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On the Position and Mode of Working the Bath Freestone

May 6, 2021 / iron_steam

From The Technologist – A Monthly Record of Science Applied to Art, Manufacture, and Culture. Volume V

October 1, 1864

By J. Randall

The paper which I have the honour to lay bofore this section of the British Association has reference to two subjects, both of equal local interest, the one in an economical and commercial point of view, and the other bearing upon the scientific conditions, both as regards the mode of working and geological positions of those beds in the great or Bath oolite, which may be called the “quarry stone,” and which are so extensively worked in the Bath district. I purpose, therefore, to divide my paper into two sections, or arrange the materials into short, and yet I hope sufficiently detailed a manner under two heads : first, to determine the true horizon or geological position of the workable beds of this valuable freestone in the series termed the great oolite ; secondly, to enter upon the mode of “working and getting” this extensively used and valuable building stone.

Geological Position.— Nowhere, I believe, in Great Britain (indeed, in Europe) are the lower members of the Jurassic group of rocks so extensively developed as in the Bath district, where each group seems to have attained its fullest recognised development; nowhere can the whole Jurassic series be so readily studied, nowhere so easily understood; and this applies to the lias itself in its three divisions — the fuller’s earth (here extensively employed); the member of the lower oolite under consideration ; and the Bath or great oolite, distinguished here for its economical value, and at Minchinhampton and other places for its fine and typical organic remains. Above this series, but intimately associated with it, the forest marble and cornbrash are highly and typically developed, succeeded by the Oxfordian and Kimmeridge groups, not omitting even the Portlandian at Swindon and the Purbecks of the Vale at Wardour. To each of these may be appended important notes bearing upon their high importance, economically considered, and which are extensively developed in the district ; but I purpose drawing the attention of the members of this section to the Bath oolite only, determining the position of that zone from which the freestone is extracted, and on which the wealth and comfort of the population of this neighbourhood, engaged in quarrying operations, so much depend. I have also endeavoured to fix, by detailed and measured sections, the workable beds of the district, and to correlate them over a considerable area, useful, it is hoped, both to the man of business and the geologist. These sections, which I may here refer to, are all coloured the same in their respective zones, and show the importance of carefully determining the place or position of the workable beds, prior to any outlay of capital ; and however difficult, indeed impossible, it may be to diagnose the quality of the freestone beds in depth, there can be no doubt as to their position and probable condition ; and when it is known that uniformity of condition over any large area is of extreme uncertainty, and knowing as we do that the thinning out of the marketable beds of freestone in this district, like the great colite en masse on the line of deposition and dip, is a fact now well understood, it becomes a matter of high importance to the capitalist to be assured and confirmed as to the chances of success in opening out or developing a new district. The natural grouping of the beds constituting the great oolite series in this district fall under three well-marked divisions, all well exhibited in the sections exposed at Murhill, Westwood, and Farleydown, Combe and Hampton Downs, Box and Corsham workings, &c., &c. Indeed, generally where conditions have exposed them, and reading downwards from the surface, we meet with over the Bath area, immediately below the forest of marble (where present), the following groupings : — 1. The Upper Ragstones. 2. The Fine Freestone, or Building Beds. 3. The Lower Ragstone. These constitute a series from 60 to 120 feet in thickness, depending upon local circumstances and conditions during deposition and perhaps subsequent denudation.

The Upper Ragstones. — This series consists of (in the upper part) coarse, shelly, and irregularly bedded limestones, with usually a few underlying beds of white fine-grained limestones, possessing a distinctly and well-defined oolitic structure and finely comminuted shells; these are again succeeded by tough argillaceous beds of limestone, usually pale brown in colour and smooth in texture, the whole ranging in thickness from twenty-five feet to about fifty feet. No beds of workable value occur in this upper series.

The Fine Freestone, or Building Beds, in the Bath Stone Series. — Succeeding the upper ragstone are the Bath freestone, or fine-grained building beds, which vary in the number and thickness of the various beds comprising the series, and also economically distinguished from each other by their structural condition, the size and structure of the oolitic grains, the presence or absence of silicious particles or finely divided shelly matters, each of which may materially affect the limestone during the process of working, or influence them after being placed in position, and subject to weathering under atmospheric changes. In some localities the beds assume an earthy structure, indistinct in texture, smooth and close-grained, and hold more moistness.

The Lower Ragstone. — Below the fine building beds, or freestone series, are the lower ragstones, which appear to be persistent everywhere over the entire area, and resting upon the fuller’s earth. They consist of numerous and generally well-defined beds of a coarse shelly texture, and hard crystalline limestone exhibiting much false bedding, especially near the base. Many species of mollusca occur in the bottom beds, such as Ostrea acuminata, Terebratula, Ornithocephala, Rhynchonella, Trikitis, Concinna, and Tancredia. These lower ragstones, as before mentioned, rest immediately upon the fuller’s earth, but this member of the oolitic series concerns us only by position, and is in this district west of Corsham and Bradford a most persistent and important zone, between the inferior oolite beds below and the lower ragstones of the great oolite above, and, in some places, very fossiliferous, and varies in thickness from 150 feet to 200 feet. Taking, therefore, as our guide in this district the above three divisions of the great oolite, we are enabled to construct vertical sections to aid us in our determinations as to the position and condition of the few feet of stone profitable to work in the series, or the “freestone beds,” at all times an anxious and im. portant question when seeking for and developing new ground. In this paper I deal chiefly with facts, and therefore give detailed and measured sections of type localities, from which may be determined by comparison the probable conditions under which the beds may occur at intermediate and unexplored stations or localities on the table lands behind such outstanding mural precipices as Farley, Murhill, Box, on the eastern side of the Bradford and Slaughterford valleys, or on the elevated downs at Claverton, Combe, Hampton, Freshford, &c., to the south of Bath, and west of the Bradford Valley, and on the receding flats to the east of Monklow, Farleigh, and Bradford, &c., conspicuous for the numerous quarries opened in the cornbrash and forest marble, the latter of which occurs in detached patches or continuous lines, stretching from Malmesbury on the north, to Chippenham, Bradford, and other localities to the east of Bath, and especially conspicuous near Corsham, Chapel Korap, South Wraxall, and on to Melksham. The most complete section, and which may be regarded as a typical one of the great oolite and forest marble beds of the Bath district is that of the Box Hill and Corshain Quarry workings. No. 1, showing those beds not usually seen or exposed, but which were cut through by the construction of the Box Tunnel, and which we are now extensively working in that neighbourhood. Another exposition of the series is shown at Murhill, on the eastern side of the Bradford Valley, where the three divisions into which the series group themselves may be studied in situ. Also at Upper Westwood, on the opposite or west side of the valley, other sections occur, tending to show the same facts ; and the variable condition and thinning out of the same beds upon the line of Diss, even at this short distance.

