Phenix gazette. [volume] (Alexandria [D.C.]) 1825-1833, 1825-06-07
TUNNELS.
To the Editors of tie National Lteligsncr.


To the Editors of tie National Lateaigencr.
GENTLEMEN: observed it stated in para
graph of New.York paper, that for the con.
nection of the Ohio and Potomac, tunnel OF
nearly four miles is proposed. The editor IS
correct in saying that such work would be
the greatest of the kind in existence, but he
is not so exact in the comparison he makes
with the tunnels already executed. AS this
subject often recurs in conversation in relation
to the magnificent project above alluded to,
the following memoranda, drawn from anthem
tic sources, will probably be interesting to
many of your readers.
The largest tunnel known is that of Rique-
val, on the canal of st. Quentin, in France,
which is 5677 metres g miles 1926 yards.)-
1t has heen executed within the present GEN.
fury. The greatest obstacle to its execution
resulted from the profuse liberation of water
into its interior, which it required all the re-
sources of art to get rid Of The deep-cutting
at the entrance of this tunnel is ia feet.
The work is executed nearly according to
the plan originally proposed by NJ. Devic
nearly century ago. Another engineer pro-
posed to pass the ridge at lower level, by a
tunnel of Ia, 900 metres (more than 81 miles
in lengthy This plan was adopted, and, be-
tween the years 1869, and 1772, more than a
million of francs were expended on it, when
the work was abandoned in consequence
of the death of the protector. The view of
the prodigious excavations thus formed, was
the occasion of the following observation of
the Emperor Joseph H.-'T feel proud of be-
ing man, when witness the conception and
execution of such work by my fellow men,"
The IIuddersfield Tunnel, in England, is
500 yards long (about 81 miles.) 1t passes
at about the depth of 800 yards under the
crown of the ridge. The centre shaft was $50
yards deep.
The following are the lengths of som, of
the tunnels in England: Sapperton, 1890
yards Pensax, $3.50 yards; Laplat, 5, 776 yards;
Ellsworth, $3.50 yards; Ripley, 300 yards,
Harecaste, the first tunnel executed in Eng
land, 1888 yards.
Many of the galleries of the coal mines of
the Duke of Bridgewater, at Worsley, have a
narrow canal in them. The amount of SUBJ
terraneous navigation thus effected in these
mines alone, is stated to be more than 16
miles.
The greater part of the tunnels hitherto ex-
ccuted, have no towing paths. The method
of passing them is, by the boatmen lying on
their backs on planks placed for the purpose
across the deck of the boat, and pushing it a.
ny Will tllClT lcel aSttlIlSI
sides. Thus they proceed about mile per
hour.
When tunnel is more than very mode
rate length, it has been found more econo-
mical to raise the rubbish from its interior
through shafts sunk for the purpose, than to
take it out from the ends. This method also
allows the tunnel to be commenced at many
points at once; whereas, if it were worked on
~ from the two ends towards the centre, the
very small number of men that could be en-
ployed without being in each others way,
would render this method extremely tedious
Tunnels were known to and executed by
the Romans. Witness the subterraneous
drain of the Lake near Alba Tonga; or Alba
no; which they executedin consequence of an
oracle which declared that they should not be
prosperous as long as this Lake oyerAowed
its bank. The waterpas through this work
at the present time.
The writer has seen the outlet of the Cloaca
Maxima into the Tiber at Rome. Th. work,
which is in fact tunnel, although intended
for different purpose from navigation, APP
pears to be in great part entire, although il
is entirely filled up by rubbish, and only its
end OH the bank of the river is visible, where
the arch is perfect. 1t was built by one of
the kings Of Rome-if recollection serves
right, by Tarquin the elder. IL.