plied the Government with designs for a saw-mill for the Ordnance department at Woolwich, and afterwards planned and superintended the erection of the extensive machinery for sawing and dressing timber in the ship-building yard at Chatham. Besides designing works for others, he also designed them for himself, and diverged from the business of an engineer to enter on that of a manufacturer. He started two concerns about this time-one an establishment for manufacturing shoes by machinery, and another for sawing timber on a large scale; but both proved unfortunate; for it must be confessed that, with all his cleverness, Brunel did not possess the commercial faculty. Inventors are not always the best manufacturers, and it is possible that their very inventiveness may stand in the way of their exercising that plodding application and persistency which are so necessary to success in business; just as the thoroughbred steed is found to draw a loaded wagon far less effectively than the humble but hardworking cart-horse. of the shoe-machinery; while Brunel, rely. 1g ing too implicitly on the moral obligation t by which he believed the Government to be bound, continued to incur the heavy liabili ties connected with a manufactory in full operation. The consequences were serious. A large stock of shoes, for which there could be no demand, was accumulated, and financial difficulties arose from which Brunel was unable to emancipate himself." It is always easy for over-sanguine projectors to lay the blame on Government. It is clear that the Government, in this case, were under no moral or other obligations to take shoes which they did not need. It is admitted that the order actually given was completed, and that the shoes delivered to order were paid for, and Brunel's business was either to look for a market elsewhere for his superior shoes, or to stop their production. If he went on manufacturing shoes which nobody would buy, that was his own fault, and not the fault of "the Government." But the shoes were probably inferior to hand-made shoes, otherwise they would have driven the latter out of the mar pired, and his invention is now free to any capitalist who may choose to take it up. But it is known to have been a failure; and other shoemaking machines which have been invented as improvements upon it have failed like it. The last speculation of the kind was wound up but the other day in the Court of Bankruptcy. Brunel's biographer alleges that he invented his boot and shoe machine from a pat-ket. Brunel's patent has long since exriotic motive, namely, to supply our soldiers with those articles" independent of the shoemaker's wax and thread, and the contractor's cupidity and Knavery." However this may have been, Brunel tried hard to secure a large Government contract for his boots and shoes. He took care, in the first place, to secure a patent for the machinery, by means of which the upper leathers were to be fastened to the soles by "metallic pins or nails." The machinery was, no doubt, very ingenious; but, notwithstanding Mr. Beamish's assertion that "the superiority of the shoes, as regarded durability, finish, and cheapness, was unexampled," we must take leave to express a doubt whether they were at all equal to shoes made in the ordinary manner. If they had been really superior, no Government opposition could possibly have prevented a general demand for the article. Mr. Beamish says, "A large order was issued by the Government, which was completed within the time stipulated; but unfortunately for Brunel, when everything was in full activity, and the workmen had become familiar with their work, the war had come to an unlooked-for termination; the Government no longer required the aid The Battersea Saw-Mills were started in 1808, and in the hands of an energetic man of business would probably have succeeded. But Brunel left the pecuniary arrangements to partners incompetent to manage them, and the concern fell into inextricable confusion. The calamities of the firm were brought to a climax by a fire which broke out upon the premises in 1814, and destroyed the greater part in two hours. Only the right wing of the building, containing the steam-engine, was saved. Brunel immediately sought for means to repair the loss, and the premises were partly rebuilt; but his capital had been destroyed, and he had besides incurred heavy debts. He submitted his affairs to a City banker, who pronounced the accounts prepared for him to be "a most extraordinary jumble." It appeared that Brunel had been in the practice of In the department of engineering he was alike busy. He designed a bridge over the Seine at Rouen, but, after long negotiation, it was declined. He furnished an ingenious design of a bridge over the Neva at St. allowing a discount of twenty per cent on study to the improvement of stereotype the prices of the work done at Battersea,- plates; but other inventors shot ahead of a circumstance which the banker held to be him in this art, and it does not appear that a striking proof of the great depreciation that he did more in this line than secure an in the credit of the concern. Mr. Brunel unproductive patent. next resorted to the lawyers, who appeared only to increase his embarrassments. His City friend wrote to him, "If you have ever been ill in your life, and depended on medical advice, fall down on your knees and bless God that you had fewer doctors than Petersburg, which was much admired; but you had lawyers about you. If that had not been the case, you might have been making saw-mills on the other side of the Styx, or inventing a steamboat for old Charon." the Czar desired it to be communicated to