CHAPTER I.

_EARLY LIFE._

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.]

_April 18_.--The faces are found extremely tender; but having proceeded with great caution, no accident occurred. None, I feel confident, would occur if all idea of piece-work were abandoned. It always operates as a stimulant, a very dangerous one. Obliged to drive on, on account of expense, we run imminent risks indeed for it. That a work of this nature, under such circumstances, should be thus carried on, is truly lamentable. It is obvious that the clay we have above our heads has been broken, by the ground beneath it running or breaking in upon us. We shall have to fight it out until we have a stronger or thicker stratum of clay. Sad prospect indeed it is for us!

_April 20_.--The ground at No. 1 broke in again, and occasioned great delay. Some bones and china came down.

_April 22_.--The diving-bell being on the spot, and Isambard having moored it over the shield, he and Gravatt[17] descended at thirty feet water. They found the same substances which had come through the ground into the Tunnel. When Isambard was in the bell, he drove a strong rod into the ground. Nelson, who was in the frame, heard the blows.

[Sidenote: A dreadful panic.]

_April 29_.--Ground improving as we advance; we are not, however, free from danger: a dreadful alarm took place this morning. While Isambard and Gravatt were at breakfast, the porter came running in, and exclaiming, ‘It is all over! The Tunnel has fallen in, and one man only has escaped.’ Gravatt was the first to get to the spot, and found all the pumpers upon the floor of the shaft, all stupefied with horror, though every one was there quite safe, and no rush of water was heard. Gravatt and Isambard were soon in the shield, where they observed that a small portion of clay had fallen from the top on the top floor.

_May 8_.--At half-past three in the morning, an irruption took place, bringing down the deposits of the bottom of the river--lumps of clay, stones, bones, wood, nails, &c., &c., with water. The pumpers and men on the stage (Irish) all ran away, some exclaiming, ‘The Thames is in! The Thames is in!’ Ball and Rogers stood to their post, and soon stopped this most formidable attack.

_May 10_.--Great difficulties present themselves, that oppose our progress; the chief, however, is the lodgment of water above our heads. There it loosens the silt or sand, and runs out, leaving cavities that cause the clay above to break, and run down in lumps and disturbed streams. This is very awful! This opens the way for the river.

[Sidenote: Consequences of want of care more terrific and mischievous than any preceding ones.]

_May 12_.--In moving No. 6, they left by some unaccountable neglect the top staves behind, and in that state two top polings were taken down. The ground being very bad, and high water at the same moment, the ground began swelling. Attention was called to several points, and Gravatt continued in No. 6. He drew out at the front of the top staves a shovel, and also a hammer, that had come through the ground above. They are the same which Isambard left at the bottom of the river, when he went down in the diving-bell.

[Sidenote: Triumph of the shield.]

_May 13_.--Notwithstanding every prudence on our part, a disaster may still occur. _May it not be when the arch is full of visitors!_ It is too awful to think of it. I have done my part by recommending to the directors to shut the Tunnel. My solicitude is not lessened for that: I have indeed no rest, and I may say have had none for many weeks. So far the shield has triumphed over immense obstacles, _and it will carry the Tunnel through_. During the preceding night the whole of the ground over our heads must have been in movement, and that too at high water. The shield must have therefore supported upwards of _six hundred tons_: it has walked for many weeks with that weight twice a day over its head. What flippancy and inconsistency in some individuals, who, without any knowledge of the subject, without so much as examining the state of the work, will without the least reflection and hesitation obtrude their suggestions upon every case. What shallow conceit for such to pretend they can know better than those that have already the experience that must result from years of deep thought, from days and nights of incessant attention; who have the advantage of the combined talents of several ingenious men, who devote their undivided study, the whole resource of their well-stored minds, to the enterprise; and to add to this, the benefit of the skill of one hundred miners and excavators. Among this class of men, some have been employed in the most perilous enterprises, when each individual must have acted upon his sole judgment, where, in fact, there is no room for an engineer to instruct and direct their efforts. How easy it is to attack everything, to detract from the merits of the best plan. There is always some weak point which may be open to the penetration of the shallowest mind. Then comes the exulting expression, _That I always said would never do, &c.,_ and all the consequences with it.

[Sidenote: How easy to detract.]

