Wall.
1. A structure of stone or brick.
The following terms are employed:—
Face; the front of a wall.
Bark; the rear.
Core; the filling-in.
Course; a layer of stone or brick.
See course.
Bond; the system of laying.
See bond.
Batter; the slope of the face (if any).
Party-wall; one common to two houses.
Flank-wall; a
return or side wall.
Fire-proof walls are made of stone, brick, or metal, but the resisting power of brick is greatest.
Granite splits and flies, sandstone scales, limestones and marble crumble into lime, iron warps and melts.
This subject has been considered, briefly, under fire-proof building, and here there is but room for a few examples of the uses of iron in forming, strengthening, or facing walls.
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Fire-proof walls. |
A is for an inside wall, having studs
a of corrugated sheetmetal for supporting a lath surface
b, whose inturned edges occupy slots in the edges of the studplate.
B has studding and frame of angleiron
c, with panels of iron lattice-work
d, which is covered in entirely by concrete material
e.
C represents on a small scale one or two rooms of a house constructed on
Seely's plan, with corrugated sheetmetal and angle-iron.
D has an open framework of metallic sections
f, with sides of double wire gauze
j. inclosing plaster of
Paris, and with an outer sheathing of metal
h, in imitation of masonry, isolated from the frame by soapstone blocks
i.
E has a filling of concrete
g around the frame
f and the sheathing
h and blocks
i, just described.
F has a wooden frame
k with a con-
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crete outside the sheathing, and an outside wall of artificial stone
l made with dovetails at the rear, which form locks in the concrete.
G has cast-iron hollow boxes, made with tongues, grooves, lugs, and locking-plates.
These are built together in their courses, and the courses fastened together in a similar manner.
H uses cast iron, hollow, rectangular, or triangular blocks, and builds them up in the manner of bricks.
I is specially intended for mansard roofs; it has an outer iron plate
m and inner wire-gauze
n, on which the plaster
e is spread.
o is an outer break-joint plate to cover the junction of the plates, and its bolt locks all the parts together.
J shows a sheet-metal cover
q to a cast-iron bracketing
p, the whole forming a cornice.
The “formacean” walls, described by Pliny, were “molded rather than built,” as he says, “by ramming earth within a frame of boards, constructed on either side.”
He declares them very lasting, and refers to the earthen watch-towers erected by
Hannibal on the summits of the mountains in
Spain.
“The earth so rammed, I can assure you, does continue for years in an imperishable state, and is neither affected by rain, by wind, nor by fire, and neither mortar nor cement is used in them.”
These must have been what are now termed pise--work (which see).
Ransome's process (
English) for rendering walls impervious to moisture is as follows:—
The external surfaces of the walls to be protected are first washed with a silicate of soda or solution of flint, which is applied again and again, until the bricks are saturated, and the silicate ceases to be absorbed.
The strength of the solution is regulated by the character of the bricks upon which it is to be applied, a heavier mixture being used upon porous walls, and a lighter one of those of denser texture.
After the silicate has become thoroughly absorbed, and none is visible upon the surface, a solution of chloride of calcium is applied, which, immediately combining with the silicate of soda, forms a perfectly insoluble compound, which completely fills up all the interstices in the brick or stone, without in any way altering its original appearance.
By this operation the wall is rendered perfectly water-tight, and, as the pores of the bricks are thoroughly filled for a considerable depth from the surface with the insoluble compound, which is entirely unaffected by atmospheric influences, no subsequent process is necessary.
Cob walls, still used in some rural districts of Britain, are made of clay and chopped straw, based upon brick or stone foundations, and having a thickness of about two feet. They are built in the manner of pise--work (which see). In some cases, however, the work is not confined within boards, but is built up by the shovel, being well incorporated before applying and after placing it on the wall.
The lintels and sills of the doors and windows are built in, but the openings are cut subsequently.
As each layer dries its surface is shaved and trimmed, receiving a final coat of plaster.
