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loaded and sunk upon as flat a bottom as could be dredged. The masonry was then built up within the casing to high-water mark, when the sides of the caisson were removed, and the work was protected by piles driven side by side all round the pier. The same system was adopted by Mylne in getting in the foundations of Blackfriars Bridge; but both have proved defective, and the failure in each case was greatly hastened by the removal of the numerous piers of Old London Bridge, which increased the velocity of the flowing tide and the consequent scour' of the stream in the bed of the river above-bridge. In securing the foundations of the Waterloo and New London Bridges, Rennie adopted the costly but effectual plan of the coffer-dam—that is, enclosing a sufficient space within double or treble rows of piles driven deep into the bed of the river. The enclosure was made watertight by planking and clay puddle packed between the piles, and the water within the dam was pumped out by means of engine power. The bed of the river, thus exposed, was dug out to the proper depth, when timber piles were driven deep beneath the entire foundation, upon which the solid masonry was then erected. The same plan continues to be pursued in many cases where great solidity of foundation in river-beds is required.

Iron began to be introduced for the purpose of securing foundations, in cases where the superstructure was of a lighter chaTacter, or where sands, or mud, or bog, had to be crossed. Hence Dr. Pott's invention of cylinder piles, which consisted in employing iron cylinders, placed in a position for sinking, the lower end being open, and then exhausting them by means of a pneumatic apparatus. The contents of the tube, whether of air or fluid, were thus sucked out, and the tube was forced downwards by simple atmospheric pressure. A succession of piles might be placed over that first sunk, by means of flanges, or other joints, so that piles of any length could be employed. In the case of Mr. Brunlees' disc piles, upon which the Morecombe Bay iron viaducts are erected, the reverse process is employed, and the air, water, and sand, instead of being drawn out of the cylinders by exhaustion, are forced out during a slight rotating motion of the piles, which gradually descend to their proper depth. By one or other of these methods, it would even be possible to obtain foundations for a lighthouse on so treacherous a basis as the Goodwin Sands, whilst for crossing the sandy, muddy beds of broad Indian rivers, the invention is calculated to be of great value. Mitchell's screw-pile is another favourite method of employing iron in securing firm foundations in treacherous ground, the pile being so constructed as to be capable of being screwed down to almost any depth. But the

most

most remarkable application of iron for the purpose of securing foundations in difficult ground at great depths, is that which has been recently adopted by Mr. Hughes, and was first employed by him in constructing the piers of the new bridge over the Medway, at Rochester. It was proposed to build the piers of the bridge upon a series of cast-iron cylinders, each seven feet in diameter; and it was originally intended to force them to a sufficient depth into the bed of the river (which indicated soft clay, sand, and gravel) by means of Dr. Potts' pneumatic process, which had succeeded in similar cases. But it was discovered, soon after the works commenced, that the bed of the stream was encumbered in many places by the ruins of an ancient bridge, which history records as having been taken down some five hundred years ago. On examination the bottom was found to be a compact mass of Kentish rag stone, through which it was impossible to force the cylinders by atmospheric pressure. It was then determined to reverse the process, and to give to each cylindrical pile the character of a diving-bell, keeping the interior clear of water by forcing air into it by means of a double-acting pump driven by a steam-engine, so that the workmen should be enabled to proceed with the excavations in the interior of the cylinder, and afterwards with the masonry of the foundations. To enable the workmen to

pass into and out of the cylinder, and to throw out the excavated uff as well as to atroduce th necessary building materials, without removing the pressure from the water held down by the pneumatic force at the bottom of the excavation, the top of the cylinder was fitted with a moveable wrought-iron cover, capable of being securely bolted to it, and over this were placed two cast-iron chambers, or air-locks. These chambers had two openings, one towards the interior, the other towards the exterior, both being securely fitted with an air-tight flap, or valve. After a loaded bucket had been raised from the bottom, by means of a light wrought-iron crane fixed within the cylinder and drawn through the opening referred to, the cover was hermetically closed, when the outer aperture was opened and the stuff cast out. Building materials were introduced by the same process, and the compression of the air within the interior of the cylinder, in which the men were at work, perhaps some twenty feet below water, was strictly preserved. Strong glass lenses were fitted into the cylinder cover, and in the chambers of the air-locks, to give light to the workmen, but when at a considerable depth candles were constantly used. As the excavation proceeded, the cylinder descended, until the pile was gradually sunk to the desired depth. The piles of the Rochester Bridge were thus carried down thirty feet into the

river's

river's bed before the building commenced ; in Mr. Stephenson's bridge across the Nile, they are sunk thirty-three feet through soil of a peculiarly shifting character ; but in Mr. Brunel's Saltash Bridge they were sunk not less than ninety feet, a depth of foundation that would have been considered fabulous but a few years ago. In the latter case, an exterior cylinder was also employed, which was afterwards withdrawn when the foundations had been secured. It is worthy of remark that the cost of getting in foundations by this process has been very considerably reduced—the total cost of completing those of the Rochester Bridge to four feet above the water-line being effected at less than one-half of the estimated cost of coffer-dams alone. The effect of the great atmospheric pressure upon the workmen employed within the cylinder, is sometimes serious. When the pile bas descended to a considerable depth, it is possible to work for only a comparatively short time. On entering the cylinder, great pain is felt in the ears, blood sometimes runs from the nose and ears, while the breathing is considerably affected; persons of weak lungs are found quite unfitted for the work. The men who persevere are said to experience an immense sharpening of the appetite, and consume increased quantities of animal fooddoubtless caused by the greater waste produced by the increased quantity of oxygen inspired.