_May 15_.--The water increased very much at 9 o’clock. This is _inquiétant_! My apprehensions are not groundless. I apprehend nothing, however, as to the safety of the men, but first the visitors, and next a total invasion by the river. We must be prepared for the worst. I have had no rest for many weeks on this apprehension. Should it occur we must make the best of it, by improving our situation.

_May 17_.--There is no doubt of the ground having improved very materially since last Saturday. Very cheering indeed.

_May 18_.--Visited by Lady Raffles and a numerous party. Having had an intimation by Mr. Beamish of their intended visit, I waited to receive and to accompany them, not only from the interest I felt at being acquainted with Lady Raffles, but also from motives of solicitude, knowing that she intended to visit the frames. Indeed, my apprehensions were increasing daily. I had given some instructions for enquiring where we could obtain clay, that we should have some barges full of clay to be in readiness. I was most anxiously waiting for the removal of the tier of colliers that was over us, being convinced that we should detect some derangement then. I attended Lady Raffles and party to the frames, most uneasy all the while, as if I had a presentiment, not so much of the approaching catastrophe to the extent it has occurred, but of what might result from the misbehaviour of some of the men, as was the case when the Irish labourers ran away from the pumps and the stage. I left the works at half-past five, leaving everything comparatively well: Mr. Beamish continued on duty.[18]

Mr. Gravatt’s account is as follows: I was above with I. Brunel looking over some prints, Beamish being on duty. Some men came running up and said to Isambard something I did not hear. He immediately ran towards the works, and down the men’s staircase. I ran towards it, but could not get down. I leaped over the fence, and rushed down the visitors’ stairs, and met the men coming up, and a lady, who I think was fainting. Met Flyn on the landing-place, who said it was all over. I pushed on, calling him a coward, and got down as far as the visitors’ barrier. Saw Mr Beamish pulled from it. He came on towards the shaft walking. I went up to him to ask him what was the matter. He said it was no use resisting. The miners were all upon the staircase; Brunel and I called to them to come back. Lane[19] was upon the stairs, and he said it was of no use to call the men back. We stayed some time below on the stairs, looking where the water was coming in most magnificently. We could still see the farthest light in the west arch. The water came upon us so slowly that I walked backwards speaking to Brunel several times. Presently I saw the water pouring in from the east to the west arch through the cross arches. I then ran and got up the stairs with Brunel and Beamish, who were then five or six steps up. It was then we heard a tremendous burst. The cabin had burst, and all the lights went out at once. There was a noise at the staircase, and presently the water carried away the lower flight of stairs. Brunel looked towards the men, who were lining the staircase and galleries of the shaft, gazing at the spectacle, and said, ‘Carry on, carry on, as fast as you can!’ Upon which they ascended pretty fast. I went up to the top and saw the shaft filling. I looked about and saw a man in the water like a rat. He got hold of a bar, but I afterwards saw he was quite spent. I was looking about how to get down, when I saw Brunel descending by a rope to his assistance. I got hold of one of the iron ties, and slid down into the water hand over hand with a small rope, and tried to make it fast round his middle, whilst Brunel was doing the same. Having done it he called out, ‘Haul up.’ The man was hauled up. I swam about to see where to land. The shaft was full of casks. Brunel had been swimming too.

The first alarm, as I heard it, was as follows: Goodwin, in No. 11, said to Roger, in the next box, ‘Roger, come, help me.’ Roger said, ‘I can’t, I have my second poling down, and my face will run in.’ In a little time Goodwin said, ‘You must come,’ which Mr. Beamish directed him to do. Roger turned round and saw Goodwin through a sheet of water. Corps, a bricklayer, went to help Goodwin: he was knocked down. Roger made his way alone, calling to Mr. Beamish, ‘Come away, sir, ‘tis no use to stay.’ Roger saw Corps fairly washed out of his box like a lump of clay.

Sir Isambard’s journal continues:--

_May 19._--Relieved as I have found myself, though by a terrible catastrophe, of the worst state of anxiety, that which I have been in for several weeks past, I had a most comfortable night. Isambard and Gravatt descended with the diving-bell, and stood upon the tails of Nos. 10, 11, and 12.

