The wonders of the world

by John Loraine Abbott

This aqueduct forms part of the Peat Forest canal, which is a branch of one of the canals extending out from Manchester in England. The latter city is the great center of the cotton manufacture for England, and perhaps the principal manufacturing town in the world. Before the invention of what was called the spinning-frame, in 1767, the entire imports of cotton into Great Britain did not amount to four million pounds a year, and the value of exported cotton goods was not over one million dollars. But so rapid has been the improvement of machinery, and the increase of manufactures, that in 1840 the imports of cotton amounted to the prodigious quantity of nearly six hundred million pounds, of which nearly five hundred million were manufactured. And in 1854, these imports amounted to nearly nine hundred million pounds, of which about the same proportion was manufactured as in 1840. Of this immense manufacture, Manchester is the center; and to this may be added various other manufactures, as in silks, worsteds, machinery, &c., &c., &c. As a consequence of this immense business, seeking, of course, outlets to market, Manchester has become a great center of internal navigation. So early as 1761, the Duke of Bridgewater’s canal was constructed; and this was soon followed by the Bury and Bolton canal, in 1791; by that to Ashton and Oldham, in 1792; and by that to Rochdale, in 1794. And these, again, are connected with other canals in such a manner as to establish an easy communication with the eastern, central and southern counties, including the ports of Hull, London and Bristol, as well as Liverpool, which, of all others, is the port of Manchester. It is on one of these side canals that the aqueduct, a view of which is given in the cut above, is located; or rather, it forms part of the canal itself. It is not so much to be noted for its greatness or expensiveness, as for the fact that it was among some of the earliest structures of this kind, which have since become common wherever canal navigation is known.

AQUEDUCT ON THE PEAT FOREST CANAL.

THE THAMES TUNNEL.

A tunnel, in engineering, is a subterranean passage cut through a hill, or under a river, for the purpose of carrying a canal, road, or railway, &c. One of the most remarkable works of this kind, ever executed, is the tunnel under the river Thames, planned by Mr. Brunel, and successfully executed under his direction. Two previous attempts had been made to carry a tunnel under the river; one in 1799, and the other in 1804; but both were unsuccessful. In 1824, however, an act of parliament, authorizing operations on the plan of Mr. Brunel, was obtained; and shortly after the work was commenced. A short account of the progress of the work will probably be the best mode of conveying a notion of the nature and difficulty of tunneling in general.

Mr. Brunel began his operations by making preparations for a shaft fifty feet in diameter, which he commenced one hundred and fifty feet from the river on the Surrey side; this he effected by constructing on the surface of the ground a substantial brick cylinder of that diameter, forty-two feet in hight and three feet in thickness. Over this he set up a steam-engine, necessary for pumping out the water, and for raising the earth to be taken from within the cylinder, and then proceeded to sink it bodily into the earth. By this means he succeeded in passing through a bed of sand and gravel twenty-six feet deep, constituting, in part, a quicksand, and in which the drift-makers of the former undertaking had been compelled to suspend their work. The cylinder having been sunk to the depth of sixty-five feet, the horizontal excavation was commenced at the depth of sixty-three feet; and in order to have sufficient thickness of ground to pass safely under the deep part of the river, the excavation was made to descend two feet and three inches in every hundred feet. This excavation is thirty feet wide, and twenty-two and a half feet high, and the process of making it may briefly be described as follows.

