The morning news. [volume] (Savannah, Ga.) 1887-1900, 1896-08-26
CUTTING STONE By AIR.
The Pneumatic Plant in Use Mt the
Public Building.

Work on the government building Is
progressing. although Just now but Few
Of the worzmen are busy. owing 10 the
lack OF material. This VIII arrive in a
few days. however. and again the full
force Of hands viii BE- az work.
Two courses OF the heavy ground stone
work have been laid around the building.
and the brick masons have commenced
their work on that as a foundation.
Though the high board fence shuts OF a
view Of the work from the exterior just
at its present stage. 1t is rapidly assuming
a hight that will admit Of public inspec-
tion from the outside. The huge derricl1s
erected are used for the placing Of the
heavy granite blocks.
During the last few days a pneumatic
plant for carving stone has been put up
on the State street side of the enclosure.
Here the work Of cutting and sculpturlng
stone win be done by means OF com
pressed air. The machinery and appara-
tus constituting the plant cost a consider
able sum. but Messrs. Miles & Bradt
considered the great amount Of orna-
mentation that the Specifications call for
in the stone. work and the great labor
saving advantages Of the pneumatic
methods. and decided to put It in.
The plant is composed OF boiler air
receiver and engine and compressor com
bined. 1t Is apparently a simple method,
though a wonderful one in saving labor.
One Of the pneumatic drills will do the
work Of five men with mallets and chiseis.
From the compressor, connections lead
to the receiver, a stout, sheet iron, cylin-
drical tank placed horizontally, and from
this receiver iron piping runs under the
md
feet from the ground At regular inter-
walls along this line Of piping are twelve
outlets. TO which are joined rubber tubes Of
One-third inch in diameter, the compressed
air being kept out Of these when not in
use by stops. At the extremities Of these
tubes are fitted iron threads to which the
cutting instruments are screwed.
When the instruments are attached to
the tubes the compressed air forces the
chisel rapidly up and down with sharp,
jarring impact. The hard stone chips off
in a stream of dust with the strokes Of
the drill. A bent shank. between the
junction point of the instrument and con-
Meeting tube and the chisel serves as a
handle by which the operator can direct
its course.
The blocks of stone are placed on benches
beneath all Of the outlets in the supply
main, and the rubber tube, being of suit
able length and flexible. does not incom-
mode the workman in handling the instru-
ment.
The capacity of the apparatus is said to
be about $50 pound to the square inch, but
a pressure Of eighty pounds is sufficient
to put all the twelve instruments into rapid
play. This eighty pounds of pressure is
not confined n the rubber tubes. for, as
said before, a stOp-cock shuts off the air
supply when the instrument is not in use,
and, while 1t is, the air finds the path Of
its exit to be in the line of the least
resistance. or the opening through which
it plays upon the drill.
AS in ordinary hand chiselling, different
sizes Of drills and chisels are used, and the
work on stone used for building purposes
can be made as delicate as is necessary.
The pneumatic plant was given its first
test yesterday in a few minutes work 1t
will be used regularly now, unless some
delay is occasioned by the new machinery
getting out of working order.