Full text of "A practical treatise on the construction, heating and ventilation of hot-houses; : including conservatories, green-houses, graperies and other kinds of horticultural structures..."

See other formats

I:-.

4-Tr '„ .

i i:

tiff!.

/ Ml I

-f

1 —

• 1

! I I I i

1 1

_L 1

: 1

i 1

1 Mill!

1 i M •

! Mi:

j-i

ill MM

PRACTICAL TREATISE

OK THE

CONSTRUCTION, HEATING, AND VENTILATION

HOT-HOUSES;

IXCLUDINO

CONSERVATORIES, GREEN-HOUSES, GRAPERIES,

ASD OTHER KInDS 01*

HORTICULTURAL STRUCT URES.

WITH PRACTICAL DIRECTIONS FOR THEIR MANAGEMENT, m
REGARD TO LIGHT, HEAT, AND AIR,

ILLUSTRATED WITH NUMEROUS ENGRAVINGS.

BY ROBERT B. LEUCHARS,

OABDXN ARCHITSCTi

NEW YORK:

C. M. SAXTON, BARKER & CO, 25 PARK ROW.

SAN FRANCISCO; H. H. BANCROFT & CO.

1860.

Satered according to Act of Congress, in the year 1880,
Bv John P. Jewett & Co.,
la tb» Ciirk's Office of the District Court of the District of MassachuMila

SlerefttVped by
HO BART (fcROBBINS;
KUyV ENGLAND TYPE AND STEREOTYPE FOUNUBH
BO S T O X.

DESIQMID TO PROMOTE THE ADVANCEMENT OF EXOTIC HORTlCULTtTRE,
OF WHICH HE IS A ZEALOUS PATRON AND AUSHRER,

LIGED AND OBEDIENT

THE AUTHOR.

PREFACE.

Having for many years past devoted my attention
to the subjects treated of in this work, and from the
general call for appliable information thereon, I have
been induced to give it to the public, in the fall
persuasion that it will be acceptable to horticultur-
ists, gardeners, and others engaged in this depart-
ment of horticulture. From the numerous inquiries
which I have received, there appears to be a great
want of practical knowledge on these subjects ; and
though much information may be gleaned from vari-
ous English works, they are either unobtainable, or
the information is inapplicable to the wants of this
country.

When I commenced this treatise, I intended it as
a series of articles for periodical publication ; but
the development of the subjects, and the accumula-
tion of facts, swelled it to such a size as to render
its publication in that form impossible. In prepar-
ing it for the press, in its present form, I have been
desirous to add nothing but what is necessary to a
full understanding of the subject in hand, and have
given figures and diagrams where illustration is
required.

The changes which have occurred, during the last
twenty years, « in the method of constructing and

VI PREFACE.

managing horticultural structures, render the works
of that period of little value to gardeners at the
present day. I have here given all the latest im-
provements and most approved methods at present
in use, with plans and suggestions for their further
improvement.

From what has been said, I hope no one will sup-
pose that this treatise is given as a complete work
on Exotic Horticulture. Much has yet to be learned,
on many points connected with hot-houses, which
futurity will, no doubt, unfold.

My warmest expressions of thanks are due to
Professor Dana, of Yale College, for the generous
manner in which he has favored me with his opinions.
The readiness with which that gentleman has replied
to my inquiries, on matters of science relating to
my subject, even in the midst of his laborious literary
pursuits, shows how willing he is to aid the most
humble inquirer. This expression of thanks is due
from me here, as the only way in which I can suf-
ficiently show the high value at which I estimate
his kindness and liberality.

K. B L.

Boston, Oct. 3, 1850.

INTRODUCTION.

The object of the following treatise is chiefly to lay before
its readers a series of facts and observations relating to the con-
struction and general management of ail kinds of horticultural
structures, drawn from the developments of science, and an
extended experience, with the view of leading those who are
interested in this delightful pursuit to a more practical inquiry
regarding the comparative cost and economy of the various
methods now commonly adopted, as well as to draw the atten-
tion of practical gardeners to the utility of studying the theory
as well as the practice of those manifold operations on which the
success of exotic horticulture depends.

In a short treatise, on such comprehensive and varied subjects,
it is impossible to be strictly scientific; but we have endeavored
to show the rationale of those methods and operations which we
have here recommended, and which have been successfully car-
ried out by us in practice. The treatise is avowedly a practical
one, and intended chiefly for the use of practical gardeners, and
those desirous of obtaining that knowledge which is necessary to
eriable them to superintend the erection and future management
of their own garden structures. In the management of hot-
houses, there is a systematic regularity required in all the oper-
ations, a neglect of which is generally attended with disorder
and confusion. In fact, there is a sj^stem, the details of which
succeed each other like the links of a chain, each operation being
essentially connected with the one immediately following and
preceding it ; and here we have a most encouraging truth, that
the more scientific our principles of working, the more simple
and easily performed are our operations, and the more reliable
are the results.

8 INTRODUCTION.

It is doubtful if any branch of horticulture has received less
aid from science than that which forms the subject of the present
work. Science has indeed been brought to bear upon horticul-
tural generalities', but, as far as regards its application to exotic
horticultural details, it is little better than a sealed book ; and
hence it is that we find cultivators clinging to antiquated sys-
tems, which the plain demonstrations of science and practice are
daily proving to be absurd. Amateurs, who adopt exotic horti-
culture as an amusement, and pursue it wnth enthusiasm, are
very apt to be misled by the advice of those who are more igno-
rant than themselves. They are easily led into extremes ; and
nothing is more common than for such persons, in their zeal,
to adopt one error, under the plausible pretext of avoiding
another.

From the importance of Light, Heat, and Air, in the econo-
my of vegetable life, it is obvious why an architect is profession-
ally incapable of constructing a house for the growth of plants
or exotic fruits, without possessing a knowledge of the require-
ments and functions to be performed by the silent inhabitants ;
and hence it is, that, by studying these principles in connection
with other branches of science, we arrive at the end more rapidly
and successfully. In other words, cultivation becomes more cer-
tain as it becomes more scientific. Practical illustrations will
hereafter be given, to show that horticultural structures, instead
of being subordinate to architectural arrangements, as they gen-
erally are, must be accommodated to the necessities and require-
ments of vegetable life, before satisfaction can be afforded to the
possessor, or cultivation carried on in perfection.

If we take a glance at the progress of horticulture in Europe
during the last twenty years, we cannot fail to perceive that its
advancement has been parallel with the developments of chemi-
cal and physiological science. Almost every succeeding year
has brought with it some new and important improvement in
practice, and thrown additional ligbt upon some hitherto disputed
question. Although gardening has, in some solitary instances,
been remaining stationary, the cause is by no means obscure.
Gardening is encouraged just in proportion to the satisfaction
it affords. It ogives satisfaction accordinir to its success, and

I^'TRODUCTION. 9

success is in proportion to the amount of practical experience
founded upon a scientific basis.

Whatever causes exist to prevent the operations of gardening
from being carried out on scientific principles, it is nevertheless
true, that no methods can be generally applicable, or universal
in their results, that have not such principles for their bases. To
be guided by them, it is not necessary that the gardener should
be a mere reader of books, a studier of theories, or a continual
performer of experiments; he must add to the precepts of others
the acquisitions of his own experience, and aim constantly at
progress, by learning practically the principles upon which his
operations rest for their success. It is not the lot of every one
to discover truths hitherto unknown, but almost every one en-
gaged in the practice of horticulture can do something towards
improvement, by enforcing those already known by stronger
evidence, facilitating them by a clearer method, and elucidating
them by brighter illustrations.

There is a wide-spread antipathy to all kinds of book instruc-
tion, and book gardening is ridiculed by many who call them-
selves gardeners. It is, nevertheless, a well ascertained fact,
that those who rail at book practice are not only the worst prac-
tical, but also the worst theorists, and the worst reasoners upon
matters of practical import. Indeed, there are few who are more
slow to recognize the benefits of the valuable knowledge to be
found in the works of the eminent horticulturists of this countr}'^,
than those by whom it is most required. ^

Notwithstanding the valuable works which have lately been
given to the world, on horticulture and the kindred arts, by
eminent writers, little or nothing has been done in the depart-
ment embraced by this treatise. Horticultural structures of all
kinds continue to be made, and managed, with the same disre-
gard to the actual habits and requirements of plants, as they
were a century ago. And, though some structures of this kind
have been constructed upon plans and principles in accordance
with modern knowledge, yet these are a very small exception.
Many apparently fine structures could be pointed to, which are
rendered comparatively useless for the purposes for which they

10 INTRODUCTIO.- .

were built, on account of a deficiency of knowledge on the part
of those who superintended their erection.

It is a common error for gardeners, and others, who erect
glazed structures, to suppose that the kind of house perfectly
suitable in one place will be equally so in another ; or that the
same arrangement answerable for one purpose will answer
equally well for all purposes lo which a glazed structure may
be applied. Some of the consequences of these errors will be
more particularly specified in a subsequent part of this work ; as
also the external forms and internal arrangements which we
have found most suitable to the different purposes. The influ-
ence which a servile adherence to o^d methods has upon the
progress of horticulture, is chiefly manifest to those who are
most liable to be censured for innovations. Yet it is doubtful
whether the odium incurred is not more than compensated by
the pleasure which arises from the rewards of perseverance, by
which we are enabled to abandon bad systems, as we gain more
confidence in those that are better.

It is said that practice is the best of all teachers; that as our
practice is lengthened, our experience is increased. However
this axiom may hold good in the common affairs of life, it is
frequently reversed among practical men, and years pass away
without any enlargement of knowledge, or rectification of
judgment. There are, indeed, many who never endeavor to
improve, notwithstanding the opportunities which may be
afforded them. The opinions they have received, and the
practice they have learned, are seldom recalled for examination,
and, having once supposed them to be right, they can never
discover them to be erroneous. From this preconceived acqui-
escence, few are entirely free ; from a dislike to apparently super-
fluous labor, and from a fear of uncertain results, many stand
still when they might go forward.

Some may say, that if a practical man performs the operations
which others have taught him, and succeeds as well as others
have done, he does all that can be expected fron him. But this
is doing nothing for improvement, and very li tic for himself.
It is every man's duty to endeavor to excel, both on account
of his profession and of himself, as well as those who employ

I^'TR0DUCT10N. 11

him. It is easy to perceive that a gardener must not only know
how to do, but have his reasons for doing, A man who continues
to do his annual operations by mere routine, without knowing the
foundation or reasons, cannot deviate from the narrow path in
which he is confined, when any unexpected accident occurs.

In the following treatise, we have endeavored to explain these
principles, as far as they have been connected with the subjects
upon which it treats, and to illustrate them in such a manner as
to be easily understood by the general reader.

The first part of the work we have devoted to the construction
of Conservatories, Graperies, Green-houses, Pits, Frames, and
every kind of horticultural buildings, giving the diflferent posi-
tions and aspects most suitable to each, and the various purposes
for which particular structures are best adapted. We have also
fully considered the different kinds of materials generally used
in thie erection of these buildings, and the respective merits of
each. Glass, and its influences on vegetation, are also fully con-
sidered and discussed in this part, — a subject which has hith-
erto received very little attention from horticultural writers, but
is nevertheless one of the most important items connected with
exotic gardening. We have given the useful experiments of
Mr. Hunt, on Light, and its effects on vegetation and germina-
tion, and all other information which we have considered use-
ful on this part of our subject.

The second part embraces the most approved methods of
heating horticultural structures, giving the principles of com-
bustion and consumption of fuel, the prevention of smoke, and
the various volatile products of the coal ; the construction of
flues and furnaces ; the different sizes and heating powers
of pipes and boilers ; the circulation of water, and the pecu-
liar modifications of apparatus suitable for particular struc-
tures. We have given a considerable number of illustrations
in this part, showing various methods of heating, with all of
which we have had extensive practice, and some of them on
entirely new principles. The various merits of hot air and
hot water are considered on scientific as well as on practical
grounds, and each acknowledged for what it is worth.

The third part may be called the theory and practice of
2

12 INTRODUCTION.

ventilation, including some valuable investigations of the p/iys-
iological effects of the atmosphere, under different circumstances,
and at different temperatures. Many of our remarks nave
assumed a greater length than we originally intended, and if
some appear repetitionary, this is in order to avoid, as much
as possible, all strictly scientific technicalities and abstruse
reasoning, whereby the minds of practical men are frequently
unable to understand fully the end to which you direct them.
We have added a section on the protection of horticultural
structures in severe weather, — a subject which is worthy of
much consideration.

I may observe, that, in pointing out and freely comment-
ing on principles and practices which are erroneous, but which
have been practised and promulgated by others, it is under the
impression that such errors, carrying with them, in general,
some plausibility, have led, and may still lead, others to fall into
similar mistakes. However invidious, therefore, be the task of
pointing out these errors, it would be manifestly impossible to
write on this subject without noticing them, and, if possible,
pointing out the difference between right and wrong. This is the
only apology which can be offered for the freedom with which
some of the opinions and methods of others have been com-
mented on in the various parts of this treatise. We have, how-
ever, expatiated on them candidly, and in the true spirit of
inquiry, pointing out the applicability of their principles and the
utility of their practice.

The different parts of the subject have been arranged under
different heads, as far as has been practicable, in order that any
of the different parts may be pursued intelligibly and clearly.
In extenuation of any errors which may be found, we hope it
will be considered that many of the points treatei on are
entirely new, and as yet undeveloped ; that no comprehensive
view of the principles of exotic culture has yet been given.
But we must not be understood to offer excuses for any errors
other than those that are embraced by this extenuating clause
which will be acknowledged if rectified in the true spirit of
philosophical inquiry.

PART I. CONSTRUCTION OF
HOT-HOUSES.

SECTION I.

SITUATION.

1. Site and position. — Before proceeding to details regard-
ing the structures themselves, it will be necessary to consider,
briefly, the situation on which the structures are to stand. A
glazed structure depends for its effect very much upon its posi-
tion; and as the position 'most desirable for effect may very
possibly militate against the utility and efficiency of the struc-
ture, the question presents a double claim to our consideration.
In illustrating the position most desirable for the erection of
houses for horticultural purposes, I assume that the paramount
object is utility. I will subsequently point out reasons which
frequently occur to render the position of green-houses and con-
servatories beyond the control of the erector.

By site and position I must not be understood to imply merely
the aspect upon which a house for horticultural purposes should
stand. The aspect of a house may be affected by circumstances
which have no relation to its site. In other words, the glazed
elevations of a house may be turned in any direction, while the
position may be altogether unsuitable whichever aspect may be
given to it. The weather, at all seasons of the year, has unde-
niably more influence on a house in some situations than it has
upon houses in others more favorably placed ; and this influence
is sensibly felt bv the products v/hich are o-rown within them.

14 SITUATION.

The climate, and especially the prevailing winds of the locality
should be studied attentively, in order to anticipate their changes,
and avoid, as far as possible, their injurious effects. No doubt
it is sonietime^s difficult to ascertain the precise spot on which to
erect hot-houses, with these considerations in view, particularly
when the ground is extensive and the choice limited ; yet, in
most places, there are some spots preferable to others. A bleak,
elevated position should never be chosen, if there be any choice
left. If a bare, elevated spot viust be chosen, either on account
{}{ there being no alternative, or from other adventitious consid-
erations, such as to obtain a commanamg view of the surround-
ing country, or to present a more imposing appearance from the
mansion, or from any other point of sight from which it may be
thouoht desirable to view them, then the backa^round should
always be planted up with trees. This is indispensable, for two
important reasons : —

(1.) For shelter. The northern winds are cold and biting in
frosty weather, and air can be admitted when the houses are
well sheltered, when it otherwise would be impossible to do so
without injury to the plants. Moreover, the north side of a
horticultural structure of any kind is the only one that can be
appropriately sheltered w^ith tall growing trees. It is, there-
fore, the more necessary that trees should be planted close
enough to break the wind, but not so close that their overhang-
ing branches, when they have attained their full size, may drip
upon the glass. This last is an evil which ought, in all cases,
to be avoided. Neither ought new houses to be placed so near
trees, already standing on the grounds, that these circumstances
may occur.

(2.; For beauty and effect. I do not mean, in this paragraph,
to allude to hot-houses in general as handsome architectural
objects in the groundsof a country residence, — to which consider-
ation I will subsequently allude, — but merely to the effect which
hot-houses of the cheapest and plainest description may be easily
made to produce, without much trouble or expense, or without
adding one cent to the cost of the structure itself. Let any per-
son take a glance at a structure of glass, or range of such struc-
tures, having nothing but the distant skv for a background, and

SITUATION. 15

compare it with another, resting upon the green, glossy foHage
of luxuriant trees towering above them, and these again reflect-
ing their irregular outlines against the cloudless horizon behind
them, and he cannot fail to be struck with the tame and spirit-
less appearance of the former, and equally, also, by the pictur-
esque and pleasing eflfect produced by the latter.

A conservatory, or green-house, avowedly ornamental, and
intended as an object of architectural beauty, or of individual
elegance, requires the most exquisite taste and skill in harmo-
nizing the objects around it. These surrounding objects,
whether for utility or embellishment, may be so arranged as to
heighten the effect of the whole, without impairing the individ-
ual effect of the structure, or hiding any of its beauties. The
various features of the structure should be presented to view
from different points ; and if, from any walk or portion of the
grounds, the structure present rather an unfavorable aspect, then
some object should be interposed to obstruct the view from this
particular point. When a walk is led along the skirt of a wood
or plantation, where a glimmering of the structure is continu-
ously visible from among the trees, the effect is bad, and ought^
by all means, to be obviated by planting shrubbery and under-
wood, leaving here and there an open vista through which a
full view of the whole building, or portion of it, may be obtained.

It has, for some time, been the rage in this country to place
horticultural buildings of all kinds upon eminences, and sur-
round them, either wholly or in front, with square terraces.
These terraces are made sometimes of brick, in all its primi-
tive redness, sometimes of small stones and mortar, and more
frequently, perhaps, of grass, nearly perpendicular. It is gen-
erally difficult to discover which is the most unnatural and
unsightly ; and, in nineteen cases out of twenty, we have found
the terrace itself, of whatever materials, of very questionable
taste. Terraces grew out of necessity, — not out of taste, —
except, perhaps, in the Dutch school, which an able writer on
this subject styles " a double-distilled compound of labored
symmetry, regularity, and stiffness." =^ A terrace may be in very
good taste, in connection with a pretty little Tuscan or Italian

* Downiiig's Landscape Gardening;.

16 SITUATION.

villa, when it is finished and ornamented as a terrace should
be, i. e., with vases, urns, &c., of sizes and forms harmonizing
properly with the architecture of the building. The same prin-
ciple may be applied to detached conservatories when placed in
the grounds as ornamental objects.

While speaking of terraces, it may not be out of place to
remark, that, about some of the finest gardens of this country,
these grass walls are introduced to absolute satiety. Nothing
like a gentle, undulating surface is for a moment tolerated, but,
as a matter of custom, the ground must be levelled, and flanked
by a terrace. Nov/ we think that when terraces are found neces-
sary in front of a garden structure, of an ornamental charac-
ter, they ought to be of a different character from those intermi-
nable sod banks so liberally constructed about some fine places
that we could mention, but forbear doing so, on the principle,
that, where much has been done, a few errors in taste may be
justified. However, it cannot be denied that a steep bank of
grass, twelve or twenty feet deep and as many from the walls
of the building, void of any architectural decoration or ornament
of any description, save its own unrelieved formality, is in as
bad taste as would be the surrounding of a mud-walled hut with
architectural balustrades and sculptured ornaments. Steep,
formal terraces, without architectural decorations to unite and
harmonize them with the structure, are, unquestionably, the
most insipid and meaningless objects that can be introduced
into ornamental grounds.

What is called an architectural terrace, consisting of a low
parapet and balustrade of handsome masonry, or other rich
ornamental work, has always a pleasing effect, especially when
attached to buildings of an ornamental character,^ whether
these buildings be for dwellings, or for horticultural purposes.
These terraces, however, are very different from those perpen-
dicular turf-banks, of which I have already spoken. The
former are truly artistical, and, in connection with classical

* The reader -vvho is interested in this subject, and wishes for further
information on this kind of ornamental terraces, is referred to the ele-
gant remarks and illustrations thereon by IMr. Downing. [See Dorvning't
Landscape Gardenijig ; sectio/i, Architectural Embdlishments.]

SITUATION. 17

Structures, constitute the harmonizing link between art in the
building, and nature in the grounds. The latter are neither
artistical nor natural.

Let the reader fancy to himself a horticultural structure, of
unusually large dimensions, situated on the southern declivity
of an open field, without a single green leaf of foliage to inter-
vene between the unbroken whiteness of the structure and the
distant sky. The very ornaments of the building are altogether
hidden, even at the distance of a dozen yards, because their forms
are viewed upon a background of cloudless vacancy ; directly in
front is a terrace, more than a dozen feet deep, and so steep as
to require a ladder to scale it, and at the bottom it terminates
with an abrupt angle, adjoining a potato and cabbage garden.
However unquestionable may be the position of the splendid
structure here referred to, there is something so irreconcilably
incongruous about its precincts, that the most untutored imagi-
nation is at once struck with the total want of harmony, unity,
and effect. The terrace itself has the unfinished appearance
of a dwelling-house, where the work has been suspended before
the roof and chimneys had been put on ; a thing appearing to
have an isolated and independent existence, having no apparent
relation either to the structure or the grounds, and heartily
despised by both. Now the position of the building referred to
is, undoubtedly, excellent, and a better site could not be found,
to produce a more imposing effect from a front view, which, in
horticultural structures, is generally the best, providing the
structure be sufficiently elevated above the axis of vision. But
in the present case the effect is destroyed ; first, by a total want
of unity and harmony in the foreground, and, secondly, by a want
of the deep, dark foliage of trees, presenting their irregular
outlines against the sky in the background, which gives all
buildings, and more especially those of a light character, as hot-
houses, &c., that picturesque and pleasing appearance, particu-
larly when the surface of the ground is broken by undulations,
and the scenery diversified with a variety of objects, distinct in
themselves, yet harmonizing with each other.

From the foregoing observations, the propriety will be seen
of placing horticultural erections in the immediate vicinity of

18 SITUATION.

large trees, and of raising them where they do not already exist.
A beautiful writer on this subject has observed, that green-
houses in the country, w^ithout trees about them, are like ships
divested of their masts and rigging, and impress the mind with
the idea of their having wandered from their right position ;
and, as Loudon justly remarks, a tree is the noblest object of
inanimate nature, combining every species of beauty, from its
sublime effect as a whole, to the most minute and refined ex-
pression of the mind.^ We cannot too strongly urge the pro-
priety of choosing a site where these advantages may be gained.
This branch of landscape gardening has been al/eady treated in
a masterly manner by various writers ; therefore we consider it
unnecessary to dwellany longer upon it.t

The choice of position may, in some instances, be decided by
other circumstances, such as an abundant supply of water. This
is indispensable, in hot-houses of every description, though it
seldom forms a very important consideration with architects, in
their designs, who are perfectly unconscious of the amount of
labor and expense subsequently created by a deficiency of this
element. It is, therefore, desirable that the site chosen should
command a plentiful supply of water, at all seasons of the year,
independent of what may be collected from the roof. It should
be considered that the period when the largest quantity of water
is required for the use of the plants, is also the time when the
supply from rains is scantiest and most precarious ; and though
ample provision must be made for collecting all the water that
falls upon the roof, into tanks and reservoirs, suitably and con-
veniently placed for that purpose, yet this supply is not to be
entirely relied upon ; and hence water ought to be conveyed by
pipes, or some other means, from the nearest source, to supply
the tanks when the rain-water is exhausted.

Where a stream of water is commanded by the position of

* Loudon's Encyclopedia of Gardening.

t Those who wish to study the principles of landscape gardening, will
find all that is requisite for their instruction and improvement in "Down-
ing's Landscape Gardening," the only work we know wherein the prin-
ciples of the art are treated in such a manner as to render them perfectly
applicable to this country.

SITUATION. 19

the structure, it would be most desirable to convey it through
the interior of the house, in a kind of rill, or small stream, run-
ning through a shallow channel, or, what would be still better.
to fall into a tank, over a small precipice, forming a little cas-
cade, or water-fall. If the stream had sufficient power by its
declivity, a small jet might be kept continually playing. In an
ornamental plant structure, this would be the ne plus ultra of a
water supply ; besides, the house would be kept delightfully
cool in the hottest days of summer, and the rippling of the
stream over the cascade, or the playing of the fountain, would
prove the most agreeable music to the ear in the hot days of
summer.

We have here alluded to water, merely in so far as it may
be likely to affect the choice of position. Of course, water may
be supplied to a house by various other means, such as force
pumps, and that admirable invention, the water-ram, by which
jets, cascades, &c., may be also obtained ; but all these are at-
tended with considerable expense, as well as subsequent labor,
and, therefore, a natural, constant, and abundant supply of water,
when possible, should not be abandoned, even at the expense of
some trifling advantages in other respects. We have known
places where the labor of carrying the water for the different
departments of the exotic establishment during summer, exceeded
the labor required to keep the garden in order."^

In regard to the precise elevation best suited for the site of
horticultural buildings, various opinions exist ; some prefer low-
lying grounds, others prefer a considerable altitude ; we have
frequently seen both parties run into extremes. Low situations
are generally warmer, and better sheltered from boisterous winds,
which, however, is more than counterbalanced by certain evils
consequent upon a very low site. In spring, low, swampy places
are always subject to heavy depositions of dew and mist, which
render them cold and damp, and expose vegetation of every
description to be destroyed by vernal frosts, which is avoided in
more elevated situations. We have this spring had abundant
evidence of this fact, in a very large tree of the Platanus Occi-

* For further information regarding cisterns and supplies of water,
see Sec. IV., Internal Arrangements.

20 SITUATION,

dentalis, which had its leaves entirely destroyed, after they
were fully expanded, and are now strewed upon the grass be-
neath. This tree, with various others that shared the same
fate, stood in a low part of the pleasure ground, beside a lake.
Trees of the same species, on higher ground, escaped without
injury.

We have invariably found, in our experience, that plant-houses
situated in very low grounds, were cold and damp in winter,
and hard upon the more tender kinds of plants. In summer, the
atmosphere is generally stagnant and unhealthy, to plants as
well as animals. If circumstances, therefore, afford any choice,
very low situations should be avoided, as it is more easy, and
certainly more profitable, to bring an elevated and airy situation
into the condition desired, than it is to obviate the injurious
effects of a low one.

2. Aspect. — We find that most people prefer a southern
aspect for their hot-houses, i. e., placing the front elevation due
south. The absolute propriety of this preference, how^ever, de-
serves to be questioned, as experience has taught us that some
valuable advantages are gained by placing hot-houses, for the
growth of fruits, on a south-eastern aspect. Let it be observed,
that we are alluding at present to what is termed lean-to, or
shed-rcofed houses, i. e., houses having only one sloping side, — a
kind of structure still generally used for the production of grapes,
&:c., during the early part of spring, and which are probably
better adapted for that purpose than span-roofed houses. In
fact, we should prefer a south-eastern aspect for lean-to houses,
whether they were intended to grow fruits or flowering plants ;
for, even in this clear and comparatively cloudless climate, this
aspect has advantages which, in our opinion, are not possessed
by any other ; and, indeed, the greater intensity of the sun's rays
at midday here than in England, gives this aspect greater ad-
vantages in this country than in any other where the sun is less
powerful. The morning sun is more strengthening and exhil-
arating to plants than during any other period of the day, and
more especially to plants kept in houses without artificial heat ;
but the same argumdnt holds good in all houses. We find that

SITUATION. 21

hot-houses, even during the early part of summer, — except fire
heat be maintained, — sometimes fall exceedingly low at night,
and become cold and chilly, with the aqueous vapors contained
in the atmosphere, by the high temperature of the preceding
day, condensed into water by the low temperature of the night,
and depending in small globules from the leaves of the plants,
the under surface of the glass, and other parts of the house,
rendering the approach of the sun's cheering beams, a few
hours earlier than if the house were placed rceridionally, above
all things acceptable.

It might be plausibly argued, that, if we take the south-east-
ern aspect for the purpose of gaining the morning sun, we must
lose it for the same period in the afternoon, v.-hich, altogether,
makes it the same thing to the house. This is not true in prac-
tice ; though the period of the sun's duration upon the house in
both cases be the same, yet the advantage gained, by taking the
morning and losing the afternoon sun, is very great. The rays
thus lost in the evening are of little consequence compared
with those gained in the morning, because the plants are then
partially enfeebled, and their elaborative powers impaired, if not
altogether suspended, by the strong midday heat. By various
experiments on the shoots of young plants, we found that their
elongation was greatest during the mild hours of the morning,
before the sun had attained its meridian fierceness.

In general, we find that plants are more prostrated by the in-
fluence of the afternoon sun than during any other period of
the day, and it is supposed, by many, that the sun's heat is more
powerful and oppressive in the afternoon — that is to saj", from
one to three — than it is when on its meridian. However this
fact may be scientifically supported, it certainly holds good in
experience."^ Supposing, then, that such is the case, we con-

* This may be accounted for by the air having been already T^-armed
to a high temperature, by the sun acting upon it during the previous
part of thi^ day ; and, the deposited moisture of the preceding night hav-
ing been already evaporated from the surface of the earth, the lo\v:er
strata are highly rarefied. The hot sun, continuing to act upon the lower
stratum of air and the dry surface of earth, gives the former that lan-
guid, oppressive, and suffocating character, which is experienced by
everv one.

22 SITUATION.

sider it another fact in favor of a south-eastern aspect, as the
sun's rays will thus be made to strike the roof more obliquely,
and will be less likely to scorch, or otherwise injure, the plants,
than if shining perpendicularly to the plane of the roof.

