Part 1
# Monthly supplement of the penny magazine of the Society for the Diffusion of Useful Knowledge, issue 32, September 1 to September 29, 1832 ### By Unknown
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Monthly Supplement of
THE PENNY MAGAZINE
OF THE
Society for the Diffusion of Useful Knowledge.
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32.] September 1 to September 29, 1832
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THE THAMES TUNNEL.
[Illustration: Transverse Section of the Thames Tunnel.]
[Illustration: Section of Drift-way.]
As far back as the year 1802, a project was set on foot by some enterprising gentlemen, with a view of opening an archway under the Thames, between Rotherhithe and Limehouse, not far from the line of the present tunnel. The engineer selected for this enterprise was
## particularly qualified for such an undertaking, being an experienced
Cornish miner. Having made some borings at the Horse-ferry and on the opposite side of the river, he reported that “he was firmly persuaded the undertaking would not cost so much as had been conceived.” A subscription was, in consequence, raised; and a company was formed, under the denomination of the “Thames Archway Company.” Surveys, plans, and estimates were made, and an Act of Parliament being obtained, the work was begun. The engineer commenced operations by sinking a shaft of 11 feet diameter, at 330 feet from the line of the wharf on the Rotherhithe side. But the obstacles which he encountered from the nature of the ground increased to such a degree, as he proceeded, that at the depth of 42 feet he was obliged to desist. A subsequent report of borings, however, having proved very favourable, an enterprising proprietor engaged to complete the shaft (reduced to 8 feet diameter) to 76 feet, at which depth it was discovered that it would be dangerous to go deeper. At this stage of the proceedings, viz. in August, 1807, a second engineer was engaged by the Company, a gentleman whose name had been coupled with very great enterprises in the mining department. Before opening the drift-way both engineers agreed to reduce its breadth to 2 feet 6 inches at the top, and 3 feet at the bottom. At the depth of 76 feet they found the ground to consist of a _firm dry sand_; and there they opened the drift, which they carried forward in a gentle ascent. In November, 1807, when 394 feet of the drift had been completed, the services of the first engineer were dispensed with after four years and a half of hard labour. The Directors then agreed to give the second engineer £1000, by way of premium, if he succeeded in reaching the opposite shore. The drift was further extended to 814 feet, through equally firm dry ground, with the precaution, which had been employed from the beginning, of a substantial planking all the way. One hundred and thirty-eight feet more were cut through a bed of calcareous rock eight feet thick. But on the 21st of December, the head of the drift had hardly entered two feet into the stratum, which lay immediately over the rock, when the roof broke down in a loose state, leaving above head a cavity large enough for a man to stand in it. It is to be observed that there was no less than thirty feet of intervening ground between the drift and the river at the time this accident happened. The engineer succeeded in filling and securing the cavity; but, such was the nature of the whole ground above the rock, that, under the influence of an extraordinary high tide (on the 26th of January 1808), the ground again made its way fast in a loose state into the drift, and the river soon broke through 25 feet of ground. This same tide caused the destruction of the Deptford and Lewisham bridges. The engineer having succeeded in filling and closing this hole, the miners re-entered the drift, which was reduced to three feet in height, for the purpose of clearing the dangerous place. The miners had, therefore, to work on their knees: however, notwithstanding every effort to attain the opposite shore, they were driven away by the frequent bursts of sand and water. The engineer having afterwards sounded the ground from above, reported that he had no doubt the two fractures communicated underneath; and therefore admitted that it was quite impracticable to go further except by means of a cofferdam or caissons. On the 30th of March, 1809, the Directors offered a reward for the most approved plan of completing the archway. Fifty-four plans having been obtained by this announcement, they were referred to the opinion of scientific men. These gentlemen reported that they were unanimously of opinion, that an archway, of any useful size, was impracticable under the Thames by an underground excavation on any of the plans that had come before them; observing, at the same time, that they did not pretend to assign limits to the ingenuity of other men. A further trial was made by a third engineer, who operated from above the river, but it proved equally fruitless. Thus ended in 1809 all the exertions and the efforts made during nearly seven years, for the purpose of accomplishing an archway under the bed of the Thames; at the end of which period not so much as a drain had been completed, nor had the miners succeeded in working in any of those strata wherein the excavation for the archway must eventually have been effected.
Several years afterwards, Mr. Brunel was prevailed upon by one of the most active promoters of the archway enterprise (Mr. J. Wyatt) to turn his attention to the subject; and, being furnished with the documents connected with the first attempt, he devised his plan with the impression that both the excavation and the structure might be made on a full scale at once.
