the boat might be able to land, and relievo him from the distress he was in. By degrees, the body became so of fensive, that it was not in his power to get quit of it without help; for it was near a month before the attending boat could effect a landing; and then it was not without the greatest_difficulty that it could be done, when they did land. To such a degree was the whole building filled with the stench of the corpse, that it was all they could do to get the dead body disposed of, and thrown into the

sea.

It is not easy to conceive a more dreadful situation than this, to a human being with a mind of any sensibility. Alone on the sea-beat rock, left to his own miserable reflections, with the putrefying remains of his companion beside him, to remind him of his own approaching end; to remind him also of mutual quarrels and injuries, perhaps of corrupting conversations, which would then press with unspeakable weight on his conscience, without a regular employment to occupy his mind, without a friend to whom he could unburden his heart, perhaps without any just views of religion, but with dark and awful forebodings, there can scarcely be imagined any thing more appalling, or more full of lessons of spiritual instruction.

TWELFTH WEEK-THURSDAY.

ARCHITECTURE.-THE THAMES TUNNEL.

ONE of the most remarkable undertakings in modern times connected with architecture, is the attempt to form a communication between the two banks of the Thames, at London, by means of a subterraneous passage or tunnel near Rotherhithe. This plan was first suggested by some private individuals, in the year 1802, who formed themselves into a company, and having taken surveys, obtained an act of Parliament, and, under direction of an experienced architect, attempted to pioneer their course by means of a drift-way; but, after this preliminary work had been

carried on for oven years, and had proceeded to a considerable extent, the whole scheme was abandoned as impracticable.

The celebrated Mr. Brunel was at last applied to, by one of the most spirited projectors of the undertaking ; and this able engineer, having turned his attention to the subject, formed the bold plan of carrying on both the excavation and the structure on a full scale at once.

It is instructive to remark, that the most important and best conceived schemes of ingenious men, have been aided in their execution by the hints which they have received from the operations of Creative Wisdom in the works of nature. I have already stated, that Mr. Smeaton took his idea of extending the base of the Eddystone lighthouse, with the view of giving it greater power of resisting the violence of the waves, by reasoning on the form of the oak, thus deriving a most valuable principle from vegetable nature; Mr. Brunel obtained a hint equally important, in overcoming the peculiar difficulties of his undertaking, by borrowing from a remarkable contrivance of animated nature. The difficulty to be overcome, was, the guarding against the effects of the river in pressing on and pervading the strata through which he had to excavate his way. It had been found by the experience of the engineer formerly employed, that on certain strata the · power of the tide was so great, that even the depth of thirty feet below the bottom of the river was no security against its influence. The first idea of the contrivance which appeared to Mr. Brunel best calculated for making an excavation fit for his object, under such an overwhelming head of water, was suggested by observing the operations of a worm called the teredo, on a piece of the keel of a ship. The erosions made by this curious insect led him to form a plan by which, as his specification describes it, he might make "a circular opening of sufficient capacity at once." His plan was to form simultaneously several contiguous excavations, by means of an apparatus which he has denominated the shield. It consists of twelve parallel frames lying close to each other, like so many volumes in a bookcase. Each frame, being nearly twenty

two feet in height, is divided into three stories, the whole thus presenting thirty-six openings or cells. It is from these cells that the miners, operating by small quantities at a time, like so many teredos, are able to erode the ground in front, while others at the back bring up a substantial brick structure, which, continuing the similarity, may be likened to the incrustation formed by the insect. For locomotive action, each frame is provided with two substantial legs, resting on equally substantial feet, or slippers, as they are technically called. These legs are furnished with articulations that fit the frames for a pacing movement, when it is necessary to advance, thus borrowing again from the mechanical contrivances of Creative Wisdom in the animal world.