Many authors might be quoted, in support of a south-eastern
aspect ; and one of the best garden authors, of his own or any
other time, says, " An open aspect to the east is a point of cap-
ital importance, on account of the early sun." When the sun
can reach the garden at its rising, continuing a regular and
gradual influence, increasing as the day advances, it has a grad-
ual and most beneficial effect in dissolving the hoar frost that
may have been deposited the previous night. On the contrary",
when the sun is excluded till about ten in the morning, and
then suddenly darts upon it with all the force derived from its
increased elevation, and increased power, it is very injurious,
especially to fruit-bearing plants, in the spring months. The
powerful rays of heat at once melt the icy particles, and, imme-
diately acting upon the moisture thus created, scald the tender
blossoms and leaves, which droop and fade as if nipped by a
malignant blight."^

These remarks, it- is true, are by an English author, and have
reference to the climate of England ; but they apply to us in
full force in this country, and, in manj^ locations here, are still
more applicable than to any country in Europe.

The morning sun is not only more agreeable to vegetable as
well as animal development, but, as we have already observed,
vegetation proceeds more rapidly under its influence than it does
during any other period of the day. This may be accounted
for by the fact, that the nourishing gases have been accumu-
lating during the partial suspension of elaboration in the night,
and, on the approach of the sun's vivifying beams, these functions
are fesumed with increased activity, and continue so, under the
mild influence of its less powerful and fierce effulgence, until
their energies are paralyzed by its burning rays, at midday, when
they make little more progress till the next morning.

We have heard similar arguments adduced in favor of a south-

* Abercrombie's Practical Gardener.

SITUATION. 23

western aspect for late nouses, and these facts have regulated
the erection of some extensive houses with which we are ac-
quainted. In this country, however, hot-houses are seldom
erected for the express purpose of retarding grapes, or other
fruits, although we have no doubt that very late grapes would
pay better than early ones, since there would be very little ex-
pense in their production. The sun's rays in this climate are
so powerful, that the difference in aspect may not be so percep-
tible, in regard to late and early forcing, as in England ; still
we have no doubt the difference will be found sufficient to justify
the erection of houses for these purposes, on the aspects we have
pointed out as being most suitable for each.

In the erection of span-roofed houses, that is, houses with
double roofs, it makes very little difference, in the opinion of
many, which way the house may stand, and, upon the whole
the arguments hitherto used, m favor of one aspect over another,
have been so feeble as hardly to deserve any consideration.
Supposing the house to be a parallelogram, or long square, with
both gables glazed, as well as the sides and roof, then, we think,
it may stand any way in which the nature of the site, or taste
of the erector, may dictate. Light being the most important
point of attention in the construction of hot-houses, these are
better adapted for plant-growing than those whose transparent
surface forms only a segment of their transverse section.

As a general principle, provided other circumstances are fa-
vorable, we would recommend the house to stand north and south,
with its longer elevations towards the east and west ; we find
this to be the opinion of some .of the best gardeners in the coun-
try, with which we fully agree. If any advantage be gained by
placing the house in one direction, in preference to another, we
think it is the one mentioned, as the rays of the meridian sun
will then strike the glass in an oblique direction, and have less
power than if they were to fall upon the glass at right angles
to it.^

The aspect of conservatories attached to dwelling-houses

* For more detailed information on this matter, see Sec. II., Design
and Slope of Roof.

24 SITUATION.

must be regnlated by the position of the building, or the fancy
of the architect. These are deplorable erections, generally;
nine tenths of them unsuitable, in the superlative degree, not
for want of cost, but for want of skill. As the remarks we have
to make, on this part of our subject, belong to the next sec-
tion, we will just add here, that a conservatory ought never
to be placed on the northern aspect of a building, nor situated
in such a manner, in relation to the dwelling-house, that the
sun's rays may be prevented from falling on the conservatory
during at least one half the day.

SECTION II.

DESIGN.

1. General Principles. — To ascertain principles of action,
it is always necessary to begin by considering the end in view.
The object or end of hot-houses is to form habitations for vege-
tables, and either for such exotic plants as will not grow in ths
open air of the country where the structure is to be erected, or
for such indigenous or acclimated plants as it is desired to force
or excite into a state of vegetation, or accelerate in their pro-
gress to maturity, at extraordinary seasons. The former class
of structures are generally denominated green-houses, or botanic
stoves, in which the object is to imitate the native clime and
soil of the plants cultivated ; the latter, comprehending forcing-
houses and culinary stoves, in which the object is to form an
exciting climate and soil on general principles, and to imitate
particular climates.

The chief agents of vegetable growth in their natural habita-
tions are light, heat, air, soil, and moisture ; and the merit of
managing these structures, and the success of cultivating vege-
tables in them, depend on the perfection with which nature in
these respects is imitated.

To carry out the imitation to perfection, or anything like an
approach to it, it is absolutely necessary, as we have previously
observed, to be acquainted with the nature and habits of the
plants under cultivation. Vegetable physiology ought to form a
part of the acquirements of the hot-house architect ; and the
chief cause of the great improvement in these structures, of late
years, in England, is traceable to the fact, that their erection is
no longer left, as formerly, under the control of mansion archi-
tects, as they are at the present day throughout the length and

26 DESIGN.

breadth of tie United States; and the chief reason why we see
horticultural structures erected so numerously in this country,
in violation of the first principles of plant culture, is undoubt-
edly due to the same cause. The conservatory is generally left
to the uncontrolled management of the architect, who, of course,
makes this structure to correspond with the rest of the building,
without giving the slightest consideration to the vegetable beings
that are to grow in it. If we consider this matter in its dif-
ferent bearings, giving to professional architects the justice
which is due them, it would be somewhat unreasonable to
expect them to plan conservatories otherwise. An architect is,
by education, taught to study and apply principles in his art,
w^hich, when carried into effect, as we sometimes see them in
the construction of plant-houses, are in direct opposition to those
laws which nature has laid down and determftied as essential
to the vigorous development of vegetable life. Can it be
expected, then, that an architect will tamely surrender the grand
principles of his art, — the antiquity of which is coeval with
Cheops, and which has been the boast and pride of the greatest
empires of the old world, — in meek submission before the yet
half-developed principles of vegetable physiology, or even to the
humble dictates of practical gardening ? To expect such a con-
cession would be tantamount to expecting an architect to build
dwelling-houses with drawing-rooms solely adapted for the
accommodation of plants, altogether irrespective of other pur-
poses to which drawing-rooms are generally applied. Hence,
we find the conservatory placed just where it is most subservi-
ent to the general design of the mansion, most frequently in a
corner or recess of the main building, having two or three sides
of solid opaque material ! To civil architecture, as far as
respects mechanical principles, or the laws of the strength and
durability of materials, they are certainly subject, in common
with every other species or description of edifice ; but in respect
to the principles of design and beauty, the foundation of which
we consider, in works of utility at least, to be " fitness for the
end in view," they are no more subject to the rules of civil archi-
tecture than is a ship or a fortress ; for those forms and combi-
nations of forms, and that composition of building, which is

DESIGN. 27

very fitting, and, perhaps, beautiful, in a habitation for man or
for domestic animals, is by no means fitting, and consequently
not beautiful, in a habitation for plants. Such, however, is the
force of habit and professional bias, that it is not easy to con-
vince architects of this truth. Structures for plants are consid-
ered by them no further beautiful than as they display some-
thing of architectural forms, which, according to the innumerable
illustrations presented to us, consist of a solid opaque building;
for it is an undeniable fact that what are called fine architectu-
ral conservavories, are designed, not for the purpose of growing or
exhibiting flowering plants, for they have not even the appear-
ance of adaptation for this purpose. One half of their entire
surface is obscured by pilasters, blocking-courses, cornices, projec-
tions, massive astragals, sash-bars, etc., until the transparent glass
forms only a small fraction of the surface ostensibly appropriated
to the transmission of light. To complete the opacity of the
structure, the whole is obscured or shaded one half the day by
the main building. There is no ideal exaggeration here ; they
form the grand rule in ornamental conservatories, and the
exceptions are few. Let us take, for example, the splendid con-
servatory erected by J. W. Perry, Esq., at his mansion at Brook-
lyn, near New York, and figured in Downing's Landscape Gar-
dening, which is extolled as one of the most beautiful conservato-
ries in the country, and with some degree of justice, for it is both
more beautiful and better adapted for the purpose than many
others to which we can allude. Yet, beautiful and fit as it may
be considered, there never was, and never will be, a plant grown
in it to perfection, nor is it possible by any species of care or
skill to do so in such a structure.

We have taken the liberty of particularizing this conserva-
tory, because it has been made the model of various others
which we are acquainted with ; and we justify our allusion to it
on the following grounds : because the house in question has
been figured and commended by such an able authority, and
consequently been regarded as a model of perfection by many
who know not the difference between a structure " fit for the
purpose," and one merely beautiful in itself; and, moreover,
because we are well acquainted with the structure itself, as well
3*

28 DESIGN.

as with the able and excellent gardener \7ho has managed it for
many years, and who finds it impossible to grow plants within,
and has long since given up the case as utterly hopeless ; the
only result which could be expected.

It may seem strange that ten or twelve thousand dollars
should be expended upon a plant-house, and, after all the
expense, the house be unfit for the growth of plants, and that
this fitness could be more extensively obtained at one twentieth
the cost. Such, however, is the case, and will continue to be
so, till the design be considered in relation to " fitness for the
end in view;" and that this is far from being the case, we have
lately experienced sufficient proof. Buildings like that we have
just alluded to, may properly be called beautiful specimens of
architecture, but if the principles of design or beauty be regarded
on fitness for the end in view, — as we believe it to be in works
of utility, — then, as plant-conservatories, these structures ought
to be condemned.

I have no doubt some of our architectural readers, and lovers
of dull, massive, gorgeous, and grotesque conservatories, will
pronounce against such a violation of the principles of architec-
ture, as would undoubtedly be perpetrated by building a mere
shell of glass to form a counterpart of the solid masonry of a
large mansion. Conversing on this point lately with a talented
architect, he said, " Conservatories can never be reconciled with
mansion architecture if they must be erected upon such princi-
ples; the thing is utterly inconsistent with beauty in a building.
Such an appendage," said he, " would be as absurd as putting a
gauze covering over a buffalo robe to withstand a snow storm."
It would be useless here to reply to the injustice and inapplica-
bility of these observations, and we will let them go for what
they are worth. They serve, however, to convey a pietty accu-
rate idea of the estimation in which architects hold the principles
of plant cukure, even when pointed out to them; or, as we might
term it, how little they care for the beauty expressed by "fitness
of purpose." Utility, however, is undoubtedly the basis of all
beauty in works of use, and, therefore, the taste of architects, so
applied, may safely be pronounced as radically wrong.

DESIGN. 29

2. Light. — In erecting horticultural structures of any
description, the first and decidedly the most important object to
be kept in view, is the introduction of light ; and really, though
this point presents itself to architects in its simplest and plainest
reality, it appears to be scarcely ever fally considered ; at least,
we are induced to conclude so, from the instances already before
us. It is easy for any person to satisfy himself of the wonder-
ful effects of light upon vegetables under artificial culture, by
the most familiar illustrations. When plants are placed against
a wall, or other opaque body, they will speedily turn the sur-
face of their leaves to the light, although the medium of its
entrance should be many yards distant. One of the principal
reasons why plants thrive so badly in dwelling-houses, is in
consequence of their being deprived of that supply of light
which is essential to their development. Set a plant how or
where you will, it will twist and turn itself in any direction for
the purpose of presenting its leaves to the light, or to the aper-
ture where it enters unobstructed. Pure air is also a most essen-
tial element in the economy of vegetation ; but we may safely
assert, after much experience, that plants under artificial culture
suffer far more from a deficiency of light than from a deficiency
of what is called pure air. The reason of this appears obvious.
By the latter deficiency a plant is merely deprived of its neces-
sary food ; but by the former deficiency the plant is entirely
deprived of its vegetable functions, or its energies are so en-
feebled as to be incapable of assimilation. We are not speaking
here of light merely as distinguished from darkness, for we are
told, upon good authority, that the luminiferous ether is radiated
in all directions from its grand source, viz., the sun,^'' but of
its properties and influence on plants when transmitted through
a transparent medium, such as glass. Every gardener knows
that plants will not only fail to thrive without much light, but
will not thrive unless they receive its direct influence by being
placed near the glass. The cause of this last fact has never
been satisfactorily explained. It seems probable that the glass,

* Principles of Chemistry, by Prof. Silliman, Jr.

30 DESIGN.

acting in some degree like the triangular prism, partially decom-
poses or deranges the order of the rays.

The theory of the transmission of light through transparent
bodies is derived from the well-known law in optics, that the
influence of the sun's rays on any surface, both in respect to
light and heat, is directly as the sine of the sun's altitude,
or, in other words, directly as its perpendicularity to that sur-
face. If the surface is transparent, the number of rays which
pass through the substance is governed by the same laws.
Thus, if one thousand rays fall perpendicularly upon a surface
of the best crown glass, the whole will pass through, excepting
about a fortieth part, which the impurities of even the finest
crystal, according to Bouquer, will exclude. But if these rays
fall at an incidental angle of 75°, two hundred and ninety-nine
rays, according to the same author, will be reflected. The inci-
dental ande, it will be recollected, is that contained between the
plane of the falling or impinging ray and a perpendicular to
the surface on which it falls.=^

In building a green-house or conservatory, then, light ought
to form the first point of importance, as success in plant culture
is entirely subservient to it, and we know full well, from experi-
ence, that no skill, however perfect, and no attention, however
zealous, will compensate for a deficiency of- light. Indeed, no
contingent or permanent advantage can justify, to the mind of
the experienced gardener, the adoption of one inch of opaque
material in the sides and roof of a horticultural building ; and
no part of the structure, from the side-shelves and upwards,
should be rendered opaque that can consistently be covered with
a material capable of admitting the rays of light. For pillars
and other appendages of strength, the material ought to be as
light as is consistent with strength and durability in the struc-
ture ; and, although we do not recommend such an erection
adjoining a dwelling-house, experience has taught that, both in
this country and in others, a mere shell of glass, so to speak, is
not only the cheapest, but also the best adapted for the artificial
culture of a 1 kinds of plants, both for fruiting and flowering ;

* See Inclination of Hot-house Roofs.

DESIGN. 31

i. e., plants that are cultivated solely either for their flowers or
for their fruit.

The exact manner in which light acts upon plants has been
studied by Dr. Daubeny, and others, and especially Mr. Hunt.
The result of these inquiries is given thus, in the Gardener's
Chronicle, of August 16th, 1845 : " Assuming, with Sir David
Brewster, that the prismatic spectrum consists of only three
primitive colors, namely, red, yellow, and blue, it is ascertained,
by experiment, that the maximum of heating power is found on
the confines of the red rays ; that the largest amount of light
is given by the yellow rays ; and that the chemical power exists
most strongly amidst the blue rays, of the spectrum. If we take
a deep red glass, which has been colored with the oxide of gold,
it will be found that the quantity of light which passes through it
is very small ; and, by using photographic paper, it may be ascer-
tained that the amount of that principle which produces chemi-
cal change is also very little, whereas the heat rays suffer no
interruption. A deep yellow glass, or a cell filled to the thick-
ness of an inch with a solution of bicromate of potash, intercepts
the chemical rays, but admits of the permeation of all the lumi-
nous rays, and offers but little interruption to the calorific rays.
If, however, we cover a pane of this yellow glass with another
of pale green bottle glass, the passage of the heating rays is
much impeded. A deep blue glass, such as is used for finger-
glasses, colored with oxide of cobalt, or a solution of oxide
of copper in ammonia, has the property of admitting freely
the passage of all the chemical rays, whilst it obstructs both
the heat and light radiations. Experiments conducted with
colors thus obtained led Mr. Hunt to the following conclusions :

(1) Light lohich has permeated Y'E'LLOW media. Light rays. —
In nearly all the cases the germination of seeds was prevented,
«ind even in the few cases where the germination was com-
menced, the young plant soon perished. The germination
seemed referable to the action of the heat rays which had passed
the medium employed, rather than to the light. Agarics, and
several varieties of fungi, flourished luxuriantly under this influ-
ence. Although the luminous rays may be regarded as injuri-

32 DESIGN.

ous to the early stages of vegetation, Mr. Hunt believes that,
in the more advanced periods of growth, they become essential
to the formation of woody fibre.

(2.) Light which has permeated red media. Heat rays. —
Germination, — if the seeds are very carefully watered, and a
sufficient quantity of water is added to supply the deficiency of
the increased evaporation, — will take place here. The plant is
not, however, of a healthy character, and, generally speaking,
the leaves are partially blanched, showing that th^ production
of chlorophyl is prevented. Most plants, instead of bending
towards red light, as they do towards white light, bend from it
in a very remarkable manner. Plants, in a flowering condition,
may be preserved for a much longer time, under the influence
of red, than under any other media ; and Mr. Hunt thinks
that red media are highly beneficial under the fruiting process.

(3.) Light which has permeated blue media. Chemical rays.
— The rays thus separated from the heat and light rays, and
which Mr, Hunt has proposed to call Actimic, have the power
of accelerating, in a remarkable manner, the germination of seeds,
and the growth of the young plant. After a certain period, vary-
ing with nearly every plant upon which experiments have been
made, these rays become too stimulating, and growth proceeds
rapidly, without the necessary strength. The removal of the
plant into yellow rays, or into light which has penetrated an
emerald green glass, accelerates the deposition of carbon, and
the consequent formation of woody fibre. It was also found
that, under the concentrated actimic force, seeds will germinate
beneath the soil, at a depth in which they would not have grown
under natural conditions. Mr. Hunt believes that the germina-
tion of seeds in the spring, the flowering of plants in summer,
and the ripening of fruits in autumn, are dependent upon the
variations in the amount of actimism, or chemical influence, of
lio-ht and heat in the solar beam at these seasons.

It must, however, be observed, that, although such experiments
have much physiological interest, the value of them is greatly
diminished by the necessarily imperfect manner in which the
prismatic colors are separated by artificial preparations. It is

DESIGN. 33

almost, if not quite, impossible to form pure colors artificially.
The yellow, for instance, of the bichromate of potass contains
both red and violet in abundance."^

It has been already ascertained that the amount of assimila-
tion, and consequently of the healthy exercise of its vital func-
tions, depend upon the intensity of the light to which the plant
is exposed. In bright sunshine they perspire most; in weak
diffused light, and in darkness, none at all. ' Hales found that a
cabbage lost nineteen ounces of weight per diem, and a sunflower
twenty. He estimated the average rate of perspiration by plants
to be equal to seventeen times that of a man. In one of his exper-
iments he found that the branch of an apple-tree, two feet long,
with twenty apples, exposed to bright sunshine, raised a column
of mercury twelve inches in seven minutes. But a dry, arid
atmosphere, especially if in motion, also robs the plants of their
moisture independently of light.

The clear and unclouded skies of this country do not, as some
suppose, obviate the necessity of surrounding the plant with, a
transparent medium in all directions, nor does the dark and sun-
less climate of England render it necessary that the houses
should be more transparent there than here. It is a practical
absurdity to fancy that in England there is less light than in
this country, and that, because the mid-day sun is more powerful,
they can do with a greater opacity of structure. Those who
make such statements manifestly know as little of the climate
of England as of the natures of its skies, and mislead those who
know as little as themselves. No argument whatever, based
upon the brightness of the sunshine at mid-day, can serve to
justify the adoption of one single inch of opaque material in a
horticultural building. It is very easy to reduce the quantity of
light, or break the rays of the sunshine, by shading; but it is not
so easy to increase the quantity of light in the dark and gloomy
months of winter ; and such sort of plant-houses will damp the
energies and zeal of the most skilful gardener, as well as his
tender exotics. When he sees these errors, which, he cannot
remedy, and observes his plants speaking in a language which

♦ For further experiments on Light, see Sect. IV., GIm%.

34 DESIGN.

cannot be mistaken, even by the most inattentive, " Give us light,
or we shall die ! " he gives up their case, in hopeless despair, as
being altogether beyond his control. And thus we have known
excellent gardeners censured for neglecting things, and for doing
badly what it was not in their power to do better.

Solar influence being necessarily connected with the roofs of
hot-houses, we will discuss these subjects in their relation to
each other, including inclination and reflection, in the following
sub-section.

3. Slope of hot-house roofs. — In regard to the theory of the
transmission of light through transparent bodies, we have already
stated that the influence of the sun's rays on any surface is
directly as his perpendicularity is to that surface ; and, accord-
ing to Bouquer, that if one thousand rays fall perpendicularly
upon a surface of glass, the whole pass through, excepting about
twenty-five rays, or one fortieth part of the whole. But falling
on the same surface at an incidental angle of about 75°, then
two hundred and ninety-nine, or nearly one third of them, will
be reflected. The influence of the sun on the roofs of hot-houses
depends very much on the principle there given, — at least, so
far as regards the form of its surface. This principle has been
applied, in various ways, for the purpose of obtaining the full
influence of the sun's rays at certain seasons of the year. We
have managed forcing-houses where the roof was laid at right
angles to the sun's rays in mid-winter, — the period when the
most powerful rays were required for forcing purposes.

Although it cannot be denied that much more depends on the
manacrement of the house, for the success of cultivation, than on
the inclination of the roof, yet it is the most satisfactory method
to proceed on what may be considered something like princi-
ples. And in this country we find this the more necessary,
because the heat of the sun's rays, at certain seasons of the year,
is so violent as to prove injurious to vegetation under any cir-
cumstances. And hence, this principle should be adopted in the
construction of hot-house roofs, that their perpendicularity to the
sun's rays, at the hottest period of the year, should by all means
be avoided.

DESIGN.

In England, the most common elevation of roof is an angle of
45°, which, in the latitude of London, would form a perpendic-
ular to the impinging ray, about the beginning of April, and the
beginning of September, — which also makes the obliquity of
the rays greatest when they are most powerful, viz., during the
month of June. " This angle is preferred by most gardeners,"
observes Loudon, " probably from habit." We think, however,
that something more than mere habit justifies the adoption of
this angle, — more especially for forcing-houses, — since by it
the benefit of perpendicularity is obtained at a period when the
rays are comparatively feeble and most necessary.

Fig. 1.

As some of our readers may hot have made themselves suffi-
ciently acquainted with the altitude of the sun in relation to the
slope of hot-house roofs, we have annexed the above figure,
(Fig. 1,) which represents the slope of five different roofs on the
angles marked by their respective complements. / represents
4

DESIGN.

the altitude of the sun in the latitude of London, the impinging
ray falling on the roof, c, at an angle of 45°. It will be seen
that the angle, contained between the back wall of the house
and the inclined plane of the roof, c, is just equal to the sun's
altitude, — the one forming an exact perpendicular to the other.
Allowing, then, for the difference of altitude betwixt the
latitudes of London and Philadelphia, for instance, we have a
difference of inclination of about 11°. Hence the roof of a hot-
house, to receive the same influence of the sun's rays at thai
period, would be at an angle of 34°. The difference will be
more closely perceived by the following cut.

Fig. 2.

In this cut we have given the altitude of the sun at Philadel-
phia, a, with the roof at right angles to it, on an angle of 34°.
At ^, we have given the altitude of the sun at London, with its
corresponding angle of elevation, 45°, and, according to the
principle here laid down, both of these roofs should be equally
influenced by the sun, notwithstanding the difference of his
altitude at the respective places.

In a theoretical point of view these principles are correct, and
are certainly preferable to the usual mode of putting on roofs

DESIGN. • 37

without regard to anything excepting the caprice or fancy of the
architect or builder. But, as general principles, we regard them
as unsafe and dangerous, were they to be practicall}?- acted upon
in the Southern States. Suppose, for instance, the roof should
be laid at right angles to the sun in mid-summer, — as is some-
times done in England, upon this principle, — then the conse-
quence would be that his rays would be unendurable by any
species of vegetation. The mid-summer sun, even in the lati-
tude of Baltimore, (39° 45',) falling on a transparent surface,
at right angles to the impinging rays, would scorch vegetable
forms, and dry them up in a few hours.

It is, therefore, absolutely necessary that the exercise of this
principle be limited to northern latitudes, where it is indispensa-
ble to economize the sun's heat, for the purpose of accelerating
the maturation of fruits. It may, also, be applied in more
southern latitudes, when all the warmth of the sun's rays is
required early in spring ; and, therefore, if the principle be
applied south of the 40° of latitude, it should be taken when
the sun is at its very lowest altitude, otherwise the pitch of the
roof will be too flat for the months of summer.

We are decidedly of opinion — and this opinion is fully con-
curred in by some of the most learned and skilful gardeners in
the country — that a great deal of error is committed in the
pitch of hot-house roofs ; probably more than four fifths of them
are made too flat; their angles of elevation are much too small
for the climate ; and yet, notwithstanding the fierce heat of our
perpendicular sun in summer, this practice is daily persisted in.
One would suppose that the scorching of vine-leaves, peaches,
and other plants, would convince people of the impropriety of
erecting their hot-house roofs at right angles to the sun's rays
in any of the summer months : and yet we know some of the
finest graperies in this country on angles of about 20^. If we
consider how very few of the rays are reflected by the glass, as
its plane approaches a perpendicular to the sun's altitude, and
how many are reflected as the angle of incidence is increased,
we will then have some notion of the advantage of increasing
the obliquity of the roof.

The annexed table will show the number of rays reflected

DESIGN.

from various angles between the plane of the horizon, and within
two and a half degrees of the perpendicular.

Bouguerh Table of Rays reflected from Glass.

Of 1000 incidental rays, when the angle of incidence is
87^30', 584 are reflected. I 60^ 112 are reflected

85^^, 543 ''

82= 30', 474 "

80=, 412 ''

77= 30', 356 "

75=, 299 "

70=, 222 "

65=, 175 "

u
II
ii
li
(I

50=,
40=,
30=,
20^
10=,

1°,

57 '

34 '

27 '

25 '

The slope of hot-house roofs, therefore, should depend on the
following circumstances :

The latitude under which they are erected. — If in a southera
latitude, the plane of the roof should be as oblique as possible
to the sun's rays. South of 40=, the angle of incidence should
not be less than 20^. It will be recollected that this angle is
contained between the sun's rays and a perpendicular to the
roof.

The position of the house, and the purposes for ivhich it is
intended. — Houses intended for the forcing of fruits in winter,
may have their roofs made on a perpendicular to the sun's rays
at that season. Conservatories attached to dwelling-houses may
also have their roofs perpendicular to the rays of the winter sun,
for the same purpose ; but blinds should be provided for them,
during the months of summer, to guard against the effects of
th* perpendicular rays when the sun is crossing his meridian
altitude.

SECTION III.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES

1. Forcing-houses, culinary houses, ^c. — Forcing-houses are
erected with the intention of forming an artificial climate for
the culture of tender plants and vegetables in winter and early
spring. For this purpose artificial heat is employed to keep up
an exciting temperature, and, therefore, it is desirable that they
should be constructed in relation to this end.

Until very lately, the form in which forcing-houses were con-
structed was that of lean-to, or single-roofed, houses, with sheds
or garden-offices on the back of them. When it is not neces-
sary that light should be received from all sides of the house,
these lean-to houses answer very well, and possess many con-
veniences which cannot be obtained with span-roofs. Climbing
plants, such as grape-vines, trained beneath the glass, and
peaches, trained in the same manner, derive a sufficiency of
light from the single roof to enable them to bring their fruit to
perfection; and it is very doubtful if single roofs will ever be
entirely superseded for the purposes of winter forcing.

Fig. 3.

^'^^^i^^i^^^i

Fig. 3 is the section of a pit for winter forcing, which we

consider well fitted for the several purposes to which these pits
4#

40 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

may be applied. The one here represented is what we have
formerly used for the culture of grape vines, French beans, and
strawberries, during winter; and where fermenting manure is to
be had in abundance, it is probably the most economical house
for this kind of forcing.

Fig. 4 is the plan of a forcing pit. This house is 80 feet long,
in two divisions of 40 feet each. It is chiefly intended for forc-
ing vines in pots, and is furnished with a bed, b, which is filled
with fermenting materials for plunging the vines in, and supplying
them with bottom heat. A shelf, c, elevated to within about 20
inches of the glass, on the back wall, ar^ extending the whole
length of the house, is intended for forcing strawberries in pots ;
d is another shelf, for the same purpose, on the front wall.

We have designed this pit with the view to procure the great-
est accommodation in the given space, at the smaallest expenditure
for construction, keeping strictly in view the purposes for which
it is intended. For winter forcing, we decidedly approve of this
kind of house above all others, i. e., where utility only is consid-
ered in regard to it. The cost of this house is only four hundred
dollars, or eight dollars per linear foot.

A house for winter forcing should never exceed 40 feet in
length, even where the operations are extensive. Thirty or 35
feet is considered, by the best gardeners, the most desirable
length. If the range be a greater length, and the operations
very extensive, it should be subdivided into either of the dimen-
sions here stated, and each division heated by a separate appara-
tus.

There is no branch of gardening that requires a greater amount
of skill, or is more calculated to display the mastership of the
gardener's art, than winter forcing. It is absolute folly for any
novice in gardening to attempt it. To be successful in produc-
ing the luxuries of summer, in winter or early spring, requires a
great degree of skill, vigilance, constant and persevering energy.
The most unwearied attention is requisite, from the day the
house is started into work, until the productions are all fully
matured. Scarcely a day passes but something happens, tend-
ing to thwart the object of our labors. Heat or cold, wind or

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

o
crq

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

Steam, moisture and drought, mice, worms, slugs, aphides, and
insects innumerable, as Cowper says, oft work dire disappoint-
ment, that admits no cure, and which no care can obviate. It
is, therefore, the more requisite that the structure intended for
these purposes should be the best that science and practice can
adopt.

