The Sun.
London, England, 1859-12-05 00:00:00

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TUNNELLING BY MACIIINEI?Y.

The resolution of the problem of tunnelling by
machinery, so important to the future of mining, is
being worked out, with continued success, in the
boring of the Alps for the tunnel of the railway that
is to connect France and Sardinia. The tunnel is
between Modane in the Sardinian territories and
Bardoneche in France, and is upwards ofeight miles
long. From the enormous height of the mountain,
no air-shaft was possible for this length, and con-
sequently the tunnel had to be carried out by
drivings at each end only. Under the old system
the want of air would have rendered this impossible,
and even if it were possible it would have taken 40
years to complete. By the method adopted all diffi-
culties of ventilation are removed, and -the work
will be finished in six years from its commence-
ment.

The holes in the end are bored by machinery,
and charged and blasted by manual labour. Upon
the latter part of the operation, therefore, there is no
economy ; but the machine bores the holes in 1-12th
the time that would be required by manual labour.
But even this does not represent the entire economy
of time, for in an end where only two men could
work, and consequently only one hole be perforated.
at a time, by ordinary means, six effective holes
can be simultaneously bored by the machine ; thus
'72 holes are bored in the time taken before to com-
plete one .

- Of course it is not to be expected that holesbored
by a machine should be quite equal in effect to
those pitched and bored by a skilful miner; but
this is ,in some degree compensated by the simul-
taneous firing of several holes, for which this ma-
chine affords such facilities, and which is known to
be so effective; besides, such minor considerations
sink into insignificance compared with the power of
boring 72 holes to 1.

The time and labour required to charge the holes
remain, as we have said, unaltered, as also those of
removing the stuff. But allowing for these, it is
estimated that altogether there is a saving of
5-6ths, or that the same amount of work can be
done in 1-6th of the time. -

The power used for working the borers em-
ployed consists of condensed air, compressed to six
atmospheres by water-power. The use of this
motive-power is the great feature of the success of
the operation, for, after working the boring machine
the air escapes into the tunnel, and, expanding to
its natural volume, not merely supplies the ne-
cessary air for ventilation, but creates a strong
and continuous outward current, carrying away
all the impurities of combustion and respiration.
And this compressed air not merely affords a
perfect ventilation ; it also keeps the atmosphere at a
very low temperature, arising from the well-known
principle that a large amount of heat is absorbed
by any, gas or fluid by expansion. So much is this
the case in this tunnel, that when the air is first
discharged from the machine its absolutely freeze.
any water with which it may come iu contact.
The average progress of the tunnel is about 10ft.
per day on each side, through hard rock. The eco-
nomy is not great, if anything, as yet, for the entire
affair being new and experimental had entailed
many expenses. But when we consider the enor-
mous economy of machinary over manual labour,
wherever the former is possible, we cannot suppose
that this will ultimately prove an exception to
the rule, when the practical details and difficulties
have been once worked out.

The importance of the possible application of such
a machine to mining purposes, even if there be no
economy in it, we need not point out to our readers.
Time is often worth anything to the miner, for in
his pursuit, alone among all others, money cannot
expedite a piece of work beyond a point. Fancy
driving a cross-cut through stiff ground at the rate
of 50 fms. per month, or sinking a new perpendi-
cular engine-shaft at a proportionate rate. There
are times when such results would be worth any
money, and we really believe that, judging from the
experience of the Alpine tunnel, there is nothing
visionary in considering such a result possible in the
future; We certainly are not inclined to think that
driving levels or carrying on other works on the
course of the lode can ever be effected by machinery,
for the direction, &c , require to be so suddenly
varied that the continued changes would more than
destroy the saving of time. But in the case of crosa-
cuts or perpendicular shafts, which have to, be
driven or sunk straight from point lo point, No are
confident that the present century will see the suc-
cessful application of mechanical contrivances.
We should be glad to see some of the teeming in-
genuity of our mechanics applied to work out this
point in a practical and sensible manner. It is one
that will probably involve many difficulties, which
can only be surmounted by continued perseverance,
and no one must be disheartened by first failures.
The primary problem of the motive-power seems to
be solved, for compressed air has the great mining
desideratum of affording a supply of pure and cool
air—an arircle decidedly in request in our deep
mines.—Mining Journal.

LADY FRANKLlN.—Everybody must admit that
Lady Franklin is not only an amiable but a strong-minded
woman, yet we have heard an anecdote of her sensibility
which is deeply affecting. A short time since, when her
ladyship was waiting most auxiously to learn the fate of the
brave men she had despatched in search of her husband,
she fell ill, and a consultation of physicians was held at her
residence. One of these gentlemen, whilst he felt her pulse,
begged her ladyship would open her hand. Her frequent
refusals occasioned him so much disappointment in ascer-
taining the precise state of her fever, that he took the
liberty gently to expand the fingers, and he then perceived
that they were grasping a small miniature of Sir John-
" Madam," exclaimed the gentleman, with deep sympathy,
"my prescription must be unavailing if you are determined
to keep before your eyes an object which, although de-
servedly dear to you, serves only to confirm the violence of
your distressing symptoms," " Sir," replied the noble
woman, "this picture has been my sole comforter over since
the departure of my husband, and I am determined it shall
be inseparable until, if he be dead, I am so heppy as to.
drop after hint intothe grave."—Court Circular.
ASSISTED EMIGRATION TO THE CAPE OF GOOD
HOPE.—The Tudor, of 1,062 tons Captain H. A rmstrong,
sailed front Southampton on Saturday for Algcy , Bay, hav-
ing on hoard 318 emigrants, under charge of
,3urgeon-Su-
perintendent William Campbell. The eraigrants were
selected by the Hon. William Field, the ce:lnni issioner spe-
cially appointed by the Cape Colony, ,and oc misted of 36
married couples, 114 single men, 74 angle. wo =en, and 58
children,