It was accomplished by means of a powerful apparatus of iron, called a shield, and which consisted of twelve large frames, standing close to each other, like so many volumes on the shelf of a book-case, these frames being twenty-two feet in hight, and about three feet in width. They were divided into three stages or stories, thus presenting thirty-six cells or chambers for the miners. The front of each one of these cells was protected by narrow boards, technically called polling-boards, each of which was separately held in its place by an apparatus constructed for the purpose. The miner commenced by removing the upper polling-board in his division of the shield, thus exposing a small portion of earth; into this earth he made an excavation of six inches in depth, throwing the earth behind him, from whence it was removed to the mouth of the tunnel, and from thence raised by steam to the surface of the ground. He then replaced the polling-board, causing it to press against the face of the newly excavated earth, and thus advancing it six inches beyond the other polling-boards of his division. Then successively taking down the remaining boards, excavating the earth six inches behind them, and replacing the boards six inches further in than before, he very soon had advanced that distance over the whole length of his division. All the other miners in the thirty-six cells having done the same, the framework was moved forward, and six inches more of earth removed. It was in this way, by these slow degrees, that the work was finally completed. As the frame-work advanced, it was closely followed by a solid mass of brick-work, inclosing two arched passages. These two passages were separated by a solid wall, three and a half feet at the top and four at the bottom. Other arches, however, were formed in this wall, for the purpose of opening a communication between one tunnel and the other. The whole of the brick-work is laid in Roman cement, and each archway is finished with a lining of cement, a carriage-road, and a narrow foot-path adjoining the central wall.

This immense enterprise was not finally completed without serious delay and apparently insurmountable obstacles. The works were thrice interrupted: in 1826, by the breaking off of the clay, leaving the shield exposed to the influx of the land-water for six weeks; also in May, 1827, and in January, 1828, when the river broke in and filled the tunnel. This was quickly remedied, however, by filling the holes or chasms with strong bags of clay; the structure, on clearing the tunnel of the water, being found in a most satisfactory state. Some time later, the works were suspended for seven years, owing to the want of funds. Parliament, however, after repeated applications, granted an advance for their completion, and the works were resumed and continued, till they were brought to a successful termination. The cost of the tunnel, with the approaches on both sides of the river, was about three million and a half dollars; much less than the cost of the modern metropolitan bridges which span the Thames between Surrey and Middlesex.

RAILROAD TUNNELS.

The establishment of railroad communication has given rise, both in this country and Europe, to some stupendous undertakings in the way of tunneling; one or two of which are worthy of notice as illustrating the nature and extent of this kind of work. And the first of these which we shall mention, and one of the most remarkable, is the Box tunnel on the Great Western railway in England. This tunnel pierces what is called Box hill, between Chippenham and Bath, part of which is four hundred feet above the level of the track. It is ninety-six hundred and eighty feet long, thirty-nine feet high, and thirty-five wide to the outside of the brick-work. The shafts for making and ventilating it, are thirteen in number, and vary in depth from eighty to three hundred and six feet. The excavation amounted to four hundred and fourteen thousand cubic yards; and the brick-work and masonry, to more than fifty-four thousand cubic yards. The number of bricks used, was thirty million. A tun of gunpowder and a tun of candles were consumed every week for two years and a half; and eleven hundred men and two hundred and fifty horses were kept constantly employed for all that time. For a considerable distance the tunnel passes through freestone rock, from the fissures of which there was, at times, an immense influx of water, by which on one occasion the works were interrupted for a period of nine months. On another occasion after an irruption, water was for some time discharged by the engine at the rate of thirty-two thousand hogsheads a day. This tunnel is on an inclined plane of one in a hundred. There are several other tunnels of great extent in England, such as the Kilsby tunnel, on the London and Birmingham road, which is over seven thousand feet long; and the tunnel from Wapping to Edge hill, on the Liverpool and Manchester road, which is over six thousand feet long, and quite a number of others of five thousand, four thousand, three thousand feet long, &c. One of these remarkable tunnels, is that on the South-eastern or Dover railway, a view of which is given in the cut on the following page, which passes through what is called Shakspeare’s cliff, at Dover, (though the cliff to which the poet alluded has been undermined and thrown down, and the name is now given to another part of the same range,) on the north side of the British channel. This cliff is a high bluff of chalk, on the west of the town, the white appearance of which gave the name of Albion (white) to England. There are two openings in the tunnel; and through these the whizzing locomotives fly along the dizzy precipice, as if it were an ordinary highway. There is, also, a second tunnel in the same cliff. This last is called the Abbot’s-cliff tunnel, and is about a mile in length, coming out on the face of the rock about sixty feet above the sea. The track passes along the front of the rampart for about a mile, and then enters the Shakspeare tunnel, which is also about a mile in length. Thence, again, it issues on the face of the cliff, and proceeds to the station at Dover.