_Walls._--The position to be given to the garden walls has been already
referred to. The shelter afforded by a wall, and the increased
temperature secured by its presence, are indispensable in the climate of
Great Britain, for the production of all the finer kinds of outdoor
fruits; and hence the inner side of a north wall, having a southern
aspect, is appropriated to the more tender kinds. It is, indeed,
estimated that such positions enjoy an increased temperature equal to 7
deg. of latitude--that is to say, the mean temperature within a few
inches of the wall is equal to the mean temperature of the open plain 7
deg. farther south. The eastern and western aspects are set apart for
fruits of a somewhat hardier character.
Where the inclination of the ground is considerable, and the presence of
high walls would be objectionable, the latter may be replaced by sunk
walls. These should not rise more than 3 ft. above the level of the
ground behind them. As dryness is favourable to an increase of heat,
such walls should be either built hollow or packed behind to the
thickness of 3 or 4 ft. with rubble stones, flints, brickbats or similar
material, thoroughly drained at bottom. For mere purposes of shelter a
height of 6 or 7 ft. will generally be sufficient for the walls of a
garden, but for the training of fruit trees it is found that an average
height of 12 ft. is more suitable. In gardens of large size the northern
or principal wall may be 14 ft., and the side walls 12 ft. in height;
while smaller areas of an acre or so should have the principal walls 12
and the side walls 10 ft. in height. As brick is more easily built
hollow than stone, it is to be preferred for garden walls. A 14-in.
hollow wall will take in its construction 12,800 bricks, while a solid
9-in. one, with piers, will take 11,000; but the hollow wall, while thus
only a little more costly, will be greatly superior, being drier and
warmer, as well as more substantial. Bricks cannot be too well burnt for
garden walls; the harder they are the less moisture will they absorb.
Many excellent walls are built of stone. The best is dark-coloured
whinstone, because it absorbs very little moisture, or in Scotland
Caithness pavement 4 in. thick. The stones can be cut (in the quarries)
to any required length, and built in regular courses. Stone walls should
always be built with thin courses for convenience of training over their
surface. Concrete walls, properly coped and provided with a trellis, may
in some places be cheapest, and they are very durable. Common rubble
walls are the worst of all.
The coping of garden walls is important, both for the preservation of
the walls and for throwing the rain-water off their surfaces. It should
not project less than from 2 to 2(1/2) in., but in wet districts may be
extended to 6 in. Stone copings are best, but they are costly, and
Portland cement is sometimes substituted. Temporary copings of wood,
which may be fixed by means of permanent iron brackets just below the
stone coping, are extremely useful in spring for the protection of the
blossoms of fruit trees. They should be 9 in. or 1 ft. wide, and should
be put on during spring before the blossom buds begin to expand; they
should have attached to them scrim cloth (a sort of thin canvas), which
admits light pretty freely, yet is sufficient to ward off ordinary
frosts; this canvas is to be let down towards evening and drawn up again
in the morning. These copings should be removed when they are of no
further utility as protectors, so that the foliage may have the full
benefit of rain and dew. Any contrivance that serves to interrupt
radiation, though it may not keep the temperature much above freezing,
will be found sufficient. Standard fruit trees must be left to take
their chance; and, indeed from the lateness of their flowering, they are
generally more injured by blight, and by drenching rains, which wash
away the pollen of the flowers, than by the direct effects of cold.
_Espalier Rails._--Subsidiary to walls as a means of training fruit
trees, espalier rails were formerly much employed, and are still used in
many gardens. In their simplest form, they are merely a row of slender
stakes of larch or other wood driven into the ground, and connected by a
slight rod or fillet at top. The use of iron rails has now been almost
wholly discontinued on account of metallic substances acting as powerful
conductors of both heat and cold in equal extremes. Standards from which
galvanized wire is tightly strained from one end to the other are
preferable and very convenient. Trees trained to them are easily got at
for all cultural operations, space is saved, and the fruit, while freely
exposed to sun and air, is tolerably secure against wind. They form,
moreover, neat enclosures for the vegetable quarters, and, provided
excess of growth from the centre is successfully grappled with, they are
productive in soils and situations which are suitable.
