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ness and 8 or 1 0 feet square; r e q u i r e s v e r y little work on the surface; and has the
nronertv of but very slightly absorbing moisture from the atmosphere, or from tlie
moist ¿ound on which it may be placed. Thus, unless when watered on purpose, it
always appears perfectly dry and agreeable, however moist the soil may be below.
Where the paths in a house are on different levels, they arc commonly united by steps ;
but an inclined plane, when not steeper than one inch in six, will generaUy be iound
more convenient for the purposes of culture and management ; and if the slope is ono m
eight, it is more agreeable to ascend ov descend than a stair.
2171. P its , as applied to the interior parts of houses, are excavations, or ratiier
enclosures, for holding bark or other fei-mentable substances ; or sand, or ashes, or some-
times even common garden soil. They should be so formed as that the plants may
stand at a moderate distance from the glass, which of course depends on whether they
are dwarf bushy plants, as the pine-apple, &c., or taller, as palms and. hothouse trees.
Tlie pits are generally suiTounded by walls of brick, 4 or 9 inches thick ; or, to save
room, hy plates of cast iron, stone, or slate. Sometimes the slope of the surface of the
pit has a similar inclination to that of the roof ; but as, in tliis case, the tan or leaves, in
the course of fermentation, do not settle or compress regnlai'ly, the pots are thrown off
their level, and therefore the more common way is to adopt a slope not exceeding 5 ,
or to form .a level surfiice. Tan will ferment with aU the rapidity necessaiy for bottom
iicat, if in’ a layer -of 2^ or 3 feet thick, and therefore no tan-pits need exceed that
dciith. Those for leaves may be somewhat deeper. Heat from fire, or steam, or
water, is sometimes substituted for that afforded hy fermentable substances, and m these
cases various forms of constmction arc adopted. Pits may be heated by steam, and hot
water, by varions modes which have been already pointed out (§ 2124. to § 2145.).
2172. Bed s a nd borders in hothouses are generally fonned on the ground level, thoagh
sometimes raised above it. They are either composed of cai-th, for the direct growth of
plauts, or of gravel or scoriæ, in or on which to place pots.
2173. Shelves, except such as are placed near tho ground, or almost close nnder the
upper angle of the roofi are extremely injurious to the vegetation going forward in the
body of the house, by the exclusion of light. This consideration, therefore, must be
kept in view in placing them : in some cases they are inadmissible, as in conservatones ;
in others, as in propagating-houses, the light tliey exclude can better be spared, than in
fruiting or flowering departments. For forcing strawberries, they may be introduced
under the roof in vino and peach houses, and removed when thcir shade proves injurious,
&c. The ordinary fonn is that of a flat board ; but an improvement consists in
nailing two fillets along its edges, and covering the board with a thin layer of small
gravel or scoriæ. This preserves a cool genial moisture, which keeps the earthen pot
moist, and lessens the effect on the earth of alternate diyings and waterings ; and it also
admits the more ready escape of water from the orifices in the bottoms of the pots. Some,
in the case of forcing strawbemcs and kidneybeans, have the fillets or ledges of the
shelves so high as to contain 2 or 3 inches of water, by which means whole rows of
pots can be inundated at one operation ; but this is too indiscriminate an application
of a material on which so much in the gi’owth of plants depends.
2174. Stages are shelves in scries rising above each other, and falling back so as their
general surface may form a slope. They vary in form according to that of the house.
The houses with shod roofs and opaque ends have merely a series of steps reaching from
one end to the other ; but wherever the ends arc of glass, by returning each shelf to
the back wall, due advantage is obtained from the light furnished by the glass ends.
The addition of ledgcinent, or tiinied-up edges, to each shelf, and the covering them with
gi-avcl, is, of course, as advantageous as in separate shelves, and smely more consonant
with natural appearances, than leaving them naked like household or hook shelves.
Shelves and platforms of stone are now veiy general, and are found more congenial to
the plants than diy painted boards.
Su b se ct. 13. D e ta ils f o r W a te i', a nd R e n ew al o f A ir .
2175. T h e reservoirs o f w ater in hothouses are commonly cisterns of stone or timber,
lined with lead, or cast-iron troughs or basins. Sometimes, also, tanks are built in the
ground, and lined with lead or cement. The cistern is sometimes placed in an angle, or
other spare part of the house, and the water lifted from it at once with the watering-
pots ; but a more complete plan is, to build it in an elevated part ofthe back wall, where
it may have the benefit of the heat of the house, and whence pipes may branch off to
different parts of the house with cocks, every 30 or 40 feet, for drawing supplies. Tanks
and cisterns below the level of the front gutter may be supplied a great part of the year
from the water -which fiills on tho roof ; but more elevated cisterns must either be
supplied by pumps, or elevated springs. The sources of supply, and the quality of the
water, must be taken into consideration before the situations of the cisterns are determined
on. In all cases, there must be waste-boxes at the cocks, and waste-pipes from the
cistern, to counteract the bad effects of leiikagc.