_May 20._--Having descended into the hole and probed the ground, I felt that the staves were in their places, and that the brickwork was quite sound. It is evident that the great hole has been a dredging spot. A large mass of bags full of clay, and united together with ropes, was let down. The Rotherhithe curate, in his sermon to-day, adverting to the accident, said it was a fatal accident, that it was but a just judgment upon the presumptuous aspirations of mortal men, &c.! The poor man!

_May 23._--Went with the diving-bell to examine the ground and the bags, which do apparently well, but it is working rather in the dark. It cannot, however, fail of making a much better stratum than that we had before. The plan is therefore good.

On the 30th a raft was sunk over the shield, and the water in the shaft was brought so low that the last flight of steps was visible. However, on the next day the river broke in again; and as it was found that the raft was open at the west side, it was raised and towed on shore.

_June 5._--There is much danger in getting out of the diving-bell, the bags are so loose in some places. One might sink and be swallowed, which had very nearly happened to-day. Isambard and Pinckney being down, the latter lost his hold. The footboard being accidentally carried away, he could not have recovered himself had not Isambard stretched out his leg to his assistance.

_June 17._--Visited by Charles Bonaparte. Isambard took him into the arch with the yawl. Isambard fell overboard.[20]

On June 19, a general meeting of the proprietors was held, to consider the position of the company. Sir Isambard addressed the meeting, and also presented a long report, in which he entered very fully into the circumstances of the recent accident and the causes which led to it. He then described the means he had taken to restore the works by sinking bags of clay and gravel. He adds: ‘I have already succeeded in closing the hole through which the water first penetrated, and feel confident that the second opening which afterwards appeared is also stopped, but a short time is necessary to elapse for the new ground over the shield to settle and consolidate. It has already supported a head of water of thirty-five feet.’

_June 25._--At 7 P.M. made preparations to re-enter the shield. Isambard, mustering the men who had been the last to quit the frames, told them they would be the first to take possession of them again--a precedence due, as he said, to them. Rogers, Ball, Goodwin, Corps, and Compton, were accordingly ordered to trim themselves for the expedition, provided with a phosphorus box, and dressed in light clothes, to be fit for a swim.

At about ten o’clock, Isambard and Mr. Beamish, accompanied by Ball and Woodward (miners), went down with the punt, and got to the large stage, the head of the crane just emerging. It was found impossible to get into the frames, as a mound of clay and silt closed the entrance. The centering was in place and quite sound, and of course the brickwork. Finding that they could not get nearer, they gave three cheers, which were rapturously answered by the men at the mouth of the Tunnel. Having placed candles upon the ground that closed the entrance, and upon the head of the crane, they returned. Isambard, having promised that the men who had left the frames last should be the first to re-enter, returned with them. This is a great day for our history!

_June 27._--Mr. Beamish was able to get to the frames, which he found firm and undisturbed.

A small tarpaulin was now spread over the frames, and operations commenced for cleaning them. This was a most difficult and dangerous work, especially as the water was still so high that the frames could only be approached by boats. The men, even the best hands, were at first greatly alarmed at the danger they were in; but the example set by Mr. Brunel and Mr. Beamish produced, as Sir Isambard notes, the best effect, and they soon became reconciled to their situation.

_July 7._--Very uncomfortable in the frames; the candles cannot burn, the ventilation cannot act. Isambard went several times to-day down in the diving-bell. On one occasion the chain slipped through the stoppers, but most providentially it jammed itself tight before being altogether run out. _The consequence might indeed have been fatal._ Can there be a more anxious situation than that which I am constantly in? Not one moment of rest either of mind or body. Mr. Beamish always ready. Poor Isambard always at his post too, alternately below, or in the barges, and in the diving-bell.

On July 11, Sir Isambard thought that matters had so far advanced that a large tarpaulin, which it was proposed to sink over the frames, ‘would have its full effect.’ It was accordingly sunk on the following day, under the superintendence of Mr. Brunel. Sir Isambard adds to his account of the operation--‘This reflects great credit on Isambard, and the apparent facility with which it was effected evinces his presence of mind, for a single _faux pas_ would have spoilt the whole.’[21]

_July 21._--During the early part of the night an alarm was given, by Fitzgerald calling for clay wedges, and exclaiming that the whole of the faces were coming in altogether. Rogers collected a quantity of wedges to go to the frames, but no boat was to be seen. He called to the men in the frames, but received no answer. Taking the small boat in the east arch, he reached the frames, but found nobody, nor any appearance of derangement in the ground. Conjecturing they might be drowned, he explored further, and saw the four men stretched on the small stage, not drowned, but sound asleep!