_Plant Houses._--These include all those structures which are more
intimately associated with the growth of ornamental plants and flowers,
and comprise conservatory, plant stove, greenhouse and the subsidiary
pits and frames. They should be so erected as to present the smallest
extent of opaque surface consistent with stability. With this object in
view, the early improvers of hot-house architecture substituted metal
for wood in the construction of the roofs, and for the most part
dispensed with back walls; but the conducting power of the metal caused
a great irregularity of temperature, which it was found difficult to
control; and, notwithstanding the elegance of metallic houses, this
circumstance, together with their greater cost, has induced most recent
authorities to give the preference to wood. The combination of the two,
however, shows clearly that, without much variation of heat or loss of
light, any extent of space may be covered, and houses of any altitude
constructed.
The earliest notice we have of such structures is given in the Latin
writers of the 1st century (Mart. _Epigr._ viii. 14 and 68); the
[Greek: Adonidos kepoi], to which allusion is made by various Greek
authors, have no claim to be mentioned in this connexion. Columella
(xi. 3, 51, 52) and Pliny (_H.N._ xix. 23) both refer to their use in
Italy for the cultivation of the rarer and more delicate sorts of
plants and trees. Seneca has given us a description of the application
of hot water for securing the necessary temperature. The botanist
Jungermann had plant houses at Altdorf in Switzerland; those of
Loader, a London merchant, and the conservatory in the Apothecaries'
Botanic Garden at Chelsea, were among the first structures of the kind
erected in British gardens. These were, however, ill adapted for the
growth of plants, as they consisted of little else than a huge chamber
of masonry, having large windows in front, with the roof invariably
opaque. The next step was taken when it became fashionable to have
conservatories attached to mansions, instead of having them in the
pleasure grounds. This arrangement brought them within the province of
architects, and for nearly a century utility and fitness for the
cultivation of plants were sacrificed, as still is often the case, to
the unity of architectural expression between the conservatory and the
mansion.
[Illustration: FIG. 2.--Lean-to Plant House.]
Plant houses must be as far as possible impervious to wet and cold air
from the exterior, provision at the same time being made for
ventilation, while the escape of warm air from the interior must also be
under control. The most important part of the enclosing material is
necessarily glass. But as the rays of light, even in passing through
transparent glass, lose much of their energy, which is further weakened
in proportion to the distance it has to travel, the nearer the plant can
be placed to the glass the more perfectly will its functions be
performed; hence the importance of constructing the roofs at such an
angle as will admit the most light, especially sunlight, at the time it
is most required. Plants in glass houses require for their fullest
development more solar light probably than even our best hot-houses
transmit--certainly much more than is transmitted through the roofs of
houses as generally constructed.
Plant houses constructed of the best Baltic pine timber are very
durable, but the whole of the parts should be kept as light as possible.
In many houses, especially those where ornament is of no consequence,
the rafters are now omitted, or only used at wide intervals, somewhat
stouter sash-bars being adopted, and stout panes of glass (usually
called 21-oz.) 12 to 18 in. wide, made use of. Such houses are very
light; being also very close, they require careful ventilation. The
glass roof is commonly designed so as to form a uniform plane or slope
from back to front in lean-to houses (fig. 2), and from centre to sides
in span-roofed houses. To secure the greatest possible influx of light,
some horticulturists recommend curvilinear roofs; but the superiority of
these is largely due to the absence of rafters, which may also be
dispensed with in plain roofs. They are very expensive to build and
maintain. Span and ridge-and-furrow roofs, the forms now mostly
preferred, are exceedingly well adapted for the admission of light,
especially when they are glazed to within a few inches of the ground.
They can be made, too, to cover in any extent of area without sustaining
walls. Indeed, it has been proposed to support such roofs to a great
extent upon suspension principles, the internal columns of support being
utilized for conducting the rain-water off the roof to underground
drains or reservoirs. The lean-to is the least desirable form, since it
scarcely admits of elegance of design, but it is necessarily adopted in
many cases.
In glazing, the greater the surface of glass, and the less space
occupied by rafters and astragals as well as overlaps, the greater the
admission of light. Some prefer that the sash-bars should be grooved
instead of rebated, and this plan exposes less putty to the action of
the weather. The simple bedding of the glass, without the use of over
putty, seems to be widely approved; but the glass may be fixed in a
variety of other ways, some of which are patented.