The Sections. — The shafts which are constructed along the line of the Box Tunnel, on the Great Western Railway, afford at the several points where they are carried through the beds of the great oolite accurate data for the construction of sections and clear evidence of the succession of the strata comprising the three divisions. I have endeavoured to maintain, as occurring through this district, and being situated considerably to the east of the Bath Valley escarpments, a large area, for the productiveness of that area is estimated by the lie, position, and condition of the building freestones, supposed to occupy the summit of the table land, stretching from the eastern escarpment of the Bradford, Box, and Slaughterford valleys to Yatton Keynell, Biddestone, and Corsham. The Section No. 1 gives accurate measurement and sufficient details to enable a practical observer to determine the series of beds at almost any point over the area above indicated, or even between the westerly extension of the Oxford clay line from Malmesbury to Corsham and Melksham, and the valley escarpments before mentioned. It is not necessary to notice the forest marble or cornbrash, which is foreign to my paper, and which, although usually present, may or may not occur on any special area above the great oolite proper, local conditions, during deposition or subsequent denudations, having removed one or the other, or both ; but everywhere, so far as I know, over the whole table land do we find the coarse shelly limestones, and some finely grained oolite beds belonging to the upper ragstones or highest members of the great oolite. In the typical section No. 1, taken at No. 7 shaft, Box Tunnel, also at the shafts 4, 5, 6, these beds occur, and were cut through when sinking, and were found to be from twenty to thirty-five feet in thickness, before proving the “capping” to the building or “fine” beds below. At Murhill, near Winsley, these upper ragstone beds are about twenty feet in thickness, and are hard, coarse, and fine shelly limestones, highly comminuted in structure, and occasionally colitic. In some localities many of the beds are of considerable thickness, and of regular and even texture, still they are too hard for those purposes for which the softer, fine-grained, whiter, and more easily worked architectural stone below in the second series) are sought for, and to which they are applied ; and again, they are not good weather stones, but rapidly fall to decay on exposure to severe changes of weather. At Upper Westwood, on the south side of the Bradford Valley, opposite Winsley and Murhill, the beds comprising this upper series are thicker and of more even texture, but as weather stones are of little or no value. At Farley Down, overhanging Bathford, this upper series is nearly thirty feet in thickness, composed of coarse shelly limestones at the top, with hard and soft ragstones down to the capping of the fine “building beds” below. At Combe Down and Odd Down the beds closely resemble those of Farley and Box, and approximate in thickness. Thus we may examine detailed sections of the upper series at Murhill, Farley, Westwood, Coombe, and Odd Down, and the Box district generally, but the beds at neither locality are deemed of sufficient value to work for transit as a building stone.

The Second or Middle Series. — Succeeding the ragstones above mentioned, and commencing the second series, there appears to be everywhere a peculiar bed extending over a large area, termed the “cover,” or capping, varying in thickness, but generally hard in texture ; this forms the roof, or ceiling, to the fine economical building freestones below, and over which it lies, and is a marked feature in extensive underground workings, both for its horizontal extent, application, and importance as protection to the workmen, and as commencing the second series, or middle beds, which occur between the “ upper and lower ragstones.” At Bradford, Westwood, and Murhill this bed is a coarse, shelly, hard limestone ; at Corsham and Box, a closer-grained and tough rock. I associate it with the building freestone, or fine beds below it, rather than with the ragstone above, from its persistency and the constancy of its conditions. Succeeding this is the true Bath stone, or fine freestone, and which I believe occupy, with minor differences, the same position or horizon over the whole of the Bath district. This second, middle, or freestone series are as a group from twenty to thirty feet in thickness, and are coloured chrome-yellow in all sections, and those beds worked for transit are usually evenly grained in texture, regularly bedded, yield well to the saw, are non-fossiliferous, and give evident proof of having been accumulated or deposited in a somewhat deep and tranquil sea, or away from any littoral or wave disturbance, and which the almost total absence of organic remains still further tends to confirm or demonstrate. It appears from observation, and the correlation of measured sections, and conditions observable underground, that the fine-grained regular beds thin away in a south-eastern direction, or upon the line of their general dip, a fact clearly determinable on examining the sections exposed in the valleys. Indeed, it cannot be doubted but that the great or Bath oolite as a group, in this neighbourhood, exists under extremely irregular conditions, and dies out and disappears in the form of a lenticular or wedge-shaped mass, to the east and south-east. This circumstance, causing the building freestones to thus vary in their relative thickness as we proceed from the western part of the area to the east and south-east, and the removing of much of the exposed belt comprising the oolitic series between Bath and Bradford, on the line of their strike, north-east and south-west, caused, it would appear, by the extreme denudation of the Bath and Bradford valleys, and the westerly extension of the cretaceous series from Melksham to Westbury, Frome, and Warminster, are due, perhaps, to physical conditions connected with the eastern extension of the Mendip axis, and the little understood, deeply-seated, but undoubted position of the Palæozoic series, between Frome on the south, and Bath and Wickwar on the north, or along the eastern edge of the Bristol coal-field ; but under any circumstances the extension or invasion of the cretaceous series in the east, the narrowing of the exposed oolitic series above-mentioned, and the mechanical arrangement of the rock structures themselves, evince and determine lccal deposition to have gone on under continued oscillation of the land at the time of the deposition of the great colite series. It is to this second grouping, therefore, or the middle series, which exist between the upper and lower ragstones, that we must assign the workable beds of freestone now extensively quarried in the Bath district.