_July 26._--Water nearly out of the arches. For the first time we could walk to the frames--a most gratifying circumstance indeed! _Two months and eight days._

_September 30._--How slow our progress must appear to others; but it is not so, if it is considered how much we have had to do in righting the frames and in repairing them; what with timbering, shoring, shipping and refitting--all these operations being in confined situations, the water bursting in occasionally, and the ground running in: in short, it is truly terrific to be in the midst of this scene. If to this we add the actual danger, magnified by the re-echoing of the pumps, and sometimes (still more awful warning!) the report of large pieces of cast iron breaking, it is in no way an exaggeration to say that such has been the state of things. Nevertheless, my confidence in the shield is not only undiminished--it is, on the contrary, tried with its full effect, and it is manifest now that it will soon replace us in good ground, and in a safe situation. No top staves have given way. That is our real protection.

_October 17._--At 2.15 A.M. Kemble, having first called upon Gravatt, came to Isambard in a hurry, and, quite stupefied with fright, told him that the water was in. Says Isambard--‘I could not believe him. He said it was up the shaft when he came. This being like positive, I ran without a coat as fast as possible, giving a double knock at Gravatt’s door in my way. I saw the men on the top, and heard them calling earnestly to those whom they fancied had not had time to escape. Nay, Miles had already, in his zeal for the aid of others, thrown a long rope, and was swinging it about, calling to the unfortunate sufferers to lay hold of it, encouraging and cheering those who might not find it, to swim to one of the landings. I immediately, I should say instantly, flew down the stairs. The shaft was completely dark. I expected at every step to splash into the water. Before I was aware of the distance I had run, I reached the frames in the east arch, and met there Pamphillon, who told me that nothing was the matter, but a small run in No. 1 top, where I found Huggins and the _corps d’élite_. They were not even aware that any one had left the frames. The cause of the panic was one of the labourers; hearing the man in No. 1 call for Ball, he ran away, jumping off the stage, crying, “_Run, run, murder, murder; put the lights out._” His fellow-labourers followed like sheep, making the same vociferations.’

_November 10._--Isambard gave his entertainment to nearly forty persons, who sat at table in the Tunnel. Nothing could exceed the effect for brilliancy. About 120 men partook of a dinner in the adjoining arch.

As the year drew to a close, the difficulty of working the silt increased, and with this difficulty increased also the expense of maintaining the staff of men required. On December 18, Mr. Brunel, writing for his father, who was absent from town for a few days, thus describes the nature of the soil through which they were then passing.

The state of the ground over Nos. 1, 2, and 3 top has caused considerable delay, particularly this week, although not such as to give any cause of anxiety as to our future rate of progress, or to have any serious effect except the increased expense incidental to this delay. My father desired me to describe to the Board the causes of these difficulties. There is a considerable spring at this point, and a corresponding soft part in the bed of the river, which seems to indicate the rising of the spring. The ground in the neighbourhood is affected by this spring in rather a peculiar manner: at the half-flood tide the pressure is greatest: dry hard clay oozes with great force through openings hardly observable, the silt and water running by starts. At high-water the pressure and quantity of water begin to diminish and on the ebb-tide the ground is hard and dry, and can be worked with ease. On the flood-tide there are as many as twelve and fifteen of the best hands, besides myself (or one of my assistants) and the foreman, engaged entirely at one face.

On January 1, 1828, Sir Isambard returned to London; and on the 12th, when about 600 feet of the Tunnel had been completed, a second irruption occurred, which put a stop to the works for seven years.