The _Conservatory_ is often built in connexion with the mansion, so as
to be entered from the drawing-room or boudoir. But when so situated
it is apt to suffer from the shade of the building, and is
objectionable on account of admitting damp to the drawing-room. Where
circumstances will admit, it is better to place it at some distance
from the house, and to form a connexion by means of a glass corridor.
In order that the conservatory may be kept gay with flowers, there
should be a subsidiary structure to receive the plants as they go out
of bloom. The conservatory may also with great propriety be placed in
the flower garden, where it may occupy an elevated terrace, and form
the termination of one of the more important walks.
Great variety of design is admissible in the conservatory, but it
ought always to be adapted to the style of the mansion of which it is
a prominent appendage. Some very pleasing examples are to be met with
which have the form of a parallelogram with a lightly-rounded roof;
others of appropriate character are square or nearly so, with a
ridge-and-furrow roof. Whatever the form, there must be light in
abundance; and the shade both of buildings and of trees must be
avoided. A southern aspect, or one varying to south-east or
south-west, is preferable; if these aspects cannot be secured, the
plants selected must be adapted to the position. The central part of
the house may be devoted to permanent plants; the side stages and open
spaces in the permanent beds should be reserved for the temporary
plants.
[Illustration: FIG. 3.--Section of Greenhouse.]
The _Greenhouse_ is a structure designed for the growth of such exotic
plants as require to be kept during winter in a temperature
considerably above the freezing-point. The best form is the
span-roofed, a single span being better even than a series of spans
such as form the ridge-and-furrow roof. For plant culture, houses at a
comparatively low pitch are better than higher ones where the plants
have to stand at a greater distance from the glass, and therefore in
greater gloom. Fig. 3 represents a convenient form of greenhouse. It
is 20 ft. wide and 12 ft. high, and may be of any convenient length.
The side walls are surmounted by short upright sashes which open
outwards by machinery a, and the roof is provided with sliding upper
sashes for top ventilation. The upper sashes may also be made to lift,
and are in many respects more convenient to operate. In the centre is
a two-tier stage 6 ft. wide, for plants, with a pathway on each side 3
ft. wide, and a side stage 4 ft. wide, the side stages being flat, and
the centre stage having the middle portion one-third of the width
elevated 1 ft. above the rest so as to lift up the middle row of
plants nearer the light. Span-roofed houses of this character should
run north and south so as to secure an equalization of light, and
should be warmed by two flow, and one or two return 4-in. hot-water
pipes, carried under the side stages along each side and across each
end. Where it is desired to cultivate a large number of plants, it is
much better to increase the number of such houses than to provide
larger structures. The smaller houses are far better for cultural
purposes, while the plants can be classified, and the little details
of management more conveniently attended to. Pelargoniums, cinerarias,
calceolarias, cyclamens, camellias, heaths, roses and other
specialities might thus have to themselves either a whole house or
part of a house, the conditions of which could then be more accurately
fitted to the wants of the inmates.
The lean-to house is in most respects inferior to the span-roofed; one
of the latter could be converted into two of the former of opposite
aspects by a divisional wall along the centre. Except where space does
not permit a span-roofed building to be introduced, a lean-to is not
to be recommended; but a house of this class may often be greatly
improved by adopting a half-span or hipped roof--that is, one with a
short slope behind and a longer in front.
[Illustration: FIG. 4.--Section of Plant Stove.]
Where the cultivation of large specimens has to be carried on, a
span-roofed house of greater height and larger dimensions may
sometimes prove useful; but space for this class of plants may
generally be secured in a house of the smaller elevation, simply by
lowering or removing altogether the staging erected for smaller
plants, and allowing the larger ones to stand on or nearer the floor.
The _Plant Stove_ differs in no respect from the greenhouse except in
having a greater extent of hot-water pipes for the purpose of securing
a greater degree of heat, although, as the plants in stove houses
often attain a larger size, and many of them require a bed of coco-nut
fibre, tan or leaf mould to supply them with bottom heat, a somewhat
greater elevation may perhaps be occasionally required in some of the
houses. For the smaller plants, and for all choicer subjects, the
smaller size of house already recommended for greenhouses, namely 20
ft. wide and 12 ft. high, with a side table of 4 ft. on each side, a
pathway of 3 ft. and a central stage on two levels of 6 ft. wide, will
be preferable, because more easily managed as to the supply of heat
and moisture. It will be seen (fig. 4) that along the ridge of the
roof a raised portion or lantern light b, b is introduced, which
permits of the fixing of two continuous ventilators, one along each
side, for the egress of heated and foul air, openings a, a being also
provided in the side walls opposite the hot-water pipes for the
admission of pure cold air. This type of house is also very suitable
for greenhouse plants, but would not need so much heating apparatus.
