_August 19._--Engaged at home in revising my plans for the manner
of carrying on the horizontal excavation, more particularly of
penetrating through the shaft. This part of the operation requires
_indeed_ very great attention, as it presents great difficulties,
arising from the wall to be broken through, and chiefly from the
angular opening that is to be made at each extremity. Then another
consideration is the uniting the brick arches to the brickwork of
the shaft.

_September 16._--Engaged in the early part of the day on revising
my plans of future operations in the Tunnel work, and in adapting
them to the nature of the ground as it is found at the various
depths we have penetrated: namely, to about 73 feet. Went
afterwards to Maudslay to request that the great shield may be
completed.

[Sidenote: Great shield.]

_October 14._--Engaged in the early part of the morning in making
some arrangements for the working of the great shield. Too much
attention cannot be given to that subject at the early part; for,
when once in its place, it would be extremely inconvenient to make
any alteration.

[Sidenote: Preparing for the frames.]

_October 15._--The dome of the reservoir will be covered to-day
about noon; the bottom of the shaft will therefore be completed.
They are now preparing to apply two frames of the shield. The
ground now open in the front is remarkably hard; it consists of
pebbles imbedded in a chalky substance, with hard loose stones of
the nature of the Kentish rag. Everything is going on well. Devised
with Isambard how to make our wells for the descent of the
materials, &c.

Thus at last the shaft was completed, and Sir Isambard was able to commence the Tunnel itself, which he ultimately determined to construct in the form of a rectangular mass of brickwork, 37½ feet wide and 22 feet high, pierced by two parallel horseshoe archways, each 14 feet wide and 17 feet high.

Before entering upon the history of this undertaking, some account must be given of the machine which Sir Isambard Brunel devised for effecting its accomplishment.

In order to avoid a quicksand of considerable depth and extent, the Tunnel had to be carried but a short distance below the bed of the river; and, as in all tunnelling through soft soil,[11] the top and sides of the excavation had to be supported until the brickwork was built in; and the front or face had also to be held up as the miners advanced. This support was given by means of a machine called ‘the shield,’ described on one occasion by Sir Isambard as ‘an ambulating cofferdam, travelling horizontally.’[12]

The main body of the shield consisted of twelve independent structures or ‘frames’ made of cast and wrought iron. They were each 22 feet high, and rather more than 3 feet wide; and, when placed side by side, like books on a shelf, against the face of the excavation, they occupied the whole area of the face, and also the top, bottom, and sides for 9 feet in advance of the brickwork. Each frame stood on two feet resting on the ground, and was divided in its height into three cells by cast-iron floors. In these cells, of which there were thus thirty-six in all, the miners stood, and worked at the ground in front of them.

The duty which the shield had to perform was to support the ground until the brickwork was built within the excavation; but it was essential that this should be done in such a manner as to allow of the mining operations being carried on; and it was also necessary that the machine itself should be capable of being moved forward.

The first point, therefore, which has to be explained in the action of the shield is the manner in which the earth was supported by it.

It has been already stated that each frame rested upon two feet, or large iron plates. These two feet together covered the ground under the frame to which they belonged, and thus the whole of the earth beneath the frames was pressed down by the feet.

The earth above was supported by narrow iron plates, called staves, laid on the heads of the frames parallel to the line of the Tunnel, the ends resting on the completed brickwork behind it. The earth at the sides was kept up by staves resting against the outermost frames.

The arrangement for holding up the earth at the face of the excavation was necessarily of a more complicated character. Each frame supported a series of boards called poling-boards, by means of small screw-jacks or poling-screws, two to each poling-board, which abutted against the frames, and pressed the boards against the earth. The boards were 3 feet long, 6 inches wide, and 3 inches thick, and were arranged horizontally. These poling-boards, more than five hundred in number, covered the whole surface in front of the frames.

To resist the backward thrust of the poling-screws against the frames, each frame was held forward by two large screws, one at the top of the frame, and the other at the bottom, abutting against the brickwork of the Tunnel. The brickwork was completed close up behind the shield as it advanced.

The way in which the earth was excavated, and the shield moved forward, has now to be explained.