Fig. 5 is the end section of a forcing-stove, which we have
seen used in various parts of this country, with considerable suc-
cess. It is sunk a few feet into the ground, so that the roof
reaches within about two feet of the ground level. In some
places this kind of pit answers very well, as in very dry and
sheltered situations. The site of such a pit must necessarily be
in gravel, or sand ; in wet clay, coldness and dampness would be
unavoidable ; and in exposed situations, it would be very unsuit-
able for winter forcing, unless provision were made for covering
it at night.

Fig. 5.

Fig, 6 shows the end section of a polyprosopic forcing-house,
which, by some, is considered superior to all other forms for
winter forcing. The roof presents the different faces to the sun's
rays, <z, a, «, at different periods of the year. This kind of roof
may be considered as exactly equivalent to a curvilinear figure,
whose curved lines shall touch all the angles of the faces, so that,
were the house built in the form of a semi-ellipse, or having
curved ends, the sun would be nearly perpendicular to some one
of the faces every hour of the day, and every day in the year.

The rafters in this house are curved the same as in a cunri-

■WMy>^^f^Am..,^^j^^mw^^^^^^

<gg

//.

'/■

■/

i
'I

I
I

.^^^-r^ ' '. ■-"^" VA,' '■""^^

•9 -StJ

44 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

linear house, and should be made of iron, as a curvature for this
purpose can be made cheaper of iron than of wood, and is
tighter and more durable. Iron beams are made to screw into
the rafters, b, b, b, b, having- a fillet in which the smaller rafters
are placed, on which the sashes run. We have seen two methods
of constructing this kind of roof, — the one just described, in
which the sashes are made to slide, and another, in which the
sashes are made to rise on hinges, by which the house may be
aired, over the whole surface of the roof, or entirely exposed, for
admission of a congenial shower of rain, or for hardening the
vines or peach trees, after the crop has been gathered. The
arrangement by which this is effected is exceedingly simple, not
liable to get out of repair, and is applicable to all kinds of houses,
whether the roof is formed of curved or straight lines. This
form of house is considered by Loudon as the 7ie plus ultra of
improvement, so far as air and light are concerned. We are of
opinion, however, that these considerations alone render it less
valuable in this country^ than it is in England, except, as we
have already stated, for the purposes of winter forcing.

The Cambridge pit, Fig. 7, is admirably adapted for early
forcing, where there is an abundant supply of stable manure.
It is heated entirely with fermenting material, and is much used
in England for the purpose of growing pine-apples, melons,
cucumbers, &;c. a, a, are shutters, which lift entirely off, or are
wrought up and down by hinges attached to the back wall of
the pit. These shutters are made to fit closely on the lining
bed, by b, which is kept constantly filled with the materials to
supply the heat, which enters the interior of the pit through
pigeon-holes in the wall. We have kept pines during long and
severe winters, in this kind of pit, keeping up a temperature of
50° to 55° in the coldest weather. During winter the linings
require to be frequently renewed, at least every week some fresh
material must be added, otherwise the heat will decline below
the minimum temperature ; and, as it will be some time before
the new linings generate much heat, a part should only be re-
newed at one time, and never both sides of the pit at once.

Saunders' forcing-pit, Fig. 8, is considered an improvement

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 45

upon the foregoing. This pit has a double roof, and is furnished
with the dung-beds, a, a, on each side of the house. The fer-
menting material is supplied by means of linings along both
sides of the pit, and communicates the heat to the beds through
the arches in the side walls. This pit has a narrow path in
the centre, which admits of the internal operations being carried
on with more facility. We have only seen this pit in use by
the inventor, and, so far as we know, it is quite original. Mr.
Saunders informs us that it answers the purposes of early forc-
ing better than any other construction he has tried, and works
admirably, in the severest weather, without the aid of fire. We
have the fact of its perfect adaptability fully verified by its pro-
ductions, and are so fully satisfied with its superiority as a
dung-pit, that we are about erecting one ourself. It ought to be
borne in mind, regarding this pit, that unless there be abundant
supplies of fermenting manure always at hand when required,
it would be useless to attempt forcing with it in winter ; but this
fact also applies to all forcing pits heated solely by fermenting
materials.

Fig. 9 is the end section of a curvilinear-roofed cold-pit, for
protecting plants not sufficiently hardy to stand the winter with-
out protection, yet hardy enough to endure a considerable degree
of cold, and even a slight frost, if kept in a dry state. Of this
class we might name verbenas, roses, pansies, &c. Indeed,
there are many summer flowers, used by the amateur, for the
decoration of his parterre and flower-garden, which he might
save, during the winter, in such a pit. The pit here given we
consider the best, for any purpose to which the cold-pit can
be applied. We have found them practically superior to all
other pits we have yet used ; and as iron is now coming into
general use, for the construction of horticultural buildings, we
believe that these pits will be found, not only the most convenient,
but also the cheapest that can be erected, a, shows the bed in
which the plants are placed — we generally put in about a foot
deep of tan, or saw-dust, for plunging the pots in ; — b^ b, show?
the sashes, elevated for the admission of air, supported by iron
rods, c, c, which are made to enter a staple, by being bent, or
hooked, at the end.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

Fig. 9.

Fig. 10.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 47

Fig. 10 is a representation of an ordinary dung-bed, with the
frame set on it. The formation of dung-beds is so simple as
hardly to need a single word of explanation ; nevertheless, a
few passing remarks may be useful to the uninitiated.

Hot-beds of fermenting materials are generally laid on the
surface of the ground. Some prefer the basis of the bed to in-
cline slightly towards the horizon ; but we can see no utility
whatever in this system, except the site of the bed be very wet,
and then we prefer building the bed on a layer of brushwood.
It is also beneficial to place a layer of brushwood every eight oi
ten inches deep, which lets the rank heat and steam escape
more readily. The bed should have a slight inclination towards
the south, when the frame is laid, though this rather tends to
prevent .the bed heating equally all over ; and, where light is
not an object, as in cutting-beds, &c., we prefer it quite level,
and even inclinino: towards the north, the inclination of the
frame turned in the same direction.

Temporary or portable frames, or cases, for covering beds,
and protecting plants, are exceedingly useful about places where
it is requisite to harden young plants, or protect individual
specimens in the open ground.

Fig. 11 shows a portable glass frame, of a rectangular shape,
and w^hich we have often found useful for hardening young
stock, in the early part of summer, which was intended for bed-
ding out in the flower-garden. It can also be set on a dung-
bed for growing early melons, cucumbers, and starting young
plants into growth ; for this it is admirably adapted, as the light
is admissible all round.

A portable frame of this kind may be made of any size. We
find, however, that about four feet wide, and six or eight feet
long, is the most convenient size for practical purposes.

Fig. 12, the portable plant protector, which will be found
exceedingly useful for covering individual plants, standing in
the open ground. Those may be glazed with coarse glass, or
covered with oil-cloth. They will be found of much utility in
covering the more tender conefirs during winter, as well as dur-
ing summer from the intense heat. By having the south side of
the case painted with a slight coat of a lime solution, to darken
5

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

Fig. 11.

Fig. 8.

Fig. 12.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 49

the glass and prevent the entrance of the solar raj^s in that
direction, the plants are better able to endure the extremes of
either heat or cold, than if exposed or covered with straw or
mats.

In using these protectors for winter covering, it is only neces-
sary to throw a garden mat over the case during severe frosts,
removing it when the weather becomes mild, or immediately on
the relaxation of the frost. 1'here is not the slightest injury
resulting from the taking off the mats, as would be the case with
mat and straw coverings without the protector, as a body of air
is always at rest inside, which prevents the temperature from
falling so low as to cause injurj^ to the tree.

Framing-Grouiid. — This term seems to have a very different
meaning in American gardens from what it has in England, for
we find the spot usually appropriated to the pits, frames, hot-
beds, &c., located in some out-of-the-way corner, with dung,
weeds, and rubbish lying about in all directions, or, perhaps, we
may observe them occupying a place in one of the squares of
the garden, a site equally objectionable.

Where frames and hot-beds are extensively used, they should,
by all means, have a place appropriated to themselves, and
sheltered, if possible, on the east, north, and west; and, as we
can see no reason why this department of the garden should not
be visited by the proprietor as well as any other, it should be
laid out and kept in a manner to make it worthy of a visit. In
fact, the frame-ground should come as naturally in the course
of promenade as the larger fruit houses. Every one, indeed,
may not take the same interest in this department as in others
of the garden, but this can form no excuse for huddling the
frames and hot-beds into some recess, out of the way, and pay-
ing no attention to order and cleanliness about them. Who,
that is in the habit of frequently visiting large gardens, has
not heard the gardener apologizing for the filthy condition of
his frame-ground, when the curiosity or interest of the visitor
led him thither ? The only reason that can be given for this
state of things is, that the frame-ground is seldom intended to
form a prominent object in the establishment; its object being

50 STRUCTURES ADAPTED TO PARTICULAR PCRPOSES.

altogether for utility, it is considered by many a matter ol
absurdity to make it also an object of beauty.

If gardeners would consider how much gratification they
sometimes lose themselves, by depriving this department of the
garden of its interest by proscription, they would exert them-
selves more to bring it forward into its right place. If it is not
a source of interest to others, it should be made so to the pro-
prietor, for it must not be forgotten, that the pleasure and satis-
faction derived even from culinary hot-beds and forcing-pits,
does not wholly consist in their receiving the produce thereof,
when ready for use, — for if so, recourse need only be had to
the markets, — but, also, in marking the progress of their devel-
opment, from the commencement to the close of their growth,
in beholding fruits and vegetables flourishing in an artificial
climate, and in the satisfaction of partaking of products of our
own growth.

When the ground rises towards the north part of the garden,
this is doubtless the most eligible site ; although we are aware
that some prefer placing them within an enclosure inside the
garden, yet we think they are better placed near the northern
boundary. As dung is at all times necessary, and at all times
being carted to the frame yard, it is a continual nuisance havmg
it taken over clean gravel walks. It is, above all things, desira-
ble to have the spot approachable by carts, without in any way
coming upon the gravel walks, which are appropriated only to
promenade.

Fig. 13 shows the disposition of the forcing-houses, frames,
etc., at a gentleman's residence in the country, which is now
being executed under our direction. The ground on the north
side of the garden rises somewhat abruptly from the principal
range, which gives the houses a fine aspect and a dry site.
Immediately behind them, and stretching along the whole length
of the forcing-pits, and frame-ground, compost-ground, etc., is a
belt of trees, which have been planted expressly for the purpose
of sheltering the spot from the north and north-eastern winds,
the same object being attained by rising ground and plantation
on the west. Abundant space is left between the diflferent
erections to afford room to promenade and inspect the whol*»

V 1 " — -

p..

J v.:

crq'

52 STRI CTURES ADAPTED TO PARTICULAR PURPOSES.

department, without being annoyed with manure under foot.
Here, also, ^heds and offices have been erected for the various
purposes of the establishment, and arranged with a due regard
to convenience and ecoPxOmization of labor in the operations
daily going on in this department of the garden.

The position of the framing-ground should command a good
supply of water; either a natural stream should be brought
through it, or a plentiful supply kept in a large tank, as in the
plan. Fig. 13, and kept always full for immediate use, either by
means of a water-ram, or other forcing-power. Pipes should be
led from this large tank or reservoir into small tanks, one of
which should be in each house, to be kept at the same tempera-
ture of the atmosphere of the house in winter, for watering the
plants. These tanks should receive the water from the roof,
and be supplied from the reservoir, when that is exhausted.

Fig. 13 is a ground plan and arrangement of frame-ground
designed by the author for a gentleman's garden.

REFERENCE TO PLAN.

a Orange house.
h h Vineries,
c c Vine-stoves for forcing in winter, the vines being grown

in pots.
d d Culinary stoves.
e Cold frames.
/ Water tank.
g Open shed for soils.
h Seed room.
i Garden office.
j Miscellaneous store room.
k Potting room.
I Store room for pots.
m Tool house.
n n Large beds, in which green-house plants are plunged in
ashes during summer, being covered, during the
heat of the day, with awnings fixed on rollers,
mounted on a slight frame-work.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 53

ilSTl-

155?,

54 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

2. Graperies, Oraiigcries, <^c. — These we have distin-
guished from forcing-houses, as not being stimulated before their
natural season of growth, artificial heat being sometimes "applied,
however, for their protection from early frosts in spring, and for
ripening the fruits or accelerating the maturation of the current
year's shoots in autumn.

A greater latitude may be taken, in the construction of houses
of this class, both as regards extent and ornament. Here the
taste and wealth of the proprietor may be indulged to any
decrree. These structures may varv in lenfTth from 30 to 100
feet, or more, although we prefer them to be limited to the lat-
ter dimensions, adding others of different proportions, rather
than continue the unbroken flatness of the roof beyond this
extent.

Fig. 14 represents a range of houses of this class, erected by
John Hopkins, Esq., in the gardens of his splendid country-seat
at Clifton Park. This is one of the most extensive structures
of this kind yet erected in this country. It is three hundred
feet in length, by twenty-four in breadth. The structure is
divided into three compartments of one hundred feet each ; the
centre compartment, which is larger and loftier than the others,
is appropriated to the growth of orange trees planted in the
ground, which, in a few years, will form a complete orchard of
orange and lemon trees.

The site of these houses is one for which nature has done com-
paratively little, but for which art and outlay have done much,
and for which the taste and munificence of the proprietor are still
doing more; but, like many other structures which have come
under our observation, they contain much inferior glass in the
roof-sashes, which is very injurious to tender foliage. Bad glass
is an abundant material in the United States, and is generally
used by tradesmen, who do the work by contract, on account of
its cheapness. This is a matter which demands particular
attention from those erecting horticultural buildings ; otherwise,
they may not discover the error, until too late to prevent it.

Fig. 15 is a representation of a model house for growing
grapes on the lean-to or single-roofed system; and, both in
regard to its dimensions and slope of roof, is just such a struc-

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 55

crq

56 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

ture as we would recommend. — that is, if a lean-to house was
desired by tlie erector, or the position would not admit of any
other kind. We need hardly mention that houses of this kind
are suitable in many positions where curvilinear houses would
be inappropriate, and where span-roofed houses would be
impracticable. This house is at once cheap and substantial,
in every way adapted for grape-growing, and presenting as
good an appearance to the spectator as one that would cost
double the sum, without any corresponding advantage.

Fig. 16 is a span-roofed house on the same scale and the
same design. Of course, span-roofed houses are to be preferred,
either for plant-houses or for cold vineries, to lean-to houses,
although, as we have said, there are positions which render
lean-to houses preferable, even as cold houses. Span-roofed
houses cost somewhat more in their erection than single roofs;
nevertheless, we consider it a matter of economy to erect a
span-roofed house where the position is suitable, because the
difference of cost is not so much as the difference of glass sur-
face available for the growth of vines. In fact, a span-roofed
house gives just two single-roofed houses of the dimensions of
one. of its sides. Hence, it is clear, that as many grapes can be
grown in a span-roofed house, 50 feet long and 20 feet wide, as
in a single-roofed house, 100 feet long and 10 feet wide, while
the back wall, 100 feet in length, is saved.

From the principles we have laid down for the construction
of hot-houses, in the beginning of this section, it will be apparent
that double-roofed houses are in every way superior to single
ones for the general purposes of horticulture, not only on account
of their superior lightness, but also as regards cost of erection.
And we find this fact is now becoming generally admitted, from
the prevailing tendency to erect double-houses, all over the
country, where the advantages of double roofs are not sacrificed
to the desire of having a more imposing and extensive appear-
ance from a single point of view.

Amongst the various forms of curvilinear houses lately brought
under our notice, is that of forming the roof of the segment of a
circle, which shall equal the width of the house, — a principle
which we think is not generally recognized, nor do %e think it

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

58 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

applicable except under certain circumstances. We ha\e seen
houses erected on this principle in Northern Europe, where they
doubtless answer the purpose much better than houses with ellip-
tical roofs, for the reasons already stated in regard to forcing-
houses; viz., the deficiency of perpendicular light, not only in the
winter and spring, but also in the early part of summer, when all
the perpendicular power of the sun's rays is required for the proper
maturation of the fruit. It must be evident, however, that these
reasons can be of no influence on this side the Atlantic, at least,
in the southern and midland states, although we know of several
houses in the state of New York, built on this principle, or a
very near approximation to it.

Fig. 17 is a single-roofed curvilinear house, built on the above
principle, the back wall being equal to the breadth of the house.
As a single-roofed house, this curve has a very good appearance,
and answers admirably where perpendicular light is desirable.
The only objection that can be urged against it, is the flatness
in the upper portion of the roof, which gives it the same faulty
character, for our hot climate, that we have urged against the
flat roofs of straight-lined houses.

Fig. 18 is intended to represent a double-roofed house, on the
same principle. Here the width of the house must be equal to
the chord of both the sides. The parapet wall being only a con-
tinuation of the semi-circle, of course this form of house is open
to the same objections as the other, (Fig. 17,) even in a greater
degree, as the flat part of the roof, in this case, is precisely
doubled. The perpendicularity of the rays is in some measure
obstructed by a portion of the segment, at the apex of the roof,
being opaque, as in the case of the house from which our sketch
is taken. This plan answers the purpose very well, without
depriving the house of its effect, and we think, where it is neces-
sary, the effect might be heightened by a slight balustrade, or
other ornament.

That curvilinear houses, properly constructed, are superior to
those with plain roofs, can hardly be questioned on practical or
scientific grounds. The construction of the monster palm house,
lately erected in Kew Gardens, at London, is an evidence that
this principle is recoijnized by the most scientific cultivators in

STRUCTURES ADAFTED TO if^ARTICULAR PURPOSES. 59

that kingdom ; and though the immense structure is avowedly
for the growth of palmaceous plants, still the objections that
might be urged against its modification as a palm-house might,
with equal propriety, be urged against its form as a fruit house,
on a smaller scale. If there be any fault in its curvilinear con-
struction, the fault is augmented as the dimensions of the
structure are increased.

The objections that have been urged against curvilinear
houses in England can have little application in this country,
whatever force they might have in the cloudy climate of North-
ern Europe. And we cannot help thinking that the arguments
against them have, in a great degree, promoted their adoption,
on account of the inconsiderate manner in which their mode of
structure has been questioned. We think it clear, that any form
of curvilinear roof, from the common rectangle to the semi-
ellipse, or the acuminated semi-dome, not only admits of a larger
run of roof, but also a larger proportion of light, than any form
of straight-lined roof that can be adopted, excepting the polypro-
sopic roof, which, in fact, is nothing more than an approximation
to the curvilinear, or spherical roof, having the advantages of
the one, without the disadvantages of the other.

Another remarkable property possessed by curvilinear roofs,
and not by straight-lined ones, is their power of reflection and
refraction, which, in the hot summers of our climate, is of much
more importance, in a horticultural point of view, than is gener-
ally supposed. Though the power of curved surfaces of reflect-
ing the rays of light be similar to that of plane surfaces, yet the
plane is so small on which the rays fall, that its position is changed
before its concentration can cause injury to the foliage on which
it falls. As the surfaces of curvilinear roofs are, or ought to be,
presented more obliquely to the sun's rays than straight-lined
roofs, the amount of refraction, in very hot weather, will be
greater in the former than in the latter case. The more ob-
liquely the ray falls on the medium of refraction, the greater the
amount refracted.

The general form of curvilinear-roofed houses, in this country,
is the common curvature already described, forming the segment
of an ellipse, the ends beincf upright as in straight-lined houses.
6

60 STRUCTURES ADAPTED* TO PARTICULAR PURPOSES.

For the purposes of grape-growing, we think a loss of surface is
sustained by the position of the gable ends. In fact, from a series
of calculations, bearing directly on this question, we have found
in some houses that stand apart from other structures a loss
equal to one third the extent of the roof surface. Some houses
may be less, but some more, than this amount. In growing
grape-vines for instance, we know that the rafters — or the slop-
ing part of the house — is the principal area for the fruit-bearing
branches of the plant. Now, supposing that your house be 50
feet in length, 15 feet wide, and as many feet high, then, by
having no vines of any account growing on the ends of the
house, you lose a transparent surface equal to nearly one half
the extent of the whole roof. If it be asserted that the perpen-
dicularity of the gables is necessary for the admission of hori-
zontal light, we think this wholly unwarranted ; for experience
has fully proved that horizontal light, entering by the medium
of upright glass, is powerless, comparatively speaking, for assim-
ilating the juices, either in proper quantity or quality, for the
production and maturation of fine fruit. Many of the oldest and
most experienced gardeners prefer hot-houses having no upright
glass at all in front, placing the roof directly upon a parapet IS
or 20 inches in height.

By way of remedying the objection here pointed out, we have
•desio'ned a house which combines the advantao-es of a curved
roof with those of a plane surface, rendering the whole of the
house available for the production of fruit. By this plan a
greater training surface is obtained, for the same extent of glass
surface, than by any other we know, or in any other structure
of similar dimensions. This we consider the most perfect form
of a hot-house that has yet been erected.

Fig. 19 is intended to convey a clearer notion of the kind of
house we have referred to. This house is 100 feet in length,
20 feet in height at the back wall, with a perpendicular rise of
five feet. The roof rises in series of successive planes, from the
upright front, and presents a continuous surface for training the
vines to, from one end to the other. Fig. 20 shows the ground
plan of the house, which may be made of any dimensions, as
easily as any of the common forms.

STRTJCTURES ADAPTED TO PARTICULAR PURPOSES.

62 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

A double-roofed house can be erected on the same plan, by
substituting a row of columns along the centre of the house for
the support of the ridge, in place of the back wall ; one of the
planes being raised the necessary height at each end, for the
doors, which must also be done in the single roof, (Fig. 19,)
unless the door enters through the back wall, which, in some
cases, may not be so convenient as having them at the ends,
though, for the economizing of glass surface, we would prefer
them in the back wall.

Although double-roofed houses are generally of a rectangular
shape, yet they admit of every combination of form without
militating against the admission of light and air. Nevertheless,
that they may be perfectly adapted to the end in view, there are
rules to be observed, and errors to be guarded against, which it
is necessary here to point out.

If the house is above fifteen feet in width, it is necessary to
have a single or double row of columns in the centre to support
the ridge of the roof, but in many houses these columns are
three times thicker and heavier than they ought to be, even with
a due regard to strength and durability. When the columns
are disproportionately heavy, the house has a dull and clumsy
appearance, and the effect within is extremely bad. Indeed,
columns ought to be dispensed with where they can possibly be
spared, consistent with strength in the structure. We have
frequently seen the internal view of double-roofed houses com-
pletely spoiled by the clumsiness of the columns supporting the
roof, even when columns were altogether unnecessary. Cast-
iron columns are always preferable to timber, even when the
structure is made of the latter material. When the colunms or
rafters are bound together by braces and crossbars of slight con-
struction, as of iron in different forms, vines and other climbing
plants may be trained upon them, and be hung in festoons from
column to column, or otherwise, as fancy may dictate; this
gives an elegant appearance, and is always pleasing to the spec-
tator.

Another common error in the construction of fruit-houses is,
the heaviness and height of the front, something in the fashion
of the heavy and dull-looking plant-houses of the last century

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 63

This results from a very general desire to give the structure a
finer effect from a front view ; but it must be regarded as a
decided sacrifice of utility and adaptation to purpose. Making
the front of graperies from eight to ten or twelve feet high,
is not less objectionable than to make the roof on a level with
the plane of the horizon. The sides of a hot-house should never
be more than four or five feet in height. This gives the struc-
ture a more characteristic appearance, and is certainly mucli
more fitted for the purpose in view, than upright sashes, which
make the roof appear to the eye only a fraction of its real extent,
whether viewed from the interior or the exterior of the structure,
apart from the consideration, that the upright part of the house
neither produces nor ripens the berries of grapes so well as the
sloping part of the transparent surface. All structures of glass,
for horticultural purposes, should have a parapet wall, from 12
to 20 inches in height, on which to rest the frame-work of the
fabric ; then about four feet of upright glass. This modification
gives the house, whether of large or small dimensions, a neat
and characteristic appearance. A span-roofed house, 24 feet
wide and 16 feet high, with a five-feet front, makes a well-
proportioned house, and gives about 16 feet of a run for the
vines*under the rafters, — the slope of the roof being upon an
angle of 45°, which, as we have already said, is the best pitch
for a hot-house roof for general purposes.

Until these few years, the forms of hot-houses were generally
plain, flat, right-lined buildings, differing in no respect from one
another than in their size and relative des^rees of clumsiness.
Lately, however, a great improvement has taken place in the
form and construction of this class of buildings. Single-roofed
houses are fast dwindling into desuetude, and right-lined houses
are giving way to the more light and elegant curvilinear roofs.
This is an important step in the right way; and we regard
those who, laying aside their prejudices in favor of right-lined
houses, adopt the curvilinear shape, as conferring a benefit on
exotic horticulture as acceptable to those interested in the pro-
fession as it is creditable to themselves.

Regarding curved houses, Loudon says, — "On making a

few trials, to ascertain the variety of forms which might be
6=^

64 6TRUCTURES ADAPTED TO TARTICULAR PURPOSES.

given to hot-houses by taking different segments of a sphere,
I, however, soon became fully satisfied that forcing-houses, of
excellent forms for almost every purpose, and of any convenient
extent, might be constructed without deviating from the spheri-
cal form ; and I am now perfectly confident that such houses
will be erected and kept in repairs at less expense, will possess
the important advantage of admitting much more light, and will
be found much more durable, than such as are constructed
according to the methods and forms which have hitherto been
recommended."

Fig. 21 is a representation of what is called the zig-zag, or
ridge-and-furrow roof, which has not, as far as we know, been
very extensively adopted. There are several places in Eng-
land where this method of roofing has been adopted, but prin-
cipally as an experiment, or merely as the fancy of the erector.
The advantage of this mode of roofing is, that the rays of the
sun are presented more perpendicularly to the glass in the
morning and afternoon, when they are weakest, and more
obliquely to the glass at noon, when they are strongest. We
doubt, however, — though the arguments we have heard urged
in favor of this kind of houses be indisputable, — whether the
additional expense required in their construction will be 'coun-
terbalanced by the advantages gained. There is no doubt the
expense of their erection militates very much against them ; and,
if they could be erected as cheap as plane roofs, they are decid-
edly superior to them for graperies, as the vine can be trained
up the middle of the ridge, and, consequently, though suffi-
ciently near the glass, the intense rays of the sun will be less
injurious than under a plane roof.

The ridge-and-furrow roof may be carried out either on com-
mon plane-roofed houses, or on the curvilinear principle, though
doubtless the latter is more difficult of construction, and, of
course, more expensive ; but we have no doubt, if the principle
of constructing horticultural structures were fully understood by
fompetent manufacturers, who had directed their attention to
the details of the structures, that this, or, in fact, any other
form of structure, could be made as cheap as the houses now in
common use.

tTRUCTURES ADAPTED TO PARTICULAR PURPOSES,

Fig. 21.

68 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

The ridge-and-furrow roof may be formed by placing the
rafters as in making a common roof, say four feet apart ; then
placing the ridge-bars in such a manner that, contiguous to each
other, they will form an angle of 45° with the furrow-b?.r, or
rafter. Or the angle included within the ridge-bar n^ay be
formed to suit the climate of the neighborhood, — beai ng in
mind the principles already laid down regarding the effe is of
intense sunshine upon fiat roofs.

The sides of the ridge may be glazed of small panes, as in
common sashes, or may be made of single panes, as in the finest
houses now erected ; but, whichever method is adopted, the
rafters should terminate in one horizontal line on the top of the
parapet : this is also desirable at the back wall. Some apparent
difficulty is thus occasioned in the lower part of the roof; but
this difficulty is only apparent, especially if the front of the
ridge be made to slope on the same angle as the side. Only
the smaller and triangular pieces of glass can be used. It
becomes, in fact, more economical, as the smaller pieces of glass
may be all used up, which would, otherwise, be thrown away.

The ridge-and-furrow roofs are especially advantageous in
countries liable to heavy falls of snow or rain, and in larc^e
houses which are parallelograms in plan. Almost any weight
of snow may be carried by such roofs, especially where the fur-
row is small, as the pressure will then be chiefly on the bars
and rafters, and not on the glass. As to hail, which is some-
times very heavy in this country, breaking the glass in flat-roofed
houses, it will alwa3^s meet the glass of a ridge-and-furrow house
at an angle which will prevent breakage.

The advantages of these ridge-and-furrow roofs, as we have
already stated, — their presenting the surface of the glass at an
oblique angle to the noon-day sun, while the morning and even-
ing sun is admitted almost perpendicular to the surface on
which it falls, — ought not to be altogether overlooked in this
country ; and we think that a great deal might be done with
houses of this kind, — probably upon an improved plan, — where-
by the effect of the intense sunshine of mid-summer might be, in
some measure, deprived of its meridian force upon glass-houses.
Whatever may be thought of the plan here given, the principle

STRUCTURES ADAPTED TO TARTICULAR PURPOSES. 67

upon which it is made is undoubtedly good ; — a principle which
may easily be illustrated by placing a few common frame-
sashes in the positions of the supposed ridge-and-furrov/ roof,
placing some tender-foliaged plants beneath them, and then
comparing the results, under intense sunshine, with the effects
produced under a common sash, whose surface is perpendicular
to the noon-day sun.