Three or four rows of flow and return pipes respectively will be
required on each side, according to the heat proposed to be
maintained.
In their interior fittings plant stoves require more care than
greenhouses, which are much drier, and in which consequently the
staging does not so soon decay. In stoves the stages should be of
slate or stone where practicable, and the supports of iron. These
should be covered with a layer of 2 or 3 in. of some coarse gritty
material, such as pounded spar, or the shell sand obtained on the
sea-coast, on which the pots are to stand; its use is to absorb
moisture and gradually give it out for the benefit of the plants. The
pathways should be paved with tiles, brick or stone, or made of
concrete and cement, and the surface should be gently rounded so that
the water required for evaporation may drain to the sides while the
centre is sufficiently dry to walk upon; they should also have brick
or stone edgings to prevent the water so applied soaking away at the
sides and thus being wasted.
[Illustration: FIG. 5.--Lean-to Vinery.]
_Fruit Houses._--The principal of these are the vinery, peach house,
cucumber and melon house and orchard house. These, or a portion of them,
especially the vineries and peacheries, are frequently brought together
into a range along the principal interior or south wall of the garden,
where they are well exposed to sun and light, an ornamental plant house
being sometimes introduced into the centre of the range in order to give
effect to the outline of the buildings. When thus associated, the houses
are usually of the lean-to class, which have the advantage of being more
easily warmed and kept warm than buildings having glass on both sides, a
matter of great importance for forcing purposes.
[Illustration: FIG. 6.--Hip-Roofed Vinery.]
The _Vinery_ is a house devoted to the culture of the grape-vine,
which is by far the most important exotic fruit cultivated in English
gardens. When forming part of a range a vinery would in most cases be
a lean-to structure, with a sharp pitch (45-50 deg.) if intended for
early forcing, and a flatter roof (40 deg.) with longer rafters if
designed for the main and late crops. (1) The _lean-to_ (fig. 5) is
the simplest form, often erected against some existing wall, and the
best for early forcing, being warmer on account of the shelter
afforded by the back wall. In this house the principal part of the
roof is a fixture, ventilation being provided for by small lifting
sashes against the back wall, and by the upright front sashes being
hung on a pivot so as to swing outwards on the lower side. The
necessary heat is provided by four 4-in. hot-water pipes, which would
perhaps be best placed if all laid side by side, while the vines are
planted in front and trained upwards under the roof. A second set of
vines may be planted against the back wall, and will thrive there
until the shade of the roof becomes too dense. (2) The _hip-roofed_ or
three-quarter span (fig. 6) is a combination of the lean-to and the
span-roofed, uniting to a great degree the advantages of both, being
warmer than the span and lighter than the lean-to. The heating and
ventilating arrangements are much the same as in the lean-to, only the
top sashes which open are on the back slope, and therefore do not
interfere so much with the vines on the front slope. In both this and
the lean-to the aspect should be as nearly due south as possible.
Houses of this form are excellent for general purposes, and they are
well adapted both for muscats, which require a high temperature, and
for late-keeping grapes. (3) The _span-roofed_ (fig. 7), the most
elegant and ornamental form, is especially adapted for isolated
positions; indeed, no other form affords so much roof space for the
development of the vines. The amount of light admitted being very
great, these houses answer well for general purposes and for the main
crop. The large amount of glass or cooling surface, however, makes it
more difficult to keep up a high and regular temperature in them, and
from this cause they are not so well adapted for very early or very
late crops. They are best, nevertheless, when grapes and ornamental
plants are grown in the same house, except, indeed, in very wet and
cold districts, where, in consequence of its greater warmth, the
lean-to is to be preferred. This type of house, cheaply constructed,
is in general use for raising grapes for market.
[Illustration: FIG. 7.--Span-Roofed Vinery.]