the engineer that circumstances did not favor the execution of his project, and that under the pressure of unforeseen and very considerable expenditure the imperial treasThe crisis in Brunel's affairs was close at ury could not commit itself to so costly an hand; in May, 1821, he was imprisoned for enterprise. He was more fortunate in his debt. Writing from the King's Bench designs of two suspension bridges proposed Prison in July to his friend Lord Spencer, to be erected in the Isle of Bourbon, which he said, "I have now been in this distressed were accepted by the French Government. situation ten weeks. I summoned as much The bridges were constructed in this counfortitude as possible to support the misfortune, but I find I can no longer bear up against what in the eyes of the world must appear a disgrace." An appeal was made to the Government on his behalf, and a grant of £5,000 was made to him, in consideration principally of the savings which continued to be effected by the use of his blockmachinery. He was thus enabled, soon after he had written to Lord Spencer, to return to the exercise of his calling. The numerous inventions which Brunel continued to make and to patent, afford abundant evidence of his ingenuity and his industry. Indeed, invention seems to have been the normal state of his mind; it embraced a very wide field, taking in such different subjects as stocking-knitting machines and steam-engines, metallic paper, stereotype printing, and the treadmill. In 1816 he patented a tricoteur or knitting-machine, by which the whole of a stocking could be made in one piece, but it never came into try, but their cost when completed-owing, it is alleged, to the misconduct of the contractors-greatly exceeded the original estimate: his biographer adds that "the same fatality which had already marred Brunel's commercial prosperity was still found to cling to him." In addition to these designs he supplied plans of swing-bridges at the Liverpool Docks and of a landing-stage at the same place, the design of a suspension bridge over the Serpentine, sundry improvements in the treadmill, and plans of machines for boring cannon at Amsterdam. Like most inventors of his time, Brunel engaged eagerly in projects for the improvement of motive power. As early as 1810 he took out a patent with this object, proposing to employ the inclined hollow screw for the purpose of forcing atmospheric air into a vessel of cold water, from which it was to escape into an inverted funnel, thence to be conveyed through a pipe to another vessel containing hot water. In this vessel a Another of his inventions was crystal- bucket-wheel was to revolve; the air, conlized tin-foil which was extensively used ducted through the pipe and rarefied in its some thirty years since, for ornamenting passage through the heated water, was to teacaddies, urns, lamps, and such like. ascend beneath the buckets, and by its buoyBrunel, however, derived little advantage ancy give motion to the wheel, as water from it, as the invention was extensively operates upon an overshot wheel in the open pirated; and while the pirates actively air. But it does not appear that the invenpushed the sale of their goods, Brunel's tion was followed by any practical result. firm was contented to wait for customers, He also turned his attention to the subject who did not come. He also devoted much of steam navigation, and experimented with use. a boat on the Thames fitted with a double-mechanics, was found incapable of realizing acting engine. When he made his first those economic conditions by which alone it voyage with it to Margate, in 1814, he was could be rendered commercially valuable." threatened with personal violence by those The last grand scheme of our engineer, connected with the sailing-packets, and the and, indeed, the crowning event of his life, landlord of the hotel at which he first ap- though it afforded ample testimony to his plied even refused to provide him with a skill as an engineer, was alike unfortunate bed. Some years later, in 1822, he took in its commercial results. We allude to out a patent for improvements in marine that extraordinary enterprise, the excavaengines and in paddle-wheels; but another tion and construction of the Thames Tunscheme, which interested him more than all, nel. The connection of the counties of was the substitution of gas for steam in the Kent and Essex by means of a roadway be production of motive power. Science had neath the bed of the Thames had long no sooner made a discovery than Brunel fol- formed the subject of speculation among lowed it up by an invention; and when the projectors, just as the formation of a railway result of Mr. Faraday's experiments upon tunnel under the Straits of Dover does now. the liquefaction of gases was communicated In 1798 George Dodd projected a tunnel to the Royal Society in 1823, our engineer immediately proceeded to patent his invention of a carbonic acid gas engine. It had been established by the experiments referred to, that this gas, when reduced to the liquefied state, could again be vaporized, and an of the most ingenious but unfortunate prointense pressure produced by the expenditure of a very small amount of heat. It therefore occurred to Brunel that, by the use of this liquefied gas, pent up within an ingeniously contrived apparatus, a very power-round to London by sea. He was the first ful engine might be produced. If the gas could be liquefied and vaporized alternately in the working of the machine, it was argued that the new power would be so cheap as completely to supersede the use of coal, water, and steam in the production of motive power. The most sanguine