Whatever might be said in favor of cold vineries, they are,
nevertheless, subject to casualties which are necessarily una-
voidable. This is more especially the case in the Northern
States ; and even as far south as the latitude from which we
now write, (39° 45',) they are liable to the same mishaps. All
houses for the production of foreign grapes should have some
mea«ns or other of commanding a little artificial heat when it is
found absolutely necessary. This does not amount to saying
that good crops have not and may not be grown in cold-houses,
without any means of raising the temperature in cold nights ;
yet it cannot be denied that good crops have, been sacrificed for
the want of a slight fire in frosty nights. This is particularly
the case in nectarine and peach houses, where we have seen the
crop completely destroyed in a single night.

Experience has fully shown that the culture of exotic fruits is
a precarious business, without some readily available m.eans of
averting those evils w^hich are neither modified nor averted by
any peculiar mode of construction, or any angle that can be
given to the roof. This circumstance is worthy of particular
attention, as many persons who design hot-houses lay particular
stress on certain trifling details in the structure, which, in a
practical point of view, are unworthy of the least notice.

We have lately had some conversations with men thoroughly
skilled in the science, as well as the practice, of vine-growing
and the details of hot-house management, and have particularly
noted the diversity of opinion regarding the upright portion of
the front of the house. Some are of opinion that hot-houses for
the culture of fruit should have no parapet-wall, but that the
sashes should rest on a water-plate level, or nearly level, with
the ground, giving, as a reason, the fact that the parapet pre-
vents the sun and light from getting to the inside border, and to

68 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

the Stems of vines. Now, with regard to small winter forcing-
houses, this may be of some effect ; but in cold summer-houses,
i. c, houses intended for growing peaches, grapes, etc., without
fire heat, this is of no importance, as the meridian altitude of
the sun durinsr summer renders the wall rather beneficial than
injurious, by shading the border during the heat of the day.
Hence, it is evident that the construction of the house for
grape-growing, etc., should be regulated according to the locality,
as well as the period of the year at which it is required to ripen
the fruit.

Many have a serious objection to upright fronts, whether of
glass or other material, from the undeniable fact that fruit is
seldom produced below the angle of the rafter ; and if it is, it
never ripens so well as that grown under the perpendi(;ular
light, nor is so well-flavored. Upright glass, however, adds so
much to the appearance of this kind of building, that it can
hardly be dispensed with, even at the sacrifice of a little fruit ;
but the latitude here allowed must be kept within certain limits,
otherwise the effect produced is worse than if the house had no
parapet at all.

The parapet wall of a peach-house or grapery should never
be more than twenty inches or two feet high; the perpendicular
sash above it, three feet more, making the upright front five feet
in all. This is, we think, a proper height for structures of the
kind here referred to ; and this will be found to give the struc-
ture, whatever its longitudinal dimensions, better proportions,
and a more handsome appearance, than if these dimensions be
either diminished or increased.

In many private establishments it is much more convenient
to have one, two, or more houses, than to have one single
house perhaps equal to the length of the whole. We happen
to know several persons who prefer erecting houses for grapes
and peaches in this way ; and, indeed, it has many advantages
over building a large house, especially for private establish-
ments of moderate extent, where the whole produce is consumed
by the family, because one house may be advanced a month or
two before the succeeding one, while the third may be protracted
as late as possible, so that the fruit season will be much longei

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

FFFT^

'EEFEEil

'/ /i

'y/,

''/■

|lv>

70 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

than if the structure was composed of a single house of the size
of the three.

In building a range of hot-houses on these principles, say one
hundred feet long, we would arrange them in the order rep-
resented in the opposite cut, Fig. 22, showing three houses
united into a neat and compact range. The centre division,
which is more elevated than the others, may be used as an
orangery, or camellia house ; or for growing figs, planting the
trees in the centre bed and growing them as common dwarfs,
which is the best way of growing figs, their strong and uncom-
pliable branches being unsuited for training on the common
trellises of a vinery, neither do they fruit so well as when
allowed to grow like a dwarf pear-tree.

These dimensions are also advantageous on account of the
trees that are to be grown in them, as different kinds of trees
require different kinds of treatment, as well as different degrees
of heat, air, and moisture. Each kind of tree can have the
treatment which is most conducive to health and fruitfulness,
without infringing on the peculiar conditions required by the
others.

Where a large quantity of fruit is required, the houses for its
production must, of course, be upon a larger scale. We men-
tion this, as very absurd ideas are frequently entertained by
individuals regarding the producing capacity of vines, etc., in
houses, being ignorant of the quantity that healthy trees can
bear without inflicting a permanent injury.

If it be desired, the centre compartment of this range may be
converted into a green-house, by placing a stage along the mid-
dle of the house, and a front shelf two feet wide along the front
nearly level with the building of the parapet wall, leaving a
sufficient space between the shelf and the stage for a pathway.
The plan of placing the green-house in the centre, between
the fruit-houses, is very common. The plans of modern archi-
tects are somewhat different from those of the last century,
in which we generally find the green-house a part of the cul-
inary department, either in the middle, j?r in a corner of the
kitchen garden. In fact, little can be said in favor of placing
the green-house or plant-stove among the fruit-houses, except

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. '"iJ

'"n small places where the limits of the ground do not admit of
a select position, or where it may be desirable to place the whcrie
of the glass structures together, either for economy, conven-
ience, or effect.

When a grapery having some pretensions to architectural
display is desired, either to correspond with buildings already
on the place, or to form a connection between some portion of
the mansion and another, then the structure may possess a
heavier and more artistic character. This may be accomplished
without in the slightest degree infringing on the principle of
adaptability. For instance, there may be a recess, with the
proper aspect, in some part of the mansion, which the proprietor
may wish to fill up with a house productive of profit as well as
pleasure ; and for this purpose, he chooses a grapery, and wishes
a suitable house for the purpose, without destroying the general
harmony of his mansion. Or, perhaps, his premises may be
very limited in extent, and he wishes a fruit-house nearly of
the same order as his Tuscan or Italian villa ; in which case, a
house with a somewhat massive parapet and blocking-course, as
in Fig. 23, would be more in unison with his taste, ns well as
with the rest of the premises.

This house, it will be observed, has rectangular ventilators in
the front wall, which give the house a more architectural
appearance ; the back wall is also surmounted by an ornamental
blocking-course, with ventilators for the admission of air throuo-h
the back wall. [See Ve?itilation.'\

We do not, by any means, justify the method of placing
fruit-houses immediately contiguous to the dwelling, yet such
is the taste of many. And as there is no valid reason why
persons may not carry out their particular fancies with their own
property, we have made the foregoing remarks for their benefit.

We do not give the above cut as a model house for an archi-
tectural vinery, — of course, its ornamental character may be
increased, according to the money that is to be devoted to its
erection ; but with regard to the principles of its design, unless
the polyprosopic roof be adopted, which is considered by some
more architectural in its appearance than curvilinear roofs,

when conjoined to the square forms of dwelling-houses.

l2 JTRUCTCRES ADAPTED TO PARTICULAR PURPOSES.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 73

8. Greeu'kouses, Conservatories, ^c. — The principal dis-
liiiction between a green-house and conservatory is, that in the
former, the plants are exhibited upon shelves and stages, while,
Hi the latter, the plants are generally planted out in a bed in the
middle of the house prepared for their reception. In many-
instances, however, there is no other distinction than in the
name ; as these structures are sometimes so arransfed that the
middle portion is appropriated to the growth of larger plants
planted out, while the sides are surrounded with shelves for the
reception of plants in pots, as in a common green-house. And
to this arrangement there can be no special objection, especially
where the structure is of small dimensions, which admits of the
sides being shelved for plants in pots, without destroying the
character of the house, or the plants, by their distance from the
glass. We have seen a few instances, a very few, where the
two characters were amalgamated together, forming a most
interesting conjunction ; but, unless the specimens exhibited be
very large and well-grown, their effect, when situated upon the
centre bed of a common-sized house, surrounded with shelves,
is meagre and defective in the last degree.

Properly speaking, a green-house is not a receptacle for large
plants, and hence it should have adequate means within it for
standing the plants within a proper distance from the glass.
This is absolutely necessary with regard to those classes of flow-
ering plants that are fitted to adorn it, both in winter and sum-
mer. Some are of opinion that green-houses are of no further
service than merely to store away a miscellaneous assortment
of rubbish during the months of winter, for the obvious purpose
of preserving them until the next summer, that they may turn
them out under trees, or in out-of-the-way corners, to keep them
from being burnt up by the hot summer sun ; and, as a matter
of course and of custom, the green-house is converted into a
lumber-room, or something else. And there it stands ! what i3,
or ought to be, the chief ornament of the garden, deprived of its
character, for want of taste, and divested of its interest, for lack
of skill! Visitors say, "Let us have a look at the green-
house." " No," replies the gardener, apologetically, " it 's not

74 STRrCTURES ADAPTED TO PARTICULAR PURPOSES.

worth your while going in, for there is nothing there to see !
A humiliating acknowledgment, but full of truth.

It is for-eign to our purpose to enter upon the present condi-
tion of green-house gardening, and the manner in which these
structures are managed by gardeners. Our present object is to
treat of their construction, and of the means of adapting them
the most easily to the culture of flowering plants, either during
winter or summer.

It is a well known fact, that plants that are grown in what
are called lean-to green-houses, have exactly the character of
the house in which they are grown, i.e., they are one-sided;
nor is it possible, without a vast amount of labor and attention
on the part of the gardener, to grow them otherwise. -In this
respect the cultivator does not imitate nature, but rather the
monstrosities of nature. Trees and shrubs only grow one-sided
when their position precludes the access of light and air around
them; but they grow naturally into a compact bush, which is
universally allowed to be the most beautiful form that plants
can assume.

Even a handful of cut flowers have their beauty, and are
generally admired, but when seen upon the living plant,
whatever shape or form the latter may possess, how much
greater their charms ! If, therefore, w^e add to these natural
beauties the additional charm of a positively beautiful form,
surely it will double their claim to our admiration. And we
may here add the gratifying fact, that this claim is now gener-
ally recognized by all who can appreciate the superior beauty
of well-grown plants.

The principles upon which plant structures ought to be built,
are somewhat different from those, which regulate the erection
of forcing-houses, culinary houses, &c., and as their purposes
are different, their shapes and forms are generally also different.
Plant-houses admit of a greater variety of shape and design
than any of the kinds previously mentioned, and as they are
generally erected in private grounds, for ornament and display,
they should have a more artistic character than the others.

The size of the green-house may vary according to the extent
of the collection to be cultivated, but it should always have a

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. <0

.ength proportionate to its height and width. There is a great
inconvenience in having the green-house very capacious, and
where it is desirable to have a large collection of plants, it is
best to have a conservatory for the growth of the larger speci-
mens, or a stove for the palmaceous families of plants. We
shall, however, allude to what is properly termed the green-
house.

A first-rate green-house should be completely transparent on
all sides ; lean-to houses are decidedly objectionable, for the
reasons already given. Houses that are only glazed in front,
and have glass roofs, but otherwise opaque, are also objection-
able, as plants can never be made to grow handsome. They
become weakly and distorted by continually stretching towards
the light, neither do they enjoy the genial rays of the morning
and evening sun, and only perhaps for a few hours during mid-
day. If such houses be large and lofty, they are still more un-
manageable, as no cjilture can keep the plants symmetrical and
of good appearance.

A green-house should stand quite detached from all other
buildings, and may be of any form the fancy may dictate, or the
position suggest. It maybe circular, oval, hexagonal, octagonal,
or a parallelogram, with circular or curved ends. The house,
to be proportionate, should be about fifty feet in length by twenty
in width, and fourteen feet high, above the level of its floor; if
more effect be required from the external view, its parapets may
be raised, to give the house a loftier appearance. The parapet
should be not more than two feet high all round, the upright
glass about two and a half or three feet more, including base,
plate, and sash bars. The house should be surrounded by a
shelf, two feet wide, level with the ^top of the parapet wall.
This shelf is of great importance to a gardener, and is gener-
ally the best place for the finer kinds of plants ; being sur-
rounded on all sides with light, and being near the glass, they
grow bushy and dwarf in habit, in which state they are most
pleasing and attractive. Next to this shelf comes the pathway,
three feet wide at least, (having just enough room between the
roof for the tallest individual to clear the glass and rafters;)

then the stage, or centre-tables, of stone or timber, and arranged

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

according to the size of the plants to be grown. The following
end section will illustrate what we here refer to. It is somewhat
enlarged, for the purpose of showing the arrangements of the
interior. The cut which follows (Fig. 25) is a perspective view
of the same house, taken at a considerable distance from it, for
the purpose of showing the effect of this plain structure in a
pleasure-ground. If desired, it may be made to assume some-
thing of the character of a conservatory, by introducing a ground
bed in the centre, instead of the shelves or tables. The fire-
place and heating apparatus may be placed at one end, and
under ground, so as to be out of sight, or may be formed in a
sunk shed, and blinded with shrubbery. The flues, or pipes, for
warming the house, must be carried round, beneath the side
shelves, dipping below the level of the floor at the doors, and
returning by the opposite side of the house to the furnace. The
cost of such a structure will very much depend upon the quality
of the workmanship, and the material used in the construction ;
but we think a very good house may be erected, according to the
foregoing plan, for about ten dollars per foot in length, or about
five hundred dollars for a house 50 feet long by 20 feet in width.

Fig. 24.

Such a green-house, though plain and inexpensive in its
character, may, nevertheless, be made to harmonize well with
flower-garden scenery, and is far superior to the clumsy, shed-
like erections frequently seen stuck into corners of buildings

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

and dwelling-houses, without reference to the position of the
structure, or the purpose for which it was buih.

Fig. 25 shows the appearance of the house, on the proportions
which are given in the above plan, (Fig. 24,) which, in our
opinion, admits of more room for plants than any other form
that can be built at the same cost ; for, although we might adopt
a semi-circular form for the end toward the most prominent
point of view, it must be remembered that this would add con-
siderably to its cost. Our object here is to give the sketch of
the best and cheapest kind of house that can be erected for plant-
growing, and such is the one here given.

This house may be placed in any situation, as regards aspect.
It may be attached at one end to any other building, without
much injury to its efficiency as a plant-house ; and where it is
found absolutely necessary to attach green-houses to the walls
of other buildings, they should, by all means, be constructed
after the plan here given, or under some architectural modifica-
tion of it, avoiding, if possible, that old, and now almost obsolete,

Fig. 25.

system, of laying the roof up to the wall, as in a common
grapery, or of making the front of heavy pilasters and massive
wood-work, like the orange-houses of the middle ages. The
method of construction here described is that in which the
plants enjoy the largest share of light; and this house is the
easiest managed — with respect to air and heat in winter, and
moisture and shade in summer — of all other methods which
have come under our experience.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

,M •-! — '

VI 1 -1 — '

-i

Mf-'

v,lu

— '

=ll=i

=i!=i

[

/i||:|ri

'■^

—

— !

—

; —

—

' I'

—

rmmm

STRUCTURES ADAPTED TO PARTICULAR PURPOSES, ^ 9

In some establishments it may be requisite to have a range
of plant-houses, or one house divided into compartments, for
the different kinds of plants ; thus the structure may be of a
highly ornamental character, as in Fig. 26, one end consisting
of a common green-house, for geraniums and soft-wooded plants,
and the other may be either a heathery, an orchidaceous, or an
exotic stove, for promiscuous plants ; the centre, being larger and
more capacious than the ends, may be an orangery, or a palm-
house.

This forms an elegant range of botanic hot-houses, and being
of glass all round, should stand in the middle of a large pleasure-
ground, or shrubbery. The smoke of the furnaces, being con-
ducted into a subterraneous canal, is carried to a distance, and
emitted by means of a shaft having the appearance of an orna-
mental column, as in the Botanic Gardens of Edinburgh and
Kew.

By having the plant-stove in the middle of the other houses,
a considerable advantage is gained by the protection afforded in
winter, when the structure requires to be kept at a high temper-
ature by artificial means ; and as both of the adjoining houses
will also be warmed in severe weather, the centre one, though
larger, will be maintained at the required temperature with a
heating apparatus no larger than the others.

From the curved disposition of the centre house, this range
has a peculiarly pleasing effect, when viewed from a horizontal
point of view somewhat distant. The proportions of this struc-
ture are excellent ; and it would, undoubtedly, form a splendid
ornament in the grounds of a gentleman's country-seat.

One of the leading errors in the erection of large plant-houses,
is in the unreasonable height to which their roofs are carried, and
which in the case of palm-houses maybe defended as necessary;
but in the case of conservatories, there is no tenable justification
of such a course, except the house is intended to be the object
of admiration, instead of the plants that are grown in it ; and
if fitness for the end in view be expressive of beauty, then, after
all, these architectural temples must decidedly fail in producing
that effect upon the mind, that the plain finished, but fitly and
efficiently designed structure never fails to produce. But the

80 STRUCTURES ADAPTED TO PARTICULAR PURPOSES.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 81

beauty, even of the plainest kind of structures, may be easily
heightened and increased by an ornamental moulding of wood
along the ridge of the roof, if a span, or on the end rafters and
front plate, as in Figs. 26 and 27, which will deprive the house
of none of its lightness, and will give it a neater and more ele-
gant appearance.

Plants placed at a distance, either under water or under glass,
are as much influenced in their development by the light as by
the heat. When plants are a great distance from the roof, they
are, of course, in a colder and denser medium at the surface of
the soil than at the "top of the house, and there cannot be a
doubt that this difference in the density and temperature of the
atmosphere has much to do with the struggle and effort which
every plant makes to rise upw^ird, and to elevate its assimilating
organs into the warmer and most humid regions of the house.
It will also be found that the difference betwixt the higher and
lower strata of air in hot-houses, is more immediately the cause
of plants drawling, and becoming weak, than anything that re-
sults from a feeble constitution, or from a deficiency of atmos-
pheric air.

Notwithstanding the practical illustrations of this prevailing
error in plant-houses, there seems to have been very little done
to counteract this fault in lofty houses. The large conservatory
in the Regent's Park, Botanic Garden, is the only structure of
great size where this circumstance has had sufficient weight to
induce the erectors to provide against it, in the general design
and construction of the building. This admirable plant-house
stands as a striking illustration of what can be done on a grand
scale, without rendering fitness for the end in view subservient
to architectural display, and yet, without depriving the structure
of that dignity and effect which fine conservatories always convey
to the cultivated mind. This conservatory, we believe, is the
result of well digested practical and scientific knowledge, and
we doubt if there be any other such erection in Ensfland, where
the effect of this rare combination is so strikingly displayed on
a scale so magnificent; and the result of this combination has
indeed been clearly manifested, in the formation and subsequent
management of this beautiful garden^

82 STRUCTURES AD.4PTED TO PARTICULAR PURPOSES.

As the influence of the upper and lower strata of air, in large
houses, will be discussed in a subsequent portion of this work,
devoted to that subject, we will not enlarge further upon it at
present, more than to observe, that lofty-domed, or curvilinear
roofs, as that lately erected at Kew, are more difficult to manage,
both in winter and summer, than low-roofed houses, whether
curved or straight, and that the impossibility of rendering these
houses in any way workable, has induced, in some instances,
their almost entire abandonment on the part of the proprietors,
owing solely to the intense heat of the superior regions of the
house.

The most experienced and enlightened men have satisfied
themselves, that structures in which the atmosphere has to be
kept at a higher temperature than the external atmosphere, and
in which plants have to be grown, should be kept at the very
lowest elevation which the use and purpose will admit, so that
the temperature of the air, at the level of the floor, and among
the roots and lower portions of the plants, may be as little dif-
ferent as possible from what it is in the higher regions of the
house; by regarding which, the house will be much easier kept
during summer, with respect to air and moisture, and, during
winter, with respect to a more equal diffusion of heat.

In the comparatively still atmosphere of a hot-house, when all
is closely shut up in a cold winter's night, the difference betwixt
the temperature of the atmosphere at the surface of the floor
and the highest part of the roof will generally be in the ratio
of one degree to every two feet of elevation ; thus, in a house
20 feet high there will be a difference of 10°, and in a house 60
feet high the same rule gives a difference of no less than 30 de-
grees. This ratio, however, is not absolutely correct, as we
have proved by experiment, in houses of various sizes, which
give, under certain circumstances, a greater diflference of tem-
perature than here stated, as will be shown when we come to
treat on this branch of horticultural science.^

We have already said enough on this point, here, to show the
advantage of erecting low-roofed conservatories, especially when

* See Ventilation.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES. 83

the object is to grow the plants in beds, or masses, irregularly
placed on the level of the floor, which is decidedly an improve-
ment upon the old method, of having a few long-legged and
branchless specimens sticking their heads up to the glass, where
their leaves and flowers are far above the common axis of vision,
and where nothing is seen below but the monotonous bed, and
the bare seems of the plants that are growing in it, compelling
the gardener, at all hazard of propriety, and in violation of
every principle of taste, as well as of his own judgment, to stick
in the commonest plants, whatever they are, among the bare
stems of the others, to fill up the unsightly blanks and vacancies
thus occasioned in the beds.

While on this subject, we will just briefly remark, that nothing
has so much tended to improve the culture of the trees and
shrubs, generally grown in houses of glass, as the improvement
that has taken place in the mode of construction. All practical
men are agreed on the point, that, to grow plants well, the
house must be low in the roof, and light as well as air must be
admitted freely to every part of the plant, from the ground to
the glass. They must also be situated in such a way, regarding
their lower parts, that the light may not be obstructed, for how-
ever powerful, and perhaps sometimes injurious, the fierce
rays of the mid-day sun may be in mid-summer, yet its perma-
nent obstruction is far more so. It is easier to obviate scorching
in the one case, than etiolation in the other.

SECTION IV.

INTERIOR ARRANGEMENTS.

1. Arrangements for the interior of forcing-houses, culinary-
houses, &c., are generally very much alike, consisting chiefly
of trellises of wood, or of wire, to w^hich the trees are trained.
The other portions of interior detail are common to horticultural
structures of every description, and will be subsequently de-
scribed in their respective places.

"Half the advantages," says Loudon, (Ency. of Gard.,) "of
culture, in forcing-houses, would be lost without the use of trel-
lises. On these the branches are readily spread out to the sun,
of whose influence every branch, and every twig, and every leaf,
partake alike ; whereas, were they left to grow as standards, un-
less the house were glass on all sides, only the extremities of
the shoots w^ould enjoy sufficient light. The advantages, in
respect of air, water, pruning, and other parts of culture, are
equally in favor of trellises, independently, altogether, of the
influence which proper training has upon fruit-trees, as the vine,
the peach, apricot, &c., to produce fruitfulness."

Notwithstanding the obvious utility of trellises in culinarj^
houses, the use of them is frequently carried to a most unprofit-
able and injurious extent, when the whole interior of the house
is filled with foliage from the glass to the floor. Here, work is
entailed upon the gardener to no purpose ; and though good
crops may be borne on the trees that are trained upon the trel-
lises crossing the house, or on the back wall, the fruit is utterly
worthless. f

The trellis, situated on the back wall, was formerly considered
the principal part of the house, for producing a crop ; but this
is only the case in small, narrow houses, and where no trees
are trained upon the rafters, or under the glass. Experience
has proved that, where the wl'.ole surface of the glass ' overed

INTERIOR ARRANGEMENTS.

tvith foliage, there is very little gained by training either peaches
Dr vines on the back wall.

The principal use to which back-wall trellises may be profita-
bly turned, is for the cultivation of figs, which are found to do
much better than peaches under the shade of others.

The trellis, whatever its form, should be as near to the glass

as possible, and placed so as to command the full influence of

the light entering the house. When the vines are trained upon

the single rafter trellis. Fig. 28, A, leaving the middle of the

lights open, for the free admission of light to plants beneath, then

the curvilinear trellis may be introduced into the centre of the

house, as represented at a. Fig. 29, from which good peaches

and nectarines may be obtained, providing the sashes be kept

open in the middle, as already stated, for the admission of the

unobstructed light.

Fig. 28.
A. B. C.

The most common method of fixing the roof trellis is by studs,
Fig. 28, B, screwed into the rafter, about eight inches distant.
Each stud is provided with an eye, or hole, at the extremity,
through which the wire is passed, and tightened at both ends
by screws and nuts. The studs should not be less than twelve
inches in length, so as to afford room for the foliage to expand
irself fully, without coming in contact with the glass, which,
when moistened with the condensed vapor, is apt to scald the
leaves that happen to be touching it. The vvires forming the
trellis are stretched horizontally from both ends of the roof, at
dbout nine inches distant.

Instead of studs screwed into the rafter, the horizontal wires
may be fixed, and kept in their places, by rods of iron, having
holes for the wires passing through, at regular distances. These

L\TERIOR AREANGEMEN'.S.

rods are attached by a loop and staple to the front wall at the
lower end, and to the back wall at the upper. This method is
preferable to having the studs screwed into the rafter, as they
can be easily removed, or the whole tegument of trellis may,
if desired, be taken down and put up again without much
trouble. This is of great importance on occasions of cleaning
and painting the sashes, etc. Fig. 28, C, shows the perforated rod
which is here referred to, the looped end being fixed in common
staples.

When provision is made for a middle trellis, this should
always have a cur^^ilinear shape, as in a, Fig. 29. This form

Fig. 29.

affords not only the largest training surface, but presents a
larger surface to the light, than any other form that can be
adopted, and, what is of more importance in regard to small
houses, it occupies less room in proportion to its training surface
than any other trellis with which we are acquainted.

Cross-trellises, or horizontal upright trellises in the middle of
the house, not only destroy the effect within, but are worse than
useless. Where the house is of sufficient size to admit of a
middle trellis, and a sufficiency of roof-surface to afford the cen-
tre of the sashes to be kept clear of foliage, we should prefer
having a sloping trellis on the back wall, and the centre bed
occupied with dwarf standards, planted either in a straight or
zig-zag line along the border, which, under good management,
will be as fruitful as if trained on a trellis, while their appear-
ance would be pleasing and handsome. Fig. 29 will convey a
better idea of our method than by description. Fig. 30 shows
the same system carried out in a double-roofed house.

Trellises are now made generally of wire, as being cheaper

INTERIOR ARRANGExMENTS.

Fig. 30.

Fig. 31.

and lighter than wood. Wire is in every way fitter for tne
purpose than wood, especially for roof trellising-. The distance
at which the wires should be placed apart depends upon the
kind of trees to be trained to them. For grapes, the distance
should be 12 or 14 inches ; and for peaches, nectarines, and
small-wooded trees, not more than 8 inches. The distance of
the wires of the roof trellis from the glass should not be less
than one foot for grapes, and for peaches and other similar trees
not less than ten inches. In properly constructed houses, there
should always be a lower trellis, with the wires placed at double
the distance of the others, for training the summer shoots to, to
prevent the crowding of the vine branches when the trees are
full of fruit, in order that there may not be a confusion of fruit
and foliage. Vines, or, indeed, any other kind of fruit trees,
should never be nailed to the wood of the house ; but, in all
cases, trained at some distance from it, however little room there
may be for that purpose.

2. The interior of the green-house is generally provided with
a stage in the centre, and shelves round the sides on which the
8^

88 INTERIOR ARRANGEMENTS.

plants are arranged ; and this is the principal object which
demands our attention. In single-roofed houses, the stage gen
erally rises towards the back wall ; but in span-roofed houses,
which are surrounded by a path, the stage or platform rises
from both sides, and meets in the middle of the house.

It is a principle with some people to place the stage on the
same angle as the roof, i. e., each shelf rising at an equal dis-
tance from the plane of the rafters. This, however, is a bad
rule, and, in cases where the roof is very steep, Avill make a
wretched receptacle for green-house plants. No general rules
can be laid down for the erection of the stage, as this will very
much depend upon the form and size of the house. We might
add, however, that the angle of the stage ought never to exceed
the angle of the roof, but, if practicable, should be rather flatter
than otherwise, to admit of larger plants being placed on the
upper shelves, which serve to give the house a larger and more
effective appearance from the inside view.

Green-houses intended for the growth of a promiscuous col-
lection of plants, some of which may reach a considerable
height, should have but few shelves on the platform, say three
or four rises are quite sufficient, leaving the upper shelves, at
least, twice the width of the others. This applies, also, to sin-
gle-roofed houses. Many commit an error in making their
stages not only too steep, but the shelves too narrow and too
high, individually. The shelves of a green-house for displaying
plants ought not to be less than one foot in width, this width
increasing towards the top shelf, and not more than eight or
nine inches in height from each other.

Houses appropriated to the growth of small plants, as nurse-
rymen's stock-houses, propagating, etc., may be staged much
closer than this. These remarks chiefly apply to the green-
houses of private individuals, and houses for the exhibition and
arrangement of a general collection of plants.

3. Conservatories, orangeries, and houses for the growth
of the palm family, have pits, or more properly beds, in which
plants are planted out. These beds are sometimes level with
the floor, and sometimes raised above it, being enclosed by a

INTERIOR ARRANGEMENTS. 89

curb. The principles of culture in these houses being some-
what different from the common green-house, it is necessary
that they be arranged to suit the plants grown in them.

The general form of conservatory beds is exactly that of the
structure. If the house be a parallelogram, the bed has the
same form, some+imes divided in the middle by a path, and
sometimes surrounded by a path on both sides. These structures,
when properly built and managed, are undoubtedly the means
of conferring on lovers of gardening and flowers, enjoyment of
the highest and purest character. When a fine conservatory of
this kind is attached to the mansion house, or connected with it
by a glazed arcade, it forms one of the most delightful prome-
nades in winter that wealth and taste can command.