The _Peach House_ is a structure in which the ripening of the fruit is
accelerated by the judicious employment of artificial heat. For early
forcing, as in vineries, the lean-to form is to be preferred, and the
house may have a tolerably sharp pitch. A width of 7 or 8 ft., with
the glass slope continued down to within a foot or two of the ground,
and without any upright front sashes, will be suitable for such a
house, which may also be conveniently divided into compartments of
from 30 to 50 ft. in length according to the extent of the building,
small houses being preferable to larger ones. As a very high
temperature is not required, two or three pipes running the whole
length of the house will suffice. The front wall should be built on
piers and arches to allow the roots to pass outwards into a prepared
border, the trees being planted just within the house. Abundant means
of ventilation should be provided.
[Illustration: FIG. 8.--Peach House.]
For more general purposes the house represented in fig. 8 will be
found more useful. One set of trees is planted near the front, and
trained to an arched trellis b. Another set is planted at the back,
and trained on a trellis c, which is nearly upright, and leans against
the back wall; or the back wall itself may be used for training. There
are no upright front sashes, but to facilitate ventilation there are
ventilators d in the front wall, and the upper roof sashes are made to
move up and down for the same object. Two or three hot-water pipes are
placed near the front wall. The back wall is usually planted with
dwarf and standard trees alternately, the latter being temporary, and
intended to furnish the upper part of the trellis, while the permanent
dwarfs arc gradually filling up the trellis from below. In any case
the front trellis should stop conveniently short of the top of the
sashes if there are trees against the back wall, in order to admit
light to them. They would also be better carried up nearly parallel to
the roof, and at about 1 ft. distant from it, supposing there were no
trees at the back.
[Illustration: FIG. 9.--Forcing House.]
A span-roofed house, being lighter than a lean-to, would be so much
the better for peach culture, especially for the crop grown just in
anticipation of those from the open walls since a high temperature is
not required. A low span, with dwarf side walls, and a lantern
ventilator along the ridge, the height in the centre being 9 ft.,
would be very well adapted for the purpose. The trees should be
planted inside and trained up towards the ridge on a trellis about a
foot from the glass, the walls being arched to permit the egress of
the roots. A trellis path should run along the centre, and movable
pieces of trellis should be provided to prevent trampling on the soil
while dressing and tying in the young wood.
The _Forcing House_.--Whenever continuous supplies of cucumbers,
melons and tomatoes are required, it is most convenient to grow them
in properly constructed forcing houses. Span-roofed houses (fig. 9)
arc probably the most useful for the purpose. They are usually 12 to
14 ft. wide, by 10 to 12 ft. high, and of any convenient length.
Heating is effected by means of hot-water pipes below the beds, and
against the side ventilators. The walls bordering the central paths
are arched or clotted to admit heat from the chambers below the beds.
Side pipes are occasionally dispensed with, heat being obtained by
means of slots at the back of the beds, communicating with the
chambers. The beds are also of use for plunging pot plants.
Ventilation is provided at sides and top.
Pits and frames of various kinds are frequently used for the
cultivation of cucumbers and melons, as well as hot beds covered by
ordinary garden frames. In these cases the first supply of heat is
derived from the hot bed made up within the pit. When the heat of the
original bed subsides, linings of fermenting dung must be added, and
these must be kept active by occasional turnings and the addition of
fresh material as often as required. It is better, however, to effect
both top and bottom heating by hot-water pipes.
_Orchard Houses_ are span-roofed or lean-to structures, in which
various fruits are cultivated without the aid of artificial heat.
Peaches, nectarines, apricots, cherries and the more tender varieties
of plums and pears succeed well in houses of this kind. The types of
houses in general use are substantially as shown in fig. 7, for
span-roofed, and as fig. 5, for lean-to; in each case without the
heating apparatus. The orchard house is among the most generally
useful of all garden structures. These houses require careful
management in early summer so as to induce the more delicate varieties
of peaches and nectarines to complete and ripen their growth before
cold, sunless weather sets in.
In commercial establishments where utility is of more importance than
ornament, the glass houses and hot water apparatus are not of so
elaborate a type as indicated in the foregoing remarks, and in many
cases excellent produce is grown in structures more or less
dilapidated. In some places movable greenhouses have been erected for
market purposes, so that the soil may be exposed to the sweetening
effect of the weather, when the glass roof is moved to an adjoining
patch.
