The Sumter banner. [volume] (Sumterville, S.C.) 1846-1855, 1855-02-14

into inc Dcu Oh tnc river 10 uepln Oh
nine feet, within which distance sand
only was encountered. In communi
eating to Maj. Gwyan a copy Of the
profile, with the result of these exam.
nations, | expressed the opinion that
8 the best plan for putting in the
foundations Of the Piers will be
by the use of DR.. Potts Pneumatic
cast IRON Piles, filled with concrete" j"
The plan was subsequently adopted
by the Board, upon the recommends.
ton Of Maj. Gwynn and it is my
purpose now to explain some of the
results which We're obtained, and to
describe particularly the improvement
and discoveries, which, | conceive,
were made during the progress of the
work. In the Reported Maj. Gwynn,
made at the last annual meeting, the
mod"s operonai is very accurately de.
scribed, but the difference between
the plan a ID principle upon which il
mas commenced, and upon which it was
finished, was not clearly defined. The
"Pncuma,i Process" upon which the
work was commenced, consists in ere.
ating vacuum within the cylinder,
which causes the water, sand, &c, to
rush up, and. in its course, carry with
it the material from the bottom of the
tube, causing it to de cend by its own
weight. The vacuum is first created
in chamber, which is placed in com.
nunication with the cylinder by ordi.
nary suction hose, and closed or open
ed by valve on a projection attached
to the vacuum chamber. Tic power,
therefore, which can be used by this
plan is governed by the relative Gu.
blcal contents ofthe vacuum chamber
and that portion of the cylinder above
The surface Of the water, and the per.
ttcti"n Of the vacuum. In the opera.
tons ut the Pee Dee, the vacuum
chamber consisted Of two sections of
cylinder, Is feet in length and, gene.
rally, the cylinder pile was 10 feet
above the water line, therefore the
power (iydroStatic aud preuinat;o}
was only s.. Is of the vacuum, obtained
III the chamber, which was usually
about equivalent to 2G inches OF mer
cury, a perfect vacuum being 80 inch,
es. The effective power, therefore,
was that due to II 1918 inches of
mercury, or about 2.lO lbs. per
square inch.
In sinking the first cylinder it en-
cnnntcrcd, 1T 4 depth of about s feet
below the bed of the river, tree
about feet in diameter. This, for Il
time, arrested the progress of The
work, ard until the Air Lock (Which
had arrived in al imperfect statc)
could he completed.
The Air Lock, us it is usually call.
ed, is not strictly part of the Pneu
matte process, but was first used in
France by NJ. Trigger in sinking n
shaft through bed Of quicksnnd to
c,'al minc, aud is accurately dcScrib
I'd in the supplement- to Urc's Dicsinn.
AIRY of Arts and Scicuccs-Art Vcnti.
Iatiom. The plan OF Air Lock, simi.
lar to that used ut the Pee Dee river
is well described III Il paper read be.
fore the Institution of Ci,il Enuineers
in London "n May 18th 1851, "on
the Pneumatic IN" lrd adapted ia
constructing The foundations Of the
new hrid.e across the Mrdwav, at
Rochester," and from which the t:.lI,w
ing is extracted: Alter describing the
obstructions encountered in sinking
the cylinders, the papc, states. "Il
was, therefore, decided that the Pncu
matte process should he reversed, so
as to give each Pile the character of
IL diving bell, for which purpose one
Of the cylinders 7 feet in diameter,
and ic,tin length had q wrought iron
cover securely hnIted to it through
which tw cast Iron chambers, D.shap.
ed in plan, with sectional era of
about 8 square feet, appropriately
called "Air Locks" projecting 2 feet
6 inches above the top Of the cy!n-
der and fret 8 inches below the GOV.
cr. The top of each Air Lock was
provided with a circular opening 2 feet
in diameter, with Flap working on
horizontal hinge, and an iron door 3
feet by 3 feet 4 inches, with vertical
hinges below the cover; each Air Lock
was also furnished with two SETS of
cocks, the one for forming Il commu.
nication between the cylinders and the
chamber, and the other between the
chamber and atmosphere"
EARLY in July, the Air Lock was
completed and every thing in readi.
nrs-, to excavatc the sand above the
tree and cut it away. At first it was
extremely difficult to induce the opc.
ratives employed on the work to enter
the Lock, while the condensed air was
escaping from imperfect joints, very
much like the escape of steam from a
leak in q Boiler. In addition to this.
during the process Of equalizing, the
change OF pressure on the tympnnum
OF the car was for some time exceed.
ingly painful; and in some instances
produced hemorrhaSe from the Lungs.
Owners Of hands, and indeed some of
the principal operatives, believed that
the constant inhaling Of the same air