The plates or staves which supported the ground at the top and sides of the shield were pushed forward separately by screw-jacks; but in order to advance the poling-boards in front, it was necessary that that portion of the ground against which they pressed should be removed.

The miner, standing in his cell, took down one, or, at the most, two of the poling-boards, commencing at the top of the cell, and having excavated the earth a few inches in advance, replaced the poling-boards against the newly-formed face, pressing them against it with the poling-screws. Thus the excavation was carried on without depriving the ground of the support it received from the shield, except at the point where the miner was actually at work.

The operation of advancing the frames was effected in the following way. When everything was ready for a move, one of the feet which carried the frames on jointed legs was lifted up, and advanced forward a few inches, and then pressed down on to the ground, until in its new position it again bore the weight of the frame. This done, the other foot was lifted, moved forward, and screwed down in the same manner, and then the frame itself was pushed ahead by means of the large abutting screws, which kept it top and bottom from being forced back on the brickwork.

It is, however, evident that these abutting screws would have been unable to push on the frame, while the ground in front was pressing back the poling-boards against it; therefore, during the process of moving a frame, it had to be relieved from the thrust of its poling-screws. Accordingly, when it was desired to advance any one of the frames, the butts of the poling-screws of the tier of boards in front of it were shifted sideways, so as to rest, not against the frame to which they belonged, but against the frames next it on either side. This done, the frame itself was advanced, and was then ready to receive again its own poling-screws, and also those belonging to the adjoining frames, so that they might in their turn be moved forward. It will thus be seen that the whole shield was not moved forward at one time, but that the frames were advanced alternately.

There were many other ingenious arrangements in the design of the shield, which need not be referred to in a description intended only to give such a general idea of the machine as may make the history of its operation intelligible.[13]

When the frames had been completed in Messrs. Maudslay’s factory, they were conveyed to Rotherhithe, and lowered down the shaft. An opening had been left at the bottom of the wall, about 37 feet wide by 22 feet high, and against this the shield was erected. It was then ready to commence its progress through the ground below the river.

On November 25, 1825, the shield made its first start. Sir Isambard was unfortunately unable to witness what was in fact the actual commencement of the Tunnel, as he had three days before been seized with a sudden and alarming attack of illness, which kept him at home till December 6. The works were left under the direction of Mr. Brunel.

_December 8._--The great shield is advancing very slowly, meeting
with much interruption by the water, which still runs within the
cells, and also by the difficulty of forming abutments for the
frames. [_Temporary abutments were necessary until the shield was
sufficiently advanced to allow of its being pushed forwards from
the brickwork built up behind it._]

_December 29._--The frames are very much out of level in the
transverse line of the Tunnel. This would be attended with serious
inconvenience if I had not provided for the means of recovering any
irregularity that might take place, and which, as it appears,
cannot perhaps be prevented; but having foreseen this, I have
provided the remedy by being able to take down the top of each
frame, and to remove the top staves in parts, or the whole, at
pleasure--a very important provision it proves to be.

_January 16, 1826._--Too much precaution cannot be taken, in the
management of the frames, to have the leg-screw particularly well
secured, as every foot-run of the arch of the Tunnel sustains 82
tons. Each frame carries as follows:--

The two end frames each 65 tons = 130
Ten others, each 52½ " = 525
---
655 tons.

_January 21._--The ground at the top and sides very good; same in
the front. In breaking the ground out of the limits of the shield
on the right a great deal of ground fell in. This indicates that,
if it was not for the protection of the shield, nothing could be
done. This accounts also for the occasional breaking of the ground
in making the drift in 1809.

[Sidenote: Tunnel begun.]

The brickwork of the entrance being carried as far as directed, the
body of the Tunnel was begun to-day.

[Sidenote: Water broke into the works.]

_January 26._--Isambard went down to Rotherhithe; the water had
broken in in great abundance upon the work over Nos. 4 and 5. [_The
twelve frames were distinguished by numbers._] A 4-inch pipe was
driven over the shield from inside the shaft, but the water did not
follow it, and the stream augmented very rapidly. The frame No. 5
was moved forward, and it checked the water for a moment, but it
came again with violence. A heading was immediately ordered by
Armstrong [_the resident engineer_] from the east well, in which
Isambard concurred.