_Pits and Frames._--These are used both for the summer growth and winter
protection of various kinds of ornamental plants, for the growth of such
fruits as cucumbers, melons and strawberries, and for the forcing of
vegetables. When heat is required, it is sometimes supplied by means of
fermenting dung, or dung and leaves, or tanner's bark, but it is much
more economically provided by hot-water pipes. Pits of many different
forms have been designed, but it may be sufficient here to describe one
or two which can be recommended for general purposes.
[Illustration: FIG. 10.--Ventilated Plant Pit.]
An excellent pit for wintering bedding-out plants or young greenhouse
stock is shown at fig. 10. It is built upon the pigeon-hole principle
as high as the ground level a, a, and above that in 9-in. brickwork.
At a distance of 9 in. retaining walls b, b are built up to the ground
level, and the spaces between the two are covered by thick boarding,
which is to be shut down as shown at c in cold weather to exclude
frost, and opened as shown at d in mild weather to promote a free
circulation of air through the pit. The height of the pit might be
reduced according to the size of the plants; and, to secure the
interior against frost, flow and return hot-water pipe e should pass
along beneath the staging, which should be a strong wooden trellis
supported by projections in the brickwork. The water which drains from
the plants or is spilt in watering would fall on the bottom, which
should be made porous to carry it away. For many plants this under
current of ventilation would be exceedingly beneficial, especially
when cold winds prevented the sashes from being opened. A pit of this
character may be sunk into the ground deeper than is indicated in the
figure if the subsoil is dry and gravelly, bat in the case of a damp
subsoil it should rather be more elevated, as the soil could easily be
sloped up to meet the retaining wall.
_Frames._--Frames (fig. 11) should be made of the best red deal, 1(1/4)
in. thick. A convenient size is 6 ft. wide, 24 in. high at the back
and 15 in front; and they are usually 12 ft. long, which makes three
lights and sashes, though they can be made with two lights or one
light for particular purposes. Indeed, a one-light frame is often
found very convenient for many purposes. The lights should be 2 in.
thick, and glazed with 21 oz. sheet glass, in broad panes four or five
to the breadth of a light, and of a length which will work in
conveniently and economically, very long panes being undesirable from
the havoc caused by accidents, and very short ones being objectionable
as multiplying the chances of drip, and the exclusion of light by the
numerous lappings; panes about 12 in. long are of convenient size for
garden lights of this character. In all gardens the frames and lights
should be of one size so as to be interchangeable, and a good supply
of extra lights (sashes) may always be turned to good account for
various purposes.
[Illustration: FIG. 11.--Hot-Bed Three-Light Frame.]
[Illustration: FIG. 12.--Span-Roof Frame.]
Span-roof garden frame (fig. 12) may under some circumstances be
useful as a substitute for the three-light frame. It is adapted for
storing plants in winter, for nursing small plants in summer and for
the culture of melons and other crops requiring glass shelter. These
frames are made 11 in. high in front, 22 at the back and 32 at the
ridge, with ends of 1(1/2)-in. red deal; the sashes, which are 2 in.
thick, open by gearing, the front and back separately. The lights are
hinged so that they can be turned completely back when necessary. This
more direct and ready access to the plants within is one of the
principal recommendations of this form of pit.
_Mushroom House._--Mushrooms may be grown in sheds and cellars, or even
in protected ridges in the open ground, but a special structure is
usually devoted to them. A lean-to against the north side of the garden
wall will be found suitable for the purpose, though a span-roofed form
may also be adopted, especially if the building stands apart.
[Illustration: FIG. 13.--Lean-to Mushroom House.]
The internal arrangement of a lean-to mushroom house is shown in fig.