anticipations were entertained as to the results; but, as Brunel himself once said of another person's invention, "Ah! my friend, it is very easy to invent a machine, but it is not so easy to make it work!" The Admiralty even went so far as to advance Brunel £200 to aid him in working out his machine by the process of experiment. Orders for the engines were obtained from abroad, and the public waited anxiously for the advent of the new power. But in vain. After exerting his ingenuity for many years in trying to overcome the mechanical difficulties of the problem, it was discovered that, after all, water was cheaper than sulphuric acid and carbonate of ammonia; that steam was a more manageable power than carbonic acid gas; and thus "the beautiful theory which had given so much promise, and been hailed as the harbinger of a new era in practical under the river between Gravesend and Tilbury, the estimated cost of which was set at so low a figure as £16,000, but nobody seems to have believed Dodd, and his project fell to the ground. This Dodd was one jectors of his day. He was the first to in-. troduce steam navigation on the Thames. He had a vessel expressly built and fitted on the Clyde for the purpose, and brought engineer of Waterloo Bridge, though he was superseded in that office by John Rennie. Amidst his projects he took to drinking, became embarrassed in his circumstances, and was thrust by his landlord into the street. He was eventually brought before the Lord Mayor as a vagrant, and requested as a favor to be allowed to stay in Giltspur Street Compter, where he died. The subject of a tunnel under the Thames was taken up and prosecuted by another engineer still more ingenious, and equally unfortunate in his end-we mean Trevethick, the inventor of the locomotive and high pressure steam engine. A tunnel company was formed in 1802, for the purpose of excavating an underground road between Rotherhithe and Limehouse, Mr. Vazie being the projector, and Mr. Trevethick the engineer. Several years passed before the works were begun; but in 1807 the driftway was driven under the bed of the river for the distance of 953 feet, when the roof broke in, and the workmen were "drowned out." Clay in bags was thrown into the hole, and the leak was thus plugged; when the pumping engine was set to work the water was cleared out, and the driftway pro- was £200,000, aud nearly the whole sum ceeded. Another and another deluge from the river flooded the work, which was at length abandoned after 165 feet more of the drifting had been excavated. The opinions of scientific men were now sought for; and amongst others Dr. Hutton, the mathematician, and Mr. Jessop, the engineer, were appealed to. The conclusion they came to in the matter is worthy of being quoted, for it has been fully borne out by the result. "Though we cannot presume," they said, "to set limits to the ingenuity of other men, we must confess that under the circumstances, which have been clearly represented to us, we consider that an underground tunnel, which would be useful to the public and beneficial to the adventurers, is impracticable." The subject was nevertheless revived in 1816 by a Mr. Hawkins, who promulgated a scheme for excavating the tunnel. Brunel was immediately attracted by the novelty, as well as perhaps by the difficulty of the undertaking, and his mind became occupied with the methods by means of which it could be carried into practical effect. While pondering the matter his attention was one day attracted by a piece of old timber lying in the dockyard at Chatham, which had been subject to the operations of that great destroyer of submerged timber, the Teredo navalis. On examining the little mollusc he found its head armed with a pair of strong shelly valves; and that with its proboscis fixed to the wood, and acting as a centre-bit, the shell working like an auger, it was thus enabled to bore its way with impunity. The mechanism of this insignificant sea-worm gave Brunel his first idea of the true method of excavating his tunnel, and to imitate its operations became for some time his chief study. In 1818 he embodied the process in his specification of a patent for "forming tunnels or driftways underground," describing a machine of iron forming auger-like cells for the miners, afterwards called the shield. He proceeded to develop his ideas with reference to the Thames Tunnel project, and by the beginning of 1824 a sufficient number of persons had been interested in the scheme to form a company, and it was shortly after launched before the public. The estimated capital required for the work was at once subscribed. The Act was obtained in the course of the same year, and Mr. Brunel was appointed engineer, at a salary of £1000 a year for three years, with the prospect of a reward of £10,000 when the tunnel was completed. Operations were begun early in 1825, by the sinking and construction of a shaft 50 feet in diameter and 42 feet high on the Rotherhithe side of the river. Among the many able engineers who were trained to difficult enterprises by the experience gained by them in the construction of this formidable work, one of the most prominent was the son of the engineer himself, young Isambard Kingdom Brunel, who entered upon his duties as assistant to his father when only nineteen years of age. At fourteen he had been sent to the College of Caen, in France; and after remaining there three years he had proceeded to the Lyceum of Henry IV. at Paris, where he spent two years more. In 1822 he presented himself for admission to the Polytechnic School, but was found ineligible in consequence of his English birth. After spending some