2176. A r tific ia l ra in . A very elegant plan has been invented and executed by Messrs.
Loddio-cs, for producing an artificial shower of very fine rain in hothouses, by conduct-
P ^ 1 .1 c „ 1 .- , i ; _ . „ f o c... Q -fXiaf o tk I liin n -n rp th p sG .
on the leaves of the plants with tlic gi-eatest reguim-ity. Aiiis nas oecu uuuc m unv: ui
the pahn-houses of these spirited cultivators at Hackney, and for \yhich a medal was
voted to them bythe Horticultural Society, in 1817. The following is a particuiar
account of this apparatus (H o rt. T ra n s , vol. iii. p. 15.) : —
A leaden v in e o f h a lf a n inch bore is introduced into one end of the house, in such a situation th at
the stopcock, which is fixed in it, and which is used for turning on the supply of water, may be withm
reach - it is then carried either to the upper part, or the back of the house, or to the inside of the ndge
of the glass framework, being continued horizontally, and in a straight direction, the whole extent of the
house, and fastened to the wall or rafters, by iron staples, at convenient distances. Trom the point where
the pipe commences its horizontal direction, it is perforated with minute holes, through
the water, when turned on, issues in a fine stream, and, m descending, is broken, and falls on the plants,
in a manner resembling a gentle summer shower. I'he holes are perforated m the pipe with a needle,
fixed into a handle, like th at of an awl ; it being impossible to have the holes too fine, very small needles
are necessarily used for th e purpose, and in the operation great numbers are of c o u r^
situation of the holes in the pipe must be such as to disperse the water m every direction ^
be required ; and in this particular tho relative position of the Pipe, and of ^he stations of the pUn^^^^
watered, must be considered, in making th e perforations. I he holes are made, on f at abo^
two inches’ distance from each other, horizontally, but are somewhat more distant near
ment, and ra the r closer towards the termination c**
diminution of pressure, to give an equal supply
l o i S r a ì ì r é t h ? t o m » d e ° t a a d a p t l i i g i t o p i a n t o a ' S ’S ' t o ' S e ? ? ?
drops; and as too strong a power may be readily controlled to f J ta to r e 'd S .'ittpriilVd to in this narticular, is to secure force enough. Irom the above d ettoa illss fitt ¥wd u11" bbe«otoDsseemrv^c^a ,tiiat
Jorae n k c t i s requfrcd in thè arrangement and formation of the machinery ; but it is only necessary to
vtov t to ito fa tlS n in Messrs. Loddiges’ house to be convinced of the extreme advantage and utility of
the invention, when it is properly executed. (S abine , m H o r t. T ra n s ., vol. in. p. 15.)
2177. A i r in hothouses has been recommended to be changed, hy Dr. Anderson and
others, by means of fans; so as to produce aeration (§ 2154.). As this is vci-y desirable,
the Eolian machine, invented by B. Deacon, may bo employed, either placed m the
house, and kept in motion by human or mechanical power, or placed at one end to force
in or draw out the air. In a range of houses forming a circle or square, or any encliess
figure, a perpetual breeze might be readily produced in the follov'ing manner : ~ i lace
undev the floor a powerful fan of the width of the house. Exactly over the fan, place
a glass division across the house, and let the fan draw iu the air through apertures m the
floor on one side of the division, and give it out througli similar apertures, or through tubes
of any sort, on the other. It is evident, a regular cun-ent would thus be produced
more or less powerful according to the size ofthe fan, and the rapidity of its motion.
2178. V e n tila to rs, ^c. The general mode of renewing the air, is by opening the sashes
or doors of the house, in periods when the exterior tempcralm-c and Avcatlier are sucJi
as not to injure the plants within. The cool air of the atmosphere, bemg tlicn more
dense than that of the housp, rushes in till it cools down the air of the house nearly to an
equilibrium with that without. The next mode most common is that of hanng a range
of boards hinged to oblong openings, in the lower and upper parts of the house, and
generally in the front and hack wall ; those in the back wall opemng to the south, or
having the opening otherwise guarded, so as to prevent the i-usliing in of cold north winds.
Sometimes these ventilators are made with a cylinder and fans to extract the air, and
sometimes, as most generally, they are mere openings of small dimensions; but, in order
to effect any circulation or renewal with this sort of ventilators, the opening must have
an area of 2 or 3 feet, and there must be a considerable difference of temperatine
between the air of the house and the open air. . ., 7 7 ,
2179 T o effect the renew al o r cooling down o f the a ir, w ith o u t m a n ua l labour, vanous
contrivances have been adopted. Dr. Anderson and J. Williams made use ot oblong
bladders made fast at one end, and with the other attached by means of a cord to a
movable pane or small sash. The bladder being filled with air at the common temperature
allowed for the house, and hermetically sealed, the window remains at rest ; but as the
air ofthe house becomes heated, so does that of the bladder, which consequently swells,
and assumes the globular- form ; its peripheries are brought nearer together, and ot course
the sash or pane puUcd inwards. In a small house this scheme may answer perfectly
well for the prevention of extreme heat. Another mode is hy using a rod of metal, such
as lead, of the wholc length of the house, and one end being fixed to the wall, on the
other is attached a series of multiplying wheels, the last of which works into one, which
in various ways may open valves or sashes. As the expansion of lead is consiilerabie,
the effect of twenty degrees of increase, with proper machinery, might perhaps guard
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