13. The length may vary from 30 ft. to 60 ft.; a convenient width is
10 ft., which admits of a 3(1/2) ft. central path, and beds 3 ft. wide
on each side. The shelves should be of slate a, a, supported by iron
uprights b, b, each half having a front ledge of bricks set on edge in
cement c, c. The slabs of slate forming the shelves should not be too
closely fitted, as a small interval will prevent the accumulation of
moisture at the bottom of the bed. They may be supported by iron
standards or brick piers, back and front, bearing up a flat bar of
iron on which the slates may rest; the use of the bar will give wider
intervals between the supports, which will be found convenient for
filling and emptying the beds. The roof may be tiled or slated; but,
to prevent the injurious influence of hot sun, there should be an
inner roof or ceiling d, the space between which and the outer roof e
should be packed with sawdust. A hot-water pipe f should run along
both sides of the pathway, close to the front ledge of the lowest
beds. The different shelves can be planted in succession; and the
lower ones, especially those on the floor level, as being most
convenient, can be utilized for forcing sea-kale and rhubarb.
_The Fruit Room._--This important store should be dark, moderately dry,
with a steady, moderately cool atmosphere, and with the means of giving
sufficient ventilation to keep the air sweet. It should also be
sufficiently commodious to permit of the fruit being arranged in single
layers on the shelves or trays. A type of building which is becoming
increasingly popular for this purpose, and which is in many respects
superior to the older, and often more expensive structures, is built of
wood, with or without brick foundations, and is thickly thatched with
reeds or other non-conducting material externally--on walls and
roof--while the interior is matchboarded. Ventilation is afforded at the
ends, usually by tilting laths, operated by a cord. Two doors are
provided at one end--an inner, and an outer--the inner being glazed at
the top to admit light. They are generally span-roofed, about 6 ft. high
at the eaves, and 8 or 10 ft. high at the ridge, according to width.
The length and breadth of these stores should be governed by the
amount and character of the storage accommodation to be provided. If
intended for storage only, a width of 9 ft. 6 in. would suffice, but
if intended to combine display with storage, the internal diameter
should be about 13 ft. In the former type, the walls are fitted with
four rows of shelves, about 3 ft. wide, and about 1 ft. 6 in. apart.
The shelves are of deal strips, 2 or 3 in. wide, laid about 1 in.
apart for ventilation. These are being superseded, however, by
sliding-out trays of convenient lengths and about 9 in. deep, working
on fixed framework. By this means the storage accommodation is nearly
doubled and the fruit is more easily manipulated. The central gangway
is about 3 ft. 6 in. wide. In the latter a central exhibition bench
about 3 ft. wide and of convenient height is provided. Gangways 2(1/2)
ft. wide flank this, while the shelves or drawers with which the walls
are fitted are about 2(1/2) ft. wide.
_Care of the Fruit Room._--This consists mainly in the storing only of
such fruits as are dry and in proper condition; in judicious
ventilation, especially in the presence of large quantities of
newly-gathered fruit; in the prompt removal of all decaying fruit; and
in the exclusion of vermin. It is also advisable to wash all woodwork
and gangways annually with a weak solution of formalin, or other
inodorous germicide.
_Heating Apparatus._--Plant houses were formerly heated in a variety of
ways--by fermenting organic matter, such as dung, by smoke flues, by
steam and by hot water circulating in iron pipes. The last-named method
has proved so satisfactory in practice that it is now in general use for
all ordinary purposes. The water is heated by a furnace, and is conveyed
from the boiler into the houses by a main or "flow" pipe, connected by
means of syphon branches with as many pipes as it is intended to serve.
When cooled it is returned to the boiler by another main or "return"
pipe. Heat is regulated in the structures by means of valves on the
various branch pipes. The flow pipe is attached to the boiler at its
highest point, to take the heated water as it ascends. The return pipe
is connected with the boiler at or near its lowest point. The highest
points of the pipes are fitted with small taps, for the removal of air,
which would retard circulation if allowed to remain. Heating by hot
water may be said to depend, in part, on the influence of gravity on
water being to some extent overcome by heating in a boiler. It ascends
the flow pipe by convection, where its onward journey would speedily end
if it were not for the driving force of other molecules of water
following, and the suction set up by the gravitation into the boiler of
the cooled water by the return pipe. The power of water to conduct heat
is very low. The conducting power of the iron in which it is conveyed is
high. It is, however, probable that conduction is to some extent a
factor in the process.
Pipes.--It is a mistake to stint the quantity of piping, since it is
far more economical and better for the plants to have a larger surface
heated moderately than a smaller surface heated excessively. In view
of the fact that air expands, becomes lighter and rises, under the
influence of heat, the pipes should be set near the floor. If intended
to raise the temperature of the structure, they should be set on iron
or brick supports just clear of walls, earth or other heat-absorbing
bodies. Those intended to provide bottom heat, however, are set in (a)
water tanks running under the beds, or (b) in enclosed dry chambers
under the beds, or are (c) embedded in the soil or plunging material.