time longer in France, enriching and storing his mind, he returned to England, and was immediately employed on the difficult work which his father had by this time undertaken. After various incidents the shaft at Rotherhithe was built and sunk to the proper depth. The process employed was highly ingenious. The shaft, a cylinder of brick, was built complete on the surface, fitted at bottom with a strong iron curb, and then, by uniformly excavating the ground underneath, it was slowly and gradually sunk by its own weight to the required depth. The most difficult part of the operation was then begun-the driving of the tunnel under the bed of the river, horizontally from the bottom of the shaft. This was accomplished by means of the great shield, for want of which, or of some similar machine, all previous excavations had failed. It will readily be understood that the chief difficulty in executing the work consisted, not so much in the actual building of the tunnel, as in supporting the ground on the face of the excavation until the permanent brickwork could be erected. The method by which this difficulty was overcome by the engineer boxes, then it was possible to stop and block exhibited his inventive capacity in its most striking light. up the run with brickbats and straw. In short, the shield might be compared to a We have already stated that Brunel bor- horizontal cofferdam, of which the polings rowed his idea of the shield from the insig- and the iron stars supporting the ground nificant teredo navalis; but it would perhaps might be regarded as the sheet piles.* The be more correct to compare the instrument whole weight of the shield was about two to a man, or number of men, with legs, each hundred tons, but the pressure which it had with a knee and ankle-joint, alternately to resist was upwards of a thousand tons; stepping on in advance of the excavation, and there were but few parts of the frame with arms to steady the whole fabric, and which were not fractured by the tremendous with a head to support the superincumbent pressure of the water which burst in upon earth, and raise or lower it as circumstances the tunnel from time to time during the might require. The machine was divided progress of the work. into twelve distinct parts, each of which In further explanation of the details of was competent to fulfil either of these duties, the shield, it may be briefly stated that each the parts being so arranged that they could frame was supported on two jacks or legs, perform the offices alternately, six of the which also bore the pressure of the superindivisions being employed in supporting the cumbent ground. When the excavation had ground while the other six were making sufficiently proceeded, these legs, by a metheir progress forward. The external di- chanical arrangement, were made to move mensions of the shield were the same as forward by means of the knee and anklethose of the tunnel, twenty-two feet three joints with which they were provided. inches in height and thirty-seven feet six Another important part of the shield was inches in width, occupying a space of about the arms or slings, auxiliary to the legs, by nine feet deep in advance of the brick-work. means of which the weight of any frame The twelve frames were each about three could be wholly thrown upon its two neighfeet wide, ranged side by side like so many bors, while its own legs were thus entirely volumes on the shelf of a library. Each of relieved from pressure. This expedient these was divided again into three by strong was found of great value when the ground iron bars, thus forming thirty-six cells or on which any single frame stood was soft boxes, which were as separate as if each had or loose, and unable of itself to support the been a distinct drifting. superincumbent pressure, as well as to enable any particular frame to be removed from its place for the purpose of repairing it. Equally careful arrangements were made for the advance of the side plates by means of which the guage of the tunnel was preserved and the excavation confined within its due limits, whilst the pressure of the water against the sides of the work was reduced to its minimum. It was also so contrived by the engineer that, under all circumstances, the frames should maintain their perpendicular position; and hence the powerful abutments with which the shield was furnished. The area of ground to be penetrated in front of the shield was supported and secured by upwards of five hundred small boards termed polings pointed with iron plates and shod with screws three feet in advance of the work. These polings held up a surface of about eight hundred square feet, over a large portion of which the influence of the tide was distinctly felt. The advantage of dividing the front of the shield into small cells by the arrangement above indicated was, that the large front area of ground, to secure which as one surface would have been impossible, was thus divided into thirty-six faces, each of small area, which were worked down and secured separately by one or two men; and when, from unusual looseness of the ground in any of the respective faces, danger was apprehended, it was easy, by introducing boards between the frames, to cut off communication with the contiguous cells; and if any ground made its way into the The first portions of the shield, manufactured by Maudslay, were lowered into their places in October, 1825; the remaining parts shortly followed, and on the 28th November *For a complete description of the shield, illusLaw, C.E., in "Weale's Quarterly Papers on Entrated by engravings, see the account by Mr. Henry gineering," Parts IX. and X. 1845. |