_February 3_.--Ordered a pit to be opened and made by sinking a curb 8 feet diameter and 18 inches thick, well bound with bolts. [_This pit was a well sunk from the surface to enable the gravel containing water, into which the head of the shield had penetrated, to be removed, and clay substituted_.]

_February 6_.--The shaft begun last night, and was sunk 20 feet to-day, and remarkably true. Had we known the ground as we now know it, we might, by having opened a well contiguous to the great shaft, have sunk the shaft in a week; but for that purpose we must have had two steam engines, one for pumping the water, and the other for taking up the ground.

[Sidenote: Unremitted attention wanted.]

_February 10_.--Went very early to the Tunnel for the purpose of giving directions to prop up the back of the staves, which, for want of weight at the new shaft, might be overbalanced by the pressure of the ground at the back. I could not rest a moment until it was done, for the consequences might have been fatal, at this moment in particular. What incessant attention and anxiety! To be at the mercy of ignorance and carelessness! No work like this.

[Sidenote: Observations on the mode adopted to check the water.]

_February 12_.--The ground having been opened carefully from under the curb of the pit [_see above on date February 3_], the greater part of the gravel was removed, and stiff clay substituted for it. This was done by driving first some wrought-iron flat bars, which kept the ground up. This shows that the shield is a most powerful protection, and would enable us to penetrate through a bed of gravel. Though the breaking in of the water had somewhat terrified the man in No. 5, he soon returned to his post, and the others have acknowledged their full confidence in the security afforded by the shield. The boring ahead had not yet been attended to: it is owing to the want of this precaution that this accident is chiefly to be ascribed; for had we known as much as we now do, we might have passed through without the pit being opened.

_March 1_.--Water at the back of the frames, but less than before. The men show a great deal of spirit in overcoming the present difficulties. Isambard was very busy yesterday and to-day in the frames, and about the works. He was severely hurt in the leg by a piece of timber falling against it. [_This accident prevented his attending again at the Tunnel until the 24th_.]

On March 6 the proprietors paid a visit to the Tunnel, and were highly satisfied with what they saw. On that evening Sir Isambard writes:--

It is of absolute necessity _now_ to provide for everything that is
conducive to the more expeditious management of the frames, and to
a greater facility in getting up the brickwork. If these two points
are realized, then indeed we may soon expect to be moving at a good
rate--not less than I have held out, namely, 3 feet per 24 hours.

[Sidenote: Water stopped as expected.]

_March 11._--Received early in the morning a report from Armstrong
stating that the water was completely stopped--that it had been
stopped during the night. Aware that we had passed the gravel, it
was of course expected that we were under the clay; means were
therefore resorted to, to drive clay and oakum at the tail of the
top staves, which was productive of a very good effect. The great
shield was soon entirely free of water. This shows the efficiency
of the shield to oppose difficulties which could not have been
overcome without the complete protection it affords, under almost
any circumstances. Indeed this has been a tedious operation since
January 25, when the water first burst upon No. 5, at the front of
the shield. The miners as well as the bricklayers have worked with
great spirit and perseverance through the whole, during a period of
44 days. The well that was made at the front of the shaft has been
of use in acquainting us with the extent of the open ground we had
to pass through. It will be made a useful opening for ventilating
the works. By means of this well we have been able to apply the
lead pipes with which the water has been diverted: it is not
therefore a useless expense. Things were put in better order to
prepare for a more expeditious way of working. Directions were
given to place the frames in a better condition. Isambard is still
too unwell to go to the Tunnel.

[Sidenote: Considerable slip of ground: how to check it.]

[Sidenote: Very dangerous.]

_March 25._--Went to the Tunnel with Isambard. Found that a
considerable fall of ground had taken place again at the right
side. No one could account satisfactorily for it. I inspected it,
and directed that, after making it good, flat bars of iron be
driven at the head of the side staves, in order to pin it up, and
in order to enable the miners to get at the solid ground. It is
very bad and extremely dangerous; the ground is evidently the same
as that which, in the report of the first attempt, was found so
loose as to have dropped upon the works, leaving a large cavity
above, when it is said the man ascended and made good the hole. We
should be warned by this, lest we should meet another as fatal as
it ultimately was on that occasion. [_This observation refers to
the driftway of 1807._]

_April 24._--By Armstrong’s report the water is entirely out, and
the men at work in the morning in removing the dirt, &c. Isambard
engaged at the Tunnel, where I am not yet able to attend as often
as I could wish. Everything goes on well, much through his
exertions.

