Virginia citizen. (Irvington, Va.) 1891-1921, 1900-10-19
HUGE GRANITE COLUMNS.
They VIII AGora the Episcopal en-
ahtIrri Ia Now York CIfr

fney VIII ACoT1 the Episcopal en-
shtdrci Ia New York City.
For the Cathedral cf ST. John the Di-
vine, IN this city. - magnificent gran
( lite columns are TO be supplied. each as
nigh as four story h0Use. and to
shape them remarkable piece of ma
chinory has recently been constructed
IN Philadelphia and sent TO the quar-
ries OF the Bodwcil Granite company,
In Ninalhaven. Me. 1t is nothing less
than turning lathe of unparalleled
strength and proportions.
a good illustration of the objects and
operation of lathe is found in a shop
where wooden balustcrs are manufac-
tured. a stick of wood, three or four
inches square and two or three feet
| long, is adjusted I'm a horizontal posi-
ton, with its ends firmly held by metal
disks, which are intended to revolve
rapidly The stick being thus set i'm
rotation, workman applies to il the
edge of chiSel or other cutting tool
which rests on fixed support. but
may be shifted from one end of the
stick to the other. The result of this
treatment is to make the stick perfect
81
ameter at different points may be va
ried. IL this is desirable, so that i'm one
place there is n graceful bulge and in
another slender taper. Lathes are
also built for working metal and the
cutter is usually shifted automatically
by screw motion, so that the lack of
uniformity which results from hand
work is eliminated and absolute adher-
ence to model insured.
The same method is now cmployed
in shaping long blocks of stone into
columns like those in front of the New
York Life building. i'm Broadway. The
stone is suspended horizontally be-
tween the head stock" and tail
stock" both of which can rotate. As
in other lathes, the power which causes
the stone to revOlve is applied to the
head stock. By arranging suitable cut
ting tools on the side the superfluous
material is Clipped off by degrees. and
the column is reduced to the desired di-
mensons as surely, though. of course,
not so rapidly, rs wooden baIuster.
The finished columns of the Episco-
pal cathedral are to be - feet long and
have a diameter of feet. When
finished, each will weigh 1G0 tons. But.
to begin with. n block is quarried ont
that is O. feet long. measures 81 by 4
feet in cross section and weighs about
$40 tons! This burden must be sus-
tanned by the two rotating ends of the
marvellous machine recently sent to
Flnalhaven. Before the lathe is mt
In operation IL is intended that n little
OF each rectangular edge shall be TAX
en- of from the block by hand. Eight
cutting tools will he adjusted close to
each other. one going a little deeper
than its predecessor. Each is designed
TO cut of three inches OF stone, so that
together they would be capable of
making cut 81 inches I'm depth. BY
suitable mechanism these cutters are
slowly shifted from one end of tho
lathe TO the other, so as TO traverse the
whole length of the column. But they
are set In such n manner that they
cannot make the diameter less than
six feet.
When column has thus been brought
down TO the proper size. IL still has n
rather rough surface. The stone must
now be polished. This second opcra.
ton is conducted with the lathe also
but the rotation is effected mt n some.
what higher rate OF speed. There are
two polishing processes. The first. or
rough polishing. is done with n cum
shaped device that has lot Of hard.
ened steel shot I'm contact with the
moving surface. In the final opera
ton sand and emery are employed. \
period of about six weeks is required
for each column. Ii will take nearly
four years. therefore. to get out the
whole % columns.
This machine Is So feet long and
weighs l3a tons. IL Is much larger
than any other stone cutting lathe ever
before constructed Ii is driven by n
% horse power engine. When engaged
IL cutting. rs speed ia III revolutions n
minute and when used for polishing.
The chang" of speed Is erected by
gearing The work of Constructing
the lathe WAS hcGm I'm December last,
and II WIS delivered 10 the Bcdwcll
Granite company In May. Eat il was
net pat !ai> Vprraticu Untu a few
weeks a~p New York Tribune.