The particulars of this accident are thus described by Mr. Brunel, in a letter to the Directors of the Company:--

I had been in the frames (shield) with the workmen throughout the whole night, having taken my station there at ten o’clock. During the workings through the night, no symptoms of insecurity appeared. At six o’clock this morning (the visual time for shifting the men) a fresh set or shift of the men came on to work. We began to work the ground at the west top corner of the frame: the tide had just then begun to flow; and finding the ground tolerably quiet, we proceeded by beginning at the top, and had worked about a foot downwards, when on exposing the next six inches, the ground swelled suddenly, and a large quantity burst through the opening thus made. This was followed instantly by a large body of water. The rush was so violent as to force the man on the spot, where the burst took place, out of the frame (or cell) on to the timber stage behind the frames. I was in the frame with the man, but upon the rush of the water I went into the next box (or cell), in order to command a better view of the irruption, and seeing that there was no possibility of then opposing the water, I ordered all the men in the frames to retire. All were retiring, except the three men who were with me, and they retreated with me. I did not leave the stage until those three were down the ladder of the frames, when they and I proceeded about twenty feet along the west arch of the Tunnel. At this moment the agitation of the air, by the rush of water, was such as to extinguish all the lights, and the water had gained the height of our waists. I was at that moment giving directions to the three men, in what manner they ought to proceed in the dark to effect their escape, when they and I were knocked down, and covered with a part of the timber stage. I struggled under water for some time, and at length extricated myself from the stage, and by swimming and being forced by the water, I gained the eastern arch where I got a better footing, and was enabled by laying hold of the railway rope, to pause a little, in the hope of encouraging the men who had been knocked down at the same time with myself. This I endeavoured to do by calling to them. Before I reached the shaft the water had risen so rapidly that I was out of my depth, and therefore swam to the visitors’ stairs, the stairs for the workmen being occupied by those who had so far escaped. My knee was so injured by the timber stage that I could scarcely swim, or get up the stairs, but the rush of the water carried me up the shaft. The three men who had been knocked down with me were unable to extricate themselves, and I am grieved to say, they are lost; and I believe also two old men, and one young man, in other parts of the work.

This statement Sir Isambard embodied in a report to the Directors of January 28, which was circulated among the proprietors.

As soon as the first excitement caused by the irruption had ceased, Mr. Brunel directed the diving-bell to be prepared in order to ascertain the state of the shield and the extent of the disturbance of the bed of the river caused by the rush of water into the Tunnel.

He was, however, so seriously injured that he could not actively superintend the preparations, but his orders were given with his usual clearness, calmness, and decision; and as soon as the barge containing the diving-bell was properly moored over the Tunnel, he was carried out and laid upon a mattress on the deck of the barge, that he might direct what was to be done.

As evening came on he became so much worse that he was taken into the cabin; but everything which took place was reported to him.

At length, the bell being ready, it was lowered early on the Sunday morning, but the chain not being long enough, proceedings were delayed until a longer chain could be obtained.

As, however, a chain of the right size and length could not be obtained, the strongest cable which could be procured in the neighbourhood was substituted for the chain. A controversy then arose between the assistant engineers and the foremen as to the sufficiency of the strength of the cable; and it was agreed to consult and to abide by the opinion of Mr. Brunel, who was then lying in great pain in the cabin.

No answer could be obtained from him for some minutes, and then he only said, ‘Don’t go down.’ This not being satisfactory to the advocates of the sufficiency of the cable, it was agreed to lower the bell empty, which was done, and it was brought up safely; but just as it was swung over the barge, the rope broke and the bell fell on to the stage.

The next day Mr. Brunel was taken home, when it was found that, besides the injury to his knee which he received while endeavouring to save the lives of the three men who were with him,[22] he had received serious internal injuries, which kept him under medical treatment for several months.

When he was able to return to Rotherhithe all hope of continuing the works was for the time abandoned. When they were resumed, in 1835, he was entirely engrossed in the independent pursuit of his profession; and, with the exception of a few occasions when he acted for his father, he had no further connection with the Tunnel.

It is not, therefore, necessary to continue the narrative in detail; but a brief summary of the subsequent history of the enterprise may be interesting to those who are unacquainted with it.

The Tunnel was cleared of water, and efforts were made, unfortunately without success, to raise funds for the completion of the undertaking. Great enthusiasm was exhibited by the general public and by many eminent persons, including the Duke of Wellington; but the money was not forthcoming, and nothing was left but to brick in the shield, and wait for more favourable times.

It was not till the beginning of 1835 that the Company was able, by the aid of a loan from Government, to recommence the works. The old shield was removed and a new one substituted, in which considerable improvements were introduced. Slings connecting the frames were added, which enabled each frame to support its neighbours when necessary, and important alterations were also made in the arrangements for keeping the frames at the right distance from one another, and for giving greater facility of adjustment to the various parts.