_May 11._--One hundred feet will be completed to-night.

_May 22._--The top plate over the frame No. 1 has been cracked
without any particular violence or stress. It appears that it is
nothing but the change of temperature that is the cause of that
rupture. The accident justifies the opinion I have of cast-iron not
being safe upon traction, and the precaution of having had
wrought-iron bolts at the back of the frames. [_These were vertical
rods which took the tensional strain._] Without these bolts what
would have become of the shield, if one casting was to break? The
fracture was accompanied with a loud report like that of a gun.
Isambard was in the works at the time of breaking: nothing could
have prevented it.

[Sidenote: The shield being too much out, resolved to move it
bodily.]

_May 25._--I observed that nothing whatever had been gained to
recover the deviation [_the shield had gradually worked 2 feet 3
inches to the westward_], which subjects us to so much
inconvenience and loss of time. The only way to bring the shield
right is by taking the frames sideways.

_June 3._--Finding it too laborious and almost fruitless to bring
the frames in the right way, I came to the determination of having
them brought bodily to the east by cutting the ground on the side.
I accordingly gave directions to Armstrong to proceed in making a
heading out of No. 12, and by securing the side staves to continue
downwards until the ground be clear. The working was accordingly
discontinued in front.

_June 4._--The mode of proceeding by the common way of mining shows
the impracticability of carrying a large excavation anywhere,
particularly under a considerable body of water. The expense of
timbering would be too great, even if it could be sound. The ground
above the frames is remarkably good, but under it there is a
stratum of silt which breaks and falls in large masses.

[Sidenote: Isambard’s service very important and most efficient.]

_June 5._--Isambard got into the drift, and gave the line for the
better disposition of the staves, which was afterwards done in a
proper manner. Isambard’s vigilance and constant attendance were of
great benefit. He is in every respect a most useful coadjutor in
this undertaking.

_June 10._--The last frame (No. 1) is brought close to the others,
and the brickwork brought up to fill the back.

[Sidenote: Dangerous state of the ground. Precautions taken.]

_June 15._--On inspecting the face of the ground this morning I
observed a breach in the front of Nos. 3, 4, and 5, where the
ground has given way in the lower cell. This was truly alarming. I
ordered iron staves to each floor in order to pin the ground, and
thereby to counteract the slipping which would immediately take
place.

_June 19._--The bricklayers left off work, but, on enquiring into
the cause, I learned there was no other but to have a libation upon
the new arrangement of piece-work.

_June 29._--Gave positive directions to cut only 4½ to 5 inches
thick at a time at the front of the top cells, instead of 9 inches,
as they had done for some time.

_July 3._--The great question is, does the clay undulate at its
surface? We should have some reason to apprehend that it does so,
because at the beginning we had not proceeded many feet into the
clay when we struck again into the gravelly stratum. The surface of
the clay must therefore have sunk at that particular spot; which
circumstance seems to warn one of the need of great vigilance and
great prudence in the progress of the enterprise.

[Sidenote: Cofferdam burst at Woolwich.]

[Sidenote: Warning for us.]

_July 10._--A cofferdam burst yesterday at the works at Woolwich,
having blown up from the foundation. How cautious this should make
our men! The cofferdam may be repaired, and very easily too, but an
irruption into the Tunnel--what a difference, particularly at this
early period!

[Sidenote: Carelessness of the miners.]

_August 10._--Found the lowest cell of No. 1 left by the workmen
_without a single poling against the ground_. This is indeed a most
unjustifiable neglect.

_August 12._--At six this morning completed 205 feet.

[Sidenote: Observations on the bad effect and consequence of
driving on as is done.]