The Lower Ragstones. — These are an extensive series of rather fine and hard, as well as coarse and shelly, limestones. The lowest beds of this series being usually finer in texture than the upper, and when exposed, are generally from thirty to forty feet in thickness. Nowhere in this neighbourhood are finer sections to be seen than at Murhill, on the north side of the Bradford Valley, and Upper Westwood, on the south side. The beds comprising this division usually occur, or are exposed, in the escarpments of the denuded valleys or the projecting downs above. Masses of the thicker and fine-grained beds frequently occur on the inclined slopes of the valleys, owing to or rising from frequent slips or slides over the fuller’s earth upon which these lower ragstones immediately rest. It is, therefore, in the narrowing of the valleys and abrupt cliffs that this series of the great colite are best exposed. The chief economical value of these beds is confined to local purposes, being utterly unfit for architectural work or exposure to atmospheric influences. The stone used in the construction of the aqueduct conveying the canal over the river Avon, at Avon Cliff, came from the beds of this series at the Westwood Quarry ; and although in situ the stone appears of fine texture and quality, yet it rapidly decomposes on exposure, and the stone work of the Avon Cliff aqueduct is a perishing evidence of its non-durability. At the Box and Corsham quarries these lower beds, though not observable at the surface, are, nevertheless, forty-three feet in thickness, and are chiefly composed of the fine-textured oolitic limestones, but are not worked, as they are of no value in a commercial point of view.

On the Mode of Working the Bath Freestones. — Having endeavoured to determine the horizon of the workable beds of oolite and the relations they hold to the ragstones, or shelly series-recognised above and below these freestones, I will endeavour to describe shortly the mode of opening, working, and extracting the rock; a matter of no little importance, when we consider that more than 100,000 tons of the Bath freestone is annually removed from its original position in this neighbourhood, and forwarded to various parts of the United Kingdom. In working for stone, the first question to determine is, whether the stone shall be reached by open or underground workings, and this must depend upon the presence and conditions of the upper ragstones (and forest marble, where they exist), as they must of necessity be passed through, unless the stone can be reached by tunnelling on the face of an escarpment, where the beds are vertically exposed, or by driving a level to cut the beds ; but if the desired beds are not too much covered, open workings are resorted to. Few persons travelling from London to the West of England, vid the Great Western Railway, through the Box tunnel, have any conception, on passing through it, that around and over them are large and extensively worked mines, from which the well-known Corsham and Box freestones are taken, or as they shoot from the tunnel-mouth into the Bath-hampton, Bath-eastern, and Bradford valleys, that it is the seat of so much quarry industry, having for its object the working of the Bath freestone. In describing the particular mode of getting the stone, I will take for my type the Corsham Down and Box Hill workings. I do so, because these mines have had more thought and attention bestowed on them than any others in this neighbourhood, and because they are the most extensively developed. It is believed that the Box and Corsham locality has been worked for stone, with more or less activity, for three centuries, but it was not demonstrated that so large an amount of good workable freestone existed in the district until the fact was evidenced by the cutting of the Box tunnel, which at once exposed the beds, and showed that to the north and north-west of the tunnel, on the strike of the beds, there existed what we may practically call an inexhaustible supply of valuable freestone. The cutting of the Box tunnel having opened to view this fact, gave an impulse to the previously limited mining operations of the district. The chief operations are situated on the north side of the tunnel ; the reason of this is, that the rock is found sounder in this direction, and the stone more even in colour, and more regular in quality and texture, than to the south or dip of the stone. The entrance to these workings is driven from the Corsham or eastern end, immediately contiguous to the mouth of the Box tunnel, and it is here that the railways of the underground workings join the Great Western Railway on the same level. The chief or main road through the workings is carried from this point due west, in a direct line towards the Box Hill escarpment, a distance of one mile and six-eighths ; rising with the strata, for the purpose of keeping on the floor of the workable beds, thus making an incline to the west of about 1 in 40 ; and as the rise to the north is about 1 in 60, advantage has been taken of this, and the works so laid out, that much of the stone can be run on trollies without draught power—that is to say by gravitation—to the loading platform, where it is transferred from the quarry trollies into the railway trucks, which are taken into the mine to receive it. To economise and facilitate the operation of loading, the platform stands on a level a few inches higher than the sides of the railway truck, into which the stone has to be loaded, and by the upper level narrow-guage tramways this platform is placed in direct connection with the whole of the headings or workings ; and by its lower level broad-guage railway it is connected with the Great Western Railway. By this loading arrangement, we are enabled to load off into railway trucks from thirty to forty tons in the hour. One uniform system of getting or working the stone prevails throughout the quarries, and this system is an inversion of the mode of working coal. The coal-miner undercuts his coal, that the mass may fall and break, but building-stone so worked would make a valueless rubbish heap. The freestone miner or quarryman has to commence his operations at the roof of the stone. This picking operation is effected by means of adze-shaped picks, on the heads of which longer handles are inserted as the work proceeds, and the men thus make their driving a distance of six or seven feet back into the rock. The width or span of these stalls must of course depend on the soundness of the rock. In the Corsham workings, they can, without danger, be driven a width of from twenty-five to thirty-five feet. In the Box quarries, where the rock is not so sound, and the capping bed, before referred to, not so regular, the drivings are limited to from twelve to twenty feet. This is, of course, regulated by the space that may be safely opened without danger to the working beneath. It must be evident that the removal of eight or nine inches of the rock immediately under the ceiling deprives the overlying strata of the support of this area of stone, as effectually as its removal throughout, from roof to floor, would do, and any tendency to settle or drop is at once determined and any risk of life thus guarded against. Another process, by a fresh agency, is now called into exercise, for the cutting of the rock into blocks of required dimensions; for this, a one-handled saw is used. These saws are worked in lengths of four, five, six, and seven feet, and are made broad, rather I should say, deep, at the head or extreme point, so as to insure the saw sinking to its work at that point. The saw is worked at first horizontally, dropping a little as the cut goes on; and after the rock is thus opened down to the next natural parting, and the block thus separated laterally from the parent rock, levers are introduced into the bed or parting at the bottom of the block, and these levers are weighted and shaken till the block is forcibly detached at the back. It is then drawn down by crane power, and the broken end and the bed dressed with the axe, so as to make the block shapely ; it is then placed on a trolly, and allowed to run to the loading platform. After the first block is removed, it will be evident that the workmen have then access by that opening to the back of the bank of stone, and they avail themselves of this to work the saw transversely, which, separating the block from its back or hinder attachment, renders all further breaking off unnecessary, so the first block of each face is the only stone broken from the rock. To each face or heading of work, a ten-ton crane is erected in such position as to command the whole face. These cranes are now constructed telescopically, so as to accommodate them to slight variations in the headings, arising from differences in the depths of the valuable beds, and the expense otherwise attendant on frequent alteration of the crane is thus avoided, and the periodical shifts from old worked-out to new localities are effected with less trouble and loss of time. Sometimes after a block of freestone has been loosened in situ, a Lewis bolt is let into the face of the block, the chain of the crane attached to it, and the block is then drawn out horizontally. By the removal of the first stratum a sufficient space is obtained to allow the workmen an entrance under the roof; and vertical cuts are again carried down through the next bed to the parting below, and a transverse cut readily made ; meanwhile, the cutting is continued in the picking bed, the upper layer removed as before, and everything below this point quarried away, with all the sides of the block sawn, except the bed on which it has rested, and those abutting on the natural joints ; hence each block comes out ready to pass into the hands of the builder, sculptor, or dealer, and this with much less cost and loss in waste than formerly attended blasting and other powerful but rough modes of extraction. The continued repetition of these several operations produces a terrace or step-like profile in the workings, extending from the highest to the lowest of the beds worked, and thus they present themselves to the view.