Before proceeding to an exposition of the plan adopted by Mr. Brunel, and of the means by which he has carried it into execution, we have to state that the structure of the Thames Tunnel, as represented in the annexed view, is 38 feet in width and 22 feet 6 inches in height externally and that a length of 600 feet, in the style of a double arcade, has been made, though one arch only is open to public inspection. The excavation therefore made under the Thames for this structure presents a sectional surface of 850 feet, which is equal to sixty times the area of the drift; but for a more comprehensive demonstration of this aggregate, the reader is to understand that the excavation which has been made for the Thames Tunnel is larger than the House of Commons, the dimensions of which are 32 feet in width and 25 feet in height, presenting therefore only 800 feet of sectional surface. At high water, the head of the river is about 75 feet above the foot of the excavation, and consequently three times the height of that room. These circumstances, independently of the nature of the ground, are sufficient to place the work of the Thames Tunnel among the boldest enterprises in the art of engineering.
Notwithstanding that the first attempt had contributed to discourage all idea of success, there were still sufficient evidences to indicate that by beginning in the stratum of dry firm sand, and keeping close under the stratum of clay forming the bottom of the river, there was space enough to effect the object, although the nature of the intervening ground had been ascertained to be very loose in many places. All the information obtained from the miner’s report concurred with the opinions of geologists in pointing out that the most eligible line for the Tunnel was to keep as near to the bottom of the river as the security of the work would permit. The first idea of the plan which appeared to the engineer best calculated for making an excavation fit for the object under so overwhelming a head of water, was suggested by the sight of a piece of a keel of a ship which had been eroded by the operation of the worm called the terido. From this he conceived it practicable, as his specification describes it, to make a circular opening of sufficient capacity at once. However, of the two modes which he described, he gave the preference to that of proceeding by forming simultaneously several contiguous excavations by means of an apparatus which has been denominated the shield. This shield upon the whole partakes of the character of a powerful cofferdam, applied in a horizontal instead of the vertical direction. It consists of twelve parallel frames lying close to each other like so many volumes in a bookcase. Each frame, being nearly 22 feet in height, is divided into three stories: the whole presents therefore thirty-six openings or cells. It is from these cells that the miners, operating by small quantities at a time, like so many teridos, are able to erode the ground in front, while others at the back bring up a substantial incrustation, namely the brick structure. For locomotive action each frame is provided with two substantial legs resting on equally substantial shoes, (not unlike snow-shoes); these legs are provided with articulations that fit the frames for a pacing movement. The shield has perambulated 600 feet of its assigned career; and has left behind a substantial structure in the form of a double arcade, which is now as long or nearly as the Burlington Arcade.
With regard to the external form of the structure, and the mode adopted for its execution, it must be obvious to persons acquainted with such matters, that the most substantial form, and the best calculated at the same time to prevent, as far as practicable, any derangement in alluvial strata of various degrees of density, is the square form, as corresponding with that mode of building which is technically called underjoining and underlaying. Thus, in fact, the bed of the river, with its contents, has been underlayed, just as the Customhouse has been, to receive the superstructure.
An indispensable requisite in a work of this nature was, that it should be made proof against the greatest disasters that were to be apprehended, notwithstanding every precaution that could be taken. Mr. Brunel’s plan was considered by his Grace the Duke of Wellington, by Dr. Wollaston, and by those engineers and scientific men who had the opportunity of examining the designs, and of hearing the description given by the engineer, as being well calculated to accomplish the contemplated object, although some apprehensions were raised at the time as to what might result from so formidable an occurrence as an irruption of the river, considering the extent of the devastation it might cause in the ground and among the works. The engineer afforded such explanations as allayed, in some degree, those apprehensions which, it must be admitted, he has since completely dispelled by undeniable facts.
It was under these auspices that the plan was brought before the public in 1823, and that in the month of February, 1824, subscriptions were obtained to a large amount to carry it into effect, notwithstanding the novelty of the scheme, and its risks.
[To be continued.]
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BRITISH BIRDS.
[An Outline of the Smaller British Birds, by Robert A. Slaney, Esq. M.P.]
This little volume is evidently the production of an intelligent, humane, and truly amiable mind, whose enthusiasm on a favourite study is calculated to win attention and to enamour others of the same subject.