There is undoubtedly much yet to be done in the way of
improving the interior of ornamental conservatories, not only as
regards their adaptability to plant culture, but also their general
effect. We seldom see anything else than the same flat, formal
bed or border, which is either rectangular, round, or square,
according as the form of the building may determine by its
walls. Even the refinement or elegancies of construction of
architecture fail to invest such buildings with any character
of distinctness or novelty, owing to the sameness or monotony
which forms the basis of the design. As far as relates to the
exterior, a considerable improvement is taking place from the
use of curvilinear roofs, and lighter and more elegant workman-
ship, and also resulting from the adoption of double-roofed
houses, instead of the dark, dull, narrow, clumsy shed-like erec-
tions which formerly used to be erected, and the various forms
of elevation, which are now so generally arranged as to produce
a very pleasing and picturesque effect.

A recent and very general improvement in the construction
of green-houses, consists in making the stages and shelves of
slate, or thin plates of stone ; this practice is now common about
London. These slates are frequently grooved or hollowed out
so that the water is retained under the pots, and thus dripping
is prevented, and evaporation is provided for in dry weather.
This may be considered as a real improvement, which is proved
by the readiness with which this practice was adopted by prac-

90. INTERIOR ARRA^'GEMENTS.

tical gardeners and nurserymen, and, from the cool nature of
that material, deserves to be more extensively followed in orna-
mental green-houses in this countr}^

The irregular method of laying out the interior of conservato-
ries, which promises to subvert the formal and monotonous
arrangements of the old school, is one of the greatest steps
towards a higher and more natural taste of artificial gardening
than any other that has taken place in this department of the
art for the last fifty years, inasmuch as it can be carried out
with equal advantage on a large, as well as on a small, scale;
and where this method is applied to a large structure, i. e.,
a structure covering a large area of ground, it necessarily leads
to the adoption of interior arrangements, as far surpassing the
old method in beauty and effect as it does in respect to econ-
omy, convenience, and comfort.

When we visit a conservatory lately erected, and see it to be
a perfect fac simile of others that had been erected a century
before, there is positively nothing to strike us with admiration,
except, perhaps, the character of its architecture. When we
see, in the costly erection before us, the exact image of conser-
vatories everywhere else, the object loses one half of the charms
of novelty and interest. It is, in fact, in the endless variety and
intrinsic beauty of which they easily admit, that their chief
fascination rests. This is the case with all other objects of art,
with private mansions, for instance. How monotonous and tire-
some would a country or suburb be, were every mansion and
dwelling an exact copy of the other ! And why should it be so
with erections for the growth of plants ? Why should these,
which are, to a certain extent, invested with the charm of rarity,
be deprived of the charm of variety ? Why should there not
be groves, and lakes, and irregular flower beds, and rocks, and
aquariums, and caverns, and jets, and waterfalls within as well
as without? In the former case, their beauties would be avail-
able, either for recreation, admiration, or study, at all seasons ;
in the latter, the fickleness and vicissitudes of our climate fre-
quently prevent the enjoyment of either.

The finest illustration of this system with which we are
Rcquaintcd, is in the beautiful conservatory of the Ro

INTERIOR ARRANGEMENTS. .91

Botanic Society's Garden, in the Eegent's Park, by Mr. Mar-
nock, and which is, perhaps, one of the best adapted structures
for the growth of plants in England, and is decidedly superior
to the many monster plant-houses lately erected in that country.
We have compared this structure with the large houses at
Chatsworth, Kew, Sion House, and other places, and, whether
in respect to convenience and comfort, general appearance or
adaptability, we consider it in every way preferable to any other
structure of the kind we have seen. This splendid winter-
garden — for its great size justly entitles it to this name —
contains collections of different degrees of hardiness, and em-
braces climates suitable to each. Its walks are gravelled, like a
flower-garden, winding through, amongst the various groups of
plants; sometimes overhung with the pendulous branches of
flowering plants of great size and beauty, and sometimes wind-
ing beneath arches and arbors of climbers in wild profusion.
Here you climb over rocks, covered with characteristic plants,
and there you descend into the humid recesses of orchids and
aquatics. This house has not the domed and lofty character of
siome other structures of the kind, which is at once a prominent
feature and a prominent fault in their construction ; it consists
of several spans, supported on light iron columns, the centre one
being somewhat higher than the others ; and, though having
little pretensions to what is generally called architectural dis-
play, yet its commanding position and its magnitude strike the
observer with a feeling of admiration, which is only surpassed
by its internal arrangements.

The general system of building conservatories in a recess
of the mansion is entirely subversive of this method of internal
arrangement, because of their total inadaptability for this pur-
pose. It must not be supposed, however, that there is any abso-
lute reason for detaching the conservatory from the mansion, if
it be otherwise desired ; but it ought to be there as a positive
part of the building, not a tributary attachm.ent to fill up a cor-
ner. That these kinds of structures for plants are being rapidly
improved, is evident, and this, indeed, must be the case, since
the improvement here spoken of springs from necessity. The
attachment of a green-house to a mansion appears to us in a'

1)2 INTERIOR ARRANGEMENTS.

questionable taste, as placing the conservatory in the middle of
the kitchen garden, or in the orchard ; and if any kind of hor
ticultural structure is to be attached to the mansion, it ought
by all means, to be a conservatory.

As an illustration that conservatories may form prominent
portions of a mansion, or even a whole wing of it, without
destroying its architectural character, we might point to a design,
in the December number of the "Horticulturist" for 1S49, by A. J.
Downing, Esq., of Newburgh, which is introduced to show how
a simple structure of this kind ought to be treated so as to give
the whole an architectural and harmonious character, and show-
ing, also, how this may be accomplished without rendering the
conservatory opaque on either side, except the one end by which
it is attached to the house, — a circumstance which will be
indispensable in conservatories attached to houses, unless they
be joined by means of a veranda, which gives them somewhat
of an isolated character. This house which we have referred
to is the kind of conservatory which we like, being satisfied,
from experience, that, unless they be constructed somewhat
after this method, they can never give the proprietors that satis-
faction which they have a right to expect ; and we trust Mr.
Downing will go on with creations of this kind, till these trans-
parent conservatories become more general than they are at
present.

Although it is not necessary, on account of perfect adapta-
bility, to place conservatories apart from dwelling-houses, yet
we generally find that structures, standing detached from the
mansion, are better suited for the growth of plants : first, because
there is less temptation to introduce massive workmanship, on
purpose to harmonize with the house ; and, secondly, there is,
in most instances, more facility of making the house to satisfy
the requirements of vegetation, and, consequently, less likelihood
of departing from the principles of erection which science and
practice have determined as essential to the successful cultiva-
tion of plants.

In many instances, it is absolutely impossible to comply with
these principles, whatever interior arrangements may be adopted.
Where the conservatory is a mere lean-to, s tuck-in attachment,

LNTF.RTOR ARRANGEMENTS. 93

compliance with the principle of plant-culture, or with the
methoQ of interior arrangement which we have here recom^
mended, is equally impossible. In the latter case, the greatet
portion of the plant-house must necessarily be formed by the
walls of the building, and the shadow of its elevated parts will
be thrown upon the plant-house for at least one half the day.
This is nearly as injurious as if the portions thus shaded
were opaque. The only way of obviating the evils consequent
upon its position, is to give every possible inch of light to the
one, to enable it to counterbalance the shade which it must bear
from the other.

When plants are planted in beds in the conservatory, they
require to be large specimens, otherwise ' they have a meagre
appearance, and must be a great distance from the roof, and
this is one of the greatest difficulties the gardener has to contend
with. It must be borne in mind that fine specimens do not
consist in plants that reach from the bed to the glass, with naked
stems, and only a few branches at the top, which is invariably
the result of lofty roofs and dark walls.

We have already shown, in the preceding section, the conse-
quence of high-roofed houses, and the difficulty of managing
them in a manner fitted for the successful cultivation of plants;
and if high-domed or right-lined roofs be improper in houses
wherq the plants are elevated on shelves and stages, they are
much more so w^here the plants are set in the beds without pots,
as the distance from the light renders it impossible for them to
grow bushy and branching below. These, when included within
the common-place curb of a square, or a parallelogram, or an
oval, or circle, which are little better, (except when sparingly
introduced, and only where they are described by the natural
curves of the contiguous figures,) invariably produce an effect
so common-place and uninteresting, as to fail in exciting the
faintest emotions of pleasure, or novelty, or interest, in one out
of a hundred individuals of taste and judgment.

94 INTERIOR ARRANGEMENTS.

REFERENCE TO FIG. 32.

A, A, A, A, A, A, Beds in which the plants are set out and

arranged according to their methods of growth, habits,
height, &c.

B, Water Tank, with jet in the centre. This tank is surround-

ed by rock-work and characteristic plants.

C, C, Seats on each side of the jet, commanding, also, views of

the surrounding grounds.

i), D, D, D, Conduit for the hot-water pipes, for warming the
structure. This . open conduit passes along the wall the
whole length and breadth of the house, and is covered with
grating, which serves as a path for watering, and conduct-
ing the necessary operations connected with the culture of
the plants.

£, E, E, an open Balcony, passing all round the house, and
surrounded by a balustrade. This balcony forms a contin-
uation of the porch on the one side, and runs out upon the
ground-level on the other. From this balcony are seen
the garden, the lakes, the hot-house, and the ornamental
grounds. The chief purpose of this balcony, however, is
to maintain the ground-level of the floor, and to make the
conservatory in harmony with the mansion, without de-
stroying its adaptability as a first-rate plant-house, of that
class intended for growing large specimens, planted out in
the ground.

F, Steps, leading from the balcony into the pleasure-grounds.

G, Door opening from the drawing-room.

if. Rock-work for alpine plants, surrounding the aquarium and

jet.
For end view of this house, see Frontispiece.

INTEEIOR ARRANGEMENTS.

Fig. 32.

'^yx^j^yyjyi^jCt'X>co'A/y^

€>

96 INTERIOR ARRANGEMENTS.

(^mseivatories are, probably, the most important structures
used in ornamental gardening; and, as we have already said in
regard to other kinds of horticultural buildings, we say, also, of
them, that no degree of gardening ability, and practical attention
on the part of the gardener, will compensate for the want of light
and air; and, where the arrangements for the working of the
house, in regard to air, heat, &;c., are imperfect, the risk is great,
and it is painful for a skilful and zealous gardener to contem-
plate the consequences which he may be unable to prevent.
One single night may destroy the labors of years past, and for-
bid hope for years to come ; and, after all, the blame may be
laid where it is least merited, and censure withheld from the
party who most deserved it.

In all buildings, and especially conservatories, the most com-
plete and elegant design, when badly executed, is disagreeable
to the view, defective in the object of its erection, and ruinous to
the proprietor, because it is incapable of giving that satisfaction
and pleasure which he was entitled to expect from his outlay.

Fig. 32 is the ground plan of a conservatory, which we have
designed, for erection at a gentleman's country-seat. It is in-
tended to form a prominent wing of the mansion. The structure
is entered at one end by a door, leading from the principal
apartments of the house. The conservatory is traversed by
curved walks, laid with marble, and bordered by a curb, on each
side, of the same material. In the centre is a basin of water,
with a jet playing over a rockery, as seen in the cut. Fig. 32.
In this design we have endeavored to combine perfect adapta-
bility, with beauty in the structure, and harmony in the whole.

This method of laying out the interior of a conservatory
admits of the most perfect arrangement in the planting of the
beds and compartments, intended for the exotic trees and shrubs,
with which the structure is to be filled. The w^alks wind
through, among the plants, as in a common shrubbery, or flower-
garden ; and, when the compartments are tastefully arranged,
and the whole kept in healthiness and luxuriance, with climbing
plants hanging in festoons from the rafters and other supporters
of the roof, it forms decidedly the most delightful and satisfac-
tory kind of horticultural structure that can be erected for com
fort, convenience, and enjoyment.

INTERIOR ARRANGEMENTS. 97

We do not think that any definite rule can be laid down for
the laying out of the area of a conservatory, as the formation of
the beds and walks may be dictated by the taste of the proprietor,
or those in whom he confides the management of the work.
Almost any curve may be adopted in the walks, without destroy-
ing the efTect of the interior view. What we condemn is the
monotonous straight lines by which the area is generally laid
out. It must be observed, however, that this method is entirely
inapplicable, unless the house be glazed on at least three sides,
and the roof so constructed as to admit the greatest possible
quantity of light in proportion to the extent of the area enclosed.
The roof should, also, be as low as is consistent with exterior
effect, and the admission of plants of good size ; for, as we have
already observed, one of the prevailing errors in the construction
of conservatories adjoining mansions consists in their being
made too lofty and too opaque. They are designed generally to
suit the place of the building, without regard to the effect of the
conservatory itself, as a structure, or as a plant-house.

There are many other advantages, resulting from houses of
this description, which, in a practical point of view, are deserv-
ing of consideration. Not the least of these is the facility with
which plants can be arranged to produce the best possible effect.
Plants are much easier arranged within curved lines, than in
squares or parallelograms ; and the curvatures of the beds are
always more spirited and pleasing than continuous straight
lines, whatever the house may be filled with, or however badly
the plants may be disposed.

We have only room to notice one feature more in the con-
struction of this conservatory, viz., the form of the roof. We
have chosen the spans of different sizes, in preference to one
single span, as much for adaptability as to harmonize with the
architecture of the mansion. This system tends to prevent the
accumulation of warm air at the top of the house, and hence
the heat is distributed more equally among the plants. For the
same reason, ventilators are provided at the top of each span, so
that the external air admitted, as well as the artificial heat ris-
ing upwards, will be more equally distributed over the house.^

* For further notice of this, see Ventilation.

98 INTERIOR ARRANGEMENTS.

An end view of this structure is shown in the frontispiece. As
the ground, in this case, descends gradually from the base of the
mansion, a considerable depth of parapet wall is necessary to
bring the floor of the conservatory to the desired level, and the
requisite distance from the roof. Curved roofs can only be
adopted where the building admits them without jarring dis-
cordantly with the general architecture, and, in some instances,
straight-lined roofs will be preferable ; but in all cases where
curvilinear roofs can be made to harmonize with the building,
they are decidedly to be preferred, on account of the superior
beauty of curved lines viewed in contrast with the surrounding
scenery, and also on account of the superior beauty of the struc-
ture from within, in harmony with curved figures of the walks
and borders of a house, such as that we have here described.

SECTION V. ■:.ai7qi.3qoi-v

:•;, ,T":'- ■■■■ I

MATERIALS OF C 0 N S T R U C T I p N,..,i ., , , ... ,,;,.-^

1. W(yfk7nanship. — However excellent and adaptable may-
be the design of a horticultural erection, if the work be badly
executed the structure will generally be defective in the work-
ing, and the trouble of management will be greatly increased.'
Bad foundations, bad roofs, bad-fitting sashes, rendering them
difficult to open and shut, bad glazing, and bad workmanship of
every description, are too common to exist without being a very
perceptible evil, and one that is much complained of by practical
gardeners, upon whom the consequences of this method of coil-'
struction generally fall. In all regular work, coming under the'
province of the architect or engineer, there is generally particu--^
lar attention directed to the facility of working, and ingenuity'
is exerted to its utmost limits to perfect and simplify those
facilities, however temporarily the structure or work may be
constructed. But horticultural buildings, relatively to civil
architecture, appear to be dn anomalous class of structures, not
coming strictly within the province of 'the architect, — except
in so far as they may be related to the house in an architectural
point of view, — and hence they are more the subject of chance
or caprice in design, ' an'd of local convenience in execution,
than any other department' of rural architecture. The subject
of horticultural architecture has not been deemed of sufficient
importance to induce civil architects to make themselves "aci^
quainted with the' ' principles on which plant-houses should be*
constructed, or to consider the nature of workmanship in relation
to its work ; arid, consequently, the construction of horticultural
buildings is either.,left,; wholly, to- gardeners, who understand
little of the science of architecture, or whoUy^to architects, who-,
understand as little of the science of horticulturei.^^j.;Tiae consewi
quence, in either case, is generally incongruity itt kppearancO'/J
9^

100 MATERIALS OF CO^'STRUCTION.

want of success in the useful results, and want of permanency
in the structure itself. In every country, no doubt, such cases
are numerous, but here, they are more numerous probably than
in any other, arising, no doubt, from that want of attention to
the details of horticultural architecture, and to the still unde-
veloped principles of science, upon which it is based.

The temporary and inferior character of the workmanship
generally bestowed on horticultural erections is a source of great
loss to those erecting such buildings, and demands the serious
attention of all who contemplate the construction of them. The
remarks, which have l^een applied by a popular writer on farm-
ing in regard to farm-buildings, are still more applicable to build-
ings for the purposes of horticulture."^ Buildings, manifestly
intended to be permanent, are put up to stand for a year or two,
when it becomes absolutely necessary to their continuation, to
spend a sum upon them equal to one ^hird the cost of their
original erection, which acts as a drawback upon the progress
of horticulture in this country, as many suppose that this early
additional expenditure is merely the consequence which the com-
mon tear and wear of time entails upon all such structures ; and
hence they are considered too expensive to keep in order, even
though willing to go to the cost of original construction. Now
experience has taught us that structures, substantially con-
structed at the first, and of good materials, will stand for at least
twenty years without any additional outlay, save a few coats of
paint during that period, which increases their durability, the
oftener it is applied.

We have been induced to dwell longer on the subject of
workmanship, from the numerous examples which have come
under our own observation, and from the trouble and annoyance
to which we are almost daily subjected on this account. In
small erections, the inconveniences arising from bad workman-

* Few things serve better to distinguish the habits, and even the
characters, of the progeny from the parent stock, — the Americans from
their English ancestors, — than ihe more perfect and durable character
of all their mechanical works, macliinery, and buildings. Th( re, things
are made to endure ; here, they are made to answer the purpoies cf the
day. — {Ed. Farmer's Library.']

MATERIALS OF CONSTRUCTION. 101

ship may be little experienced ; but where the structures are
large and extensive, the results become of the deepest impor-
tance, in an economical point of view.

It is not easy to point out a course wherein these difficulties
may be avoided, or to discover, at all times, to whom blame is
attributable. Tradesmen, who take the work by contract, prob-
ably endeavor to do the best they can with the job they have
taken in hand, and it is generally their policy to get over it as
easily and as quickly as possible. Gardeners who may have
the superintendence of the work, probably do the best they can,
but from their wanting the necessary knowledge of the details
of construction, are unable to exercise that surveillance which is
necessary to the proper execution of the work.

2. Materials of the Frame of the Buildhig, ^-c. — The most
suitable material for the frames of horticultural buildings has
lately been made the subject of considerable discussion and ex-
periment, which has not been without its use in the elucidation
of facts hitherto unknown, or, at least, unnoticed in general
practice. The case of wood versus iron has been investigated
on various grounds, by practical and scientific men, without,
however, coming to a unanimous decision on the superiority of
either. In this matter, as in some others like itself, some have
adopted extreme views of the various merits and defects of the
different materials, and have come to their conclusions by refer-
ence to some single or specific property. These views and con-
clusions, however, have been of considerable utility in bringing
the subject before the bar of unbiased inquiry, which, if it has
not already done so, is likely to result in the adoption of modi-
fied views, and the recognition of specific principles, that, when
fully considered and duly weighed against each other, will ulti-
mately lead to a more definite result.

The use of iron in the construction of hot-houses, like every
other really valuable improvement, has met with much opposi-
tion from the still slumbering spirit of prejudice, which is gener-
ally slow to believe in the superiority of anything different from
that with which it has been long acquainted, even when this
superiority cannot, on reasonable grounds, be denied. This

102 MATERIALS OF CONSTRUCTION.

spirit, however, which has long held undisputed sovereignty
over the minds of gardeners, is fast giving way before the sweep-
ing current of mechanical inventions ; and when science comes
to the aid of mechanism in the building of hot-houses, as in the
erection of factories, steam-engines, and other works of art, then
the flimsy barriers reared by prejudice will be swept away, and
I think I may fearlessly assert that, in regard to the opposition
that has been given to the erection of iron hot-houses, this has
nearly taken place.

Gardeners, from the early ages of Abercrombie and Nicol,
have been prejudiced against metallic hot-houses, and, to our
knowledge, this prejudice is still entertained by some whose
learning and intelligence would encourage us to look for more
accurate judgment.

The objections which have been raised against metallic houses
for horticultural purposes, are chiefly the following : —

Contraction and expansion, oxydation, abduction of heat, at-
traction of electricity, and original cost.

In regard to the first, and principal cause of opposition, viz.,
its susceptibility to the influences of heat and cold, a fact which
cannot be denied, yet it is proved by experience that if a house
be properly constructed of good material, this susceptibility is
of no practical importance. In very small houses the incon-
venience occasioned by sudden fluctuations of temperature may
be more sensibly felt, although, in the management of small iron
vineries, in England, we have never seen the slightest incon-
venience result from external changes ; indeed, all our expe-
rience in the management of hot-houses goes to prove the
superiority of iron over wood, for every purpose to which timber
is generally applied. It has been stated that metallic roofs are
more liable to break the glass than wood ; practice has also
proved that this statement is without foundation, and if it has
ever taken place, can only be in copper or compound metallic
roofs. Cast-iron or solid wrousfht-iron bars have never been
known to cause breakage of glass, or displacement of joints, and
some have asserted that the breakajre of <r\ass is even more
during sudden changes, by wood than by iron roofs.

The expansibility of copper being greater than that of iron.

MATERIALS OF CONSTRUCTION. 103

in the proportion of 95 to 60, therefore copper is above one third
more likely to break glass than iron. But when it is considered
that a rod of copper expands only x^uVtrir P^^^ of its length with
every degree of heat, and that iron only expands y^uVs^-B" P^rt,
the practical effects of even the hottest portion of our climate
on these metals can never amount to a sum equal to the expan-
sion required for the breakage of glass.

The second objection which we have mentioned is also unde-
niable. All metals are liable to rust; but painting easily rids us
of this objection, at least it will so far prevent it as to form
hardly any objection.

The power of metals to conduct heat is an objection which,
like the others, cannot be denied, but m.ay be partially obviated.
The abduction of heat, like the expansibility of metallic roofs,
is very little felt in using them ; the smaller the bars, the less
their power of conduction. The paint, also, and the putty used
to retain the glass, obviate this objection. Heat may be supplied
by art, but light, the grand advantage gained by metallic bars,
cannot, by any human means, be supplied but by transparency
of roof.

The objection raised on the ground of attraction of electricity,
is easily answered. If metallic hot-houses and conservatories
attract electricity, they also conduct it to the ground, so that it
can do them no harm. What is corroborative of this position
is the fact, that no instance has come under our knowledge of
iron hot-houses having been injured by the electric fluid.

The objection regarding the expense of iron hot-houses, has
been sufficiently refuted in England, and we have observed,
with pleasure, a refutation of the same objection, by an enter-
prising gentleman of Cincinnati, who has lately erected an iron-
roofed vinery. Mr. Resorr has given a cut, and description of
this house, in the " Horticulturist " for Sept. 1849, p. 117. This
is the only substantial account we have seen of the comparative
cost of iron and wood roofs. This gentleman, who is in the
foundery business, has every opportunity of knowing the accu-
rate cost of such a house, and plainly states, " that those wish-
ing to build a good, substantial house, can do it, and make the
roof of iron, as cheaply as of \yood, the other parts costing th»

104 IVIATERIALS OF CONSTRUCTION

same." From inquiries and calculations which we have made
we have come to the same conclusion, although, from a want
of the requisite knowledge, and from the expense of having
patterns made for the castings, it may, in some localities, cost
more than a structure of wood.

In small houses, sudden changes of the external temperature
are much sooner and more sensibly felt than in large structures,
whether they are constructed of wood or iron, which arises from
the fact that the smaller volume of air confined within becomes
more rapidly heated, and hence the change is the sooner felt.
Supposing the circumstance to be more strikingly sensible in the
case of small iron houses, — then all that is necessary to coun-
terbalance it, is just a little more attention to ventilation, during
sudden changes of external temperature.

For large structures iron is incomparably superior to wood,
and even for forcing-houses we would decidedl}?- prefer the same
material. The contraction and expansion of metallic hot-houses
may be dreaded in the Southern States, if built on a very small
scale, and badly managed ; but in structures of moderate size,
this evil will be found practically of little importance, unless
they are badly constructed, and negligently managed.

The finest horticultural structures that have yet been erected
m Europe are made of iron, and no houses of any importance
are now being erected of wood, which proves its superiority over
the latter material. The great conservatory, or Palm-house,
at Kew, is wholly of iron, constructed under the auspices of the
most scientific men in England. The Botanic Society's conser-
vatory, in the Regent's Park, (already spoken of,) is made of
iron. The fine plant-houses in the Glasnevin Botanic Garden,
near Dublin, are constructed of iron, and the quite unequalled
range of forcing-houses at Frogmore, in Windsor Park, are also
of iron. In fact, the most extensive horticultural erections in
Europe are made of iron, and many others, now in course of
erection, are being made of the same material.

Admitting that properly constructed iron houses would cost,
at the outset, somewhat more than wooden ones, their lightness
and elegance render them much superior in point of appearance
and, when their durability is taken into consideration, they y/ill

MATERIALS OF CONSTRUCTION. 105

undoubtedly, be found cheaper in the end. But the cost of con-
struction will vary, according as the details are understood by
the constructors ; for if Mr. Resorr can make a vinery of iron as
cheaply as of wood, then other tradesmen, when they have prop-
erly understood the nature of the work, will surely be able to
do the same. The Palm-house at Kew was constructed by a
tradesman from Dublin, while some of the most extensive hot-
house builders in England lived within the sound of their ham-
mers, and the material and workmen were all brought across the
channel, costing nearly as much as if brought to America ; yet
the workmanship was superior, and the cost said to be less, —
proving that practice and knowledge of the details lessen the
original cost of construction.*

* As instances of comparatively easy transportability of iron hot-
houses, we might mention, that the whole of the materials of the
immense structure at Kew were manufactured and fitted together at
Dublin, and transported from thence to London. The unequalled range
of forcing-houses at Windsor, one thousand feet in length, was made at
Birmingham, and fitted together in the works, before they were trans-
ported to their final destination. Now it would have been just as easy,
and perhaps little more expensive, to have shipped them to New York,
or Boston, or Philadelphia, or Baltimore. When this is done in England,
how long will American enterprise be behind them ? We prophesy, not
long.

SECTION VI.

GLASS.

1. Experiments which have hitherto been made, in regard to
the physical properties of glass as a transparent medium, have
been conducted, generall}'', on purely chemical principles, and
mostly without reference to observed facts, as regards the growth
of plants, excepting, perhaps, those of the most common and
obvious character. Partly for this reason, and partly from care-
less negligence, hot-houses have long been, and still continue
to be, glazed with material of a very inferior description. If
any one doubts this, let him look at some of the finest hot-
houses in the country, and he will easily perceive the truth of
this statement ; the sickly and scorched appearance of the
plants under its influence, being far more painful than agreeable
to the eye of any one who takes an interest in the vegetable
kingdom. This evil, alone, renders the very best cultivation of
no avail.

The most elaborate and practically useful investigations that
have yet been made, in this department, are those lately under-
taken, with the view of securing the very best material that
science and art could produce, for the glazing of the great Palm-
house at Kew. We cannot do better than present our readers
with the following extract from Mr. Hunt's report to the com-
mittee, which we take from Silliman's Journal of Science and
Art, vol. iv., p. 431.

" It has been found that plants growing in stove-houses, often
suffer from the scorching influence of the solar rays, and great
expense is frequently incurred, in fixing blinds, to cut off this
destructive calorific influence. From the enormous size of the
new Palm-house, at Kew, it would be almost impracticable to
adopt any system of shades that would be effective, this building
being 363 feet in length, 100 feet wide, and 63 feet high. It

GLASS. 107

was, therefore, thought desirable to ascertain if it would be pos-
sible to cut off these scorching ra^^s by the use of a tinted glass,
which should not be objectionable in its appearance, and the ques-
tion was, at the recommendation of Sir William Hooker and
Dr. Lindley, submitted, by the commissioners of woods, &c., to
Mr. Hunt. The object was to select a glass which should not
permit those heat rays, which are most active in scorching the
leaves of plants, to permeate it. By a series of experiments, made
with the colored juices of the palms themselves, it was ascer-
tained that the rays which destroyed their color belonged to a
class situated at the end of the prismatic spectrum, which ex-
hibited the utmost calorific power, and just beyond the limits of
the visible red ray. A great number of specimens of glass, vari-
ously manufactured, were submitted to examination, and it war.
at length ascertained, that glass tinted green appeared most likely
to effect the object desired, most readily. Some of the green
glasses that were examined, obstructed nearly all the heat rays ;
but this was not desired, and, from their dark color, these were
objectionable, as stopping the passage of a considerable quantity
of light, which was essential to the healthy growth of the plants.
Many specimens were manufactured purposely for the experi-
ments, by Messrs. Chance, of Birmingham, according to given
directions ; and it is mainly due to the interest taken by these
gentlemen, that the desideratum has been arrived at.

" Every sample of glass was submitted to three distinct sets of
experiments.

'* First. — To ascertain, by measuring off the colored rays of
the spectrum, its transparency to luminous influence.

" Second. — To ascertain the amount of obstruction offered to
the passage of the chemical rays.

" Third, — To measure the amount of heat radiation which
permeated each specimen.

" The chemical changes were tried upon chloride of silver, and
on papers, stained with the green coloring matter of the leaves
of the palms themselves. The calorific influence was ascer-
tained by a method employed by Sir John Herschel, in his ex-
periments on solar radiation. Tissue paper was smoked on one
side by holding it over a smoky flame, and then, whilo t!:e
10

108 GLASS.

spectrum was thrown upon it, the other surface was washed
with strong sulphuric ether. By the evaporation of the ether,
the points of calorific action were most easily obtained, as these
dried off in well defined circles, long before the other parts pre-
sented any appearance of dryness. By these means it is not
difficult, with ease, to ascertain exactly the conditions of the
glass, as to its transparency to light, heat, and chemical agency,
(actinism.)