Before the Wapping side was reached there were three more irruptions of the river, namely, August 23, November 3, 1837, and March 21, 1838; but in October 1840 the shaft on the Wapping shore was commenced. It differed from the Rotherhithe shaft, in being sunk the whole depth without underpinning, and was made of a slightly conical form, to reduce the friction in sinking, and had a larger quantity of iron hoops introduced into the brickwork, in order to increase its strength. When this structure had been sunk to the required depth (70 feet), the excavation of the Tunnel was resumed, and at last the shield was brought up to the brickwork of the shaft. The operation of making the junction between the Tunnel and the shaft was one of much difficulty, but it was at length satisfactorily accomplished, and the Tunnel was opened to the public on March 25, 1843--eighteen years and twenty-three days after the commencement of the work.[23]

Sir Isambard Brunel, whose health had for some time been failing, now retired altogether from his professional labours. After passing a few years in peaceful and happy seclusion, surrounded by those he loved, and watched over by their affectionate care, he died on December 12, 1849, in his 81st year, having been spared to carry to completion his greatest work, and to see his son following in his footsteps with a success which must have exceeded his most sanguine expectations.

* * * * *

The education Mr. Brunel received from his father was well calculated to form the foundation of his future career. During the later and more arduous part of the contest, which was ended by the irruption of January 1828, he held both the nominal and actual post of Resident Engineer of the Thames Tunnel; but from the commencement of the works, when he was only nineteen years old, he had been, as stated by Sir Isambard, ‘a most valuable coadjutor in the undertaking.’ While placed in this responsible position he acquired habits of endurance and of self-reliance, and learnt to act with promptitude and decision in the application of those measures which experience had shown to be effective in each particular class of emergency. But beyond all other advantages, he had before him the example of his father’s character, in which a rare degree of gentleness and modesty of disposition was joined to unflinching energy, and a determination to overcome all difficulties.

NOTE A (p. 5).

_The Bourbon Suspension Bridges_.[24]

The suspension bridges designed by Sir Isambard Brunel for crossing rivers in the Ile de Bourbon were two in number. One of them had two spans of 122 feet each in the clear, and 131 feet 9 inches between the points of suspension of the chains. The second had but one span of the same dimensions as those of the larger bridge. In the design of these bridges one of the most important points to be attended to, was to render them secure against hurricanes, which are both frequent and severe in the Ile de Bourbon.

In the larger bridge there was a pier of masonry, built in the middle of the river up to the level of the roadway of the bridge. The suspension chains of the bridge were in three groups, 9 feet 8 inches apart, so as to leave room for two roadways, each about 8 feet 9 inches wide. Each of these groups of chains consisted of two chains side by side. Each chain was made with long links like those of the chain cables used for moorings.

These links, which were made of iron 1·36 inch in diameter, were 4 feet 8 inches long, inside measure, and were each connected together by two short coupling links, 8¾ inches long, inside measure, of iron 1·36 inch by 1 inch, and two pins, each two inches in diameter.

The two chains of each group were placed side by side, with the links upright; one of the pins at each joint was made long enough to serve for both chains, and, in the middle of its length between the two chains, was passed through an eye at the upper end of one of the suspending rods of the bridge. Thus to every joint in each group of the main chains, or at intervals of about 5 feet, there was a suspending rod. These rods were 1¼ inch in diameter.

The pins of the joints of the main chains had half heads at each end of them. They could thus be easily inserted in erecting the bridge, but once in place were quite secure. At every fourth joint in the main chains one of the joint pins was made in two halves, with wedges inserted between them for adjusting the length of the main chains.

Thus there were six chains, and as the links of these had each two parts of iron 1·36 inch in diameter, the total sectional area of the six chains was 17·4 inches.

Each group of the main chains was supported at a height of 25 feet 6 inches above the roadway at the centre pier, and at a height of 5 feet 3 inches at each of the side piers, the lowest portion of the curve of the chain being about 1 foot below the points of suspension of the side piers.

