The Sun.
London, England, 1868-06-01 00:00:00

THE HOOSAC TUNNEL.

Thirty miles west of Greenfield, in the north-
west corner of Massachusetts, rises the Iloos:►c
Mountain. At its east base flows the Deerfield
River through a small but beautiful valley, with
steep hills rising around to a height of 1,000 feet.
Two miles from the west base is North Adams, in
a fertile valley, overshadowed by the Saddle Moun-
tain, the highest peak in Massachusetts. The
Hoosac tunnel is intended to continue the railway
direct from Troy to Boston, by Greenfield, and the
work was undertaken in 1850 by the Troy and
Greenfi.ld Railroad Company, the State of Massa-
chusetts aiding with a loan of $2,000,000. The
Railroad Company failed in 1862, and upon the
State fell the burden of the task. In 1866, by an
Act of the Legislature, the general supervision, both
of the tunnel and of the Troy and Greenfield Rail-
road was imposed on the Governor and Council,
directing them, at least once a year, to visit and in-
spect the works, a visit, judging by the last, which
is made a pic-nic, at which the members get jolly, the
boys who saw them crying that the liquor law was
recently repealed. The same Act appointed Benj.
11. La Trobe, of Baltimore, consulting engineer of
the tunnel. A contract was made to complete the
road to the eastern entrance by July 15, 1868, and
it was leased to the Fitchburg, and the Vermont,
and Massachusetts Railroads at an annual rent of
$30,000. The road is now graded nearly to the

Hoosac mountain from Shelburne Falls. The rails
will be laid through Charlemont now that the frost
has left the ground. We may here mention that in
1867 thegross earnings of the road were $534,511 ; the
running expenses $193,122, leaving a net profit of
$41,422. The length of the tunnel is 25,031 feet,
or nearly five miles ; the dimensions being 24 feet
wide by 22 high for a distance of 2,400 feet. From
the east portal nearly 5,000 feet are finished
through what is termed mica slate, with fine
seams of white and bluish flinty quartz. For
a short space near the entrance only does
the water drip, further in the tunnel is dry and well
ventilated, presenting a curious sight as the 170 men
employed are approached, their lights shining at
various altitudes, giving the semblance of an illu-
minated village in a narrow ravine. A correspon-
dent of the San Francisco Mining and Scientific
Press writes an interesting account of this work,
more especially describing the Burleigh Drill now
employed in the tunnel. There are eight air-engine
drills thundering away in various directions, at
from 200 to 300 strokes per minute, each striking
from the hard rock a meteoric shower. This, a
mile within the mountain, added to the blasts of
the escaping compressed air, produce an extra-
ordinary effect. Beyond the 2,400 feet from
the east entrance, the tunnel was at first
15 feet wide x 6 feet high, but this has
been enlarged to 21 by 81. The mountain presents
a sort of saddle aspect in profile, the highest point,
the west summit, being 1,710 feet above the tunnel,
and the east summit 1,249, the direction being
almost due east and west. The work finished in
March, from the April report of the State engineer,
W. P. Grainger, was as follows :

East end heading ...
West shaft—east heading
West shaft—west heading

Advance. Total.
... 112 feet 4,951 foot
... 31 „ 1,396 „
... 6.8 , 692 „
... 18 „ 659 „
... 17 „ 612 „
... 22 „ 2,)7

West end
West end arch
Well No. 4

Depth of central shaft

DISTANCE YET TO GO.
From east end beading to central shaft 7,836 feet
From central shaft to east heading west shaft 8,331 „
Frain west heading west shalt to well No. 4 232 „
From well No. 4 to west ending heading
From bottom of well No. 4to grade
From bottom of central shaft to grade

fir. Charles Burleigh's drill at first proved a failure
by reason of constant breakage ; but discerning the
remedies he has rectified the errors, and the ma-
chine has already saved the State $lOO,OOO. The
drills are attached to carriage frames over 20 feet
in length, six feet high, by eight feet four in. wide,
One on each side the tunnel, fronting the heading.
When in operation the frame is raised so as to rest
its entire weight upon jack screws. On the forward
end of each frame four or more drills are attached,
with universal motion. Each machine is a com-
plete engine, working independently, and receiving
its power (condensed air) through a 11-in. rubber
hose. Weight of machine about 400 lbs. It contains
8b pieces. The machines are of 3-horse power, and
when in perfect order, with a pressure of 50 pounds
to the inch, are capable of dealing from 250 to 300
blows per minute. Considerable repairing is re-
quired, but by a quick method of adjusting the ma-
chines, and an extra supply of the same, all serious
delay is avoided. They can be operated by
steam. Air being quicker than steam, thirty
pounds of the former is there considered equi-
valent in effect to forty pounds of the lat-
ter. It is more than fifteen months since these
drills were introduced into the tunnel. In four
weeks one machine, without repairing, working but
about six hours out of the twenty-four, including
the time of changing the drill-points and positions,
has made 2,250 feet of 2i-inch hole. Alvah
Crocker, chief superintendent, reports that, " not-
withstanding the size of the heading has been in-
creased, from 6x15 feet to Bfx2l feet, the actual
progress for the last seven mouths has been 116 feet,
against an average of 55 feet during the last
seven months of hand labour. By hand drill, in
the enlargement, two men average about 8 feet of
li-inch hole in 11 hours." In 6 hours the ma-
chines drill holes enough to employ the balance of
the 24 hours in blasting and clearing away the
rock knocked down. By hand labour $2B per
cubic yard has been the cost of excavating rock at
the heading ; it is now accomplished at less
than eight dollars with the aid of the machines.
[his machine is so constructed that the piston bar
is the only part of the machine which receives the
shock resulting from the blow upon the rock. This
piston bar, to which the drill point is directly
attached, is made from a solid bar of cast steel. It
is provided with an automatic feed and rotating de-
vice, by means of which the drill is partially ro-
tated at each stroke, and advanced toward the rock
as required. The machines vary in size from 50
inches length, and cross sections of 12 x 15 inches
to 84 inches, and cross section of 14 x 16 inches,
and will feed forward, without change of drill points,
from 30 to 81 inches, according to size of machine.
The tunnel, the managers say, will be finished in
five years, for when steam takes the place of the
Deerfield River it is expected that 150 feet of head-
ing will be made per month, which will be 40 feet
above the average of the last eight months, the cost
being $10,000,000. When the Tray and Green-
field Railway is completed, which it is thought will
mainly 18 x 27, and worked through the solid rock
to a depth of nearly 600 feet. A sad accident oc-
curred there some months ago, by which thirteen
workmen lost their lives, and every attempt to
recover their bodies, which lie under 300 feet of
water has as yet failed. The contractors threw up the
undertaking, which the State is now prosecuting.
It is doubted whether the central shaft, if
ever finished, will be of use as a means of venti-
lating the tunnel. Cold air descends, and that at
the bottom is 20 degrees colder than that at the
top of the shaft. Nothing but a huge fire kept con-
stantly burning could make the air ascend, and it
is considered that as in the Mont Cenis Tunnel,
which is 40,000 feet long, without a shaft, the best
means of ventilating will be found the rush of
trains through. The West tunnel is 9,747 feet
west from the Central Shaft.
The Watchman and Reflector, writing oil the an.