The first-named method is distinctly superior to the others. Pipes of
2 in., 3 in., 4 in. and 6 in. diameters are mostly used, the 4 in.
size being the most convenient for general purposes. The joints are
packed or caulked with tow, smeared with a mixture of white and red
lead. Flanged joints are made to bolt together on washers of
vulcanized rubber.
_Boilers._--There are numerous types of boilers in use, illustrative
of efforts to secure as much exposure as possible to the action of the
flames. The water-tube type, with multiple waterways, consists of a
number of separate tubes joined together in various ways. Some of
these are built in the form of a blunt cone, and are known as conical
tubular boilers. Others are built with the tubes arranged
horizontally, and are known as horizontal tubular boilers. The
majority of the latter are more or less saddle-shaped. Boilers with a
single waterway are of three principal types, the Cornish, the saddle
and the conical. The Cornish is cylindrical with the furnace occupying
about half the length of the cylinder. The saddle is so named from its
supposed resemblance to a saddle. It is set to span the furnace,
additional exposure to heat being secured in a variety of ways by
flues. Exposure in the conical boiler is direct on its inner surface,
and is supplemented by flues. Tubular boilers, especially the
horizontal types, are very powerful and economical. The Cornish type
is a rather slow and steady boiler, and is much used for providing
heat for large areas. The saddle boiler is very commonly employed to
provide heat for moderately sized and small areas. Both are powerful
and economical. Conical boilers are more expensive to set by reason of
their shape, and are not so convenient to manipulate as the horizontal
kinds. All the above types require a setting of masonry. Portable
boilers are convenient for heating small areas, and are less expensive
to install than those described above. They are less economical,
however, owing to loss of heat from their exposed surfaces. What are
called sectional boilers as used in America and on the Continent are
being introduced to British gardens. Portions can be added or taken
away according to the amount of heating surface required.
_Water Supply._--Wastage of water in the boilers should be made good
automatically from a cistern controlled by means of a ball-cock. It
should be placed as high above the boiler as practicable. The feed
should connect with the return pipe near the point at which it enters
the boiler.
_Stokeholds._--These have usually to be excavated to admit of the
boilers being set below the level of the pipes they are intended to
serve. In consequence of their depth, the draining of stokeholds often
presents difficulties. Care should be taken to allow sufficient room
to properly manipulate the fires and to store fuel. It is important
that the ventilation should be as efficient as practicable, especially
where coke fuel is to be used.
_Stoking._--The management of the furnaces is relatively easy, and
consists in adapting the volume and intensity of the fires to
particular needs. It involves the keeping dean of flues, ashpits and
especially the fires themselves. Where coke or ordinary hard coal are
used, the removal of clinkers should be done systematically, and the
fires stirred. Anthracite coal fires should not be stirred more than
is absolutely necessary, and should not be fed in driblets. They
require more draught than coke fires, but care must be taken not to
give too much, as excessive heat is likely to melt or soften the
fire-bars. Draught is regulated in the ashpit by opening or closing
the bottom door of the furnace and by the damper on the smoke shaft.
The latter must be of a fairly good height, according to
circumstances, to secure a good draught.
_Solar Heat._--The importance of sun heat to the general well-being of
plant life, its influence on the production of flowers and the
ripening of edible fruits, has long been appreciated in horticulture.
The practice of "closing up" early in the afternoon, i.e. the closing
of ventilators (accompanied by syringing and damping of surfaces to
produce a humid atmosphere) has for its object the conservation of as
much solar heat as practicable.
_Ventilation._--This consists in the admission of air for the purpose
of preventing stagnation of the atmosphere and for the regulation of
temperature. Means of affording ventilation in all plant houses should
be provided in at least two places--as near the floor as practicable,
and at the top. Mechanical contrivances whereby whole sets of
ventilators may be operated simultaneously are now in common use, and
are much more convenient and economical than the older method of
working each ventilator separately. Efficient ventilating can only be
effected by the exercise of common sense and vigilance, and care must
be taken to avoid cold draughts through the houses.