Professor Phillips said such a paper as this was of the utmost practical importance in connection with science.

Professor Ansted pointed out that the Bath stone, when carried for building purposes to a distance, was exposed to rapid destruction by the action of the atmosphere. He attributed this to the manner in which the stone was quarried. It had been observed that this did not occur with the stone that was used in the immediate neighbourhood of Bath. This, no doubt, was attributable to the fact that the stone was not taken away from its own atmosphere, as is done. He would suggest, therefore, to the quarry-owners, that all the stone to be sent to a distance should be exposed to its own atmosphere for some considerable time, until it had became seasoned, as it were. He believed that if this were done, the stone would be as durable everywhere as it was in the immediate neighbourhood of Bath.

Obituary of John Armstrong

December 16, 2020 / iron_steam

From Minutes of Proceedings of the Institution of Civil Engineers, Volume 14, 1855

John Armstrong was born at the village of Ingram, Northumberland, on the 13th of October, 1775; his early years were spent in agricultural pursuits, and he scarcely had any opportunity of acquiring more than the rudiments of education; he then became the apprentice of a millwright, and the first mechanical engagement he received was under the late Mr. Thomas Dodgin, millwright, of Newcastle-upon-Tyne, by whom he was employed at the White-Lead Works, Bill Quay, where his Brother was the foreman.

About the close of the last century he settled in the neighbourhood of Bath, where he ultimately was engaged in the construction of the Pulteney Bridge, for a portion of which he became the contractor.

In the year 1804 he was employed, under the late Mr. Jessop, in the construction of the Docks, at Bristol, where he remained until their completion; all the lock-gates, swivel-bridges, cranes, steam-engines, pumps, sluices and other machinery being constructed under his immediate directions.

For some years he remained chiefly at Bristol, practising as a Millwright and Engineer, and generally engaged in such works as the lock-gates at Lydney, in the Forest of Dean, the gates and sluices of the Congresbury Drainage, &c.; he was then engaged under Sir Robert Smirke upon the construction of the bridge across the Severn, at Gloucester, and in 1821 his services were secured by Mr. Rennie and subsequently by Mr. Telford, for superintending the construction of the new arch of Rochester Bridge, on the completion of which he undertook the direction of the works for the Grosvenor Canal.

His next engagement was at the Thames Tunnel, under the late Sir Isambard Brunel, from whence his services were transferred to Messrs. Bramah, by whom he was employed, among other works, upon the construction of the lock-gates for the St. Katherine Docks, and subsequently in the direction of their building speculation at Calverley Park, near Tonbridge Wells.