It is painful to reflect, that while we are everywhere surrounded by natural objects, animate and inanimate, each replete with interest and beauty of its own, so many of us should be ignorant, and thence insensible and heedless of these charms. This negligence is almost culpable, for so slight is the expense of time and study required to render ourselves familiar with many of the works of nature, that the busiest and poorest could afford the sacrifice, and thus put themselves in possession of a pure and cheap source of enjoyment. But old writers encumbered the simplicity of natural history with Latin and Greek terms, and words of _interminable_ length, making appear difficult and abstruse what in reality is not so. It has been the laudable object of Mr. Slaney, as of other writers of the present day, to make these matters easy, as they should be. In the little volume now before us, our readers will find every thing perfectly intelligible to the commonest capacity, and its attentive perusal will delight and enrich their minds with numerous interesting accounts of the formation and habits of the beautiful winged creatures we every day see flitting around us, while, by indicating the course and modes of observation to be pursued, it will facilitate their acquirement of other and more extensive branches of natural history.
In allusion to the general ignorance on these subjects even among the wealthy and educated classes of society, Mr. Slaney says very amusingly, “We have sometimes asked our fair young friends if they knew as many of the smaller birds as they could count on their fingers? They usually answered confidently in the affirmative, but could seldom get much beyond one hand.”
Now this ignorance, which is mere negligence, we again say is almost culpable, and, as it tends to remove this ignorance by a single and delightful process, we therefore warmly recommend this ‘Outline of the Smaller British Birds.’ The reader will find in it, beside Mr. Slaney’s own descriptions and observations, many amusing and instructive extracts from some of the most distinguished writers on natural history, such as White of Selborne, who has so admirably described what passed under his own eyes in a province of England; Wilson, originally a common weaver of Paisley near Glasgow, who found an unknown world of beauty in the birds of the American wilds, his accounts of which unite the accuracy of philosophy with the beauty and glow of poetry; Knapp, the author of the ‘Journal of a Naturalist;’ the late Sir Humphry Davy, &c. &c.
The following extracts will give an idea of the work:--
“Perhaps, if we take a short view of our common birds, beginning with the missel thrush, the largest British songster and coming down to the golden-crested wren, it may repay our trouble. Within these limits we shall find about seventy birds, varying in size, form, habits, structure, and notes: most of which are seen, at one or other time of the year, in the fields and woods which surround our dwellings, and many of them are constantly with us. They may be divided into hard-billed birds, feeding on grain, seeds, and fruits; and soft-billed birds, on insects and worms. Some feed on both; and many grain-eaters devour insects, though few of the soft-billed eat seeds. These are again divided into families, from some peculiarity in their formation (chiefly the beak): as the finches, buntings, warblers, &c.
“In considering the birds to which we have confined our view, we find they divide themselves into three sets--winter visiters, summer visiters, and sojourners.
“The smaller winter visiters, about five in number, come to our hospitable shores in autumn, and leave us in the spring. They all come from colder climates; and as the frost locks up their sources of subsistence in the north, (where, in summer, they have built their nests and reared their young,) led by that wonderful instinct which their Maker has implanted, they direct their airy flight across the mountain and the flood.
“The summer visiters, on the other hand, coming to us in the spring, and leaving us in the autumn, all come from the south; and depart again to the regions of the sun as winter approaches.
“The winter visiters are all (except the grey wag-tail), hard-billed birds, fitted to feed on seeds, berries, and fruits found during our winters. They are chiefly gregarious, and seem by their numbers to band themselves together against the piercing season!”
The Fieldfare, the Redwing, the Starling, are the commonest of these winter visitors.
“Let us turn to our summer visiters. They come to us in the spring, as the weather becomes warmer, the earth clothed with vegetation, and the air and surface of the ground begin to teem with insect life; when the chrysalis bursts its case, the worm, and slug, and caterpillar, ‘and every creeping thing after his kind,’ come forth; then appear, led by an unseen hand, myriads of soft-billed warblers from distant lands, formed to thin the insect race, and whose services warmly deserve our gratitude and protection.
“From March till May ten thousand busy pinions ply the air, by day and night, and bring those melodious visiters from all the southern countries, where the parching heat at this season renders their food difficult to procure. As they arrive, they disperse throughout the country,--
‘They to their grassy couch, these to their nests.’
Each grove and shrubbery, each ‘bosky dell from side to side,’ each heath and upland common, each hedge and garden and petty rural homestead, receives some of these wandering minstrels. It is probable they return year after year, if undisturbed, to the same haunts; and perhaps revisit with as much pleasure as ourselves the well-known scenes of their youth--
‘When Nature pleased, for life itself was new, And the heart pictured what the fancy drew.’