" The glass thus chosen is of a very pale yellow green color,
the color being given by oxide of copper, and is so transparent
that scarcely any light is intercepted. In examining the spec-
tral rays through it, it is found that the yellow is slightly dimin-
ished in intensity, and that the extent of the red ray is diminished
in a small degree, the lower edge of the ordinary red- ray being
cut off by it. It does not appear to act in any way upon the
chemical principle, as spectral impressions, obtained upon chlo-
ride of silver, are the same in extent and character as those
procured by the action of the rays which have passed ordinary
white glass. This glass has, however, a very remarkable action
upon the non-luminous heat rays, the least refrangible calo-
rific rays. It prevents the permeation of all that class of heat
rays which exists below, and in the point fixed by Sir William
Herschel, Sir H. Englefield, and Sir J. Herschel, as the point
of maximum calorific action, and it is to this class of rays that
the scorching influence is due. There is every reason to con-
clude that the use of this glass will be effectual in preserving
the plants, and at the same time that it is unobjectionable in point
of color, and transparent to that principle which is necessary for
the development of those parts of the plant which depend upon
external chemical excitation, it is only partially so to the heat
rays, and it is opaque to those only that are injurious. The
absence of the oxide of manganese, commonly employed in all
sheet glass, is insisted on, it having been found that glass, into
the composition of which manganese enters, will, after exposure
for some time to intense sun-light, assume a pink hue, and any
tint of this character would completely destroy the peculiar
properties for which this glass is chosen. Melloni, in his in-
vestigations on radiant heat, discovered that a peculiar green

GLASS, 109

glass manufactured in Italy, obstructed nearly all the calorific
rays. We may, therefore, conclude that the glass chosen is of
a similar character to that employed by the Italian philosopher.
The tint of color is not very different from that of the old crown
glass, and many practical men state, that they find their plants
flourish better under this kind of glass, than under the white
sheet glass, which is now so commonly employed."

We understand the glass employed in the Kew Palm-house
has fully answered the intended purpose, viz., of obstructing the
most injurious portion of the heat rays; and we have learned,
also, that it has answered all expectations as to its influence on
the health of the plants, although its perfect utility, in this
respect, has been doubted by some practical men. We think,
however, that an absolute decision on its merits, in this respect,
is rather premature, as we should prefer seeing the plants attain
a greater size, so as to fill the structure more completely, and
their foliage reach nearer to the glass, before pronouncing defi-
nitely upon the calorific effects of the latter.

As to the appearance of this glass, it is altogether a matter
of taste, which we consider ourselves having no right to ques-
tion ; and, upon the whole, we think it in this respect unob-
jectionable. When viewed obliquely, from a distance, it is
slightly green, but when viewed from within, and at ri2:ht
angles to its surface, it is clear and nearly white. This kind
of glass is highly worthy of the attention of glass-makers and
horticulturists in this country, and we have no doubt, when its
qualities have been fairly tested and made known, it will be
extensively employed in horticultural buildings.

No kind of economy is more sure to defeat its end than
using cheap glass in horticultural structures. Many suppose,
if a house is merely covered with glass and made transparent,
that all is well. We know this to be a common opinion ; yet
we are fully prepared to prove its falsity, not by mere assertion,
but by indubitable facts, — facts so clear that the most ignorant
in these matters will be convinced, from his own observation,
and on a scale so extensive, as to justify the conclusions that
have been drawn from them.

We know of nothing -onnerted with the erection of horticul-

110 GLASS.

tural buildi igs so vexatious as having the roof glazed with
bad glass ; plants of almost every kind are certain to suffer
under it. Knotted and wavy glass is the worst of all, as the
knots and waves form lenses, and concentrate the sun's rays
upon the plants, and that part on which the concentrated ray
falls is sure to be burnt. It cannot for one moment be doubted
that the glass used in the majority of horticultural buildings is
not only inferior, but is of the very worst description ; and, on a
recent examination of one hundred houses, we found scarcely
one free from the defects here spoken of. Indeed, we are fully
aware of the difficulty of procuring really good glass, at reasona-
ble prices, for glazing hot-houses. But there cannot be a doubt
that the money saved is money lost; and if the vexation and
annoyance subsequently incurred by the use of inferior glass, be
taken into consideration, few persons of sound judgment will
hesitate in paying an increased price.

No doubt many of our readers will suppose that we are
unnecessarily particular on this point, but our experience has
taught us a severe lesson, and one, too, which no doubt has
been strongly impressed upon the mind of every gardener, of
lengthened experience in these matters. Against such an evil
there is but one resource, — and a bad one it is, — which is
shading, either by means of cloth blinds, or by painting, the
worst method of the two ; but the one or the other is absolutely
necessary. The first is troublesome, the other is unsightly;
and, to be done right, both are expensive. We have a large
house now under our management, on which the glass is so bad
as to render its opacity absolutely necessary to prevent burning,
even when the sun's rays have lost their meridian power.

In very small houses bad glass may be used with less chance
of injury, as they may be easily shaded with blinds during the
noonday sun ; but in very large structures this is only accom-
plished at very great expense ; and in curvilinear houses, and
houses with irregular roofs, covering them with blinds is almost
impossible. Painting the glass, then, is the only resource,
unless glass be used which does not require it.

Little has been said on the effects of glass used in hot-houses,
by writers on practical horticulture. Although facts are obvious

GLASS. Ill

atid familiar in regard to it, yet the evils seem to be passed over
as results which cannot be prevented. We can at this moment
point to houses standing side by side, in one of which it is
impossible to grow, and keep in health, any species of vegeta-
tion whatever, — no matter how hardy the tissue of the foliage
may be, — without shading the glass almost to opacity ; while, in
the other, plants with tender and delicate foliage stand compar-
atively uninjured. The cause is obvious : the glass with which
the one is glazed is full of waves and blotches, and altogether
of the worst description ; while that of the other, though not the
best, is yet of better quality. The poorer glass burns vegetation,
even when the incidental ano-le, between the impinging ray and
a perpendicular to the roof, is as much as 45°.

From what has been already said reofardino- the influence of
the different solar rays on vegetation, and, more especicUy, the
experiments made with regard to the Palm-house at Kew Gar-
dens, by which it has been found possible to manufacture glass
which is opaque to the scorching rays, without at the same time
obstructing the light, heat, and chemical rays which are essen-
tial to the development of plants, there can be no doabt that
the scorching of vegetation in hot-houses, which has long been
a serious drawback in exotic horticulture, can be prevented.
And when more extended experiments have been made, a good
material for glazing can undoubtedly be manufactured at a price
that will insure its universal adoption in horticultural structures.
It is to be earnestly desired that some of our enterprising manu-
facturers,— a class so remarkable for their fertility of invention,
— will take up the matter seriously, and supply us vvith the
material which exotic horticulture so much requires.

2. Glazing. — Common sash-glazing is generally performed
with a lap of from one to three fourths of an inch, and, by many,
with a full inch lap. This is a most objectionable method, as
the broader the lap the greater the quantity of water retained
in it by capillary attraction, and, consequently, the greater the
breakage of the glass , for when the internal temperature falls,
and this water becomes frozen, the glass is certain to crack in
the direction of the bars. The lap should never be broader than
10^

112 GLASS.

a quarter of an inch, but where the panes or pieces of glass are
not above five inches wide, one eighth of an inch is sufficient.
Half an inch in roof-sashes, unless they are placed at an angle
of not less than 45°, is almost sure to produce breakage, except-
ing the temperature within be kept sufficiently high to prevent
the water retained between the panes from freezing.

Broad laps are objectionable, also, on other accounts ; for the
broader the lap the sooner it fills with earthy matter, forming
an opaque space, and these spaces are so numerous as to have
a very considerable effect upon the transparency of the roof,
which is injurious by excluding the light, and is also unsightly
in appearance. It may be puttied, but its opacity is the same,
and its appearance no better than if filled with dirt. Where
the lap is not more than one fourth of an inch, it may be puttied
without any very disagreeable effect, but if the glass be per-
fectly smooth in the edges, puttying is useless, and the glass is
better without it.

The most approved practice as to the laps, whether in roofs
or common sashes, is, to make the breadth of the lap equal to
the thickness of the glass, leaving it entirely without putty.
But it is extremely difficult to get glaziers to attend to this, and
it Qan only be obtained by employing good workmen, and keep-
ing strict supervision over the work. This is not only the most
elegant of all modes of glazing, but the safest for the glass,
which, as we have observed, is seldom broken by any other nat-
ural means but the expansion of frozen water retained between
the laps. This mode is also by far the easiest to repair, and is
more durable than any method of filling the laps with putty, or
with lead.

There are various other modes of glazing, as the lead and
copper-lap methods, which, however, are so very objectionable
as to be unworthy of occupying space in our description. The
methods of shield glazing are equally objectionable, and little
used. Curvilinear glazing has been used somewhat extensively
and is, in the opinion of some men of undoubted skill, superior
to the other methods already spoken of.

Curvilinear lap-glazing appears preferable to the square mode,
for various reasons, one of which is, that the curve has a ten-

GLASS. 1 13

dency tc conduct the water to the centre of the pane, which is
let out by a small opening at the apex of it. If the lap is broad,
however, the water is accumulated by attraction precisely in the
point where it is calculated to do most injury, — acting, in fact,
as a power on the end of two levers of the second kind. But
when the lap is not more than one sixteenth of an inch in width,
no evil of this sort can happen.

It ought to be borne in mind that puttying, or otherwise fill-
ing up the laps, is in no case necessary if care be taken of the
glazing, and smooth glass be used, and if the lap never exceeds
one fourth, nor falls short one sixteenth, of an inch. However
careful the laps may be puttied, in a very few years the putty
begins to decay by absorption of moisture, and, when evapora-
tion is great within, it becomes saturated with water, which
readily freezes in frosty nights, (unless the temperature of the
house is adequate to prevent it,) and breakage of glass is inevi-
table.

Reversed curvilinear glazing consists in making the lower
edges of the panes to curve inwards, in a concave form, instead
of curving outwards, in the common way. The effect of this
method is the throwing of the condensed moisture down upon
the bars, and thus conveying it off at the bottom of the roof,
which prevents the moisture from being retained in globules,
and dropping down upon the plants. This method is nothing
more than reversing the position of the panes in common cur\'i-
linear glazing, and is, according to our opinion, preferable to it.

These are the most common and approved modes of glazing,
although some others have been used that have not proved
worthy of general adoption. Ridge-and-furrow roofs may be
glazed in the same way. The size of the panes used makes no
difference, — large ones only tending to reduce the opaque sur-
face. Anomalous surfaces may be glazed with panes according
to the figures of the bars.

3. Color of Walls. — The color usually applied to hot-houses
is white. As affording the finest contrast with the plants m the
interior, and the vegetation around the outside of the house, the
general taste is manifestly in favor of this color; and, as it ia

114 CLASS.

the best reflector of light, it is, also, on that account, preferable
to any other. There are some considerations, however, in favor
of a dark color, which, as has been already stated, absorbs a
larger quantity of heat, and parts with it again on the cooling
of the atmosphere. A yellow color we consider the most objec-
tionable of all, both on account of its contrasting badly with the
glass of the house and the verdure of vegetation, as well as the
effects produced by it on the light, which, as will be seen from
the preceding investigations, exercises an injurious influence on
vegetation. The influence may not be so great in the reflected
light, as when permeating yellow or orange-colored media, but
the power is, nevertheless, exercised to some extent. The same
investigations show the beneficial influence of a blue, or dark
color, which perfectly accords with our observations on plants
growing against dark bodies, otherwise exposed to abundance
of lio-ht ; and, when it is in accordance with the taste of the
proprietor, we think the interior walls of hot-houses should be
of a dark color.

In England, where the rays of light are less powerful than
here, dark-colored walls are now very common. There, light is
a more important consideration than heat : the latter can be
applied by artificial means ; — not so the former. This probably
tends to prevent the adoption of a dark color for the interior of
their hot-houses. Here, dark walls are more desirable than
white, as they absorb the heat-rays, during a powerful sun, and
prevent the atmosphere from becoming so rapidly hot. This
fact is sensibly felt on standing before walls of the diflferent
colors during the mid-day sun. By a white wall, the rays are
reflected from the wall back into the air, or on any other body
which is near it, by which the temperature of the air and the
body is very much increased. A dark-colored wall, on the con-
trary, retains the heat which falls on its surface ; and though it
miiy feel colder, it contains more latent heat, which it only parts
with when it is abstracted by the reduced temperature of the
atmosphere. This, alone, is a good argument in favor of dark-
colored walls in lean-to hot-houses.

The inner side of the rafters, astragals, and sash-bars, should
approach to the color of the glass. As the light-rays do not

GLASS.

115

fall on them, nothing is gained by making them dark, and it
gives the house a heavy and gloomy effect. The structure is,
or should be, transparent. The impression on the mind is
that of a house covered with glass ; and, as the rafters and
astragals are only there as supports to the glass, they should be
deprived, as much as possible, of their opaque character. When
they are painted a dark color, the reverse effect is produced. A
glaring white color is, also, objectionable ; it is hurtful to the
eye, and generally displeasing to a refined taste : some of the
different shades of cream, or light stone color, will be more
effective and pleasing. The same may be said in regard to the
external portions of the roof. It may, by way of contrast, be a
shade or two darker than the interior; but a decidedly dark
color should be avoided. We have seen various plant-houses
painted dark, and even dark red, but have seen very few who
admired them. We do not wish to incur censure by finding
fault with the taste of those who may fancy these colors, and
admit that every one has an undoubted right to gratify his
own taste. We give our opinions for the benefit of those who
may choose to adopt them.

It is a good plan to give the wood-work of the structure a
coat of some anti-corrosive paint before the color is put on. The
timber is preserved much longer ; and the house requires less
painting, as the timber is hardened, and more impervious to
moisture. For numerous preservative solutions, see Table
XVIII, Appendix.

SECTION VII.

FORMATION OF GARDENS.

.. Form of the Garden. — The form of the garden must be
determined by two conditions : first, the natural disposition of
the ground chosen for its site ; and, secondly, by the aspect and
position of the walls and hot-houses. If there are no hot-houses
or walls, the form of the garden will be regulated mainly by the
first cojidition. In most kitchen or culinary gardens, of any
importance, if no walls are erected, wooden palings are generally
substituted for them, which also regulate the disposition of the
ground. The site having been fixed upon, with due regard to
the considerations necessary in choosing the site for horticultu-
ral structures, (see Sect. I,) these considerations being in both
cases equally applicable, the next thing to be done is the dispo-
sition and formation of the walks, which also define the size
and shape of the borders and principal compartments of the
garden.

2. Walks. — The principal walks from the house to the
garden should be somewhat broader than the garden walks, and
should, if possible, enter the garden at the south side. This is
more especially desirable if there be hot-houses on the south
side. In either case, however, it is desirable, as a more favor-
able impression is produced on the mind of the spectator than if
entering at either side. The north side is the very worst for
the principal entrance, as the necessary offices connected with
the garden, — the mould-heaps, rubbish-piles, manure, &c., —
are generally located in that quarter; besides, the impression,
produced by the best trained trees on the walls or fences, and
the general view of the ground, is lost. Next to the south, the
east or west sides should be chosen.

There are various methods of forming walks, according to the

FORMATION OF GARDENS. 117

character of the soil and sub-soil, and the kind of material at
hand to form a surface. Where the ground is naturally wet, or
w}}ere there is a liability of the accumulation of water, the soil
should be taken out to the depth of at least twenty inches, —
the section formed by the excavation forming an obtuse angle
towards the centre, or forming the segment of a circle. These
excavations should lead into drains, at the lowest points, to carry
off the water that percolates through among the stones with
which they are filled. They may be filled to within two inches
of the intended surface of the walk, — the largest in the bottom,
and the smaller toward the surface. This forms a durable and
drv walk at all seasons; and, where the soil contains a consid-
erable quantity of stones, which have been thrown out in the
process of trenching, or the rubbish of building-materials, this
affords a good medium of getting them out of the way.

On dry, gravelly ground, however, these excavations are use-
less, so far as drainage is concerned; and, shovelling aside the
mere surface-soil, the walk may be laid dow^n on the substratum
beneath it. If the walks are on a level, or nearly so, the water
generally finds its way off as quickly as it falls, and the cost of
excavation is saved.

The surface of walks may be formed of grass, gravel, or sand.
Good gravel is the best, sand the very worst, and grass can only
be introduced with propriety in particular places. Sand, or
loose gravel, makes a very uncomfortable walk, and, when of
great length, is tiresome and disagreeable to walk upon.

A very common error, among those not acquainted with the
proper method of making walks, is, to lay on too much surface-
material; and, in many places, we have seen trenches taken
out for walks, and filled, to the depth of a foot or more, with
gravel, which, if laid on a hard surface to the depth of an inch
or less, v/ould have made a good w'alk, but which, at such a
depth, all the walking, rolling, and pressing of years could never
make it bind. It requires more skill than is generally supposed
to make good walks. Among all the operations of the garden-
maker there is scarcely one which we are so much disposed to
find fault with, as in the making of walks ; and this is precisely

118 FOKMATION OF GARDENS.

our reason for adverting to a matter which is apparently irrele-
vant to the general character of the present work.

The durability and comfort of walks consist chiefly in their
power of resisting the action of the feet in walking on them, at
all seasons of the year. Soft gravel walks, that yield no resist-
ance to the motion of the body, are obviously unfit for being in
a place where frequent walking is resorted to. Sand, also,
makes a pretty walk to look at, bat should never be employed
where a good hard walk is required, unless it naturally pos-
sesses the property of binding.

It is quite possible, however, to have a hard solid walk, capa-
ble of resisting the action of the feet, and yet appear to have a
gravelly or sandy surface, which is frequently admired. This
is effected by preparing the lower strata of open material, then
a substratum of binding material, and lastly, a thin layer of
whatever material is wished for the surface, which should be
sifted before being laid on. It is then well watered, if dry;
then rolled well in, which has the effect of mixing it with the
binding stratum beneath, and leaving a smooth surface, that
becomes harder the longer it is used. In making up the sub-
strata, it is necessary to tread each layer firmly as it is made
up, so that no hollows or inequalities may occur on its subsida-
tion, and subsequent use.

It must be remembered that the material of which the surface
of a walk is composed, will not bind by any mechanical means,
unless it contains something of a binding nature within itself.
Clean gravel will not bind by any degree of mechanical pres-
sure, unless it contains something to induce a general compact-
ness and solidity over the whole surface.

The best material which we have met with in this country,
and which is no doubt abundant in many places, is a land of
soft decomposing sandstone rock, containing a large quantity of
oxide of iron. It must be laid down where it is finally to
remain, when newly taken out of the pit, then subjected to a
good shower of rain, or watered, and afterwards rolled or well
trodden with the feet; it makes a solid walk, nearly as compact
as the rock itself. It may be objectionable on account of its

FORMATION OF GARDENS. 119

color, but this is easily changed by a thin layer of any other
material on its surface, which partly mixes and binds with it.

Broken, or what is sometimes called rotten rock, containing'
oxide of iron, is to be preferred to gravel for making a surface,
and pit gravel is to be preferred to river or sea gravel, as it con-
tains generally more oxide and earthy matter. Clay forms a
good under-surface, and when thinly covered with small gravel
and well rolled, forms a most excellent and durable walk.
Common gravel may also be mixed Avith coal ashes and lime
rubbish, which tends to bind it, and also with common garden
soil ; but this is a last resource. Grave] mixed with earth, and
more especially vegetable earths, has a great tendency to pro-
duce weeds, and is therefore very troublesome to keep clean.
It also readily absorbs moisture and becomes soft in wet weather,
and especially during, winter frosts.

Where expense is not spared, a composition may be made,
consisting of small shell gravel, or pounded granite, about one
tenth part of brick-dust, and cement, mixed together. This, laid
down upon a firm, prepared surface, in a wet state, and well
rolled, will form a surface as hard as marble.

The form of the surface should be nearly fiat ; grass walks
should be completely so ; gravel walks may rise slightly towards
the middle, but not so much as to afiect the convenience of as
many persons walking abreast as the breadrfi of the walk will
admit. A walk six or eight feet wide should not fall more than
an inch towards each side, this being sufficient to throw the
water that falls on it towards each side, without being any
inconvenience to pedestrians occupying its whole breadth.

If the walk be edged with turf, the crown of the walk should,
when finished, be on a level with the turf at each side, one inch
being quite enough for depth of edging ; besides, the walk gen-
erally subsides, while the verges become higher, for which an
allowance must be made. The same rule applies to walks
edged with box, which are most suitable in a kitchen garden.

3. Borders and Interior Compartme7its. — The width of the

borders and size of the compartments must be regulated by the

height of the wall or fence, and the extent of the garden. The
11

120 FORMATION OF GARDENS.

best general rule that can be laid down is to nake the breadth
of the borders equal to the height of the wall or boundary fence,
whatever it may be ; they may be made broader, but not nar-
rower, for then they produce a bad effect ; a narrow bordei
beside a high fence is very displeasing to the eye.

The size and number of the compartments are determined by
the number and disposition of the walks. It is decidedly a bad
plan to have too maTiy walks, as the ground is not only taken
up with them, which require a deal of labor to keep them clean,
but the effect of the garden is lessened. If less than two acres
be enclosed, a walk running parallel with the boundary, say
twelve feet distant from it, and another intersecting the garden
in the middle, running south and north, will be sufficient; if
more than two acres be enclosed, another intersecting walk, run-
ning east and west, may be introduced. If the garden be
worked by horse labor, the larger the compartments the better;
if wrought entirely by manual labor, these compartments may
be sub-divided for the crops, by rows of fruit-trees, or fruit-
bushes, as may be required. It should be observed, that to
have a few walks, and those of good width, gives the garden a
better appearance, and is in every way preferable to having a
large number of contracted ones, and it leaves the compartments
to be sub-divided by alleys or other means, as may be most con-
venient for access to the crops.

In many gardens, trellises or espalier rails are adopted. The
proper place for an espalier rail trellis is on the inside of the
principal walks, leaving a border of at least six feet. Many
gardeners condemn them, and perhaps justly, in small gardens,
as it confines the ground too much ; but in large gardens, espa-
liers, if well managed, are both useful and ornamental. The
railing should be plain and neat, not more than five or six feet
high, with the upright rails, to which the trees are tied, about
eight inches apart.

It is not our purpose, at present, to dwell on the laying out
of gardens. We have merely adverted to the subject, in so far
as it is connected with the object of this treatise.

FORMATION OF GARDENS. 121

Walls. — As garden walls may be regarded as horticultural
structures, we will here make a few remarks upon them.

In Europe, walls are built around gardens of all kinds,
whether the enclosed space be one or twenty acres. Their
chief use is for training the more tender kinds of fruit-trees
upon their southern aspect. The enclosed space is generally
appropriated to the growth of culinary vegetables, and contain-
ing also the hot-houses, which occupy a part of their south
aspect. These gardens are of various forms, and we have seen
them circular, oval, square, and oblong. The latter shape, with
the angular corners cut off, is undoubtedly the most desirable
shape for a vegetable garden. The oval and polygonal forms
are preferred by some, on account of their affording a more equal
distribution of sun and shade. But we are at a loss to find out
how this can be the case, as, however a wall may be placed,
it can only obtain a certain amount of direct sunshine during
the day, and the inconvenience resulting from the adoption of
these forms is very considerable, both in the management and
culture of the interior compartments, and in the training of the
trees. Moreover, an equal distribution of sunshine is not so
desirable as may appear; as, while the warmest portion of the
wall may be appropriated to the more delicate and early fruits,
the coldest, or northern portion, may be as profitably appropri-
ated to late sorts, or for retarding earlier kinds, both of which
purposes are as useful as an early aspect.

In this country, walls have been little employed in the forma-
tion of gardens, and only in a few places have they been
adopted, as at the fine gardens of Mr. Gushing, at Watertown,
and Col. Perkins, at Brookline, in the vicinity of Boston, — two
of the finest gardens in this country. Some other places have
also portions of walls surrounding the garden, but we have seen
none where any principles of design have been adopted and car-
ried out so much as at the former place."^

* In Hovey's Magazine of Horticulture, pp. 50 — 53, vol. xvi., we
have described the beautiful gardens at this place, from a visit which
we gave them at that time. We have subsequently visited them, as
well as many other places, and still consider them the finest gardens we
have seen in America. They are made precisely in the style of moderu

Ii2 FORMATION OF GARDENS.

In nearly all gardens, trellises and wood fences are employed
instead of walls, as enclosures to the garden ground; and these
are well adapted for the purpose, as the fruits which require
the protection of walls in England thrive and produce their
fruit in greater perfection as open standards here. The utility
of walls, however, around a garden, cannot be doubted, even in
this country, especially as regards the protection they afford to
trees trained on them, in early spring. Walls may be consid-
ered as useful to plants trained on them, or near to them, in
three ways: — first, by the mechanical shelter they afford
against cold winds; secondly, by giving out the heat they had
acquired during the day; and, thirdly, by preventing the loss of
heat which the trees would sustain by radiation. [See Experi-
ments by Dr. Wells, in the third part of this work, Section VI.
Protection of Flant-houses during Night.]

The same arguments which have been applied in favor of
the best aspect for hot-houses, [see Section I.,] are equally appli-
cable to walls. In the middle and southern states, we should
think walls having a due southern aspect decidedly objectiona-
ble, and, for tender and delicate kinds of fruit-trees, would decid-
edly prefer either a south-eastern or a south-western aspect.

The height of walls, or fences of any kind, round a garden,
should always correspond to the space inclosed. Twelve feet
may be taken as a maximum height. In England, low walls
Droduce a greater effect in accelerating fruit than high ones ;

English gardens, surrounded with fine walls, with the principal range
of hot-houses, about 300 feet in length, on the southern aspect of the
wall on the north side of the garden, and a smaller range on the inside
of the east and west walls, all lean-to houses. There are convenient
back-sheds and other offices on the north side of the hot-houses. There
is no wall on the south side of this garden, which we think is very
appropriately dispensed with. We regard this as a general rule, and
more especially in gardens of small size, as it gives the enclosed spaces
a less meagre and confined appearance. This garden, alone, of any
which we have seen in this country, bears an impress of the style and
genius cf Loudon. And though we have some faults to find with the
surrounding grounds, nevertheless, we believe, taking it all in all, it is
the most perfect specimen of molern European gardening in this coun-
try.

FORMATION OF GARDENS. 123

but in this country the great radiation of heat from the earth,
during the heat of summer, would render low walls of little use.
On the other hand, high walls have always a gloomy efTect, and,
where it is necessary to have high walls round a garden, it is
better to relieve the monotony of the wall by making it of differ-
ent heights.

Hot, or flued, walls are very common in European gardens,
and have been used upwards of a century; and, in our opinion,
where walls can be of any importance in this country, in the
practice of horticulture, it must be chiefly as fined walls. In
summer, the protection of a wall is not required to ripen the
common fruits, and in hot summers they are frequently injuri-
ous, by the attraction and radiation of heat during the midday
sun, by which the leaves are sometimes scorched. It must be
as protectors of peach and apricot blossoms in spring, and accel-
erating the ripening of grapes in autumn, in which they can be
most serviceable to the horticulturist ; and for these purposes hot
walls are of great benefit. [See Wall Heating, Part II., Sec. V.]

Flued walls can be built as cheap, if not cheaper, than solid
ones, and are invariably built of brick; indeed, a considerable
saving of material is effected, as little more than half of the
bricks required to build a solid wall will build a hollow or flued
wall ; and, unless a flued wall be desired, it is better to dispense
with a wall altogether, for although a wooden paling will not ab-
sorb so much heat as a brick wall, as a structure for mechanical
shelter it is in every way equal to it, providing it be boarded
perfectly close, and sufficiently high. The comparative cheap-
ness of wooden fences, for gardens, must give them the prefer-
ence, and the comparative beauty of brick walls and wood
palings is a matter of taste which must be decided by the pro-
prietor.

Walls, or close palings, must, in all cases, be faced with a
light trellis, made of laths or wire, to which the trees can be
trained. The injury resulting to trees nailed on walls, in oar
gardens, is owing to their touching the material of the wall.
The branches should be trained at least six or eight inches from
the surface, so as to admit a stratum of air between the wall
11^

124 FORMATION OF GARDEN'S.

and the branches. When this is attended to, no injury results
to the foliage, even in the hottest of seasons.

Boarded walls have long been used in northern countries, and
are frequently made to incline considerably ton'^ards the north,
so as to present a better angle to the sun's rays than if standing
upright ; an expedient which here is unnecessary.

We cannot help thinking that flued walls are worthy of more
attention from horticulturists than they seem to have had, espe-
cially when early fruit is desired, without the trouble and expense
of a glazed structure, as an expedient for a hot-house. [See cut
50, in the next part of this work, page 245.]

PAllT II. HEATING.

SECTION I.

PRINCIPLES OF COMBUSTION.

1. To warm hot-houses, etc., most economically and efficiently,
we must study not only the principles of heating, but, also,
the principles of combustion. And as we are yet far from
having obtained a complete knowledge of the most profitable
manner of submitting coal and other kinds of fuel to the process
of combustion, or, of applying the caloric so obtained to increase
the temperature of hot-houses, it will, therefore, be desirable to
begin at the beginning of this part of our \vork, and before treat-
ing on the different mechanical contrivances in common use for
the generation and diffusion of heat by combustion, let us first
consider the principles upon which these ends are to be obtained.

The subject before us involves a consideration of the nature
and properties of the various kinds of fuel. It examines the
chemical action of their several constituents on each other. It
applies those inquiries to the class of chemical results which
may be useful, and avoids those which are injurious. It involves
also, in an especial degree, the closest observation on the sepa-
rate influences which each of the constituents of atmospheric
air exercises on combustible bodies, in the generation of those
extra ordinar}'' elements of nature, heat and light. ' And, finally,
it investigates the cause and character of flame and smoke, and
the influence these have on the former.

