The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1914-10-22
Driving the Hoosac Tunnel and the
Lessons It Taught
p B. Mcponald in Mining and scientihc Press)

small. Air at from IS to 6O-pound
pressure was used in the tunnel
First Machine Drills.
The first drilling machines were
complicated, costly. and failed to do
the work: It was difficult to get drill
which would hit hard fast blows and
not Jar to pieces from the impact. Fin
ally the Burleigh Rock Drill company
perfected a machine which was com.
paratively light and simple; 1t struck
800 blows per minute. For use in tn,
tunnel these drills were mounted on
drill carriages on wheels, four drills on
carriage. It Is interesting to note
that modern European practice in rock
drilling (reputed to be superior to the
American practice) still uses drill car
riages; and shorter holes than are
common in America are drilled and
blasted. The use Of drill carriages does
away with the slow process of rigging
up columns or tripods, and facilitates
moving the apparatus back and forth
when blasting; they are probably not
50 flexible for pointing the holes Rec
ords Of the rock drill work in the Hoo.
sac tunnel state that "a hole from to
feet deep could be put down in an
hour" The modern reciprocating rock
drill would probably accomplish this in
10 or Is minutes. It Is recorded that
the greatest heading advancement in
any month Of the work was 1874 feet
driven from the central shaft in Sep
TENDER, 1873. AS a comparison, the
Mount Royal tunnel Of the Canadian
Northern railway, near Montreal, was
driven $40 feet in one heading through
hard limestone during 81 working days
in May. 1913. Allowance should be
made, showever, for the fact that al
though on the Hoosac tunnel there
were three S-hour shifts per day, there
was no Sunday work; and that Sep
TENDER has one less day than May. In
driving the Hoosac tunnel, heading
feet high by "a feet wide was carried
ahead, 500 feet beyond the enlarged
part. This heading was in the middle
/ of the enlarged section; that is, to en-
large to the full size, 22x24 feet, slice
was taken of the top, as well as the
bottom taken up. Temporary tracks
for tram cars were maintained on the
5O0-foot stretch from the end of the
heading to the enlarged section, and
q light trestle constructed at the bench
to facilitate dumping rock from the up
per level cars into the lower level cars.
New England Mining Camp.
! There were no high temperatures to
contend with in the tunnel on account
of the moderate height Of the noun
tain above; the flow Of water was COM
paratively small and did not give much
trouble, although there were one or
two bad freshets in spring. Many
stories are still told by old residents
concerning the odd incidents of these
early days Of tunneling in America.
The city of North Adams, at the west
ern portal Of the tunnel was then
lively place for New England town,
anu HIduy lICC"lOI hShe '"'''
place between the cousin Jacks on
one side and the Irish or "Cork men"
on the other, especially after celebrat-
ing "holing through" or shaft sink
ing exploit.
Early Drill Valves.
1t has been stated that the history
Of the Hoosac tunnel Is the early his
tory of the rock drill development IN
America. The drills used in the tunnel
were Of course, not nearly, as efficient
as the modern types. The designers
had no precedent to follow as to valves
and construction, and the only sug-
gestions available had to be derived
from steam engine practice. Thus the
first rock drills were much too heavy
and cumbersome. Lighter, simpler
drills were designed later. but win
valve motions which, although suit.
able for steam engines, did not give
satisfactory results for the peculiar
functions Of rock nuncher. Mvst Oh
the early rock drills had some iorfn OF
rocker thrown slide valve. 1t was not
until later that air-thrown valves came
into use, and the early types OF spooi'
valve drills had three spools all OF 'ie
same size.
The modern spool valve and the out'
terfly valve represent the best diner
entail ir-thrown valves, and 1t is gen.
orally conceded that they are raster
and more efficient than the tappe''
valve type. Tappet-valve drills haa
long run Of popularity because ih'
tappet- valve pumps. they do not easns
get out Of order. even II they arc
slower than other types. Air-thro"n
valve drills are disliked by some MN
ers because Of their tendency to freeze,
however, later types have re"eo'e'
this to large extent.
| First Use Of NitrogIycerine.
| Until 1865 the principal explosive
used was black powder or gun pow
der as II was called. Now black pow
der Is rarely used in underground
work. but on account Of Its slow On
plosive action Is used in open GUS
where It IL desired not to scatter the
debris too much. In 1867 George NOW
bray was requested to come to No,.s