Straw houses are made in
England by an inventor who proceeds as follows:—
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The great Chinese wall: the Nang-Kao pass. |
He compresses straw into slabs, soaks them in a solution of flint, to render them fire-proof, coats the two sides with a kind of cement or concrete; and of these slabs the cottages are built.
By ingenious contrivances, the quantity of joiner's work is much reduced, and the chimney is so constructed as to secure warmth with the smallest consumption of fuel, and at the same time to heat a drying closet.
The cost of a single cottage of this description, combining “all the requirements of health, decency, and comfort,” is $425. See also list under masonry.
The walls of
Babylon were possibly 75 feet high.
They had been gradually decreasing in height since the time of
Herodotus, who reported them 200 royal cubits = 337 feet (
English);
Ctesias, 300 feet;
Xenophon, 100.
It is probable that the reputed dimensions decreased as more reliable estimates were transmitted.
The
Chinese wall was built by Chi-hwang-ti, 220 B. C. The feudal system was about that time in course of demolition in
China, and was accomplished by the Han dynasty.
The process is now being repeated in
Japan.
This great wall is 1,200 miles long, from 20 to 25 feet high, and from 15 to 20 feet broad.
It was built as a barrier against the hordes of Tartar cavalry, and was everywhere constructed of the materials found in the immediate neighborhood.
Fig. 7027 is a view of a portion of the
Great Chinese Wall, at a point three days journey from
Pekin, on the route to
Siberia.
On plains and terraces which afforded clay and loam, it was formed with an earthen core, built up in well-pounded layers, growing narrower toward the top, and faced with large tiles laid flat.
The top was also paved with tiles and defended with a parapet.
On mountains of stratified rock the facing was made of masonry, and the interior filled with earth and cobble-stones.
On the mountain of Kal-gan, where the rock is a trachytic porphyry, which breaks only into most irregular shapes, the wall is of solid masonry, the stones being laid in cement; its section is here an isosceles triangle, the crest being brought to a sharp edge.
In other localities it is built of hewn rock, and has a brick parapet.
Where it ascends a mountain the top is built into steps to facilitate the passage of soldiers.
Throughout its entire length it is defended by towers, which rise from it at regular distances of a few hundred feet. Many of these towers are several stories high, and are provided with loopholes and with arched windows.
In many places the northern side was defended with ditches and embankments, which may originally have existed throughout the whole length of the wall, or they may have been constructed to resist local attacks.
Every mountain pass and every weak point was defended by a fortified town.
The wall is now in very different states of preservation, according to the material used.
In the valleys, the points where it was originally most needed, it has crumbled into a mere line of rubbish, which is being rapidly graded down by the plow.
The
Abbe Huc says of the Chinese wall, that one of the embassy of Lord Macartney in 1793 estimated the cubic masonry of the great wall was greater than that of all the houses in
England and
Scotland. “But it is evident that he has taken for the basis of his calculation the part of the wall immediately to the north of
Pekin, which is really fine and imposing, but it must not be supposed that this barrier is equally large and solid throughout its whole extent.
We have had occasion to cross
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it at more than fifteen different points, and have often traveled for days together without ever losing sight of it; and, instead of the double battlemented stone-wall which is seen at
Pekin, it is sometimes a very humble-looking wall of clay; and we have even seen it reduced to its simplest expression, and composed only of stones piled up together.”
It appears that it suffered the fate so common to contract work; well done at special points, and “the mere pretense of a wall on those distant points, which had besides little to fear from the Tartars, — such, for instance, as the frontiers of Ortons and the
Alechan Mountains.” — hug.
For information of the construction of Roman walls see “Murus” ; “Paries,” in
Smith's “Dictionary of
Greek and Roman Antiquities.”
2. (
Mining.) The rock inclosing a vein.
The upper and lower portions are known as the
roof and
floor respectively.
Where the
dip is considerable, the upper boundary is the
hanging-wall, and the lower the
foot-wall.
3. (
Nautical.) A large knot worked on the end of a rope; as of a man-rope, for instance.