Economy of fuel being one of the most important points to be
sought for in a heating apparatus, we must inquire whether our
common furnaces be so constructed as to give us the maximum
quantity of caloric, for the fuel that is consumed. We, there*

^2(^ HEATING.

fore, must look into the furnace, and consider chemically as well
as practically, the operations vs^hich are there going on, so that
we may improve its arrangements, and adapt them so as to give
full practical effect to the several processes which constitute
combustion.

To enable our practical readers to obtain a more accurate
knowledge of the processes going on in the furnace, and of the
results of the common mode of managing the fires of extensive
forcing houses, we will enter more fully upon the constituents
of coal, and the gases thereby generated, which form such an
important part of the fuel itself, and which, by their escape into
the atmosphere from the chimney, or into the atmosphere of the
house from the flue, become the source of immense loss of heat.
And, in the latter case, the loss is more than doubled, as they
are destructive in the highest degree to every kind of vegetable
life.

In undertaking to show how these evils may be remedied, we
must not be understood to concur in the exploded opinion, that
these gases may be consumed by the methods hitherto used for
that purpose, viz., by passing the smoke over a body of red-hot
fuel at a distance from the burning and smoking mass. And
however desirable it may be to know of some way of preventing
smoke from being emitted in clouds from the chimney of hot-
houses, yet, if we can discover no other method of obviating the
evil, except " burning it," according to the common acceptation
of that word, I fear we must continue to put up with the loss
and annoyance as if is.

It is not our purpose here to show how the smoke from fuel
may be burned ; but rather, we will attempt to show how fuel
may be burned without smoke. And, let it be observed, this
distinction involves the main question of economy of fuel.

When smoke is once produced in a furnace or flue, we believe
it to be as difficult to burn it, (and convert it to heating pur-
poses,) as to burn and convert the smoke issuing from the flame
of a candle to the purposes of light. If, indeed, we could collect
the smoke and unconsunied gases of a furnace, and separate
them from the products of combustion which the flues carry ofT,
they might, subsequently, be made instrumental to the purposes

PRINCIPLES OF COMBUSTION. 127

of heat ; but, by the common method of constructing furnaces,
their collection is impossible.

When we see smoke issuing from the flame of an ill-adjusted
common lamp, the heat and light are diminished in quantity. Do
we attempt to burn that smoke ? No ; it would be impossible.
Again, when we see a well-adjusted lamp burn without pro-
ducing any smoke, the flame is clear and white. But here, the
lamp has not burned its smoke ; it has burned without smoke;
and it remains to be shown why the same methods may not be
employed with regard to common furnaces, whereby they may
burn without smoke, and thereby give out a greater quantity of
heat, as in the case of the commion and Argand lamp, since the
elements of combustion in both cases are the same.

2. In pointing out the leading characteristics in the use of
coals, it is unnecessary to enter into detail of the various pro-
cesses of gasefaction. We will, however, give this part of our
subject a little attention, as the greater portion of the practicable
economy in the use of coal, and the management of furnaces,
will be found more or less connected with the combustion of the
gases which arise from the combustion of fuel, and as the numer-
ous combinations of which they are susceptible embrace the
whole range of temperature, from that of flame down to the
refrigeratory point.

The subject of gaseous combinations, then, is undoubtedly an
important part of our inquir}\ And those who would study the
economy of fuel, and the obtaining from it the greatest quantity
of heat, cannot altogether dispense with the part of our subject
which at present lies before us. Though it may not appear
equally interesting and important to every one, it is, neverthe-
less, the alpha and omega of the whole process of combustion.
The gardener may say, what has this to do with gardening?
But we tell him, plainly, that this is an essential part of his
business, which will be generally admitted by intelligent men,
that so long as a furnace is connected with a hot-house, and
fuel consumed in that furnace, this must necessarily be a part
of his business.

On the application of heat to bituminous coal, the first result

128 HEATING.

is its absorption by the coal, and the consequent disengagement
of gas, from which all that subsequently bears the character of
flame is exclusively derivable. This gas, whether it be in a
close retort, or in a furnace, is associated with several other
substances, more or less tending to deteriorate its inflammable
properties and powers of giving out heat and light. In the
preparation of gas, or smoke, for illuminating purposes, these
impurities are separated, and the pure gas alone is used. As,
however, this separation cannot be effected in a common furnace,
and, as the entire gaseous products of the coal, good and
bad, are indiscriminately consumed together as they are gener-
ated, it is the more incumbent on us to be cautious, lest, by any
injudicious arrangement, we force these impurities into more
active energy, and thus increase their deleterious power.

We will not stop here to consider the nature of those impuri-
ties arising out of the unions of sulphur, and the other injurious
constituents of coal, although they exercise a mischievous in-
fluence on the calorific effect of the gas burning in the furnace,
but will consider those constituents alone, which unite in form-
ing the useful gases, and from which we are to derive heat.

These constituents are the hj^drogen and the carbon. And
the unions which alone concern us here, are, first, carhuretted
hydrogen ; and, second, hi-carburetted hydrogen, commonly
called olefiant gas. These two, and their unions with the air,
in the process of combustion, we will shortly examine.

Gases, as well as other bodies, endowed with the power of
giving out heat and light, have been called combustible. This
term has been a source of much error in practice, from a mis-
conception of its meaning, under the received impression that
combustibles possess, in some undefined manner, and within
themselves, the faculty of burning. And, though every person
knows that they will not burn u-'dhout air, still the part which
air acts in the process is but little inquired into. It is but lately
that the nature of this union of the gas with the air has come to
be fully understood; and, although the abstract question as re-
gards the immediate cause of that chemical action, which we
rail combustion, may continue to be disputed, and new theories
continue to be broached, still, for all practical purposes, it is
sufficient! v defined and understood.

PRINCIPLES OF COMBUSTION. 129

And here we are called on to inquire, with reference to the
gases under consideration, whether there are any peculiar
conditions which can influence the amount of heat to be ob-
tained from them ? and, if so, what they are ? This, again,
involves other questions in reference to air, and the part which
it has to act in the process ; and thus we find ourselves intro-
duced into the chemistry of combustion.

One advantage of receiving the subject in this light, is, that
we shall see how idle would be any calculations or arrangements
as to the dimensions or details of a furnace, before we had well
examined and understood the rationale of that process on which
these details must necessarily be contingent. For what chemist
would begin by deciding on the dimensions of his retort, or other
apparatus, before he had considered the particular purposes to
which they were to be applied ? Yet such is the every-day
practice of those who profess to instruct us in these matters.
The absurdity of this practice, and the dangers into which it
leads practical men, will be more apparent when we come to
consider the nature of heating apparatuses, and the powers and
properties which Belong to each.

Combustibility, then, is not a quality of the combustible taken
by itself. It is merely a faculty which may be brought into
action through the instrumentality of a corresponding faculty in
some other body. It is. In the case now before us, the union of
the combustible with oxygen, and which, for this reason, is
called the supporter. Neither of which, however, when taken
alone, can be consumed.

To effect combustion, then, we must have a combustible, and
a supporter of combustion. Strictly speaking, combustion
means union; but it means chemical union, — one of the ac-
companying incidents of this union being the emission of heat
and light. What the nature of heat is, or how it is liberated
during chemical action, it is not our province to consider ;
nor does it relate much to our present inquiry. Sufficient for our
present purpose, is the fact, that the chemical union of the com-
bustible, (the coal,) and the supporter of combustion, (the oxygen
of the air,) is the cause of heat being given off; and, further,

130 HEATING.

that exactly in the ratio that such union is complete, is the quan-
tity of heat increased.

But we have not the means of obtaining this necessary sup-
porter in sufficient quantity, in a separate state, except at an ex-
pense which would render it incompatible with the purposes of
a furnace. Our only alternative then is to apply to the atmos-
phere, of which it forms a part, in order to satisfy our wants.
Had we to purchase this oxygen, we would, necessarily, be more
economical of its use, and inquire more respecting its application.
But, finding an abundant supply at hand, in the atmosphere,
and obtaining it without expense, we are careless of its use, and
unconscious of its value, and take no note of the largq
quantity of the noxious ingredients with which it is accompanied,
or loss sustained, by diminishing the supply; and hence, many
of the evils, such as bad apparatus, bad fuel, and bad furnaces,
might be easily remedied, were the properties of these gases fully
understood.

The unions we have now to consider are those which take
place between the constituents of the coal and the atmospheric
air, namely, the hydrogen and carbon of the former, and the
oxygen of the latter. Dr. Ure calls the carbonaceous part of
coal, " the main heat-giving constituent." In this he must be
understood to include that portion of the carbon which forms
one of the constituents of the gases alluded to, and, although,
for the purposes of t\\e furTiace, so much value is set upon the
solid part — the coke — we must not, on that account, undervalue
the heat-giving properties of the gas. Indeed, the extent of
those powers is strikingly brought before us, by the fact, that for
every ton of bituminous coal no less than 10,000 cubic feet of
gas are obtained.

When we consider the immense heating powers of such a
mass of flame as would be produced by 10,000 feet of gas, we
cannot resist the conclusion, that there must be something es-
sentially wrong in the mode of bringing it into action within a
furnace^ as compared to its well known efficacy in an argand
burner. That this is the fact, will appear manifest as we pro-
ceed. And one of our objects is to show how greater heat may
be obtained by the combustion of the volatile products of the

PRINCIPLES OF COMBUSTION. 131

coal, than by allowing the whole body of gas to escape into the
atmosphere.

Let us bear in mind, that smoke is always the same, whethef
it may be generated in a common fire-place, in a furnace, or in a
retort ; and that, strictly speaking, it is not inflammable, as by
itself it can neither produce flame nor permit the continuance
of flame in other bodies, as is proved from the fact that a lighted
taper being introduced into a jar of coal gas, (or smoke,) is
instantly extinguished.

How, then, is it to be consumed or prevented, and rendered
available for the production of heat ? The answer is, solely by
effecting a chemical union, not with the air merely, as is the
dangerous notion, but with the oxygen of the air, — the '''■sup-
porter'^ of flame, the heat-giving constituent of the air, in given
quantities, and at a given temperature.

This at once opens the main question. What are these quan-
tities, and what is this temperature ? and, are there any other
conditions requisite for eflecting the chemical union of the
oxygen of the air with the inflammable gas, to the best
advantage ?

Effective combustion, for practical purposes, is, in truth, a
question more as regards the air- and the gas ; and the former,
as referable to our object, would appear better entitled to the
term combustible than the latter, inasmuch as the heat is in-
creased in proportion to the quantity of air we are enabled to
use advantageously. Besides that, we have no control over the
gas after having thrown the fuel on the furnace, but we can
exercise a control over the air, as we shall show, in all th(j
essentials of perfect combustion. It is this which has done so
much for the perfection of the lamp, and may be rendered
equally available for the furnace.

Now, although this control, and the management arising out
of it, influences the question of perfect or imperfect combustion,
and, therefore, affects that of economy, yet, strange to say, in an
age when chemical science is so advanced, and in a matter so
purely chemical, this is precisely what is attended to in practice.
The how, the when, and the where, this controlling influence
over the admission and the action of the air is to be exercised,
12

132 HEATING.

are points demanding the most attentive consideration from all
who are interested in these matters.

Much confusion at present prevails in all that regards hot-
house furnaces, as well in their practical working as regards the
adraission of air and the combustion of fuel. In commenting
briefly upon the constituents of coal smoke, or coal gas, car-
buretted hydrogen, and the quantity of air required for their
combustion, we will be as explicit as possible, without going
more into scientific detail than is consistent with the means and
opportunities of that class of practical men for whom we write.

3. The first step towards effecting the perfect combustion of any
combustible gas, is the ascertaining the quantity of oxygen with
which it will chemically combine, and the quantity of air re-
quired for supplying such quantity of oxygen. Here, then, we
are called on for strict chemical proofs — these several quantities
depending, not on the dictum of any chemist, but on. the faculty
which each particular gas possesses of combining with certain
definite proportions of the other — the supporter ; these respec-
tive proportions being termed " equivalents,'''' or combining vol-
umes. This doctrine of equivalents must, therefore, be under-
stood before we can be prepared to admit the necessity of any
precise quantities. This question, as to quantity, is also the
more important when we consider that the quantity of effective
heat obtained by the combustion of any body, will be in exact
relation to the quantity of oxygen with which it will chemically
combine.

Let us begin, then, by inquiring into the constitution of the
coal gas, and the relative proportions in which its constituent
elements are combined, as these necessarily govern the propor-
tions in which it will combine with the oxygen of the air.

Now, the doctrine of " equivalents," that all-convincing proof
of the truths of chemistry, being clearly defined and understood,
reduces, to a mere matter of calculation, that which would
otherwise be a complicated tissue of uncertainties. And let no
mechanic feel alarmed at this introduction to "elementary atoms"
and " chemical equivalents," or imagine it will demand a deeper
knowledge of chemistry than is compatible with his sources of

PRINCIPLES OF COMBUSTION. 133

information ; neither let him suppose he can dispense with the
knowledge of this branch of the subject, if he has anything to
do with the combustion of coal. Without it, he is at the mercy
of every speculative "smoke-burning" pretender; whereas,
with it, his mind will be at once opened to the simplicity and
efficiency — I may add, to the truth and beauty, of nature's
processes, as regard combustion.

There is not, indeed, a more curious or instructive part of the
inquiry than that respecting the conditions and proportions in
which the compound gases enter into union with the constituents
of the air; neither is there one more intimately connected with
the practical details of our furnaces. These introductory remarks
are, therefore, necessary for those who are not already familiar
with it. Indeed, without some information on this head, the
unions of the gases might appear capricious or uncertain;
whereas, in fact, they are regulated by the most exact laws, and
subject to the most unerring calculations.^^

* Mr. Parkes observes : — " We are unfurnished with any definite,
determinate experiments regarding the proportions in which air and fuel
Qnite during combustion. We are, practically speaking, altogether ig-
norant of the mutual relations which subsist between the combustible and
the supporter of combustion, (the fuel and the oxygen ;) and, though we
know that, without oxygen, we cannot elicit heat from coal, we have yet
to discover the most productive combinations of the two elements.

"Here, then, remains a wide field for research and experiment, wor-
thy, and, indeed, requiring the labors of a profound chemist."

These matters are now better understood, and those " most productive
combi?iatio)7s" rendered familiar and certain, by the labors of that "pro-
found chemist," John Dallon, who first drew the attention of the chemical
world to the subject of equivalent proportions, and taught us the impor-
tance and necessity of ascertaining those proportions — in fact, of
"reasoning by the aid of the balance.''^

Dalton's papers were first read before the Manchester Philosophical
Society, and published in their memoirs, in the year 1803. These vol-
umes are very scarce, and I have not been able, anywhere, to meet with
a complete copy of them. The Royal Institution, where Davy brought
his great discoveries to light, contains but the fiv^e volumes of the first
series. These volumes, or, at least, the papers of Dalton, should be re-
published, for the purpose of showing the correct chain of reasoning
by which the mind of that acute philosopher proceeded.

134 HEATING.

Much of the apparent complexity which exists on this head
arises from the disproportion between the relative volumes^ ol
bulk, of the constituent atoms of the several gases, as compared
with their respective iceights.

For instance, an atom of hydrogen (meaninof the smallest
ultimate division into which it is supposed to be resolvable) is
double the bulk of an atom of carbon vapor ; yet the latter is
six times the weight of the former.

Again, an atom of hydrogen is double the bulk of an atom of
oxygen ; yet the latter is eight times the weight of the former.

So of the constituents of atmospheric air, nitrogen and
oxygen. An atom of the former is double the bulk of an atom
of the latter ; yet, in weight, it is as fourteen to eight.

A further source of apparent complexity arises from the
faculty of condensation, or diminution of bulk, which, in certain
cases, attends the union of the gases. For example, one volume
of oxygen and two volumes of hydrogen, lohen united, condense
into a volume equal to that of the hydrogen alone, (the weight
being, of course, the sum of both ;) that is to say, one cubic
foot of oxygen chemically combined with two cubic feet of
hydrogen condense into the bulk of two cubic feet : and so on,
each union bearing its now ratio of volume and weio^ht. This
apparent complexity, however, we shall soon see give way to a
systematic consideration of the subject.

We have stated that there are two descriptions of hydro-carbon
gases, in the combustion of which we are concerned; both being
generated in the furnace, and even at the same time, namely,
the carburetted and bi-car buret ted hydrogen gases. For the
sake of simplifying the explanation, I will confine myself to the
first, as forming the largest proportion of the gas to be consumed,
namely, the carburetted hydrogen, or common coal gas, as I shall
call it for the sake of brevity.

Now as, during combustion, the atoms of this gas become
decomposed, and its constituents separated ; and as these will
be found to exercise separate influences during the process, it is
essential that we exnmine them as to their respective properties
weights, and volumes..

On analyzing this mixed gas we find it to consist of two vol-

PRINCIPLES OF COMBUSTION.

335

umes of hydrogen and one of carbon vapor; the gross bulk
of these three being condensed into the bulk of a single atom of
hydrogen ; that is, into two fifths of their previous bulk, as shown
in the annexed figures. Let figure A represent an atom of coal
gas — carburetted hydrogen — with its constituents, carbon and
hydrogen ; the space enclosed by the lines representing the rela-
tive size or volume of each ; and the numbers representing their
respective weights — hydrogen being taken as unity both for vol-
ume and weight."^

Carburetted Hydro ge7i. Bi-carburetted Hydrogen,

1 atom of

the above gas,

weight 8.

1 atom of
Hydrogen,
weight I.

its
constituents,

1 atom of
Hydrogen,
weight 1.

I atom of
Carbon, 6.

1 atom of

the above gas,

weight 14.

Its
constituents.

1 atom of

Hydrogen,

weight 1.

I atom of

Hydrogen,

weight 1. j

1 atom of '

Carbon, 6. \

1 atom of '

Carbon, 6. j

* '' Ce gaz (carburetted hydrogen) est compose de 75.17 parties (by
weight) de carbone, et 24.33 d'hydrogene ; ou, d'un volume de carbone
gazeiix et quatre volumes de gaz hydrogene, condenses a la moitie due
volume de ce dernier, ou, aux 2/5 du volume total du gaz, de maniere
que de cinq volumes simples, il n'en resulte pas plus de deux de la com-
binaison." — Berzelius, vol. i., p. 330.

12=^

136

HEATING.

Or they may be represented thus :
Carburetted Hydrogen.

its constituents,

Bi'Carburetted Hydrogen.

its constituents, [Carbo

Although not intending to take any further notice, in this
place, of the bi-carhiretted hydrogen, I have, however, annexed
the above diagrams, representing this gas and its constituents,
that both may be under view at the same time ; and by which it
will be seen, that although, in volume, the two gases are precisely
the same, there is yet double the quantity of carbon in the bi-car-
buretted that there is in the carburetted hydrogen : this circum-
stance is of great importance, and must be kept in our recollec-
tion, as these proportions will be found to have a considerable
influence during the subsequent process of its combustion. ^

* The mode of representing the volumes of gas, by rectangular figures,
as adopted by Mr. Brande and other chemists, is favorable, so far as
tingle atoms are concerned, inasmuch as the eye at once recognizes the

PRINCIPLES OF COMBUSTION.

137

1 would here observe on the importance of keeping in mind
this double relation of weight and volume^ and the atomic consti-
tution of these gases, as it will prevent much of that confusion
which too often embarrasses those who are not familiar with
the subject of gaseous combinations.

Let us now, in the same analytical manner, examine an atom
of atmospheric air, the other ingredient in combustion. .

Atmospheric air is composed of two atoms of nitrogen and one
atom of oxygen : and here again we find a great disproportion
between the relative volumes of these constituents ; one atom of
nitrogen being double the volume of an atom of oxygen, while
their relative weights are as 14 to 8 : the gross volume of the
nitrogen, in air, being thus four times that of the oxygen ; and
in weight, as 28 to 8, as shown in the aimexed figure.

Atmospheric Air, (or thus,) Atmospheric Air.

I atom of
Nitrogen,
weight 14.

1 atom of
Nitrogen,
weight 14.

1 atom of
Oxygen, 8.

1-^

o -J

B %

< «

V, %

i-H

Here we are relieved from the complexity arising out of any
difference in volume between these constituents, when united and
when separate. In the coal gas we found the constituents con-
densed into tioo fifths of their gross bulk when separate : this,
we see, is not the case with air ; an atom of which is the same,
both as to bulk and weight, as the sum of its constituents.

relation between volumes and half volumes. As, however, I shall have to
do with masses of these gases, I have adopted circular figures, the rela-
tion between the sizes of the volumes of the different gases being the
same.

138 HEATING.

Thus, we find, the oxygen — the heat-giving constituent of
the air — bears a proportion in volume to that of the nitrogen, as
1 to 5 ; there being, in fact, but 20 per cent, of oxygen in atmos
pheric air, and no less than 80 per cent, of nitrogen ; a circum
stance which should never be lost sight of in all that has to do
with its admission and application.

Having shown the composition of coal gas, and also of air
with the weights and volumes of their respective constituents,
we now proceed to the ascertaining the separate quantity of oxy
gen required by each of those constituents, so as to effect its per-
fect combustion, and produce the largest quantity of available
heat ; in other words, to find the " chemical equivalent,'''' or vol-
ume of air, required for the saturation of this mixed gas.

Now, this is to be decided, not by the quantity of air we may
admit or force into the furnace, but solely by the faculty with
which each of these constituents is endowed of uniting chemically
with the oxygen.

With respect to this power, or faculty of reciprocal saturation,
the first great natural law is, that bodies combine in certain fixed
propoi'tioTis only, — a remarkable feature in this law, as far as
gaseous bodies are concerned, being, that it has reference both to
volume and 'weight ; thus, by their concurrence, establishing the
principle which now no longer admits of any doubt. ^

The important bearings of this great elementary principle of
proportionate combination cannot be more strikingly illustrated,
or its influence rendered more familiar, than in the several com-

* " L'experience a demoutre que, de meme que les elemens se com-
binent dans des proportions fixes et multiples, relativement a leur poids,
ils se combinent aussi, d'une maniere analogue, relativement a leur
volume, lorsqu'ils sont a I'etat de gaz : en sorte qu'un volume d'un
element se combine, ou, avec un volume egal au sien, ou avec 2, 3, 4 et
plus de fois son volume d'un autre element a I'etat de gaz. En com-
parant ensemble les ph^nomenes connus des combinaisons de substances
gazeuses, nous dycouvrons les memes lois des proportions fixes, que celles
que vous venons de deduire de leurs proportions en poids : ce qui donne
lieu a une maniere de se representer les corps, qui doivent se combiner,
sous des volumes relatifs a I'etat de gaz. Les degres de combinaisons
sont absolument les memes, et ce qui dans I'une est nomme atome, est
dans I'autre apelle volume^ — Berzclius, vol. iv., p. 549.

PRINCIPLES OF COMBUSTION.

139

binations of which the elements of atmospheric air are suscepti-
ble, and the extraordinary changes of character and properties
which accompany the changes, in the relative quantities alone,
of the combining elements.

For instance, oxygen unites chemically with nitrogen in five
different proportions, forming five distinct bodies, each essentially
different from the others, thus :

Atoms. Weight. Atoms. Weight. Gross Weight.

of Nitrogen 14 unites with 1 of Oxygen 8 forming Nitrous Oxide . . 22

({

{(

14
14
14
14

2
3
4
5

((

16
24
32
40

Nitric Oxide . . 30
Hyponitrous Acid 38
Nitrous Acid . . 46
Nitric Acid ... 54

Or thus :

Atmospheric Air.

Nitrous Oxide.

....Nitric Oxide.

„Hyponitrou8 Acid,

Nitrous Acid.

Nitric Acid.

140 HEATING.

A description of the properties of these distinct t)oJ^<*5 may be
found in any chemical work of authority, and I only mention
these unions to exemplify the importance of attending to the
proportioJis in which bodies unite ; as we here find the very ele-
ments of the air we breathe, by a mere change in the pi-oportions
in which they are united, forming so many distinct substances,
from the laughing gas, nitrous oxide, up to that most powerful
and destructive agent, nitric acid, commonly called aqua-fortis.

This case of the combination of nitrogen and oxygen also
shows the importance of the distinction between mechanical and
chemical union ; these two elements being only mechanically
united in forming atmospheric air, by which the essential prop-
erties of its two constituents as preserved unaltered ; whereas,
in the five bodies above enumerated, the union is chemical, and,
consequently, the essential characters of their respective con-
stituents are lost, and new ones obtained.

Now, to apply these principles to the bodies under considera-
tion, nam.ely, the carbon and hydrogen, and ascertain the propor-
tions of oxygen they respectively require to produce chemical
union.

These two constituents, though united in the one body — the
gas — yet, not only separate themselves during combustion in a
remarkable manner, but, by two distinct processes, form two essen-
tially different unions. This is an important feature of the
development of chemical action which the law of equivalents at
once points out and enables us to satisfy, although this double
process does not appear to be understood, much less to be pro-
vided for, in practice, though familiar to every chemist.

On the first application of heat, or what may properly be
termed the firing or lighting the gas, when duly mixed with air,
the carbon separates itself from its fellmu-constituent, the hydro-
gen, and forms a union with the former, the produce of which
is carbonic acid gas.

Now, the laws of chemical proportion teach us that carbonic
acid is composed of one atom of carbon vapor, (by weight 6,)
and two atoms of oxygen, (by weight 16,) the latter, in volume,
being double that of the former, as in the annexed figure :

PRINCIPLES OF C031BUSTI0N. 141

Carbonic acid.

Thus, as far as the carbon is concerned, we obtain the infer
mation we sought, namely, its saturating equivalent of oxygen
and which we find to be just double its own volume ; or, by
weight, as 16 is to 6. But, without the aid of chemistry, we
should here have remained satisfied ; combustion would appear
to have been complete ; there would be no smoke, and no visi-
ble indication of an imperfect or unfinished process. Yet, chem-
istry tells us, we have only disposed of the one constituent of
the gas, namely, the carbon, and that the hydrogen, the second
constituent, remains yet to be accounted for, and converted to
heating purposes. ^

It is true, the carbon was, in weight, equal to six parts out of
eight (the original weight of the gas.) In bulk, however, it was
but one fifth; and when it is recollected, that, although the
illuminating properties of the carbon are superior to those of the
hydrogen, yet that the heating properties of the hydrogen are
far superior to those of the carbon, we can appreciate the loss sus-
tained should these four fifths of the gas remain unconsumed.

To this may be added, the probable injury done to the heat-
ing powers of the flame by the conversion of any part of this
otherwise valuable hydrogen into one of the most destructive
compounds which can be met with in the furnace or flues,

* I have here stated the case of the oxygen uniting with the carbon,
before the hydrogen. Chemists are undecided on this point ; and, indeed,
Ihe evidence at present is quite contradictory.

It is to be observed, however, that the argument, drawn from the
combustion of the carbon before the hydrogen, or vice versa, is the same,
as regards the point now under consideration. Whichever half passes
off uncombined, is lost.

142 HEATING,

namely, ammonia, composed of unconsumed hydrogen and a
portion of the nitrogen liberated from the air. Thus we have a
double motive for providing against the escape, unconsumed, ol
the hydrogen of the gas.

What, then, is to be done ? Let us complete this second
process as we did the first : let us supply this hydrogen, this
remaining 80 per cent, in volume of the gas, with its own proper
equivalent of oxygen, as we did in the case of the carbon.

But what is this second equivalent ? By the same laws of
definite proportions, we learn that the saturating equivalent of
an atom, or any other given quantity of hydrogen, is, not double
the volume, as in the case of the carbon, but one half its volume
only — the product being aqueous vapor, that is, steam; the
relative weights of the combining volumes being 1 of hydrogen
to 8 of oxj^gen ; and the bulk, when combined, being two thirds
of the bulk of both taken together, as shown in the annexed
figure 8. ^

We thus find, that to saturate the one volume of carbon vapor,
two volumes of oxygen are required ; whereas, to saturate the
two volumes of hydrogen, one volume only of oxygen is required :
thus,

FIRST CONSTITUENT.

Carbon. Oxygen.

Vol. Atom. Weight. Vol. Atom. Weight. Vol. Atom. Weight.

i . . 1 . . .6 unite with 1 . . 2 . . .16 forming ) i -j 92

carbonic acid. |

SECOND CONSTITUENT.
Hydrogen. Oxygen.

Vol. Atom. Weight. Vol. Atom. Weight. Vol. Atom. Weight.

2 . . 2 . . .2 unite with 1 . . 2 . . .16 formins: '

steam.

2 . . 2 . . .18

Here we see, that, in the case of this first constituent, as
above, the half volume of carbon and one volume of oxygen

* Professor Brande puts this so clearly that I here give his own
M'ords : — ''The simple ratio which the weights oi the combining ele-
ments bear to each other involves an equally simple law in respect to
combining volumes, where substances either exist, or may be supposed
to exist, in the state c^f gas or vapor.

" Thus, w'ater may \)e considered as a compound of 1 atom of hydro-
oen and 1 atom of oxygen, the relative weights of which are to each

PRINCIPLES OF COMBUSTION.