At that period (1831) the post of City Surveyor, at Bristol, becoming vacant, he was unanimously elected to the position by the Paving Commissioners, and fulfilled the duties to their entire satisfaction, until within the last week of his life.

He was a very valuable public officer, and the loss of his services to the city will be felt, not in his own department only, as his general amenity of disposition and impressiveness of manner enabled him to become a mediator in many cases, so as to avoid litigation. He had in the course of his varied practice, during a long life, amassed a great store of useful information, which he knew how to apply with judgement; he was a sound good mechanic and millwright, of the school now fast passing away; his steadiness and punctuality could always be relied upon, and his decease, on the 17th of March, 1854, at the advanced age of seventy-eight years, was acutely felt by his family and a large circle of friends.

He was elected an Associate of the Institution of Civil Engineers, in the year 1828, and during his residence in the Metropolis was a constant attendant at the meetings.

Obituary of Marc Isambard Brunel

December 10, 2020 / iron_steam

From the Minutes of Proceedings of the Institution of Civil Engineers, Volume 10, 1851

Sir Marc Isambard Brunel was born in the year 1769, at Haqueville, in Normandy; his family had for several centuries held an honourable station in the Province, living on the estate on which he was born, and numbering among its members Nicholas Poussin, of whom France is justly proud.

He was educated at the seminary at Rouen, with the intention of his entering holy orders, but his predilection for the physical sciences was so strong, and his genius for mathematics and mechanics so decided, that, on the advice of the Superior of the establishment, he was removed, to follow a more congenial career.

His father then destined him for the naval service, which he entered on the appointment of the Mareschal de Castries, the Minister of Marine, and made several voyages to the West Indies. In this position, although only in his fifteenth year, his mechanical talents developed themselves actively on many occasions, and he surprised his Captain by the production of a sextant of his manufacture, with which he took his observations.

On his return to France, in 1792, he found the Revolution at its height, and, like all who entertained Royalist principles, was compelled to seek safety in emigration, which, with considerable difficulty, he accomplished, and found refuge in the United States of America, where, driven by necessity to the exercise of his talents, as a means of support, he followed the bent of his inclination and became a Civil Engineer and Architect.

His first engagement was on the survey of a tract of land near Lake Erie; he then became engaged in cutting canals, and was employed to erect an arsenal and cannon foundry, at New York, where he applied several new and ingenious machines; his highly ornamental design for the House of Assembly, at Washington, was rejected, as being inconsistent with the simplicity of a Republic. He was, however, engaged to design and superintend the construction of the Bowery Theatre, New York, since destroyed by fire; the roof of which was peculiar and original.

The idea of substituting machinery for manual labour, in the making of ships’ blocks, had long occupied his mind, and, in 1799, having matured his plans, finding the United States unable to afford full occupation for his inventive genius, he determined on visiting England.

Earl St. Vincent was at that time at the head of the Admiralty, and after the usual delays and difficulties, which were ultimately overcome, chiefly through the powerful influence of his steady friend and patron Earl Spencer, and aided by the recommendation of Brigadier-General Sir Samuel Bentham, who at once perceived and appreciated the merit of the machines, and the talent of the inventor, the system was adopted, and eventually the beautiful and effective machinery was erected, which has continued to the present time, without alteration, to produce nearly all the blocks used in the Royal Navy.

The construction of these machines was intrusted to the late Henry Maudslay, who with true discrimination, he selected for the purpose, and by whom he was ably assisted. The beautiful simplicity of these machines, their perfect adaptation to their various purposes, and notwithstanding the recent advances in mechanics, their continuing for nearly half a century in active work, without any improvements having ever been suggested, must rank themas among the most complete and ingenious pieces of mechanism ever invented.

A description of these well-known machines would be superfluous, but it should be remarked, that in them are combined all the motions and functions, since so universally applied to machines for working metals, the introduction of which, into engine and machine factories, has induced the substitution of machinery for manual labour, and has tended so essentially to secure for English machinery the deservedly high reputation which it has acquired.

The block machinery was completed in 1806, and it was estimated that the economy produced by it, in the first year, was about £24,000, two-thirds of which sum were awarded to the ingenious inventor, who was soon after engaged, by the Government, to erect extensive saw-mills, on improved principles, at Chatham and Woolwich; when he suggested modifications of the systems of stacking and seasoning timber, which, it is understood, are, after this lapse of years, to be carried in effect.

Some time previously, he invented the ingenious little machine for winding cotton-thread into balls, which, simple as it may at first sight appear, has exercised great influence in the extension of the cotton trade.

He found time, also, to invent an instrument for combining the use of several pens, for producing simultaneously a number of copies of a manuscript; a simple and portable copying machine; a contrivance for making the small boxes used by druggists, which had been previously imported in large quantities from Holland; a nail making machine also occupied his attention, and he discovered the system of giving the efflorescent appearance to tinfoil, by which it was fitted for ornamental purposes.

Among other more important improvements, must be mentioned, that of cutting veneers, by circular saws of large diameter; and to that is mainly due the present extensive application of veneers of wood to ornamental furniture.

A short time before the termination of the war, he devised the system of making shoes by machinery; and, under the countenance of the Duke of York, the shoes so manufactured, in consequence of their strength, cheapness, and durability, were introduced for the use of the army; but at the peace in 1815, manual labour becoming cheaper, and the demand for military equipments having ceased, the machines were laid aside.

Steam navigation also attracted his attention, and he became deeply interested in establishing the Ramsgate steam vessels, which were among the first that plied effectively on the River Thames; and on board of them, it is believed, that the double engines were first used.

About this period, after much labour and perseverance, he induced the Admiralty to permit the application of steam, for towing vessels to sea, the practicability of which he had strenuously urged. The experiments were tried chiefly at his own expense, a small sum in aid having been promised, but it was eventually withdrawn, before the completion of the trials; the Admiralty considering the attempt ‘too chimerical to be seriously entertained.’

