The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1897-06-28
terror views of Tunnel Showing CassOn method

over London bridge, so that, at some
point about six miles below this bridge,
it became absolutely necessary for lne
accommodation of about l,fGO,OOO peo-
ple (ecual to the population of New
York and greater than that of chi
ca-o) who live east of the river, 10
build either a bridge or tunnel. Inc
former was hardly practicaole IN the
mds. of all the docks and that I'M
mense shipping which makes London
the greatest port in the world. II was
decided. therefore, to build by the eX-
penditure of another Si,OOO,6O a great
Under-river tunnel to provide for TINS
traffic. Near the location of this tun-
mel. at Greenwich and Woolwich, there
had been already provided by the
county council of London a free ferry.
to accommodate the isolated parts OF
London north of the Thames. Tnls
ferry. inadequate as it is for this I'M
mense traffic. carries 100000 pas
sengers each year and about 100000
vehicles 1t serves certain districts
quite well. but certain other districts
cannot conveniently use it. So the
Blackwell tunnel was built.
LIGHT, AIRY AND COMFORTABLE.
This great hole, burrowed under the
river. which is nearly a quarter of
mile wide, and through all sorts of
troublesome materials, is not a dark
and forbidding place, but pleasant 10
ride or walk in and light enough to
read the London Times anywhere in;
in fact, this was one of the require
ments of the contract; and it is also in
every way wholesome and sweet 1t is
safe to say that such an underground
transit way in New York City, or in
anv of our large cities, with electric
cars passing through ii. would be so
entirely different from what the ordi-
nary citizen expects to see that he
would travel in il in preference to
elevated or surface cars. The subway
now being built in Boston is the clos
est approach to this eunnel in regard
to light and comfort. unless ii may ne
the beautiful underground transit way
at Buda Pesth, Hungary. Glistening
white tile rejecting hundreds of electric
lights, and easy grades like the easiest
going up to the city bridges. a COM
Portable roadway of Belgian blocks,
the level spaces of the tunnel proper
smoothly paved with asphaltum: and
with a sidewalk for foot passengers on
either side. This is the tunnel which
the bountiful provision of a great city
and the skill of its engineers and con-
tractors have given to this part of
London.
Now let US see how this Blackwell
tunnel was built, state some of the
difficulties and the methods of over
coming them, and evolve it, from a
mass of mud and water and other
treacherous materials of that great
alluvial valley, into a beautiful, light
and comfortable paSsageway for
human beings With two or three
Drofiles. sections, pictures. and brief
descriptions. the work may be clearly
understood by anyone. The profile or
longitudinal section shows the work
completed exactly as it would look if
we could, with a huge cleaver cut it
straight open from end to end, just as
a piece of timber looks cut through in
the middle lengthwise in the sawlnill.
The cross section shows it as it would
look if we cut it square across from the
surface of the water to the bottom of
the tunnel and took the mud and
water awav from one end and thus
brought To the eye all the strata of
material and the end of the cut off tun-
rel with the water above it and the
boats and ships moving therein.
The reader will understand that in a
length of $500 feet, nearly a mile and a
quarter. depth of so feet. is shown by
a natural or true scale, could hardly be
seen by the eye. In fact, the entire
depth, from the surface of high water
TO the bottom of the tunnel would be
less than one-eishth of an inch. The
engineer. therefore, distorts or exag-
gerates his vertical scale so as to bring
the work 10 the eye. The profile is dis
torted in this case ten times for this
purpose. 1t therefore shows the grades
a great deal sleeper than they really
are. The figures, however, show them