Evening journal., 1898-03-17
1nNnnN.s NEw RA1LRoAD.

London viii soon be the owner of the
most daring rapid transit ever attempt
ed. A line is to be run from the Royal
Exchange to Shepherds Bush, passing
all the way in a straight line from
Cheapside, Newgate and Oxford streets
and the Bayswater and UXbridge roads.
II will be between six and seven miles
long and will contain fourteen stations.
The entire distance can be made in i've
minutes were it not for the stops. There
will be both express and way" trains.
This rapid transit will lie sixty feet
beneath the street surface, deep enough
down to escape all of the sewers with
which London is perforated, deep
enough to avoid gas and water pipes,
and further down than the foundations
of the tallest buildings.
When the Central London Railway
obtained the franchise to build its rapid
transit it was stipulated that the work
should be done without interfering
with the surface traffic. Not for an in
slant must the busy corners Of Queen
Victoria street, the Poultry, Princess
street, Mansion House Place Lombard
street, Threadneedle and Cornhill to
be interfered with, nor must any debris
cucumber the thOroughfares.
There was only one way to do it, and
that was by the Greathead Shield, the
invention of the recently deceased
engineer who designed it for the build
ings of the City and South London
Railway, that marvellous tunnel affair
that runs beneath the Thames.
The shield is a wonderful invention.
1t consists Of great steel cylinder.
The front end is closed with a strongly
made bulk head, in which there are
small openings. The front of the bulk
head is also furnished with knives and
chisels for ploughing their way through
the earth. All kinds of burrowing tools
can be fitted to the front of the bulk
head, according to the substance to be
penetrated. There are tools sharp,
round, scoop-like, and Of every other
conceivable shape
The shield is just a little larger than
the tunnel which is to be constructed.
At the beginning it is put in place be-
meath the surface of the earth at the
right depth, and the machinery set
going. II is worked by hydraulic Jacks.
Instantly the knives in the front
/ bulkhead begin their work and the
shield is forced forward like a locomo-
tive. AS the knives cut away the sand
rock in front of them it is forced in
side the shield through the small open
ings. AS the shield fills up il is stopped
and the earth and rocks are sent up 10
the surface through the shafts sunk
at intervals from the street for that
purpose.
This machine burrows its way along
| at the rate of sixteen feet per day
| There are twenty-eight of the shields
burrowing from each of the fourteen
stations in opposite directions, and they
will keep at work until they meet mid
way.
Meanwhile the worl1men inside the
tube are busy. AS the shield carries
them along they are building up the
iron tube which forms the tunnel This
they do from inside the shield. AS sOOr
as the iron tube is completed. the shield
is moved along. There is no chance
for the earth above to slip, for the tube
holds It up. Just before the tube is
moved forward grouting is blown in
between it and the earth above. Grout
ing is a fluid cement. which hardenl
and holds all perfectly secure.
One of the most interesting of The
features presented Is that of reaching
these underground trains The ap
proach will be by an elevator. The pas
senger descends at the station and find
himself in a sub-statiOn only a few
feet below the street. Here he can res