He introduced various improvements in the steam-engine, and for nearly ten years persevered in the attempt to use liquefied gases, as the source of motive power, in which he was ably assisted by his Son; the necessary experiments were most laborious, and needed all the persevering energy and resources of a mind determined not to be foiled; in spite, however, of his efforts, after a great sacrifice of time and money, the plan was abandoned.

He furnished designs, also, for some suspension bridges, which, being for peculiar localities, exposed to the violence of hurricanes, in the Isle of Bourbon, exhibited, as usual, some original features.

The whole power of his mind, however, was soon to be concentrated on one great object, the construction of the Tunnel, for traversing from shore to shore, beneath the bed of the River Thames. It is said, that the original idea occurred to him, as applied to the Neva, at St. Petersburgh, in order to avoid the inconvenience arising from the floating ice; a plan which he offered to the Emperor Alexander, on the occasion of his visit to this country in 1814.

Undismayed by the previous signal failures, in the attempt to tunnel beneath the Thames, Brunel, confident in his own powers, persevered in his efforts, and in 1834, under the auspices of F. M. the Duke of Wellington, who always entertained a favourable view of the practicability of the scheme, a Company was formed, for its execution, and after numerous accidents, and suspensions of the works, accounts of which were frequently laid by Sir Isambart before this Institution, and are recorded in the Minutes of Proceedings, this great and novel undertaking was successfully accomplished, and opened to the public in the year 1843.

In the prosecution of this work, he received great assistance from his son, Mr. I. K. Brunel, V. P., and in a scientific point of view, the construction of the Tunnel will be regarded, as displaying at the same time, the highest professional ability, an amount of energy and skill rarely exceeded, and a fertility of invention and resources, under what were deemed insurmountable difficulties, which will secure to the memory of Sir Isambart Brunel, a high position among the Engineers of this country.

He received the honour of Knighthood, in 1841: and the Order of the Legion d’Honneur, in 1829, was a Corresponding Member of the French Institute, a Fellow of the Royal Society, and joined this Institution as a Member, in the year 1823, constantly attending all the meetings, giving accounts of the progress of his works, bringing forward subjects, taking part in the discussions, serving on the Council for some years, and aiding in the advancement of the Society, by every means in his power.

He was unaffected and simple in his habits, and possessed indomitable courage, perseverance and industry; whilst his general benevolence of disposition, constantly prompted him to the kindest acts, as it did to the forgiveness of injury, or slight, offered to him. His labours had so seriously impaired his health, that for some years after the completion of the Tunnel, he was unable to mix in active life, and he expired on the 12th of December, 1849, in his 81st year, after a long illness, as much regretted, as he had been loved and respected, by all who knew him.

Extract from Letter Entitled “The Ascent of Popocatapetl”

December 8, 2020 / iron_steam

From Proceedings of the Geological Society of London, Volume 1 (November 1826 to June 1833)

An extract of a letter was read from Lieutenant William Glennie, R.N., dated Mexico, May 6th, 1827, entitled “The Ascent of Popocatapetl.”

Many contradictory reports having long existed respecting the volcanic nature of this mountain, the author felt desirous of ascertaining its actual condition in person.

The ascent commenced during the month of April 1827, from the village of Ameca, situated in the province of Puebla, and near the N.W. foot of the volcano, at an elevation of 8216 feet above the level of the sea, and distant 14 leagues from Mexico.

The author describes the sides of the mountain as thickly wooded with forests of pines, extending to the height of near 12,693 feet, beyond which altitude vegetation ceased entirely. The ground consisted of loose black sand of considerable depth, on which numerous fragments of basalt and pumice-stone were dispersed. At a greater elevation, several projecting ridges, composed of loose fragments of basalt, arranged one above another, and overhanging precipices 600 or 700 feet deep, presented formidable impediments to the author’s progress; and, in one direction only, a ravine was observed to pass through these ridges, having its surface covered with loose black sand, down which fragments of rocks ejected from the crater continually descended.

After twelve hours of incessant fatigue the author gained the highest point of the mountain on the western side of the crater, 17,884 feet above the sea; at which station the mercury in the barometer subsided to 15.63 inches, and the temperature indicated by the attached and detached thermometers, was respectively 39° and 33° Fahr. at 5 o’clock P.M., when exposed to the direct rays of the sun. The plain of Mexico was enveloped in a thick haze, and the only distant objects visible at that time, were the volcanoes of Orizaba and Iztaccihuatl. The crater of Popocatapetl appeared to extend one mile in diameter, and its edges of unequal thickness descended towards the east. The interior walls consisted of masses of rock arranged per- . pendicularly, and marked by numerous vertical channels, in many places filled with black sand. Four horizontal circles of rock differently coloured were also noticed within the crater; and from the edges of the latter, as well as from its perpendicular walls, several small columns of vapour arose smelling strongly of sulphur. The noise was incessant, resembling that heard at a short distance from the sea shore during a storm; and at intervals of two or three minutes the sound increased, followed by an eruption of stones of various dimensions; the smaller were projected into the ravine before mentioned, the larger fell again within the crater.

The sensations experienced by the author were analogous to those usually felt by travellers at considerable elevations; viz. weariness, difficult respiration, and headache, the latter inconvenience having been first perceived at a height of 16,895 feet. Tobacco smoke and spirituous liquors were also found to produce an unusually rapid effect upon the sensorium.