_August 21._--This piece-work has not been productive of much
effect as to quantity of work. As to quality it is very
questionable. A work of this nature should not be hurried in this
manner. Fewer hands, enough to produce 9 feet per week, would be
far better than the mode now pursued _from necessity_, but not from
inclination on my part. Great risks are in our way, and we increase
them by the manner the excavation is carried on. The frames are in
a very bad condition.

_September 5._--It is much to be regretted that such a work as the
Tunnel should be carried on by the piece. Obliged to drive on, no
time is left to make any repair, or to recover any lost advantage.
Isambard is most active. Mr. Beamish shows much judgment in his
exertions, and zeal in his attendance.[14]

[Sidenote: Water breaking in at back of frames.]

[Sidenote: How to check it. Isambard’s exertions.]

_September 8._--About 2 P.M. I was informed by Munday that water
was running down over No. 9. I went immediately to it. The ground
being open, and consequently unsupported, it soon became soft, and
settled on the back of the staves, moving down in a stream of
diluted silt, which is the most dangerous substance we have to
contend with. Some oakum was forced through the joints of the
staves, and the water was partly checked. Isambard was the whole
night, till three, in the frames. At three I relieved him. He went
to rest for about a couple of hours; I took some rest on the stage.

[Sidenote: Things improving.]

_September 9._--Towards noon the stream changed its character. The
clay, being loosened by the water, began to run, but it thickened
gradually. It was late in the evening before the loosened clay
acquired the consistency of a loose puddling, which covered the
staves, and made them a complete shield against further irruption,
or rather, oozings of mud. If we consider that at this place we
have at the utmost 9 feet between the top staves and the gravel,
over which the river flows, it is most satisfactory and most
encouraging to have this additional proof of the protection which
the shield affords. At nine o’clock at night Isambard sent me word
that ‘tout va à merveille;’ indeed it was so, for it was like a
stopper interposed between the river and the top-staves. Instructed
as the men were by the first accident, they went on as usual in the
irrespective occupations. Pascoe, junr., and Collins were
remarkably active and persevering, and some other men equally so;
while old Greenwell encouraged them by a speech of his own in high
commendation of the security of their situation.

[Sidenote: Water more abundant. Is it from the river?]

_September 12._--The water, bringing with it a sort of clay broken
in small particles, increased to an alarming degree. In consequence
of this continued displacement of the silt and clay, a cavity had
been formed above the staves. At about three, when I had gone to
the Court of Directors, the ground fell upon the staves with great
violence, causing a surge most alarming as to probable
consequences. Isambard was at that moment in the upper frames, and
he gave directions for increasing the means of security. On my
return I found things much worse than I left them, but every means
of security was judiciously applied. During the night in
particular things presented a very unfavourable appearance. The
men, however, were as calm as if there were no other danger to be
dreaded than wet clothes or the splashing of mud. I observed the
men in the lower cells were _sound asleep_.

[Sidenote: Exertions by the men.]

[Sidenote: Slight improvement.]

_September 13._--Every means were resorted to in the course of the
night and during the early part of the day to stop the water. The
men have shown great zeal and good management in their respective
avocations, and above all the utmost confidence. Isambard has not
quitted the frames but to lay down now and then on the stage. I
have prevailed on him to go to his bed, or rather, used my
endeavours to induce him; but he has not since last Friday night
(the 8th). Things were rather better at the close of the day.

_September 14._--Things upon the whole have assumed a more
favourable aspect. The situation is nevertheless very critical.
Nothing but the utmost precaution in following up what has begun
can bring us out of it. This has been a most eventful week!

_September 18._--Isambard was the greater part of the night in the
works, and the benefit of his exertions is indeed most highly felt:
no one has stood out like him! Everything is quite safe, the water
is kept back, and the work proceeds in a most satisfactory manner.

_October 22._--It is evident [_from a flow of silt which had taken
place on that day_] that with the shield we have passed close under
a body of collected water a few inches only above the staves.
Isambard is too unwell to stay long in the works.

[Sidenote: The want of a drain subjects us to much inconvenience.]

_October 24._--The want of the main drain which was originally
intended to carry the water to the main reservoir is felt
everywhere. This drain is in my original plan, but the committee
expressing on several occasions a wish that I should dispense with
it, I complied, most reluctantly however, to prove my earnest wish
to reduce the expenses. It will not, I apprehend, be found an
economy.

