Year: 1865

engineering Work which Is now enGeaVorlng


to bore through Mount Gents to connect
France and Italy by railroad. Apart from
the interests attached to any great improve
ment which is to facilitate intercourse be-
tween two countries, and promote trade and
traffic, there are several important mechan
ical novelties, which draw more than usual
attention to this great work The distance
tunnel is to be bored through the Alps is
about seven miles. Four of these have
been completed, and the boring has been
done by the application of compressed or
condensed air. as motive power. The air
Is compressed to five atmospheres, by water
wheels about a mile and half distant from
the boring machine. This is the first sue
cessive application, we believe, of the use of
compressed air, pumped by engines at con-
venient distance from the machinery which
directly operates upon the work to be per-
formed, and it is suggestive of the practica


bihty of generating steam, at a safe dis
tance from workshops where its mechanical
force is desirable, and sending it to them
through pipes to engines which are to do the
work The large mechanical force of four
hundred horse power. is exerted by five of
these water-wheels at a distance, to provide
twenty-seven horse power, working nine jum
pers at the place OF excavation; and to at
ford sufficient ventilation to the interior.
Cylindrical boiler shaped reservoirs receive
the compressed air as it is pumped by the
water wheels below, supply for half day s
working being pumped at intervals when the
boring machines are not at work.


1t is estimated that it will yet take eight
years to finish the three miles Of tunnel yet
to be constructed, and this long delay sug-
gests another temporary Improvement and
mechanical novelty, to get advantage Of an
easier and quicker communication over the
mountain while the work is progressing.
The mountain is crossed by a common turn
pike road, forty seven miles long, SO steep
and difficult that 1t requires from nine to e.
leven hours, according to the season, to ocross.
The road is wide enough for ordinary traffic
and a railroad besides, and here is where
the new mechanical principal is to be APP
piled


An ordinary locomotive drawing load
could not surmount such gradients trusting
to its weight for the adhesion of the wheels
70 the rails, therefore third rail between
the ordinary bearing rails, acted upon by
been resorted to. This is the revival of an
Improvement which has been suggested,
but never before applied practically. Be
tween the original rails, in the middle Of the
permanent way, another rail is laid down, on
its side, and at an elevation of some seven
or eight inches above the rails outside. To
bite upon this middle rail horizontal wheels
are constructed, driven by pistons of their
own, and between these horizontal wheels
the middle rail is firmly clipped The en-
CINE thus obtains double hold upon the
road by two systems of driving wheels"
acting at right angels to each other, and the
result is such accession OF adhesion and pow.
er as will enable locomotive to draw train
up the slopes of Mount Gents.


This will remind Philadelphians of the
many oontrivances which were suggested
some twenty-five years ago, to get over the
Bridge, and which called forth a great a
mount of inventive ability We remember
one model, invented by Mr.. Coleman, mu-
sician, accomplished its object by a rack and
endless screw on middle rail. 1t was new
er practically applied because the necessity
for it was superseded by abandoning the in
cline. The English inventor has had the
test of practical application on an expert
mental line of 500 yards, in England, and
on a line of one mile and a half on the
French side Of Mount Gents. with mean
gradient of l in 3 and a maximum gradient
of | In y, with very sharp curves. The
engines carried up and down this expert
mental road a load of 16 tons in three wag-
OnS, including the weight OF the wagons,
and it performed in the ascent / 800 metres
in 81 minutes, with loss of IA lb. of steam,
and of 81 inches of water in the guage
glass, at steam pressures varying between
90 lb. and l25 lb. to the square inch in the
boiler, as the average. The engineer main
tains that the power of guiding and check
ing furnished by the middle rail and the ho-
rizontal wheels acting upon it is so great
that the balance of considerations is in fa-
vor of safety, the railway in fact being safer
than the diligence The plan works so sat
isfactory that it is a question with the Eng
lish engineers whether this arrangement
would not have been preferable in the first
to building a tunnel.-Philadelphia Ledger.


A letter from Newbern, North Carolina,
H.. .,f1