, 1872-12-17
THE E0OSAC TUNNEL.

Ehc Opening Between the Ccatra1
Shaft and the East End-A Full His
tory-SiEhts and Sounds Under.
ground.
Worth Adams, Mass. dee. -, Correspondence e5 Tie
Bo8ton AdreTnser.
It is now several weeks since the near approach
of the tWo headings in the Hoosac Tunnel be-
gan to be se1sibly observed. The sharp click Of
Ehe power-d-ills could be heard through the sep
arating wall Of rock at distance Of 400 or 500
feet, remarkable illust1stion of the conductis-
ity Of sound through a folid. Que would have
supposed that the souni would have been COM
pletely dissipated before it had been carried so
far. As the headings approached each other the
two gangs did not blast at the sar1e time. Each
was notified BY cerhin number Of strokes on
the rock when the otber VAS to fire the charges,
and after the blastanother signal gave intelli-
that no holes had missed fire. OF course the
sound OF the blast vas heard distinctly from one
heading to the othe. This code Of signals WAS
OF great practica use at last, as will be seen
hereafter.
The progress made during the month Of No
vember was alna,st ordlna1y,--greate than
had been made any previous month. On Mon
day, the Sd Instant, the two headings we're
that, with nc unforeseen obstacle, the breach
would be maze On Saturday, the 18th. Mr. Wal
ter shanly, rho very seldom leaves the works 80
long, left forth Adams on the Sd, intending to
return On he 10th, in ample season for the final
blasts. Cn the morning Of his return, Tues
day last he received dispatches which an
uounce6 d gain even upon the extraordinary
progress OF November, and 3 rectifcation Of
MEASUREMENTS which led him to suppose that
the vorkmen were nearer together BY several
feet than had been supposed. Accordingly, he
Immediately made the tour Of the mountain,
ane arranged his plans for the junction. The
east end heading WAS to be driven for certain
disance az speedily as possible, but blasting
ha wholly Et0nnnH at the rEntrq1 shaft.
In rider to show the exact position and direc-
tim Of the two headings, each must be de-
eczbed-
: 4 Of the tunnel shout seven feet high only,
tlt the full width Of the tunnel when COM
feted. Workmen follow at a distance OF
evera1 hundred feet enlarging it at the top.
Water has been q great difficulty at the central
shaft. About $50 feet west Of the shaft the wet
granite formation Of the western heading was
struck and water made SO fast that operations
in that direction had to be suspended. Two
ponderous pumps, one with seven-inch pipe
and tha other with q ten-inch pipe, we're required
to raise the water in four Lifts Of $50 feet each
to the surface. For convenience OF working
the tunnel WAS driven from the central shaft
eastward at the roof; that is, the upper part was
As tic first piercing is about seven feet high and
The whole height of the finished tunnel is twenty
feet, the continuation Of the two approaching
tunnels would finally cause them to overlap, the
separating them. As a matter Of fact the grade
Of the tunnel, which is descending, 26 feet to
the nile from the central shaft, Was for the
last rod or two made more rapid, go that It all
the measurements were correct only four feet Of
rock would form the vertical distance between
the two when their faces had met in the same
plane. may eay here that the wafer which
drips from all parts Of the tunnel flowed in g
small stream away from the shaft, was caught
in pit and pumped back to the pump beneath
the central shaft elevator.
Tvs orders with reference to the central shaft
bedding. The two gangs we're expected to be on
Wednesday afternoon but Il feet apart, horizon
tally. Mr. Shanly, therefore, directed the .Lill-
ing OF holes Is feet deep, starting from points
near together near and upon the floor of the
central ehaft heading, these holes to diyerge,
the upper pointing towards the roe Of the east
end heading, the lower pointing to its breast.
It will be seen that, should the distance be as
was expected, a blast from these holes would be
likely to throw quaint J Of rock into the east
end from the central shaft, thus opening COM
muuication betwe,n the two. In order to
make sure how the two parties we're to
approach each other in fact, Mr. John
E.. Roscrow, the Superintendent at the
central shaft, directed the drilling OF two test
holes on Tuesday evening, to start from the
angle between the floor and the breast Of his
beading, ard to point directly where the angle
between the roof and the breast OF the east end
heading should be. These we're to be drilled
longest driIls had been put in their full length,
eighteen feet
On Wednesday morning visited the east end,
md subsequently tho central shaft, in company
Filth Mr. BhanlY. to whom am indebted. not