Worcester daily spy. [volume] (Worcester [Mass.]) 1850-1888, 1872-03-07
EInRENCE Eeh IL 191

FLORENCE, Feb. H. 1872
DEAR SIR:-I have but little time apart from
my work 10 answer your inquiry in regard
to the thin arches built here for dwelling
houses.
The builders first throw up all the walls with
out any flooring whatever. The walls are
bound, when necessary, all around with iron
rods, VARYING from an inch to an inch and a half
diameter.
Standing below, and looking up, you at first
might not perceive a slight recess in the walls
at the point where the arch is to rest. 1t is
about one and half inches deep, and two and a
half inches high.
When they are ready to bcgin the arch, stag
ing is made all around the room, for the masOnS
to stand on. They first of all, make with plaS-
ter OF paris a smooth place on the walls on
which to draw the curve intended for the arch.
COZ curse, this curved line presents the appear
ance of a bow, the ends meeting at the base of
the arch at each corner Of the room. Bricks,
one foot long and six inches broad, and one and
a half inches thick, well burnt, but not so harl
as nor TO absorb water, are brought, and plaster
of paris, instead of mortar, TO lay them with.
The masOns now stretch small cords across from
corner to corner of each wall, the ends fastened
six inches distant from the latter, and on the
curve of the arch. They then, with trowes and
brush, mix upon their boards a small quantity
Of plaster to the consistency of mortar, and each
taking brick, apply the plaster to one end and
one side of it, and instantly place it in position,
where they hold it for moment to allow the
brick, by absorbing the water, SO to thicken and
stitfen the plaster as TO hold the brick in its
place.
They then take another, placing it against the
wall and the first brick, and so they 70 on I'M
I'll the four misOnS have projected their arch out
into the space, and inclined upwards according
TO the curve of the arch.
The maSOus n)w stretch their cords on the
curve of the arch, another six inches out, and so
they 90 on until some support is required, which
is obtained by placing four rafters from the cen
tire of each wall, and all meeting in the middle
of the space, so as not to project above the high
est part of the arch.
They then place brick or two on each of
these rafers endwise, until they touch both raft
er and arch; little plaster oil perls is used 10
stay the bricks. This done, they 90 on again
until the arch is completed. But note-where
the bricks meet at the corners, they pass one
another little at every alternate row, so as TO
make a serrated junction. THIS makes the COR
nerS stronger than any where else.
When the arch is done, it is nowhere more
than an inch and a half thick, nut you can
safely walk upon it, and it sounds like a drum
The upperm )st or garnet vaults are usually
stitfencd with braces of bricks from the walls
toward the middle. These vaults have no floors
on them.
The vaults done, we now want to fill up the
spaces and lay the tile floors The first we do
with number of small arches, deeD at the
walls, but coming to nothing as they approach
the centre. These serve a double purpose-they
brace and stiffen the arch, aud also fill up the
spaces, until, by using old wall rubbish, which
IS lighter than sand, the ground for the brick
| flooring is prepared, which flooring is laid not
| with plaster of paris, but mortar. Thus this
thin arch is honey.combed, as it WERE for light
ness, and it is so strong that a room twenty-five
feet square is quite safe for dancing party.
| Bat it is important that you have good mortar
for your walls, much lime and little sand-the
mortar should become as hard as the bricks. |
| have seen mortar in walls of six years standing,
| in Cincinnati, that | could dig out with nv
| naiSl This is not the wall for anv kind of arch
| to rest on and against. Observe, that the curves
OF the little arches on top Of the main arch, run
| counter TO the curve of the main arch.
still think that if several builders could club
together, it would be well to send out here for a
mason who fully understands the matter |
| have been told that there are arches of this de-
scription at Voltcrra which have Stood certainly
several thousand years. They are in the tom6s
OF that very ancient city, and the arch is called
The VoterraDo." | have seen these arches
without any plaster on them, the bricks so laid
as TO present a beautiful mosaic appearance
The cost of them is very smlll, as YOU mus
have perceived from the above description, and
| they are so light as to require no very great
thickness OF outer wall. Yours faithfully,
HIRAM POWERS.
Henry Howard, Esq.