Wheeling Sunday register. [volume] (Wheeling, W. Va.) 1882-1934, 1882-09-17
TUNNELS BENEATH RIVERS.
work BuiIs, How Building. asa yet %
be built.


y,,,,, The address Of John Fbscter, President o.
The MechdnicR Science Section.
Tunnels under broad navigable rivers
and ostuaries have been a subject OF aus
cussion by engineers for at least q
century, but the only one at present
comnleted ia the unfortunate and costly
Thames tunnel. Two important works
of the class are, however, now Wen III
hand-namely, the Severn tunnel Al
Portskowet and the Mersey tunnel ~
Liverpool. One lesson enforced by tue
Thames tunnel was the necessity OF
leaving a reasonable thickness ofground
between the water and the tunnel. In
the Severn tunnel the maximum thick.
ness is 40 feet, and the Mersey tunnel
~ feet. The width Of the river NJ the
point of crossing of the former tunnel Is
~ miles and the maximum depth OF the
rails below high water l62 feet. In the
case of the Mersey tunnel the width Is
nearly three quarters of a mile and the
depth l4i feet. The Thames tunnel, AZ
almost every one knows, was carried on
nv means of q special contrlvance
termed by Brunei "shield." No
special appliances have been adopted In
the case even Of the Severn or the Mer-
sew tunnels. Both are driven In the
ordinary way, but, Of course, enormous
pumping power is required ana mas
been proyi,led. Where no special ap..
nliances are used i'm the construction of
a subaaueous tunnel, 1t will be clear
that unknown risk Is encountered. All
may 90 well, and the engineer WILL then
Justly receive congratulations from every
one for his boldness and success. But,
on the other hand, something may 10
wrong, even at the last moment, ana
the engineer then would be abused ny
the minimizing public for the tenerity
and consequent failure. In many cases
of tunnels under estuaries, special ap::
pliunces could be used which would
obyiate all risk and make the successful
completion of the work mathematical
certainty, A tunnel over q mile In
length now in progress under the Huu-
SON river ut New York is being driven
through a silly stratum by the aid OF
compressed air, and with certain
amount of success, as only some ~ men
have been drowned up TO the present
time. The principle upon which the
compressed air is used IL, however, u
false one, since it is merely forced into
the tunnel with a view TO uphold the
around by its pressure, like 80 mucn
finLering, and not To keep out the water
OH the principle Of diving-bell. IL Is
clear, Their, fore, that the completion OF
the Hudson river tunnel, il the present
system be- preserved in, Is purely mat
ter Of conjecture, and all we can do Is to
hone for the best. The same remark
apples, of c0urse, to the Severn tunnel
and the Mcrsey tunnel, although In
those cases the character Of the ground
is such that the contingencies are small
ia comparison with those encountered
in the construction OF the Thames tun-
mel and the Hudson river tunnel.
Nevertheless, unless special appliances
Of the nature of the pneumatic process
he used, u subaqueOus tunnel, whether
it be the Channel tunnel itself or one
but few yards in length, must neces-
sarily present an unknown risk. The
prototype of all these tunnels Is the one
commenced at Rotherhithe in 1903,
which was successfully driven u dts
lance of $40 feet under the THAMES, aud
failed when within little more than lO0
feet Of the opposite shore. a tunnel
about one and half miles in length
was commenced about 10 years ago un-
der the Detroit river i'm America, but
was abandoned in Il similar manner.
So far good fortune has attended both
the Severn and the Mersey tunnels, and
there il, am glad TO see, every chance
OF its continuing. Only IA few months
ago became aware of the fact that
scheme identical IN all its main features