A dictionary of modern gardening - University Library

—
—
W AL 621 W A L
the copings to project much further darkness of its colour, if a proper screen
than they are usually made to do, even
as much as twelve inches ; but his reabe
then employed.
Gard.
Johnson's Princ. of
soning refers more immediately to the Inclined or Sloping Walls have been
manaizement of wall fruit.
recommended, but have alwavs failed
It is a practice sanctioned by econo- in practice. It is quite true that they
my, to build the wall half brick thick, receive the sun's rays at a favourable
on a nine inch foundation, and to com- angle, but they retain wet, and become
pensate for its want of strength, a so much colder by radiation at night
waved form is given. Both the small- than perpendicular walls, that they are
ncss of its substance and its form, are found to be unfavourable to the ripenfound,
however, to be inimical to the
ripening of fruit.
In every instance a wall should never
ing of fruit,
" The F/ucd-u-all or Ilot-iral!,'" says
Mr. Loudon, " is generally built entirebe
lower than eight feet. The thick- ly of brick, though where stone is
ness usually varies with the height of abundant and more economical, the
the wall, being nine inches, if it is not
liigher than eight feet; thirteen and a
back or north side may be of that raa-
tcrial. A flued wall may be termed a
half inches, if above eight and under hollow wall, in which the vacuity is
fourteen feet; and eighteen inches, thrown into compartments, to facilitate
from fourteen up to twenty feet.
the circulation of smoke and heat, from
Fruit trees will succeed quite as well the base or surlace of the ground, to
against a stone wall as against a brick within one or two feet of the coping.
one, although the former is neither so Such walls are generally arranged with
neat in appearance, nor can the trees hooks inserted under the coping, to adbe
trained in such a regular form upon mit of fastening some description of
it as npon the latter. The lastdisadvantage
may be in a great measure remcprotecting
covers, and sometimes for
temporary glass frames. A length of
died by having a wooden or wire trellis forty feet, and from ten to tifleen high,
affixed to it. Gard. Chron. may be heated by one fire, the furnace
If it be desirable that the roots of the of which, being placed one or two feet
trees should benefit by the pasturage
outside the wall, it is very common to
below the surlace of the ground, the
first course or flue will commence one
build it upon an arched foundation. toot above it, and be two feet six inches.
'
'
Colour has very considerable influence or three feet high, and the second, third,
over a body's power of absorbing heat, and fourth courses, narrower as they
If a thermometer on a hot summer's ascend. The thickness of that side of
day, be exposed to the sun, it will indi- the flue, next the south or preferable
cate a temperature of about 100°; but if side, should for the first course, be four
the bulb be blackened with Indian ink inciies or brick and bed, and for the
or the smoke of a candle, it will rise other courses, it were desirable to have
from ten to twenty degrees higher, bricks cast in a smaller mould : say for
The reason for this is tli;it the polished the second course three, for the third
surface of the glass reflects some of the two and three (juarters, and for the
sun's rays, but the blackened surlace fourth two and a half inches in breadth,
absorbs them all. Blue absorbs all but
the blue rays—red all but the red
This will give an opportunity of bevel-
ng the wall, and the bricks being all of
green and yellow all but those of their
own name—and white reflects all the
rays. The lightest coloured rays are
the same thickness, though of difl'erent
widths, the external appearance will be
everywhere the same." Enr. Gard.
the most heating, therefore light co- Mr. Paxton has the following excelloured
walls, but especially white, are lent observations upon Conservative
the worst for fruit trees. The ther- Walls, or walls so constructed as to
mometer against a wall rendered black shelter trees trained against them from
by coal tar, rises 5^ higher in the sun- winds, and other natural modes of
shine, than the same instrument sus- rapidly lowering the temperature:
pendcd against a red brick structure of " In forming a conservative wall, it is
the samii thickness; nor will it cool necessary that it should have a south or
lower at
power is
night, though its
increased by the
radiating a south-western aspect. It is also desi-
|
increased' rable, in order to give it an ornamental
—
—
—