LETTER XXI.

THE THAMES TUNNEL.

Bridges across the Thames-Proportion of the City below London BridgeNecessity of some Thoroughfare across the River, below the BridgesSir I. Brunel's Project-Operation of the Shield-Foot People alone can pass through the Tunnel-Toll-gatherer's Room-Descent into the Shaft-Objects on the Platforms-Rotunda-Arches of the TunnelFaney and Toy Shops-Gas Lights-Number of Visitors.

LONDON, AUGUST 9, 1851.

To cross a river over the water on a bridge, is a very common thing; and we think little of it, unless it be to notice the skill displayed in the structure, or wonder at its cost as we pass along; but to cross a river under the water's bed, through a hole cut from one shore to the other deep, navigable waters, at whose bottom huge anchors hold floating ships, or on whose surface they proudly sail, deeply laden with the treasures brought from distant continents- this is a different thing, and altogether more rare, withal.

The world has heard of the Thames Tunnel. It is, indeed, regarded as the eighth wonder of the world. For years our newspapers in America have contained accounts of it, and yet our people hardly seem to have a right idea of it. This afternoon I have visited and passed through

that wonderful structure. I was somewhat disappointed in it, and therefore propose, before I conclude this letter, to attempt a brief description of it.

Let it first be remarked that " London Bridge" crosses the river in just about the centre of the city. The wharves and docks, including Greenwich and the East India Docks, extend some half a dozen miles below this bridge, which is the lowest one on the river; and there are eight bridges crossing it within five miles, in the upper part of the city. Two others are projected, within the same space, and will be built in due time. All these thoroughfares are necessary to connect the parts of the city on the opposite sides of the Thames; and they are built so high that steamers without masts, and other vessels with masts made to fall backward as they enter the arches, may pass up and down at pleasure. These bridges are most substantial and costly structures, with paved carriage-ways, marble sidewalks, and hewn granite balusters railed and capped, with occasional recesses for stone seats; and staircases descending to piers, at which steamers and boats receive passengers. These bridges cost about five millions of dollars each. Below, as far as can be seen, the river and docks are filled with sailing vessels, war-ships, and steamers, holding intercourse with all parts of the world. Such a tide of life as is beheld upon the Thames, from any one of the London bridges, is to be seen no where else on all the face of the earth. It is the aquatic part of London, and as well worth seeing as the portions on terra firma.

For more than fifty years, various plans have been projected for gaining some sort of pontal accommodation between the opposite parts of the city below London

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Bridge, without interfering with, or being impeded by, the countless water-crafts upon the bosom of the river. Ferries were out of the question. So great is the passage of vessels &c., that a ferry boat could seldom get across without great risk and an insufferable delay. At last, Sir Isambert Brunel projected a scheme for a subaqueous passage a tunnel under the bed of the river, about a mile and a half below London Bridge, connecting the two parts of the city known as Wapping on the north side, and Rotherhithe on the south side of the Thames. work was commenced in 1825, by sinking a shaft on the Rotherhithe side, fifty feet in diameter, and eighty feet deep. This was made water-tight all the way, excepting at the bottom, towards the river, where an opening was left, large enough to receive a "shield," or sort of wormexcavator, that would eat a horizontal track as it passed under the bed of the river, of thirty-eight feet wide by twenty-two feet high, allowing the workmen to carry off the dirt as fast as it ate its way into the earth.

It is said that Brunel took his idea of this shield, in the following manner. He was sitting on an old log by the roadside one day, in a "brown study" as to how he could contrive to bore a hole under the river. Beneath him he heard a worm gnawing into the log, and noticed the chips that it discharged from the hole it was cutting. seized his jacknife, dug out the worm, examined his jaws, and from them learned how to make a similar machine to bore under the Thames with.

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The great hole, or tunnel, left behind the shield as it advanced, was lined and protected by two arches in masonry, which kept the earth from filling in, or the water from penetrating. Thus, in eighteen years, during which

time operations were suspended seven years, the shield worked its way through to Wapping, where a corresponding shaft had been sunk to come out of, and leaving the Thames Tunnel finished behind it. This, as I have said, is in two arches of solid and beautiful masonry, extending from one side of the river to the other, a distance of 1290 feet. I do not know the depth of the top of the Tunnel below the bottom of the river, but should judge that from the surface of the river at high water where the ships ride at anchor, to the vaults of the Tunnel beneath, might be forty or fifty feet.

Nothing can pass through the Tunnel, but as it first descends one of these shafts-consequently, no horses or carriages can, as yet, travel in it. It is used by pedestrians altogether. Indeed, it is more of a curiosity-shop than a passage-way; and of those who enter it, there are many more visitors than passengers.

Let us go into it and see what is there. Supposing ourselves to be on the northern side of the river, let us pass from the old Tower of London, down by and amongst the St. Katharine and London Docks, to Wapping. Amongst the blocks of buildings that separate the street from the river, we notice an octagonal edifice of marble. We enter by one of several great doors, and find ourselves in a rotunda of fifty feet diameter, and the floor laid in mosaic work of blue and white marble. The walls are stuccoed, around which are stands for the sale of papers, pamphlets, books, confectionery, beer, &c. A sort of watch-house stands on the side of the rotunda next the river, in which is a fat publican, or tax gatherer. Before him is a brass turnstile, through which you are permitted

to pass, on paying him a penny, and, entering a door, you begin to descend the shaft, by a flight of very long marble steps that descend to a wide platform, from which the next series of steps descends in an opposite direction. The walls of the shaft are circular, finished in stucco, and hung with paintings and other curious objects. You halt a few moments on the first platform and listen to the notes of a huge organ that occupies a part of it, discoursing excellent music.

You resume your downward journey till you reach the next story, or marble platform, where you find other objects of curiosity to engage your attention whilst you stop to rest. And thus you go down-down-to the bottom of the shaft eighty feet; the walls meanwhile, being studded with pictures, statues, or figures in plaster, &c. Arrived at the bottom, you find yourself in a rotunda corresponding to that you entered from the street, a round room, with marble floor, fifty feet in diameter. There are alcoves near the walls in which are all sorts of contrivances to get your money, from Egyptian necromancers and fortune-tellers to dancing monkeys. The room is lighted with gas, and is brilliant. Now look into the Thames Tunnel before you. It consists of two beautiful Arches, extending to the opposite side of the river. These Arches contain each a roadsted, fourteen feet wide and twentytwo feet high, and pathways for pedestrians, three feet wide. The Tunnel appears to be well ventilated, as the air seemed neither damp nor close. The partition between these Arches, running the whole length of the Tunnel, is cut into transverse arches, leading through from one roadsted to the other. There may be fifty of them in all, and