The upright standards, carrying the chains both at the centre pier and at the side piers, consisted for each group of chains of a triangular framework of cast iron, strengthened by long bolts of wrought iron. There were thus three of these triangular frames parallel to each other at each of the piers, and those at the centre pier were braced together over the carriage road. The main chains were not bolted to the standards, but were slung from them by a vertical suspension link, which thus allowed them to move a little lengthways. This link, in fact, performed the function of the rollers now generally put under the saddles of suspension bridges.

The ends of the main chains were held by back stays, formed of bars 3 inches broad by 1¼ inch thick, and 10 feet long, with joints made with short links, and 2⅜ inch pins. The ends of those back stays were secured to holding down plates 3 feet in diameter, sunk deep in the ground and well loaded.

As there was a vertical suspension rod at each joint of the main chains, there was a suspension rod hanging from each of the three groups of chains at about every five feet of the length of the bridge. To each set of these rods was attached a cross girder of cast iron of a =T= section, with a large rounded bead at the lower edge of the upright web; and connecting these under each of the main chains was a longitudinal timber beam about 8 inches square.

The cast-iron cross girders carried longitudinal teak planking, the planks on which the carriage wheels ran being 12 inches wide and 4 inches thick, protected at the top by wrought-iron plates running longitudinally. The horse-path was protected by iron plates arranged crosswise.

Under each span of the bridge were four chains curved upwards and also sideways. These chains were fastened at their ends into the piers, and were connected to the roadway by ties drawn up tight and attached to the main longitudinal bearers of the platform; the object being to stiffen the platform.

These under tie chains were made each of a set of rods 1¼ inch in diameter with eyes at their ends, the ends being connected by short joint links and 1¼ inch pins; and to these joint links were attached the tie rods which connect these inverted chains with the platform of the bridge, and so prevented its being lifted or blown sideways by the force of the wind.

In the smaller bridge, which, as has been said, consisted of one span of 131 feet 9 inches between the points of suspension, these points were 15 feet 5 inches above the roadway, and the lowest part of the chain was 9 feet 7 inches below the points of suspension. The details of this bridge were similar to those of the larger one.

NOTE B (p. 5).

_Experiments with Carbonic Acid Gas._

In 1823 Mr. Faraday made the important discovery that under certain conditions of temperature and pressure many gases could be liquefied, and that these liquids exerted great expansive force by slight additions of temperature, returning quickly with regularity and certainty to their original state upon the application of cold.

The discovery of this new force appeared of such importance, that Mr. Faraday lost no time in publishing it to the world; and Sir Isambard Brunel very soon afterwards commenced a series of experiments to determine the value of the liquid gas as a mechanical agent.

The first experiments were made at Chelsea; but the prosecution of them was soon transferred to the care of Mr. Brunel at Rotherhithe, where he devoted all his spare time to the construction of his father’s proposed ‘Differential Power Engine.’

That the progress of this discovery, and of the experiments made with a view to the application of the liquid gas, as a motive power, may be understood, it is necessary to state that in March 1823 Mr. Faraday communicated to the Royal Society the results of his first experiments on the liquefaction of gases.

The fluid was then produced by the decomposition of the hydrate of chlorine by heat in a closed tube, the amount of gas evolved being so great as to produce a pressure in the tube sufficient to condense the gas into a fluid of the same volume.

This interesting experiment was followed by others with that rapidity and success so remarkable in everything undertaken at that time in the laboratory of the Royal Institution; and within a month another paper was read before the Royal Society, in which the degrees of pressure and temperature at which several gases could be liquefied were recorded, and the means employed to produce and liquefy each gas accurately described.

On April 17 a third paper was communicated by Mr. Faraday, ‘On the Application of Liquids produced by the Condensation of Gases as Mechanical Agents.’

The question is thus stated: ‘The ratio of the elastic force dependent upon pressure is to be combined with that of the expansive force dependent on temperature; and the development of latent heat on compression and the necessity of its reabsorption in expansion must awaken doubts as to the economical results to be obtained by employing the steam of water under very great pressures and very elevated temperatures.

No such doubt can arise respecting liquids, which require for their existence even a compression equal to thirty or forty atmospheres, and where slight elevations of temperature are sufficient to produce an immense elastic force, and where the principal question arising is whether the effort of mechanical motion is to be most easily produced by an increase or diminution of heat by artificial means.’