“We may smile at the idea of fancy or feeling in a bird; yet those who have closely watched those beautiful beings will readily believe as much difference in their dispositions as Cowper found in the temper of his hares. The ‘mellow lark who at Heaven’s gate sings’ must be endowed with instincts--superior to those of the ‘poor beetle that we tread upon.’ Memory birds possess in a considerable degree. Swallows will choose out the same nook for their nest year after year. That elegant little bird, the common fly-catcher, is attached to the same spot. A pair built for three summers successively in the same place, close to the writer’s study window; and their chase for gnats and other insects was under his view, as he sat reading: and for a considerable period the parent birds, ‘from early dawn till latest eve,’ might be observed catching assiduously our English muskitoes.”
Among the most interesting of these summer visitors are the nightingale, the whitethroat, the redstart, the fly-catcher, the swallow, and the cuckoo.
The third division, viz., sojourners or resident birds, are then considered. Of these only five belong to the soft-billed birds, namely, the robin and the wren, the hedge-sparrow, and the black and white water wagtail. In the classes of hard-billed birds always with us, are the nuthatch, the blackbird, the thrush, the greenfinch, the bullfinch, the goldfinch, the chaffinch, the sparrow, the lark, and others too numerous to mention here, but which will be found classified, and very ably described in Mr. Slaney’s volume.
“About twenty song birds of passage come to us, and rear their young in our island. Of these some are local species, and some but partially and thinly scattered. These guests of summer remain to enjoy our finest weather, when the warmth of the climate, and the richness of vegetation, and the harmony of nature, invite us abroad. We think that our fair readers might double the pleasure of their walks if they knew each note of their tiny visitant, and distinguished the form and plumage of every feathered songster.--p. 12.
“The nightingale is celebrated in all countries: its sober plumage of tawny brown would never attract our attention, though its light and elegant form might excite admiration. This delightful songster is not found north of Shrewsbury in the west, or Doncaster in the east; and is seldom seen in Devonshire or Cornwall. ‘It has been observed that it is not seen but where cowslips grow plentifully,’ indicating a damp, cool soil, and probably yielding those insects it delights in. All writers praise the song of this bird. We will only quote the eloquent expressions of a naturalist (Wilson) called forth by a songster of the new world:--
“‘When every object around conveys the sensation of joy, and heaven’s abundance is, as it were, showering around us the grateful heart beats in unison with the varying elevated strains of this bird. We listen to its notes in a kind of ecstasy as a hymn to the great and most adorable Creator of all. Abject must that heart be, and callous those feelings, and depraved that taste, which neither the charms of nature, nor the melody of innocence, nor the voice of gratitude or devotion, can reach.’”--p 16.
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LAMBETH PALACE.
[Illustration: Gate-house of Lambeth Palace.]
Lambeth Palace, which stands on the right bank of the Thames, within half a mile of Westminster Bridge, has been for many centuries the principal residence of the Archbishops of Canterbury. The manor belonged originally to the see of Rochester, to which it had been granted, before the Norman Conquest, by a sister of Edward the Confessor; and it was obtained in exchange for some other lands, by Baldwin, Archbishop of Canterbury, in the year 1189. There is reason to believe, however, that the Archbishops had a house here for at least a century before this time. The ancient possession of Lambeth by the see of Rochester is still commemorated by the payment to the latter, in two half-yearly sums, of five marks of silver, in consideration of the lodging, fire-wood, forage, and other accommodations which the Bishops of Rochester had been accustomed to receive here whenever they visited London. When the Archbishops of Canterbury first obtained possession of the place, the buildings on it appear to have been old and mean. With the exception of the Chapel, the whole of the present structure has certainly been erected since the middle of the thirteenth century.
The Palace, as it now appears, is an irregular but very extensive pile, exhibiting specimens of almost every style of architecture that has prevailed during the last seven hundred years. The oldest part of it, as we have just said, is the Chapel, which is supposed to have been built towards the close of the twelfth century. It consists of two apartments, divided by a richly-ornamented screen, and measuring together 72 feet in length by 25 in breadth. The height of the Chapel is 30 feet. Under it is another apartment of smaller dimensions, formed by a series of arches, supported by pillars, and now used as a cellar, though in ancient times it may not improbably have served as a place of worship. Another of the most remarkable portions of the edifice, the Great Hall, was originally erected by Archbishop Chicheley in the beginning of the reign of Henry VI.; but after the Palace had been sold by the Parliament in the time of the Commonwealth, this magnificent apartment was pulled down. It was rebuilt, however, on the old site, and in close imitation of the former hall, after the Restoration, by Archbishop Juxon, at an expense of £10,500. It stands on the right of the principal courtyard, and is built of fine red brick, the walls being supported by stone buttresses, and also coped with stone, and surmounted by large balls or orbs. The length of this noble room is 93 feet, its breadth 38, and its height 50. The roof, which is of oak and elaborately carved, is
## particularly splendid and imposing. The Gate-house, which forms the