It would lead us into too minute a detail, to state all the difficulties which were to be encountered in this extraordinary work; but some idea of them, and of the ingenuity with which they have been overcome, may be conceived, when it is remembered, as already stated, that the influence of the tide on the strata at the bottom of the river, was found to extend to the depth of at least thirty feet; and when to this is added another fact, of which the engineer was experimentally made aware, that, at the depth of about eighty or eighty-five feet, there was a very dangerous stratum of quicksand, which it was necessary to avoid. Between these two dangers, it was of essential importance to operate so as to keep as much as possible out of the influence of both. Of the two, the effect of the tide was most to be dreaded; and, such was the nature of this difficulty, that it required all the resources of art to conquer it. In its natural state, the ground was found to be compact, even when it consisted of sand or gravel; but an excavation on so large a scale could not be made, without opening new vents for the exudation of water, which disturbed the strata, decomposing and softening some, kneading others into various degrees of consistency, and reducing others almost into a liquid state.

Notwithstanding these discouragements, however, the work was commenced, in the month of March, 1825. The scheme was to carry two arch-ways, on the plan of

a double arcade, below the river, of sufficient dimensions to form commodious carriage-ways; but, in order to accomplish this, it was found necessary to erect an immense mass of brick-work, thirty-eight feet in width, and twentytwo feet sixteen inches in height externally, of which the arch-ways in the centre were only to form a comparatively small proportion. The work proceeded with various. success, and under constant danger, till the 18th May, 1827; during which interval, the ground was frequently in so loose a state, that the river deposits were found in the way of the excavation, and the influx of water was excessive. Once, indeed, a shovel and hammer having been left at the bottom of the river, during an inspection by a diving-bell, these tools disappeared, and were soon afterwards found, in advancing one of the frames of the shield, having descended at least eighteen feet into the ground.

On the day last mentioned, some vessels having been accidentally moored over the head of the tunnel, this obstruction to the stream caused those loose substances which protected the softer ground from the action of the tide, to be washed away; in consequence of which, the river soon made its way into the tunnel, forming at first " a transparent curtain between the shield and the brick structure." Every exertion to oppose its progress proved unavailing. The river broke in, and filled the tunnel. On examining the whole with the diving-bell, the structure was ascertained to be perfectly sound, and the shield, to all appearance, undisturbed. A plan was immediately adopted to stop the gap, by means of clay in bags, armed with small hazel rods. About three thousand tons of these materials, along with some loose soil, were required to fill the chasm, which was found to exceed thirty-eight feet in depth.

The tunnel was cleared of water by means of the steamengine, which had been originally erected for the purpose of draining, and the work was recommenced with renewed spirit; but on the 12th January, 1828, a second irruption of the river took place, in which six men lost their lives, and the younger Brunel very narrowly escaped.

These repeated irruptions, though discouraging, by no

means damped the hopes of the ingenious engineer. He had, by the extraordinary resources of his mind, been able to overcome difficulties, which had been esteemed insurmountable, having constructed six hundred feet of tunnel, the sectional surface of which was greater than that of the House of Commons, through ground wherein experienced miners had not been able even to construct a drain. It is true, indeed, that in the work still to be performed, the difficulties of the undertaking, instead of being diminished, were expected to increase; but experience had taught much, and there appeared to be no obstacle which genius and perseverance might not be able to overcome.

The pecuniary resources of the company, however, were now nearly exhausted, and it was necessary to discontinue the work till fresh funds could be obtained. After a cessation of seven years, government was induced to furnish pecuniary aid, for the accomplishment of what might well be called a great national object,-not so much, indeed, on account of the immediate advantage to be gained, though this will be considerable,-as on account of the triumph which it will afford to practical science, and the stimulus which may thus be given to still more gigantic undertakings.

At

During the second irruption of the river, the shield had been torn in pieces by the violence of the stream; but a new and more substantial shield was formed, and the work was so actively carried on, that by the middle of September, 1837, a very great advance had been made towards low-water-mark, on the Wapping side of the river. this period, an irruption again took place; but, owing to the precautions which experience had suggested, it was not attended with any violence, and comparatively little evil resulted, beyond the interruption of the work, and the filling of the tunnel with water and mud. The aperture

was again filled up with bags of clay, and the operation is at present proceeding with so much spirit, that it is confidently expected that this great work will, in a short time, be placed beyond all danger.