South Branch intelligencer. [volume] (Romney, Va. [W. Va.]) 1830-1896, 1870-12-09
Editors Correspondence.



MR- HARPER 1T has been my inten-
ton for some iime TO write you and my
friends in old Hampshire an account of a
work under my charge at this place, but
want of time has compelled its postpone
ment so far, aud must now limit me to o
very short one. We are now sinking the
last Pier of the eight required for the Rail.
road Bridge over the Missouri, for the North
Missouri Rail Road. The River is here
twenty-five hundred feet wide, and has a
rise and fall in extreme seasons of thirty
eight feet. The current, at times, Is very
strong, removing and forming large bars
with wonderful rapidity. For this'reason,
nothing short Of solid bedrock will give a
secure foundation, aud to reach it we have
to penetrate through sand aud gravel sixty
live feet below low water, so that the ordi-
nary wooden Golfer dams are not sufficient.
1t was determined then to adopt the Pneu-
matte or Compressed Air Principle, by
which an air-tight Iron Cai,son, or work
ing chamber, open at the bottom, and
strongly rooted, is sunk to the rock by ex-
cavating inside, the water being excluded
by air forced in from powerful pumps on
barges alongside. The masonry of the pier
is built up on top, as the caisson settles,
keeping it always above water. When the
rock is reached, the chamber beneath Is
filed up with concrete of cement aud bro
ken stone, and the work is finished
This method has long been in use in Eu-
rope, but is comparatively new in this coun-
try. Our caisson is forty-six feet long by
twenty three wide, with rounded cuds-i;
is nine feet nigh to the iron roof, and is
built of plates of wrought iron, rivetted to
gether, aud stiffeued by ribs and belts OF
angle iron; when put in position last Sep
TENDER, 1t weighed eighty.throe tons. Ga
the roof was then laid an oak Gri!lage OF
Platform, Of heavy squared timbers, five
aud half feet thick, on which the mason.
ny is laid. The iron sides of the caisson
are also carried up along with the masonry
to diminish the friction against the sand IL
going down.
Access to the chamber is provided for by
two well-Eoles or shafts, Of iron, built W
IN the masonry, and furnished with lad
ders. These shafts terminate below ir
small cast IRON chambers, within the main
chamber. The workmen, in gangs Of ten
descend the shaft, and pass through anal
door into the clock they then close III,
door, aud admit the compressed air from
the warm chamber through 4 tube, till the
Pressure is oqualized in the Lock. Th,
door behind them 10 now sealed by an in.
visible power, and they pass through the
now open door at the side, into The caisson
Here the work of removing the sand and
gravel is carried on by gangs relieved every
three hours, night and day. The sand !.
fed into pipes passing up through the pior
aud carried out by the pressure of water
forced in by powerful pumps above, whilc
the gravel Is screened out, passed through
the 'L1ck" and hoisted up by staam pow
er. As the excavation proceeds, the cais
son settles down by its great weight, some
times aided by allowing part of the air with
in to escape. Above, the masons are rapid
ly building up the Pier, the Iron worker,
rivetting up the sides, and the Engines
with ccaselcss stroke, force 10 the life civ.
ing air About one hundred and fifty mcr
are employed on this piece of work, iuclul
ing Engineers, Machinists, Iron Workers
Masons, Carpenters, &c while the amount
of machinery does the work of several hun.
dred more.
The cai.son il now sixty feet below tho
River, with four feet yet to go This give,
an air Pressure Of twenty-seveu pounds tC
the square inch, over atmospheric pressure
But little bad effect has resulted from it Sc
far. Persons in good health stand over
thirty pounds without injury, if not expos.
cd to it too long, while as high as fifty
pounds has been used at the St Loui.
Bridge, but not without some loss Of life.
The masonry is now built scventy-twc
feet above the caissoU, amounting to ;hr
teen hundred cubic yards Of solid stone. and
giving a gross weight, with the caisson it
sell, Of seven million pounds, Of which three
million is neuiralized by the upward pres
sure Of the air within the caisson. NJ
more masonry will be laid till the rock !.
reached, and the chamber Gled-the pier
will then be carried up sixty i've feet high
er to the "Bridge scat"
Two spans Of the superstruclure have al.
ready been raised together with three thou
sand feet Of iron Trcstle worl, on shore, and
it j, hoped the work will be completed
ready for the passage Of trains by July
next. The Chief Engineer Of the Brdg
is Mr. G.. s. SMITH, Of Baliimore Over
a million Of dollars has already been spent
What pity part Of it could not gladden.
the hearts Of your merchants, mechanic,
and farmers. But with her worthy Gov
ernor elect, and her asylum, Bomncy seems
entering upon new era Of progress. S,
may 10 be. S.
RsTMr NTcKerzis announce Lie ipfo,.
ton to contest Eraxton's scat in Congress.
from the seventh Virginia district Mr.
Brlx'on' majority is upwards Of 800.