New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-11-27

shaft was sunk prior to 1851 by hanp aiteF DIS en-
end He sunk II as 10 enter the mountain where 1t
was solid. aud as he supposed free from water
The central shaft sunk for two purpOscs FIRST, 10
secure two facngs eat and one west ana thus eX-
pedte the work. and, secondly, to afford ventilation Tor
the tunnel 10 Is Viii gradn from eeb poF
tai To the center would venate itself ~ all. siuce
this built, and connection made With the east
end strong draft IL obtained from II, ad the tunnel -
readily cleared from smoke and gases Before commu-
ncaton from the east was opened with the shat the
Introduction of locomotive into the tunnel TO carry on
the debris source u great discomfort and even
sickness to the Now this dicqltY Is entirely re-.
moved On the completion OF the whole tunnel tho west
shaft will be closed up TO secure better draft for the
central one.
The central shaft eipse ~ feet long by u feet
wide. It's position was established by series OF sec
natey each side OF the shaft aud the position trans
tied until exactly determined between the two pin
cipal tunnel SUBMITS.
INSTRUMENTS AND DEVICES FOR SECURING ACCCRACY.
Ihave already described above the means b. Which
the line carried through the tunnel from the two por-
tals When the central shaft sunk 1t OF course
necessity In order TO work headings east and west 10
meet those coming from the portals that the line from
above should Ia some way be accurately carried down
the shaft TINS was n work requiring much nicely and
exactness OF observation aud the employment o! some
unuEua devices AT the distance OF about 70 feet "
the east and west from the center Of the shaft find
small hus inslosng the nstrumenial piers These are
mepts for observing aud finding the position OF hl sey-
eTal machine. for Alignment placed more nearly adJa
sids aro built small piers from which securely
bolti what are called the alignment frames These are
coInpIlcated contriVances with divided scales, motion
screWs caups and other devices for Tocorng and es
tabIshing every position Inade by the engineer Prom
these von the alignment has been definitely Ct
abshed twO parallel lines OF very me steel wire are
stretched with very strong tension across the SHAFT SO
mai he true line Of tunnel IL represented by the
narrow space OF the twentieth part OF an inch that in
tcrgenes he yeen them Through tins narrow space the
nnmnci wires Of copper let down into tbs shaft
,ssng between but not touching the steel wires on
tb.r side by which the sure position Ia so exactly De
unoo Following these wires down tue smart. We nuu
Iaf az arc IN ,snded ia tight sqnaro boz or hue,
iniir Of % aux VI about sSs Inches on the interior Iee
Loxts arc I'D sone,y necessary 90 piotect tie wires rom
ne JsnrIuc innuenre ~ air ouroEtB or from drops oi
wafer Scn Z siosed TO fa aioug the wire w2nid cause
ma eral OWING 90" % o h u,,
a vinHusf OF sboat 10 pounds weight attaehed, 'us-
pended IN bucket Of waten when Is hnD,gcr pre- W
cin,tiop Tbe 80 buckets Stand on hoOr tsro"h hHos
~, shaf nc no level Of ony 10" ieet aoove tue 'ooi
- 49," ,nruaI I'rou this floor wooden frames NIo
.recfei 40 an 10 .u al eaCh ono OF mo wan hl Nh''
and 10 support system Of diyied phtes and 'e''e'H