Scilla Autumnalis on St. Vincent’s Rocks

December 5, 2020 / iron_steam

From The Journal of Botany: British and Foreign, Vol. XXVII, 1889

Scilla Autumnalis on St. Vincent’s Rocks. — It is gratifying to be able to announce that the hope expressed in the ‘Flora’ [of the Bristol Coalfields] (p. 201), that this rare bulb might yet be rediscovered on St. Vincent’s Rocks, has been justified. We are indebted for this pleasure to Mr. J. C. House, who, during a scramble in autumn, came upon a patch of about a hundred plants. It was somewhat perplexing, however, to find that the spot was made ground, the site of ancient quarrying; but this circumstance has been explained and accounted for in a very interesting and satisfactory manner. Mrs. Glennie Smith has kindly furnished information on the matter that was conveyed to her by Mrs. Glennie, widow of Mr. William Glennie, who was engineer, under Brunel, of many great works in the West of England. The account runs as follows:- When Brunel was about to commence the construction of the Suspension Bridge, Mrs. Glennie told him that he was going to destroy the Clifton locality of Scilla autumnalis, as it grew just where the approach on the Gloucestershire side was to be made. The engineer immediately informed himself carefully of the exact spot, and, before the ground was broken, he made some of his workmen dig up the turfs containing the bulbs, and transplant them safely beyond the reach and influence of the works he was about to begin. Mrs. Glennie could not remember if she ever knew the place to which the transference was made, but it seems tolerably clear that Mr. Brunel’s care was effectual in preserving for us a choice plant, the locality for which, when undisturbed, was evidently of very small dimensions.-J. W. WHITE (in Proc. Bristol Nat. Soc. v. iii. 232).

An Account of the Thames Tunnel

September 25, 2020 / iron_steam

By Marc Isambard Brunel

The Minutes of the Proceedings of the Institution of Civil Engineers, 1837

April 11, 1837

Mr. Brunel gave an account of the Thames Tunnel. Having described the nature and difficulties of the undertaking, and the previous attempts which had been made by others to effect a similar work, he explained, by reference to sections, the nature of the strata below the river. He had adopted the rectangular form of the present excavation, because the work would set better than if it had been of any other form, and it also had a better sustaining surface. The necessity of supporting the ground, and of having a sufficient shelter, had led to the adoption of the shield, respecting which so much had been said. The construction of this would be most easily understood, by conceiving twelve books set side by side on their ends. These would represent the parallel frames which, standing side by side, but not in immediate contact, filled up the excavation. Each frame was divided into three boxes or cells, placed one above the other, the adjustment of the floors of which, and other details, were minutely described by Mr. Brunel.

Each frame was furnished with two large slings, by which it might derive support from, or assist in supporting, its neighbours; it had also two legs, and was advanced, as it were, by short steps, having for this purpose an articulation which might be compared to that of the human body. The frame rested on one leg, and then one side was hitched a little forward; then resting on the other leg, the other side was hitched a little, and so on. Hence the shield might be called an ambulating coffer-dam, travelling horizontally.

The brick-work was built in complete rings, and the advantages of this system of building had been fully proved, by the fact of two dreadful irruptions of the river having produced no disruption. Such was the violence of the irruption, that the brick-work had in one part been suddenly reduced in thickness by one-half, and in one place there was a hole, as if pierced by a cannon-ball. At a few feet beneath the tunnel was a bed of quicksand 50 feet deep, and above it were strata of most doubtful consistency, some of which fell to pieces immediately they were disturbed. Still, however, the progress was certain, and only required patience, to allow the ground above to acquire sufficient density. He found gravel, with a mixture of chalk or clay, extremely impervious to water; in some cases he contrived to let out the water from the sand above, and thus obtained ground of sufficient density. The progress had been considerably retarded by land springs, which produced cutaneous eruptions, and destroyed the finger-nails of the workmen.

April 18, 1837

Mr. Brunel continued his description of the works of the Tunnel. He explained how the ground above had suddenly sunk down, owing to the run of at lower stratum of sand. This running sand, which was a great annoyance, consisted of five parts of water to one of sand. Bags of clay and gravel were not so effective, where there were many stones, as the interstices did not become properly filled up; in such cases the coarsest river sand was a better material; the water ran through it at first, but it soon stopped ; a mixture of gravel and clay was nearly impervious to water, but not so impervious as gravel and pounded chalk.

The Ventilation of the Tunnel was provided for by a pipe 15 inches square, passing out under the fire-place of the steam-engine boiler.

Mr. Gibbs stated, that he had found bags filled with clay and tow-waste, exceedingly impervious to water. Being called upon to build a sluice, in a place where piling was impossible, in consequence of the stony nature of the ground, he had formed a coffer- dam, by laying down bags full of clay and tow-waste, in tiers, on the top of each other, up to the surface of the water.

Notice Concerning the Thames Tunnel

September 24, 2020 / iron_steam

By Richard Beamish, M. Inst. C.E.

The Minutes of the Proceedings of the Institution of Civil Engineers, 1837

April 4, 1837

The paper states that several attempts had been made in former years to effect a communication betwixt the opposite shores of the Thames by means of a tunnel, all of which, however, failed. In 1798, Dodd proposed a tunnel at Gravesend; in 1804, Chapman projected one at Rotherhithe; and in 1807, Vazie commenced the construction of a shaft, II feet diameter, at a distance of 315 feet from the river. With Vazie was associated Trevethick, a man of great practical knowledge as a miner, and by indefatigable labor, a drift-way 5 feet in height, 2 feet 6 inches in breadth at the top, and 3 feet at the bottom, was carried 1046 feet under the river. In the spring of 1808, having first ascended from under a rocky stratum, though with a depth of at least 25 feet betwixt them and the bed of the river, the Thames broke in upon them, and not a single brick having been laid, the work was irretrievably lost.