Difficulties were suggested by Mr. Faraday as to the possibility of obtaining sufficient strength in the apparatus, but the small difference of temperature required to produce an elastic force of many atmospheres, he considered would render the risk of explosion small.

To construct the machinery whereby this new force could be practically applied as a substitute for steam, occupied the time of Sir Isambard Brunel and his son at intervals for several years; for although Mr. Brunel was satisfied at an early period of the enquiry that the liquefied gases could only be advantageously employed where the cost of motive force was secondary to economy of space and to the avoidance of the cumbrous apparatus required for the use of steam, still he was so impressed with the importance of the subject, if the difficulties he foresaw in its application could be overcome, that he continued his experiments for a long period with unflagging energy and perseverance.

The facts relating to the liquefaction of the gases, their elastic force when liquefied under different temperatures, the rapidity with which they could be alternately expanded and condensed, and the best mode of producing each gas, were determined by Mr. Faraday; and as Mr. Brunel was at that time attending the morning chemical lectures at the Royal Institution, he was in constant communication with him, and thoroughly conversant with his experiments.

After Mr. Brunel had made a few preliminary experiments, Sir Isambard determined to employ liquefied carbonic acid gas for the motive power of the proposed new engine, the facility and cheapness of its production, its great expansive force, and its neutral character distinguishing it from any other gas; but it was long before vessels were constructed, in which gas could be produced in sufficient quantity and purity to exert the force required to liquefy it in its own volume, for it was soon found to be impossible to obtain the required pressure with pumps.

Carbonate of ammonia and sulphuric acid were the elements used, and the generator was so arranged that it could be charged, emptied of atmospheric air, and the joints made perfect, before the commencement of the formation of the gas which was to be liquefied.

To the generator was attached a receiver, which could be surrounded with a freezing mixture, so that the temperature of the gas in the cylinder might be below that in the generator.

The gradual formation of the liquid, the development of its elastic force, and the regularity and rapidity with which it increased or diminished by each degree of heat or cold, were carefully watched through a glass gauge, and the receiver when filled with liquid could be disconnected from the generator.

The mechanical difficulties as they arose, one after the other, in the construction and arrangement of the various parts of the generator and receiver were at length overcome; and the receiver was not only filled with liquid gas, but found to be capable of retaining it, whether exerting an elastic force of 30 atmospheres at ordinary temperatures, or of 100 atmospheres when subjected to a slight degree of heat.

The receiver being satisfactorily completed, the next object of attention was the design and construction of a working cylinder capable of resisting at least 1,400 lbs. pressure on the square inch; a task which was one of great anxiety, as any weakness might have caused a serious accident.

It was only after the trial of every known method of making joints to resist high pressures had failed, that an arrangement was devised, requiring the most perfect workmanship, by which packing of any kind was dispensed with, and the cylinder fitted for use.

With the improved tools of the present day it is not easy to realise the difficulties, delays, and disappointments which forty-five years ago occurred from the failure, first of one part of a joint, and then of another; but the construction of vessels capable of producing and also of retaining the gas in its liquid state, with the means of alternately expanding and condensing it from thirty or forty to eighty or one hundred atmospheres, having been accomplished, the object of the expenditure of so much labour and inventive power appeared to be within reach.

The construction of the machinery to utilise the elastic force contained in the cylinder was now proceeded with. Day by day new difficulties arose, and each as it was successfully met seemed but to leave another of greater importance to be surmounted.

It is not necessary in this Note to describe the various arrangements which were devised for transferring the great elastic force in the cylinder of small diameter to a piston in another cylinder of much larger dimensions; it is sufficient to say, that after the devotion of much valuable time extending over several years, and a very large expenditure of money, and after carefully considering the cost of the liquid carbonic acid gas, the difficulty of preventing waste, and the necessarily very expensive character of the machinery, Mr. Brunel was satisfied ‘that no sufficient advantage in the sense of economy of fuel can be obtained by the application of liquefied carbonic acid gas as a motive power’; but so thoroughly did he exhaust the subject before he committed himself to this opinion, that no one has since renewed the enquiry or attempted to make a machine to be moved by the elastic force of liquefied gases, the construction of which, it was well known, had baffled the inventive genius of Sir Isambard Brunel and his son.