[Sidenote: Effect of the shoes in keeping the ground dense.]

_October 26._--Every step we take shows how much security is
derived from the shoes, supporting as they do the shield and the
superincumbent weight. They press down in the same proportion the
ground on which they bear. They keep it as dense as it originally
was, and fit it for the structure that is to come upon it. It is
evident, therefore, that what is wanted is that the ground should
be kept pressed. It is with this object in view that I have
holdfasts and jacks. What incessant vigilance is required, what an
incessant call on the resources of the mind, not only to direct,
but more particularly to provide for many things that may occur.

_November 17._--At this date 307 feet 9 inches had been
completed.[15]

_December 8._--The evil [_that of not having a proper drain_] is
going on with us, and without any remedy except the drain, or a
cesspool by way of expedient. How much anxiety must one feel at
being so circumstanced! Should any water break in, how should we
proceed? This is another source of great solicitude. We have no
command of the frames when they rest upon wooden legs, or when the
screws are bent; and what is worse is that the men drive on without
any consideration or any fear of consequences. This circumstance,
and the apprehension of the water breaking in, are matters of the
most dreadful anxiety.

[Sidenote: Superincumbent weight varying daily, and still more
every fortnight. What stress on the frames. The shoes have never
yielded; a most important circumstance.]

_December 12._--Little do others know of the anxiety and fatigue I
have to undergo day and night. Advanced as we are, we have only
gained somewhat more experience, but the casualties are just the
same. An accident now might be as fatal as it would have been 200
feet back, or as it would be 200 feet forwards. We have not a
period when we can think ourselves safe except when we have
connected these arches with a shaft on the other side. Loaded as we
are with the weight of the river, we have to advance our shield and
build our structure under that weight, a weight which varies twice
a day, and twice a month to a much greater extent. _The shoes are
the great foundation of our security._ When once pressed down with
the greatest power that can be applied, they do not give in the
least afterwards. They have not yielded even upon loose gravel; we
must therefore congratulate ourselves that they have answered so
completely. We have now walked our frames upwards of 350 feet; we
have had to renew the legs and the heads, but it is not through
want of strength so much as from mismanagement. The first legs were
never injured so long as their action was limited to 3 inches, but
when it was increased to 6 inches, they immediately gave way one
after another, without however any damage to the structure or to
the shield. The heads gave way, or began to give way, from the
moment the legs did; because, when a leg gave way, it brought upon
the contiguous frame an increased weight which broke the heads one
after another. That the breaking of so important a part of our
shield should not have been attended with any bad consequences is a
proof that provision had been made for the casualty. The proof that
it had been foreseen and provided for is in the manner these heads
were adapted to the frames. By the way they were fixed they would
be easily taken down and replaced. Though the heads gave way, the
top staves were not materially affected by it, and the service
continued until new heads were substituted. Some have fancied that
the ground did not bear wholly upon the shield and the arches, but
supported itself in parts. Experience proves that the pressure is
rather more than that which rests artificially on the frames. The
ground is compressed all round by the increased weight of high
water: we might therefore conclude that the shield operates as a
pillar, that supports beyond the limits of its base or cap. It is a
great satisfaction to be able to say that so long as we followed
the original plan, nothing gave way except the back screws. These
again were damaged by being run out of the sockets. We may
therefore ascribe most of the evils and damages to the increased
range of action, and still more to the rude implements the men have
used, whenever they met with any difficulty in moving the frames.
If it is considered that we had no other men to train in the use of
this immense machine but excavators and miners, very great
allowance must be made for what has occurred.

[Sidenote: Falling of three facings from neglect. Awful!]

_December 20._--An accident of an alarming nature occurred. The
poling-screws of Nos. 10 and 12, being on No. 11, Moul, the miner
in that frame, removed his butting screw; the consequence was that
the frame started back, the polings and poling-screws fell down
with a tremendous crash, and the ground followed to a considerable
extent. This is the most formidable accident that has yet occurred
in the face of the work. The ground was fortunately unusually firm,
and no fatal consequences ensued.

