Litchfield enquirer., 1869-11-18
THE NEW THAMES TUNNEL.
The London Times says:

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 The London Times says:
 , The new Thames Tunnel may now h
 said to be virtually complete. The whoI
 length from Tower Hill to the end of Nin
 street in T0oley street, on the south gid
 of the river, is 1, ,320 feet. There is ever
 sign that the water-bearing stratum ha
 been nearly passed, and that the clay wi]
 soon be reached. When this is attaine,
 only one lining of iron rings to the shaf
 will be used to within, few feet of th bottom, where bricks faced with olazet tiles, to reflect the light, will be employed as in the shaft on Tower Hill. Night ant day every four hours the shield driyins the tunnel moves forward eighteen inches
 so that there is an advance of nine feet ii every twenty-four hours.
 The manner in which this rapid ad vance is accomplished is as simple and in genious as it is safe and quick in it's mode of operation. The shield is disc of mix ed wrought and cast iron, weighing about two and half tons. In the front next tt the city is concave: in the rear where the men work it looks like gigantic cart wheel, having six spokes and an enormous hollow felloe in the centre. To this shield and extending backwards over the men al work is powerful iron rim, just like the cap to the end of telescope. Thus, the miners who work it excavate enough clay through the centre opening to enable one man to pass in beyond the face of the shield, and he soon cuts away clay enough to find room for two, and when comrade joins him there is soon room made enough for three workers, but seldom for more, The clay is of the kind well Known as the stiff London clay, of blackish green col. or-just moist enough to give it thor. ough tenacity, but without any water.
 When about two feet have been exca- Sated all round in front of the shield, the miners return back through the central hole, and with ordinary hand-screws they force the shield on to the length of the distance they have excavated, its long rim still keeping them under shelter as it is advanced. Within this rim a segment of the iron tunnel is at once built in three segments eighteen inches long, and so on the process is repeated over and oyer again. The inner face of the shield is so con- structed as to receive the pressure of six screw jacks-one in each of the six spokes we have spoken of. By these means a pressure of sixty tons could be brought to bear on the whole shield. As rule, how ever, one screw jack and one man is suffi- cient to move it forward, and this with ease. In case of any water being come to such as 8 spring-for the whole tunnel is far below the bed of the river water-it would give indications of its presence in the moisture of the clay long before the miners reached it. In the course of the excavations of the shield about 2,OOO cubic yards of the London clay have been dug out for the tunnel alone. This as fast as it was cut out was run out in little trol- leys' to the Tower Hill shaft and hoisted over to outer air. But every trolley dropped it's quantum in the tunnel till base of the tube became covered with some six or seven inches of sticky wet clay.
 "This has all been removed; and the tunnel, as far as it has gone, is now clean from end to end. The result is that all that passes on the river overhead is ten times more distinctly heard than ever. The passage of steamer is heard with noise so loud and vibrating in the at present confined air of the tunnel that it is only the knowledge of the unalterable and al- most immoyable strength of the structure on which you stand that gives the nearer Not only can every vessel be AOoIO pnScluS- cp0ohs VI COuT6e, Ol steamers large or small-but even such slight noises as hammering on the ships in the Pool above can be distinguished, not Uuiy by tho sound but even by the slight though perceptible vibration of the air. Yet, the whole tunnel is not only water tight but air-tight. Thestests taken for de- hection or any settlement in the iron tube since it has been built, give results that show stability that apparently nothing but an earthquake can unsettle. The great est defection was only one-eighth of an inch from the true level, and only in two instances was 1t one-sixteenth.
 "As far as the tubes bearing pressure, they are equal now that they are formed in circles to about ten times the pressure they can possibly have to bear, and to more than twenty times the pressure that is now laid on them. Altogether about eight hundred and sixty-four rings have been laid and bedded in with blue lias cement. About twenty more rings will complete the entire tunnel from Tower Hill to Too ley street. The omnibus at the foot of the shaft is to hold fourteen. The time .oi transit from Tower Hill to Tooley street is to occupy three minutes, and the fare is to be penny"
 4tz. .F sa ~ $