Year: 1874

The Proposed Tunnel Under the Eng


IIsh Channel.


Strange as it may sound, says the
New York Herald, the great project of
tunneling the English channel is, ac-
cording to late reports, in process of
experiment, and the preliminary steps
toward the stupendous undertaking are
being steadily advanced. Not an un-
favorable omen for its prosecution is
the withdrawal of the scheme from
merely popular agitation and the quiet
action of its originators.


The first thing to be ascertained was
the geologic formation of the channel
bed, with reference to the permeability
of its strata. As the laying of the first
Atlantic cable was discovered to be
practicable by the discovery of the
telegraphic plateau" lying between
Newfoundland and ireland and furnish
ing a safe bed for the strand, it is
claimed that the geological survey of
the channel demonstrates the FEAST
bility of the tunnel project. Mr.. Prest-
wich, the leading English geologist, in
an exhaustive discussion of all the con-
ditions of the channel bed, has recently
paved the way for confident and en-
ergetic prosecution of the magnificent
design to connect England and Europe.
This cautious investigator thinks the
scheme can be carried out and that the
geologic conditions are not unfavora-
BILE. He shows that the deeper rocks
are protected by impermeable everything
strata of great dimensions, and SO com
pact as to offer the secure construction
of submarine tunnel And he cites
the fact that these strata have, at
Whitehaven and Mons, been actually
and safely worked at considerable dis
tances under great bodies of water. So
far as theory can throw light on the
subject this has been done, leaving the
question solely for the engineers.


But, apart from Mr.. Prestwich's re-
searches, it is now known that the gray
chalk-a mass of strata, five hundred
feet thick and impervious to water
which forms the principal cliffs at
Dover and Calais, strikes across the
channel and so nearly approaches hori,
zontally that tunnel could be bored
within its vertical limits. A high me-
chanical authority on the other side of
the Atlantic states that the most eligi-
BILE line for the tunnel ia now pretty
we'll concluded to run from st. Mar
garet's bay, South Foreland, to point
about midway between Saugatte and
Calais. This line of the main tunnel,
which has been fixed upon by the pro-
moters of the enterprise, is accidentally
almost coincident with that of the Dover
and Calais submarine cable. 1t has
been selected after some hundreds of
borings (Which have been made by an
ingenious apparatus for perforating the
sea bed and bringing up the rock speci-
! mens) were examined and a complete
geological chart constructed from the
data.


The greatest depth of water over.
lying the selected tunnel line is less
than two hundred feet, and it is pro-
posed to penetrate two hundred feet Oh
more beneath the bed by long descents
of four miles from either shore. This
would make the total tunnel length
about thirty miles, and would afford
great security and ease of gradient to
the structure. The whole perforation
will be wide enough for double rail.
way.


In an engineering point of view it is
doubtless a practicable undertaking,
the only question being it's financial
expediency. This must depend on the
action of President Mahon's govern
ment, which, it is said, is favorable,
and likely to grant the concessions
asked for by the French and English
company who have the matter in
hand.


The actual distance from Dover to
Calais does not exceed twenty miles,
and if the piercings on either shore
could be nearer the sea it would seem
that six or eight mi es of the esti-
mated tunneling could be saved. This
might save one-fourth of the estimated
cost (ten millions of pounds sterling),
and reduce the expenses of construc.
ton within the limit of remuneration,
The undertaking, even at these figures
which are said to be the highest esti-
mates-would be cheap and inexpen-
sive, compared with our proposed
isthmian canal.