In 1823 the subject of a tunnel was again agitated, and a company was formed, to carry into execution the plans of Mr. Brunel. The first proceeding was to sink a shaft. Twenty-four piles, with a shoulder on each, were first driven all round the circle intended for the shaft. One side of a wooden platform, or curb, was then laid on this shoulder, whilst the other side rested on an iron curb, having an edge below to which it was attached. Through this curb ascended forty-eight wrought-iron bolts, 2 inches diameter, to the height of 40 feet, the height to which it was proposed to raise the shaft. The regular building of the tower on the curb, with bricks laid in cement, was proceeded with, and yet farther bound together by twenty-six circular hoops of timber, half an inch thick, as the brick-work was brought up. At the top of the tower was placed another curb, and the long iron bolts passing through it, having their ends formed into screws, the whole was screwed solidly into one mass, and completed in three weeks. In a week after it was finished sixteen of the piles having been driven, two by two, opposite each other, the whole structure was sunk half an inch, carrying down with it the remaining eight piles, on which it was brought to a rest uniformly and horizontally, thus permitting the sixteen piles to be abstracted by opening the ground at the back. The whole weight supported by these eight piles was about 910 tons (the weight of the shaft). Having been left for three weeks to dry, and gravel having been heaped under the curb, the remaining eight piles were removed, two by two, till the mass rested on a bed of gravel. The machinery, viz., the thirty-horse high pressure steam engine, with gear for raising the excavated soil was now fixed on the top. The miners were placed inside, and by excavating from around the bottom, the whole descended by its own gravity.

Mr. Beamish then describes the peculiar difficulties which were experienced, previous to the first irruption.

The chasm in the bed of the river, formed by the irruption of 1827, was stopped by bags filled with clay, with hazel rods passed through them, the interstices thus formed being filled with gravel. The irruption of 1828 was met by similar means; but the funds of the company not being then sufficient for proceeding with the work, the shield was blocked up with bricks and cement, and a wall 4 feet in thickness was built within the Tunnel.

The work was then abandoned, and remained untouched for seven years. In 1835 a Treasury loan was granted, subject to the condition, that the most dangerous part of the Tunnel should be executed first. On resuming the works, the first object was to provide a drain for the water from the shield, for which purpose two reservoirs were formed under the middle pier, from which drifts were formed to the bottom of the great excavation and shield. The water was abstracted from the shield at the lowest point, and the pipes of two pumps, worked by the steam engine, being brought into the reservoir, all the difficulty of the drainage was overcome.

The removal of the old and the introduction of the new shield, was a work of no ordinary difficulty. The bricks and cement had, by the strong oxide of iron which the water contained, been converted into a mass harder than most rocks ; and not less than 1646 feet of surface, 342 feet of which constituted the ceiling, had to be supported, on the removal of the brick-work, previous to the introduction of the new shield. The means, however, adopted by Mr. Brunel, and which are described in the paper, were perfectly successful.

Obituary of William Froude

September 23, 2020 / iron_steam

The Minutes of the Proceedings of the Institution of Civil Engineers, 1880

William Froude, LL.D., F.R.S., the fourth son of the Ven. R. H. Froude, Archdeacon of Totnes, was born at Dartington Parsonage, on the 28th of November, 1810.

He was educated at Westminster School, and went thence to Oriel College, Oxford, being for some time a pupil of his elder brother, R. Hurrell Froude, an advantage to which he often referred. He took a first class in Mathematical Honours in 1832.

In the beginning of the year 1833, he became a pupil of Henry Robinson Palmer, V.P. Inst. C.E., then Resident Engineer of the London Docks. Mr. Froude was afterwards employed under Mr. Palmer on some of the early surveys of the South Eastern Railway and on other undertakings.

In 1837, Mr. Froude joined the engineering staff of Mr. Brunel, V.P. Inst. C.E., upon the Bristol and Exeter railway, where he had charge of the construction of the line between the Whitehall Tunnel and Exeter, and remained until it was opened in May, 1844.

Obituary of William Pole

September 13, 2020 / iron_steam

The Minutes of the Proceedings of the Institution of Civil Engineers, 1901

William Pole was born in Birmingham on the 22nd April, 1814, his father being Thomas Pole, of that town.

At the age of fifteen he was articled for six years to Mr. Charles H. Capper, an Engineer in Birmingham who represented the Horseley Company, at whose extensive works the pupil was enabled to lay the foundation of the extensive knowledge of engineering which he afterwards attained.

One of his early experiences was a visit paid to the Horseley Company by the Princess Victoria, then eleven years of age, who was much interested in seeing one of the old copper coins, weighing an ounce, forged to an ingot and then rolled out to a strip nearly 25 feet long, with a thickness of about inch. In 1836, a year before the Princess became Queen, young Pole came from Birmingham to London, and, as he died three weeks before Her Majesty, there was a marked coincidence in the duration of their life-work.

Obituary of William Bell

September 2, 2020 / iron_steam

The Minutes of the Proceedings of the Institution of Civil Engineers, 1892

William Bell was born at Leith on the 21st of September, 1818. He was educated at the High School, Leith, and afterwards at Edinburgh University, where, in 1839, he gained the gold medal and prize for Natural Philosophy, and was second in Mathematics.

On leaving the University in the following year, he became a pupil of the late John Hammond, then Resident Engineer on the Great Western Railway at Reading, where William Bell had many opportunities of making practical experiments on the working of locomotive engines, and on other subjects connected with mechanical engineering.

In 1842 he was placed by Mr. Hammond with the late John Thornhill Harrison on the Bristol and Gloucester Railway, and was subsequently Resident Engineer on the Cheltenham extension and on the Dawlish contract, which he measured up.