The last great project in iron bridge building that we have heard of—and a project it is likely for some time to remain—is a tubular bridge across the Straits of Dover. A French engineer, M. Thomé de Gamond, having projected a tunnel under the sea between England and France, which he states has received the favourable consideration of the French government, Mr. Boyd, not to be outdone in daring, projects his bridge over the sea from Shakespeare's Cliff to Cape Grinez. Mr. Boyd proposes a bridge of iron tubes of 500 feet span, laid upon 190 towers 300 feet high, to be constructed at an estimated cost of 30,000,0001. sterling. Apart from the question of practicability, we greatly doubt the utility of such a bridge. The entire number of persons annually travelling between England and all the ports of France, does not amount to 250,000 persons, or less than four days' traffic over London Bridge. Seventeen millions of persons annually pass through the railway stations on the south of the Thames, the greater number of whom have to cross the bridges to and from the north side of the river. We are ready to recognise the necessity of an iron railway bridge across the Thames to a convenient station on the north bank-a measure which would, more than any other project, relieve the block' of the bridges, and the crowded thoroughfares leading to and from

the

the City.

But there is no such pressure of traffic across the Channel, the existing means being more than sufficient for its accommodation. To this we must add that there is considerable force in the observation of a celebrated English wit to a Frenchman on the subject of Anglo-French relations: The best thing that I know of between England and France is—the sea.'

THIG

Art. IV.-Fasciculi Zizaniorum Magistri Johannis Wyclif, cum

Tritico. Ascribed to Thomas Netter, of Walden, Provincial of the Carmelite order in England, and Confessor to Henry V. Edited by the Rev. Walter Waddington Shirley, Tutor and late Fellow of Wadham College, Oxford. Published by the Authority of the Lords Commissioners of Her Majesty's Treasury, under the Direction of the Master of the Rolls.

London, 1858. THIS volume is among the first fruits of the grant made by

Government for rendering accessible to the public the original materials for the mediæval history of England :

On the 26th January, 1857, the Master of the Rolls submitted to the Treasury a proposal for the publication of materials for the history of this country, from the invasion of the Romans to the reign of Henry VIII.

* The Master of the Rolls suggested that these materials should be selected for publication under competent editors without reference to periodical or chronological arrangement, without mutilation or abridgment, preference being given in the first instance to such materials as were most scarce and valuable.

• He proposed that each chronicle or document to be edited should be treated in the same way as if the editor were engaged on an Editio Princeps ; and for this purpose the most correct text should be formed from an accurate collation of the best MSS.

"To render the work more generally useful the Master of the Rolls suggested that the editor should give an account of the MSS. employed by him, of their age and their peculiarities, that he should add to the work a brief account of the life and times of the author, and any other remarks necessary to explain the chronology; but no other note or comment was to be allowed, except what was necessary to establish the correctness of the text,

• The proposal of the Master of the Rolls was approved by the Lords of the Treasury, who only added the suggestion, that “the preface to each work should contain a biographical account of the author so far as authentic materials existed for that purpose, and an estimate of his historical credibility and value." Such is the code of instructions which has guided the re

spective

spective editors, and fixes the standard by which their labours are to be tried; and on the whole we entirely approve the judgment with which it bas been framed.

It may doubtless appear to the general reader, that in some instances the documents might be retrenched or abridged with advantage ; but it is no easy task to decide what is absolutely worthless to every inquirer and with reference to every subject, and garbled extracts inspire no confidence. Original documents have been contemptuously compared to thrashed straw, but the grains of wheat they contain, if few, are singularly precious, and no one man's discernment can be trusted to collect them all. With more reason perhaps the reader may complain that amid the difficulties of an obscure subject and of obsolete language, he is denied the belp of a commentary. But it must be remembered the object of the Treasury grant is to bring within the reach of the student the original materials of history, not to produce a series of historical works; and so many are the controverted points which perplex mediæval antiquities, that if the editors were invited to put forward their own views, each volume would speedily swell to an inconvenient bulk, and involve an unreasonable expense.

In selecting the documents for publication, those which throw light on the life and writings of John Wycliffe have a strong daim for preference.

That the world knows nothing of its greatest men’ is true in more senses than that which the poet * intended to convey. Of many who have exercised the largest influence on the minds of their fellows little remains but a name. The very personality of Homer is disputed. In modern days how meagre is the biography of Shakespeare. Wycliffe, the patriarch of the Reformation, has been compared to the voice of one crying in the wilderness '-a voice and nothing more--a mighty agency which is known only in its effects. He has passed away and has left behind him little or no certain record of himself. He was not an egotist; intent on instructing others, he seems to bave taken no note of the workings of his own mind—ardent in the pursuit of truth, he never paused to measure the extent or recount the steps of his progress. Thus, but scanty materials for his biography can be extracted from his works, and though a prodigious number of his MSS. have escaped the destructive zeal of his enemies, they are scattered through various libraries of Great Britain and the Continent. They cannot be deciphered except by the antiquary, and the catalogue of those which have been made accessible to the general reader by printing, is very brief (p. 529).

* H. Taylor, ' Philip van Artavelde.'

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