The Dallas daily herald. [volume] (Dallas, Tex.) 1873-1887, 1881-04-21
Tunneling the English Channel

Progress hos been reported in the work of
constructing railway tunnel under the
Straits of Dover between England and
France. The operations have so far been
conducted with satisfactory results, and the
managers of the enterprise are hopeful Of
final success, although 1t is altogether too
early to speak with any confidence, as the
point where the real difficulties Of the under.
taking may be looked for have not vet been
reached.
The feasibility of tunneling under the bed
Of the English channel between Dover and
Calais was asserted many years ago by
engineers of experience. The ground for
their belief was the identity of the geological
formation Of the opposing shores, and other
evidences of continuity of the geological
formation common to both sides. Sound
ing made at very short intervals along
the line between the opposing
hesdlands confirmed this theory. The
chalk bluffs on both sides of the channel
rest upon blue clay, and the lower part of
the chalk formation, to great thick n, s., is
Of clayey character sufficiently impervious
to water to permit boring. The soundings
showed this formation to extend from shore
to shore, defending gradually to depth of
$50 feet below high wster 10 mid channel,
and rising to the same grade TO the other
side.
In 1872 company was organized to make
a tunnel that would permit railway transit
under twenty.one miles Of water between
the two countries at their nearest approach
to each other. Preliminary surveys we're
made and the results presented
to the governments Of France aud England
with appeals for countenance and
aid. A joint commission was appointed to
investigate on behalf of the two govern
ments. Concessions were subsequently OBJ
tanned from both countries, with assurances
that If private enterprise should succeed in
demon trating the practicability of the un-
dertsking, material aid would be furnished
With this encouragement work was begun.
Trial shafts were sunk on both shores to
determine the character and thickness Of the
chalk foi nation intended to be pierced. 1t
was determined TO follow tho line of two
hundred feet below the bed of the channel
at the loves! point of the line.
These prelimnaries occupied several wears.
When all preparations had been made, the
wo. upon the tunnel was commenced. The
plan proposed Is to follow by descending tun.
mel the natural eastward dip of the grey chalk
toward Dover, until the depth oftwo hundred
feet below the sea bed is reached aLu then
to push straight across To- ,u.uuel with a
horizontal passage way until ito opposite
shore is reached. The luunel will then
sweep around and ascend 10 the surface by
an incline, following the dip of chaf for
nation as on the English side. The grey
chalk Is In this method entered and followed
In its natural position throughout from
daylight on one side OF the channel to day.
light on the other. II is proposed 10 carry a
cicular bore, seven feet in diameter, from
side to side, and when this has been accom-
plished the two governments agree to subsi.
die the work, that 1t may DO enlarged to
the dimensions equired for practical opera.
ton.
The cutting Is done BY boring
machine advancing half an iren a
minute. The horizontal bore hes reached
but a short distance beyond low water tidal
level on the English side, and
II Is not yet known whether difficulties may
DO expected from jets Of water forcing their
way through cracks and assures. The prob.
lem which the first boring Is intended to
solve Is the possible-snd feared-existe nee
ola break or fault In tho chalk about midway
OF the channel, causing deep assure. Should
this exist all hope of tunnel communication
would DO at an end. With the boring con.
tnued INCREASINGLY at present maximum rate
ofsixty feet day, |. will DO o considerable
time before tho ten and half miles TO mid.
channel arc bored through and tho existence
or non-existenco Of tho DREADED central
ts.ure demonstrated.