The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1898-02-12
LONDoN's NEW RAILWAY.
1t VIII he Sixty Feet Under Ground
How Ii Is being Built.
ST. Louis Star.

Ol. IOulS Sbdi.
London will soon be the owner of the
most daring rapid transit ever attempted
A line is to be run from the Royal TX
change to Shepherds Bush, passing all the
way in nearly straight line from Cheap
side, Newgate and Oxford streets and the
Bayswater and Uxbridge roads. 1t will be
between six and seven miles long ana Will
contain fourteen stations. The entire dis
tance can be made in five minutes were 1t
not for the stops. There will be both eX-
press and way trains.
This rapid transit line will lie sixty feet
beneath the street surface deep enough
down to escape all the sewers with which
London is perforated, deep enough to avoid
gas and water pipes, and further down imam
the foundations of the tallest buildings.
When the Central London Railway OBJ
tanned the franchise to build rs rapid
transit ii was stipulated that the work
should be done without interfering with
the surface traffic. Not for an instant must
the Poultry, Princes street. Mansion House
place. Lombard street, Threadneedle and
Cornhill be interfered with, nor must any
debris cumber the thoroughfares.
There was only way to do 1t, and that
was by the Greathead Shield the invention
of the recently deceased engineer who de-
signed il. for the building of the City and
South London Railway, that marvelous
tunnel affair that runs beneath the Indmes.
The shield is a wonderful invention. II
consists OF great steel cylinder. The front
end is closed with q strongly made bulk
head in which there are small openings.
The front of the bulkhead is also furnished
with KNIVES anu c1lSetS III PiOWiiS thClA
way through the earth All kinds of bur
rowing tools can be fitted to the front OF the
bulkhead. according to the substance to be
penetrated. There are tools sharp, round
scoop-like and of every other conceivable
shape.
The shield is just little larger than the
tunnel which is to be constructed. AT the
beginning it is put in place beneath 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 bulk
head begin their work, and the shield IS
forced forward like locomotive. As the
knives cut away the sand rock in front of
them it is forced inside the shield through
the small openings. AS the shield nils up
il is stopped, and the earth and rock are
sent up to the surface through shafts sunk
at intervals from the street FOR that pur-
pose.
This machine burrows its way along at
the rate of sixteen feet per day. There are
tW enty-eight of the shields burroWlng from
each of the fourteen stations in opposite
directions, and they will keep at work until
they meet midway.
Meanwhile the workmen 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 in
side the shield. As soon 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 ii UP. Just before the
tube is moved forward grouting is blown in
between ii and the earth above. Grouting
Is a fluid cement, which hardens and holds
all perfectly secure.
One of the most interesting of the fea-
lures presented Is that OF reaching these