_December 31._--Isambard and nine friends sat down to a dinner
_under the Thames!_ Now a year is over since we began to make any
progress horizontally, for we had only 11 feet of arch when the
water broke in on January 24 last. We may therefore say that the
whole of what has been made of the Tunnel has been made in that
period. It is worthy of remark that until the end of April no
fracture whatever, no bending of the legs, had taken place,
notwithstanding that we had supported for a period of nearly three
months a greater weight than we ever had since. The ground nearly
40 feet high _kept sinking upon us_ as we advanced, and yet no
stave, no top, no leg gave way. Each leg was capable of carrying
nearly 80 tons at the point of fracture, consequently the aggregate
strength of 36 legs was equal to 2,880 tons, which is six times
over the greatest effort that could be exerted by the
superincumbent weight. The heads, after they had given way,
remained in place, some--namely, Nos. 1, 8, 12--for seven months,
and the others from four to six months. It cannot be said therefore
that there was a want of strength, since the broken heads continued
to perform for so many months after being so much damaged; nor is
there any defect in the iron. If the frames were, as some have
fancied, lanky, which implies weakness in their sides, how could
they have supported the alternate stress to which they are put by
standing alternately on one leg? Not one single joint has yet
started. Every frame has been upwards of 2,000 times in that raking
posture, consequently the shield has been upwards of 24,000 times
strained under the weight that has broken the heads. One single
side has broken, and is now as good as the rest. Is such a machine
to be stigmatised as it has been, without looking more minutely
into its operations?

[Sidenote: Observations on the responsibility attached to this
enterprise.]

_January 4, 1827._[16]--A work that requires such close attention,
so much ingenuity, and carried on day and night by the rudest hands
possible--what anxiety, what fatigue, both of mind and body! Every
morning I say, Another day of danger over!

_January 12._--It is astonishing how the silt resists the sliding
of the top staves. Assured as we were of having stiff clay from 33
to 37 feet, with what confidence we might have looked to making 18
feet per week. There would be no difficulty in having accomplished
it. We must not look back, but overcome all difficulties!

[Sidenote: Isambard on duty several successive nights.]

_January 16._--Isambard having been up several successive nights,
went to bed at ten, and slept till six the next morning. I am very
much concerned at his being so unmindful of his health. He may pay
dear for it.

_February 2._--Work done to this day 405 feet 4 inches.

_February 3._--I visited the works; and, being in the cabin, I
complained of the dust there. _Dust under the Thames!_

_February 26._--I went to the Tunnel. The arch being well lighted
up, and the whole walk completed, a few visitors were admitted. The
coup d’œil was splendid. Mrs. Brunel, Emma, Sophia and her three
little children were the first. It gave me great pleasure to see
the whole of my family in the new scene.

_March 21_.--There being no clay above us, there is much to
apprehend from the springs. It would be much better to work slower
than we do. It is indeed very hard to be under the necessity of
driving. Anxiety increasing daily.

[Sidenote: No clay above head; should work slower.]

[Sidenote: Water increasing daily.]

_March 28_.--The top pumps failed; the water rose above the
abutting screws. The frames of some of them could not be advanced,
nor could the bottom brickwork be laid down--great source of
complaint. Isambard called the men in at 10 o’clock; they went on
cheerfully. It is surprising that the men are so steady.

[Sidenote: Our situation is getting much worse daily.]

_March 29_.--Things are getting worse every day by the influx of
water; by which the ground is softened, and the operation rendered
extremely complicated and slow. As to the ground, it is evident we
are now as Isambard found it by his borings of August last. We have
nothing above our heads but clayey silt, and it is of a nature to
be detached and run into mud by the action of water.

_April 3_.--The pumping now requires forty hands. There is no
exaggeration in saying that the influx of water, and the badness of
the ground, cause an extra expense of 150_l_. a week.

[Sidenote: Obstacles in every way.]

_April 7_.--It may now be said that we are contending with the
elements above and around, gaining and disputing every inch that we
add to the structure.

_April 9_.--Isambard’s birthday, he being of age to-day.

_April 14_.--Doing as well as can be expected from the nature of
the ground, and the difficulties that increase upon us.

[Sidenote: To be obliged to drive too fast is a sad alternative.]