, 1888-09-02
HOW GRANITE Is POLISHED.

Putting n Smooth Surface on the Hard
tone-Mcthod In Detail.
The form Is given to the stone by the
hands of skilled masons, in much the
same way as is done with other stones of
softer nature. OF course the time re-
quired is considerably greater in the case
of granite as compared with other stones.
If the surface is not to be polished, but
only fine axed, as 1t is called, that is done
by the use of q hammer composed of a
number of slips of steel of about a six
teenth of an inch thick, which are tightly
bound together, the edges being placed
OF the same plane. With this tool the
workman smooths the surface of the
stone by a series of taps or blows given
at a right angle to the surface operated
upon. By this means the marks of the
blows as given obliquely on the surface
of the stone are obliterated and a smooth
face produced.
Polishing is performed by rubbing in
the first place with an iron tool and with
sand and water. Emery is next applied,
then putty with flannel. All plain sur
face and molding can be done by ma
chinery, but all carvings, or surfaces
broken into, small portions of various
elevations, are done by the hands of the
patient hand p%olishers.
The operation of saving a block of
granite into slabs for panels, tables or
chimney pieces is a very slow process,
the rate of progress being about half an
inch per day of ten hours. The machines
employed are few and simple. They are
technically called lathes, wagons and
pendulums or rubbers. The lathes are
employed for the polishing of columns,
the wagons for flat surface, and the
pendulums for molding and such flat
work as is not suitable for the wagon.
In the lathes the column is placed and
supported at each end by points, upon
which it revolves. On the upper surface
of the column there are laid pieces of
iron, segments of the circumference of
the column. The weight of these pieces
of iron lying upon the column, and the
constant supply by the lathe attendant of
sand and water, emery or putty, accord
ing to the state of finish to which the
column has been brought, constitute the
whole operation.
While sand is used during the rougher
state of the process, these irons are bare,
but when using emery and putty the sur
face of the iron next to the stone is COW
cred with thick flannel.
The wagon is a carriage running upon
rails, in which the pieces of stone to be
polished are fixed, having uppermost the
surface to be operated upon. Above this
surface there are shafts placed perpen-
dicularly, on the lower end of which are
fixed rings of iron. These rings rest
upon the stone, and when the shaft re-
wolves they rub the surface of the stone.
vt the same time the wagon travels back
ward and forward upon the rails, SO as
to expose the whole surface of the same
to the action of the rings.
The pendulum is a frame hung upon
hinges from the room of the work shop.
To this frame are attached iron rods,
moving in a horizontal direction. In the
line upon which these rods move, and
under them, the stone is firmly placed
upon the floor. Pieces of iron are then
loosely attached to the rods and allowed
to rest upon the surface of the stone.
When the whole is set in motion, these
rons are dragged backward and forward
over the surface of the stone, and so it is
polished.
When polishing plain surfaces, such as
the needle of IN obelisk, the pieces Of
iron are flat, but when we have to polish
a molding we make an extra pattern of
its form and the IRONS are cast from that
pattern.-Stone Mason, England.