143

become condensed into one volume of carbonic acid (as shown in
the last figure) ; and that, in the second constituent, the two vol-
umes (meaning double bulk) of hydrogen, and 07ie volume of
oxygen, become condensed into two volumes of steam, (as
shown in the annexed figure.)

other as ] to 8. Hence, the equivalent of the atom of water will be, 1
hydrogen -\- 8 oxygen = 9. But oxygen and hydrogen exist in the gase-
ous state, and the weight of equal volumes of those gases (or, in other
words, their relative densities, or specific gravities) are to each other as
1 to 16 ; hence, 1 volume of hydrogen is combined with ^ a volume of
oxygen to form 1 volume of the vapor of water, or steam : for the specific
gravity of steam, compared with hydrogen, is as 1 to 9. The annexed
diagram, therefore, will represent the combining weights and volumes of
the elements of water and of its vapor."

Hydrogen, 1.

Steam, 9.

Oxygen, 8.

Steam.

or thus,

The following is also much to the point : — "La composition de I'eau
est un des elemens les plus necessaires aux calculs des chemistes, les
demiers experiences de MM. Berzelius et Dulong out fourni pour sa
composition des nombres qui sont adoptes r)ar tous les chemistes. Elle
est formee d'apres eux de

Oxygene 88.90 1 volume, oxygene.

Hydrogene . . . .11.10 2 volumes, hydrogene.

100.00

1 volume eau.

Parmi les nombreuses decouvertes que la science doit a M. Gay Lussac,
on remarquera toujours la belle observation sur la composition de I'eau,
qui le conduisit a trouver les vrais rapports des gaz et des vapeurs dans
leurs combinaison. Des experiences tres exactes, qu'il avoit faites con-
jointement avec M. de Humboldt, lui prouverent que Veav formte dhin
volume cf oxygene et de deux volumes de hydrogene, resultat plaiuement
confirme depuis par tous les phenomenes ou I'eau joue un role actif, et
qui s'accorde avec la composition trouve par MM. Berzelius et Dulong."
— Dumas, vol. i., p. 33.

144 HEATING.

No facts in chemistry, therefore, can be mort* decidedly
proved, than that one atom of hydrogen and one atom of
oxygen [the former being doithle the bulk oj the latter) unite in
the formation of water; and, further, that one atom of carbon
vapor and two atoms of oxygen {the latter being double the bulk
of the former) unite in the formation of carbonic acid gas.

Thus, the uhimate fact of which we were in search is, that
the one condensed volume of the gas, as generated from the
coal, requires two volumes, or double its bulk of oxygen^ that
being the quantity required for the saturation of its constituents
ivhen separated.

Now, this is the entire alphabet of the combustion of the car-
buretted hydrogen gas.

Having thus ascertained the quantity of oxygen required for
the saturation and combustion of the two constituents of coal
gas, the only remaining point to be decided is, the quantity of
air tliat will be required to supply this quantity of oxygen.

This is easily ascertained, seeing that we know precisely the
proportion which oxygen bears, in v^olume, to that of the air.
For, as the oxygen is but one-fifth of the bulk of the air,y?i"C
volumes of the latter will necessarily be required to produce one
of the former; and, as we want tivo volumes of oxygen for each
volume of the coal gas, it follows, that to obtain those two vol-
umes, we must provide ten volumes of air.

Thus, then, by strict chemical proof, we have obtained these
facts : — First, that each volume of coal gas requires two vol-
umes of oxygen ; secondly, that to obtain these two volumes of
oxygen we must employ eight atoms of air ; thirdly, that these
eight atoms of air are equal to ten volumes of the coal gas ;
each volume of the latter, in fact, requiring ten volumes, or ten
times its bulk of air : thus,

Ten volumes of air are the same as eight atoms ;

Eight atoms of air produce four atoms of oxygen ;

Four atoms of oxygen are equal to two volumes of the same ; and

Two volumes of oxygen saturate one volume of the coal gas :

Therefore, ten volumes of air are required for each one volume of this gas.

We now see why ten volumes of air are required for each

PRINCIPLES OF COMBUSTION. 145

volume of gas, and why neither more nor less ^vill satisfy the
conditions of its combustion. For, if more^ the excess, inde-
pendently of the mischievous chemical unions that might enter
into it in the furnace, would be the means of carrying away as
much heat as it would take up by its expanding faculty. And
if less, a corresponding quantity of either hydrogen or carbon
would be deficient of its supporter^ and necessarily pass off
uncombined and unconsumed.

The only observation here necessary to make on the difference
between these two gases is, that as this latter gas contains two
atoms of carbon instead of one, it follows that a proportionate
additional quantity of oxygen will be required for this additional
atom of carbon. Hence, if carburetted hydrogen requires two
volumes of oxygen for combustion, the bi-carburetted hydrogen
will require three volumes. And so of air : if ten volumes of
air are required for the one gas, fifteen volumes are consequently
required for the other gas.

4. We have seen that, in the formation of the carburetted
hydrogen, a considerable portion of the carbonaceous constituent
of fuel is separated, and carried away by the hydrogen in the
gaseous form, forming the carburetted hydrogen ; the remainder
of such carbonaceous matter is what we have now to deal with ;
the difference as regards combustion between these two portions
of carbon being so important as to demand especial notice.

In observing this curious arrangement by which the saturation
of the combustible atoms is effected, we perceive that three atoms
of the combustible are apportioned to four of the supporter.
This, we see, is the result of one atom of carbon requiring two
of the supporters, while the two of hydrogen are satisfied with
one each.

Now, in this arrangement no excess or deficiency appears
among the heat-producing ingredients. Could we have dis-
pensed with or avoided the presence of such an excess of nitro-
gen, (which is neither a combustible nor supporter of combus-
tion,) the several unions would have been less embarrassed, —
their combustion more rapid and complete, — and the intensity
of their action much increased. That, however, was impossible.

146 HEATING.

The presence of so large a quantity of nitrogen being the una*
voidable condition of obtaining the oxygen through the instru-
mentality of atmospheric air,

It is to be observed that the process of combustion here
described is the most perfect that could be produced, either in a
furnace or lamp. Any deviation, therefore, by means of excess
or deficiency, or from any interruption or interference, such as
the interposition of another gas, must be more or less destructive
to the desired effect, viz., the generation of the greatest quantity
of available heat.

5. When we speak of mixing a given quantity of oxygen
with a given volume of smoke, (or coal gas,) we do so because
we know that such quantity of the former is required to saturate
the latter, and by such saturation every atom of both gases
enters into union, without excess or deficiency of either, pro-
ducing entire and complete combustion.

So, when we speak of mixing a given volume of atmospheric
air with a given volume of smoke, we do so for the same pur-
pose, knowing that the precise quantity of air will provide the
required quantity of oxygen.

Thus, if we know that two cubic feet of oxygen are the exact
saturating equivalent, or combining volume, for effecting the en-
tire combustion of one cubic foot of coal gas, we know that ten
cubic feet of atmospheric air will effect the same purpose,
because ten cubic feet of air contain the required two cubic feet
of oxygen.

We require ten cubic feet of air to supply two cubic feet of
oxygen, which, if the air be pure, effects the combustion of one
cubic foot of coal gas, emanating from coals in the process of
combustion in a furnace ; but if this quantity of air does not
contain this 20 per cent., or one-fifth, of oxygen, it is clear we
cannot obtain it. The air, in this case, may be said to be viti-
ated, or impure. It is therefore desirable that the air admitted
into a furnace should be direct from the atmosphere ; otherwise,
the oxygen contained may be deficient, although the volume
of air admitted be sufficiently large.

PRINCIPLES OF COMBUSTION. 147

Let us now inquire how far the ordinary mode of constructing
and managing our furnaces enables us to satisfy this condition.

In ordinary furnaces, the supply of air is obtained by means
of the ash-pit ; and the larger the ash-pit, the greater the quan-
tity of air admitted. The ash-pit is made larger, under the
mistaken notion that the more air we give, the better will be the
draught, the more complete the combustion, and the greater the
quantity of heat produced.

There can scarcely be a more absurd practice than is involved
in this one-sided view of the principles of combustion, even sup-
posing that the introduction of air is tantamount to the introduc-
tion of oxygen. It is manifest, however, that there are two
different processes going on in the furnace, and two different
combustibles, requiring their respective volumes of oxygen to
consume. them, namely, the gas or smoke generated in the body
or cavity of the furnace, and passing off by the flues, and also,
the solid carbon resting on the bars, both of which require sepa-
rate volumes of oxygen to effect their combustion.

All that seems to be concluded in practice is, that air is
essential to combustion ; and that if air be admitted to the fuel,
through between the bars, it will work out the process of com-
bustion satisfactorily in its own way. And hence the many
errors and absurdities of the present system of practice.

There can be no greater mistake than letting a large quantity
of air act directly on the burning fuel, which acts like a blast
upon the red-hot mass, driving off the gases more rapidly, but
also driving off the contained heat, and consuming the fuel with
unnecessary rapidit3^

It seems to be taken for granted, that if air, by any means, be
introduced to the fuel in the furnace, it will, as a matter of
course, mix with the gas, or other combustible, in a proper man-
ner, and assume the state suitable for combustion, whatever be
the nature or state of such fuel, and without regard to time or
other circumstances. Now, it might as well be supposed, that
by bringing large masses of nitre, sulphur, and charcoal to-
gether, we could form gunpowder. We know that it is by the
proper mixture and incorporation of the different elementary
atoms that simultaneous action is imparted to the whole ; and

13^

148 HEATING.

SO, alsOj by bringing different kinds of gases into a state of
preparation for simultaneous action.

The complete combustion of a body depends upon the
chemical union of its atoms, or elementary divisions, with theil
respective equivalents of the supporter^ oxygen; and which
necessarily implies the bringing together, and the mixing of
such atoms, previous to the mixture being fired for combustion.

It is not our purpose to enter upon the theory of atomic mix-
tures, or the time required to effect their combination, — which
will be found in the numerous chemical works of the present
day. We will now proceed to consider the means by which air
may be introduced to the furnace, to effect the combustion of the
gases therein generated.

In lookinof for a remedy for the evils arisinsf out of the hurried
state of things which the interior of a furnace naturally presents,
and observing the means by which the gas is effectually con-
sumed in the Argand lamp, it seemed manifest, if the gas in the
furnace could be presented by means of jets to an adequate
quantity of air, as it is in the lamp, the result would be the
same, — namely, a quicker and more intimate mixture and diffu-
sion, and consequently a more extensive and perfect combustion.
The difhculty of effecting a similar distribution of the gas in
the furnace, by means of jets, however, seems insurmountable.
One alternative alone remains : since the gas cannot be intro-
duced by jets into the body of the air, the air might be intro-
duced by jets into the body of the gas ; and this will be an
effectual remedy.

Fig. 33 is a section of Williams' furnace for the prevention
of smoke. In this furnace, the fuel, as will be seen from the
cut, is thrown immediately upon the grate bars, ond through
them the air finds admission to it for the purpose of consump-
tion. The gases pass over the bridge C ; here they meet a cur-
rent of air entering just beyond the bridge, which has been
admitted by the air-tube b, below the ash-pit /, into the air-
chamber d, and from thence escaping through a great number
of small apertures in the diffusion plate above.

The force with which the air enters through this series of
jets or blow-pipes enables it to penetrate into the gases, and

HEATLNG.

149

Fig. 33.

loO HEATING.

obtain the largest possible extent of contact-surfaces for the air
and gases ; which is important, since the short time allowed for
the diffusion would otherwise be insufficient, in consequence of
the rapid passage of the smoke and gases over the diffusion
plates ; e is the spy-hole for ascertaining the state of the smoke.

Fig. 34 is an apparatus invented by Mr. Jeffreys, of Bristol, as
long ago as 1824, for precipitating the lamp-black, metallic
vapors, and other sublimated matters from smoke, by washing
the latter by means of a stream of water. Where the necessary
supply can be secured, this plan is both effectual and economi-
cal, and well adapted for situations where the presence of smoke,
as well as the impurities produced by it, is an annoyance.

In the vertical section, B B is the smoke flue. The smoke
passing in the direction of the arrows at A, the flue turns down-
ward ; and at the top of this vertical portion is a cistern E, the
perforated bottom of which lets down a constant stream of
water, after it is set to work. The shower, in its descent, carries
all the smoke and the sublimated matter which has passed from
the fire, which runs off at the bottom, F. The flue may then
turn upwards, or enter a common chimney ; but little or nothing
will pass up it, providing the water be kept constantly running.
This apparatus is easily constructed, and is admirably suited for
hot-houses situated in the midst of pleasure-grounds, where
smoke is unsightly and disagreeable.

Whether these methods of consuming the gases generated in
the furnaces and flues of hot-houses may be considered worthy
of general adoption, we cannot tell. It is, nevertheless, pre-
sented to the consideration of the ingenious mechanic, not
doubting that were the subject fully taken up by energetic fur-
nace builders, something good would be the result. That
immense quantities of fuel are wasted by imperfect combustion,
cannot be doubted, when we see the dense volumes of smoke
proceeding from chimneys where much heat is required.

Professor Brande says, " when air is admitted in front of the
furnace, or through or over the fuel, it obviously never can
effect those useful purposes, which are at once obtained by
admitting it in due proportion to the intensely heated inflamma-
ble vapors and gases, or, in other words, to the products of the

yfvATjjia,

151

Fig. 34.

152 HEAT1^G.

distillation of coal, at such temperatures that they may take fire
in its contact." If a number of jets of air be admitted into a
heated inflammable atmosphere, as the body of a furnace, its
combustion will be attained in such a way as to produce a great
increase of heat, and, as a necessary consequence, destroy the
smoke.

In some of the large gardens of Europe, as will as in some
manufactories, attempts have been made to consume the smoke
or gases of the furnaces, by bringing them in contact with a body
of glowing incandescent fuel, producing a result the reverse of
what was expected, namely, the absorptioQ of heat by their
expansion and decomposition, instead of giving out heat by their
combustion. It is strange that this erroneous notion should be
persisted in, even at the present day, when any chemical work
of good authority would satisfy any one wishing for such knowl-
edge that decomposition^ not combustion, is the effect of a high
temperature being applied to hydro-carbon-gases; — that no
possible degree of heat can consume carton ; — that it is a well-
known property of both the varieties of carburetted hydrogen,
that they deposit charcoal, (carbon) virtually become smoke,
when heated ; — that the amount of carbon deposited is propor-
tioned to the increase of temperature, and that its combustion is
merely produced by, and is, in fact, its iinion with, oxygen,
which these smoke-burners take no care to provide.^^

* Numerous methods have been devised for burning smoke, and
patents have been issued for supposed inventions of this kind, showing
the want of chemical knowledge on this subject. One consists in hav-
ing a double set of fire-bars, so that when the fuel is red-hot, it is
thrown back on the innermost bars, and the smoke of the fresh coal in
front passing over this incandescent fuel, is supposed to be consumed in
its passage. Another proposes a sliding carriage for this purpose,
working on castors inside the furnace. Others of a sin ilar kind have
"!)een put forward, and aii on the same principle ; an manifesting the
same neglect or ignorance of chemistry, — for chemistry teaches us
that heat has nothing to do with the combustion of smoke beyond this, —
that a certain temperature is essential to the development of chemical
action between the combustible and the supporter, when they are
brought together. But producing heat is not producing air ; and decom
^Hisition is not, in this respect, combustion.

PRINCIPLES OF COMBUSTION. 153

Tho neglect of chemistry when treating of combustion, and
the results of this neglect in these smoke-burning furnaces, can-
not be too strongly exposed ; neither can its study be too strongly
enforced, seeing that it is practically within the reach of all.
For chemistry is no longer the mysterious alchemy that it was
a century ago ; it is now a mere rigid inquiry into nature's pro-
cesses and laws, by the aid of those proofs and illustrations
which nature herself has supplied. It has taken its place among
the exact sciences, and now recognizes no man's dictum or opin-
ion, apart from experimental tests, and strict, substantial evidence.

Looking, then, to chemistry, we would add, in reference to
these smoke-burning expedients, that, in seeking to obtain heat
from gas, (or smoke,) the bringing it into connection with ignited
carbonaceous matter, or to anything approaching the temper-
ature of incandescence, is absolutely useless, if not injurious,
until we are assured of having the means of contact with air
fully provided for.

The mere enunciation of a plan " for consuming smoke^''^ is
prima facie evidence that the inventor has not studied and con-
sidered the subject in its chemical relations. Chemists can
understand a plan for the preveiition of smoke ; but as to its
combustion, it is so unscientific, not to say impossible, (if there
be any truth in chemistry,) that such phraseology should be
avoided. The popular phrase, " A furnace burning its own
smoke," may be justifiable, a? conveying an intelligible mean-
ing ; but, in a work having any pretensions to science, or from
any one pretending to teach those who are unable to distinguish
for themselves, and who may easily be led into error, is wholly
objectionable.

6. Constriiction of Furnaces. — From what has been already
said, in the preceding part of this section, it will be seen that
the construction of furnaces is a matter of great importance in
the economy of heat. To investigate the various varieties of
furnaces which have been recommended, v*"ould occupy too much
of our space at present, especially as we shall have to refer to
them hereafter, when treatinof of the different methods of heat-
ing ; besides, in small apparatuses, the intense heat required

154 HEATING.

for large boilers is unnecessary. A ver}- moderate heat, ap-
plied on the most economical principle, and the furnace so con-
structed as to make the fuel burn for a lonof time, without much
attention, and without much escape of smoke, is the grand
desideratum, and which is easily accomplished, with a moderate
degree of care and skill in the erection.

Passing over, then, as unnecessary for our purpose at present,
the many ingenious forms which have been given to furnaces,
we will proceed to describe the most simple plan, which, in our
expei*Sence, is the most effectual in the combustion of the fuel,
as well as the least expensive in the construction.

It should be an object of consideration, in building the fur-
nace, to confine the generated heat within the cavity of the
furnace as much as possible, so that the gases generated by the
combustion of fuel may be prevented from passing too rapidly
along the flue ; this is more especially requisite with boiler
furnaces. The throat of the furnace should be contracted as
much as possible. In furnaces where the only entrance for ail
is by the bars, provision should be made for the entrance of
enough — but no more than enough — for the combustion of
the fuel, and the entrance should, in all cases, be regulated by
a damper, on the ash-pit door. It should be considered, that
the rarity of the heated g-ases causes them to force their pas-
sage through the throat of the furnace, just in the proportion
of its size.

We have already shown that any air entering through the
door of the furnace reduces the intensity of the heat, although
it is supposed by some that the passage of air over the burning
fuel promotes the more perfect combustion of the gaseous pro-
ducts of the coal. But even if this be correct, the heat will be
reduced, and less heat will be generated in a given time, than
if the whole gaseous products escaped by the chimney.

The kind of fuel to be burnt must, in all cases, determine
the width of the bars ; and as a certain open area is necessary
for the admission of air to effect combustion, it is desirable that
this area should be known.

Supposing the ordinary kind of furnace bars to afTord about
thirty inches of opening for air for every square foot of surface, —

PRmCIPLES OF COMBUSTION. 155

then supposing you wish to erect a hot water apparatus — the
relative proportions between the area of the bars and the length
of pipe would be as follows : —

Area of Bars. 4 inch pipe. 3 inch pipe. 2 inch pipe.

15 square inches will supply 150 feet, or 200 feet, or 300 feet.

" '' " 200 " 266 " 400

" " " SCO " 400 " 600

" '< 400 '' 533 '' 800

" " 500 " 666 " 1000

100
150

200
250
300
400
500

" " " 600 " 800 " 1200

" " " 800 '' 1066 " 1600

" " " 1000 " 1333 " 2000

Thus, suppose there are six hundred feet of pipe, four inches
in diameter, in an apparatus, — then the area of the bars should
be three hundred square inches, so that thirteen inches in
breadth, and twenty-three inches in length, will give the re-
quired quantity of surface. When it is required to obtain the
greatest heat in the shortest time, the area of the bars may be a
little increased.

In order to make the fire burn for a lonof time without atten-
tion, the furnace should extend beyond the bars, both in length
and breadth ; and the coals, which are placed on this blank part
of the furnace, in consequence of receiving no air from below,
will burn slowly, and will only enter into complete combustion
when the rest of the coal, on the bars, has been consumed.

It may be observed, that as the maximum effect of the furnace
is seldom required, the register on the ash-pit door, and the
damper in the flue, must be used to regulate the draught, and
thus limit the consumption of fuel.

SECTION II.

PRINCIPLES OF HEATING HOT-HOUSES.

1. Effects of artificial heat. — The effects that are produced
upon the functions of vegetables, by atmospheric air that has
passed over intensely heated surfaces, are perceptible to the
most casual observer. The changes, therefore, that are produced
upon atmospheric air by subjecting it to a high temperature, are
of the utmost importance to the horticulturist, and consequently
demand our particular attention.

When common air passes over highly heated surfaces, the
small particles of animal and vegetable matter, (organic mat-
ter,) which are always held in suspension by it, are decomposed
by the heat, and resolved into various elementary gases. This
is one of the causes of the unpleasant smell which results from
this method of heating, as in common stoves, Polmaise furnaces,
&c. But, in addition to this, the aqueous vapors of the atmos-
phere are almost entirely decomposed, the oxygen entering into
combination with the iron, and the hydrogen mixing with the
air. The changes which have thus taken place, render the
atmosphere extremely deleterious to both animal and vegetable
life.

The mixture of the hydrogen thus disengaged is even more
injurious to the plants than the alteration which bas taken place
in its hygrometric state, as this will be partly supplied by the
moisture contained in their tissue, until it be restored to the
atmosphere by evaporation, which is easily effected.

The particles of animal and vegetable matter — as we have
said — are decomposed by the heat; and they then produce
extraneous gases, consisting of sulphuretted, phosphuretted, and
carbi\retted hydrogen, with various compounds of nitrogen and

PRINCIPLES OF HEATING HOT-HOUSES. >157

cjirbon, which, in the state in which they exist, are highly inim-
ical to vegetable life. ^

The quantity of hydrogen which is eliminated by the decom-
position of water contained in the air is one thousand three hun-
dred and twenty-five cubic inches for every cubic inch of water
that is decomposed ; and if the dew point of the air be 45° at an
average, this quantity will be given out from every seventy-two
cubic feet of air which passes over the heated surface. It is,
therefore, not difficult to account for the effects produced on
vegetation by hot-air stoves, in consequence of the air, when
thus artificallv dried, abstracting too much moisture from their
leaves. It is also clear that the injury must increase in propor-
tion to the length of time the apparatus continues in use, b}?" the
plants being surrounded by, and compelled to inhale, these extra-
neous gases, which are evolved from the decomposition of the
constituents of the atmosphere.

The extreme dryness of the air, after it has been deprived of

* I am unable to ascertain the exact nature and extent of the change
which atmospheric air undergoes by being passed over intensely heated
metallic bodies ; but whatever be the chemical alteration which occurs,
a physical change undoubtedly takes place, by which its electrical con-
dition is altered.

From some experiments recorded in the Philosophical Transactions of
the Royal Society, made with a view of ascertaining the effect produced
on the animal economy by breathing air which has passed through
heated media, it appears that the air which has been heated by metallic
surfaces of a high temperature must needs be exceedingly unwholesome.
A curious circumstance is related, in reference to these experiments,
which is illustrative of this fact.

" A quantity of air, which had been made to pass through red-hol
iron and brass tubes, was collected in a glass receiver, and allowed to
cool. A large cat was then plunged into this air, and immediately she
fell into convulsions, which, in a minute, appeared to have left her
without any signs of life ; she was, however, quickly taken out and
placed in the fresh air, when, after some time, she began to move her
eyes, and, after giving two or three hideous squalls, appeared slowly to
recover. But on any person approaching her, she made the most violent
efforts her exhausted strength would allow to fly at them ; insomuch,
that, in a short time, no one could approach her. In about half an hour
she recovered, and became as tame as before."

158 PRINCIPLES OF HEATING HOT-HOUSES.

its hygrometric vapor by passing over a hot-air stove, such as
polmaise, is productive of the worst consequences to growing
plants. To remedy this evil, a trough of water is laid over the
heatino- surface, which m some deofree mitirates this evil. The
evil, however, cannot be entirely got rid of by this means ; for
even if the proper quantity of moisture can be again restored to
the air, the effects which result from the use of extraneous
gases are in no way removed. When the surface of radiation is
an iron plate, these injurious effects are much greater.

The heating by means of brick flues is, in some respects,
similar to the effects produced by hot-air stoves, but only when
the flues are heated to a high temperature, which is unneces-
sary. In the latter case, an unwholesome smell is also produced,
by the decomposition of the organic matter in the atmosphere,
and in some cases, probably, by a small portion of sublimed
sulphur from the bricks, as well as by the escape of various
gases through the joints or accidental fissures of the flues.
These contingent causes ma}^ however, be in a great measure
avoided. The hygrometric vapors of the atmosphere are not
decomposed by this system of heating, as by a hot-air stove,
because when the flues are warmed to a common temperature,
the heat is perfectly pure, and the materials of which the flues
are built having but little affinity for oxygen, they are conse-
quently more healthy than hot-air stoves.

Air passing over a highly heated surface of iron is, therefore,
more injurious than when passed over any other body, as stone,
or brick, as the power of iron to decompose water increases with
the temperature to which it is heated. The limit to which the
temperature of any metallic surface ought to be raised, for warm-
ing horticultural buildings, (or indeed any other buildings,) is
212°, if a healthy, uncontaminated atmosphere be desired. The
importance of this rule cannot be too strongly insisted on, for
upon it entirely depends the healthiness of every system of
artificial heat. *

2. Laws of Heat. — Heated bodies give off their caloric by
two distinct Y(\ei\\ods — radiation and conduction. These are
governed by different laws ; but the rate of cooling — or parting

FRESrCIPLES OF HEATI^-Q HOT-HOUSES. 159

with heat — by both modes, increases in proportion as the
heated body is of greater temperature above the surrounding
medium.

The cooling of a heated body, under ordinary circumstances,
is evidently the combined effects of radiation and conduction ;
the conductive power of the air is, evidently, owing to the ex-
treme mobility of its particles, for otherwise it is one of the
worst conductors with which we are yet acquainted, so that
when confined in such a manner as to prevent its freedom of
motion, it becomes useful as a non-conductor.

The proportion which radiation and conduction bear to each
other has, in general, been very erroneously estimated. Count
Rumford considered the united effect, compared with radiation
alone, was as five to three, and Franklin supposed it to be as
five to two.

No such general law, however, can be deduced, for the relative
proportions vary with the temperature, and with the peculiar
substance, or surface, of the heated body; for, while the cooling
effects of the air, by conduction, is the same on all substances,
and in all states of the surface of those substances, radiation
varies very materially, according to the na^^ure of the surface.

The influence of the air, by its power of conduction, varies
also with its elasticity. The greater its elastic force, the greater
also is its power of cooling, according to the following law : —
When the elasticity of the air varies in a geometrical progres-
sion whose ratio is 2, its cooling power also changes in a geo-
metrical progression whose ratio is 1.366.

The same law holds with all gases, as well as with atmos-
pheric air ; but the ratio of the progression varies with each gas.

To show the relative velocities of cooling at different temper-
atures, the following table, constructed from the experiments of
Petit and Dulong, is given. The first column shows the excess
of temperature of the heated body above the surrounding air ;
the second column shows the rate of cooling of a thermometer
with a plain bulb, and the third column giv^es the rate of cooling
when the bulb was covered with silver leaf. The fourth column
shows the amount due to the cooling of the air alone ; and by

deducimg this from the second and third columns respectively

14=^

160

PRINCIPLES OF HEATING HOT-HOUSES.

we shall find what is the amount of radiation under the two
different states of surface, noticed at the top of the second and
third columns. '^

Excess of leniperalure
of ihe llierniiimeler
a!x)veihaiofiheair.

Centigrade Scale.

Total velocity of
cooling of the na-
ked bulb.

Total velocity of cool-
ins; of the bulb cov-
ered with silver leaf.

Amount of cooling due
to conduction of air
alone.

260°

24-42

10-96

8-10

240°

21-12

9-82

7-41

220°

17-92

8^59

6-61

200°

15-30

7-57

5-92

180°

13-04

6-57

5-19

160°

10-70

5-59

4-50

140°

8-75

4-61

3-73

120°

6-82 •

3-80

311

100°

5-57

306

2-53

80°

4-15

2-32

1-93

60°

2-86

1-60

1-33

40°

1-74

•96

•80

20°

•77

•42

-34

10°

•37

•19

-14

Some very remarkable effects may be perceived by an inspec-
tion of the above table. It appears that the ratio of heat lost by
contact of the air alone, is constant at all temperatures ; that is,
whatever is the ratio between 40° and S0°, for instance, is also
the ratio between 80° and 160°, or between 100° and 200°.
This law is expressed by this formula :

* i;.33;

where t represents the excess of temperature, and n a number
which varies with the size of the heated body. In the case
represented in the foregoing table, n = 0.00S57.

Another remarkable law, is that the coolino- effect of the air is
the same, for the like excess of heat, on all bodies, without
regard to the particular state or nature of their surface. This

* The temperatures of this table are expressed in degrees of the Cen-
tigrade thermometer, as the zero of this thermometer is the freezing
point of water, and from that to the boiling point of the same fluid is
100°. In order to find the number of degrees on Fahrenheit's scale,
which answers to any given temperature of the Centigrade, multiply
the number of degrees of Centigrade by 9, and divide the product by 5 ;
add 32 to the quotient thus obtained, and this sum will be the number
of degrees of Fahrenheit required.

PRINCIPLES 0-F HEATING HOT-HOUSES. 161

was ascertained by Petit and Dulong, in a series of experiments,
not necessary here to detail, but which proved the accuracy of
the de due Hon.

By comparing the second and third columns of the above
table, it will be immediately perceived that the loss of heat by
adiation varies greatly, with the nature of the radiating sur-
face ; though, whatever be the nature of the surface, the loss of
heat is the same in all cases, though in a different ratio.

It should be observed, that, in this table, the second, third,
and fourth columns show the number of degrees of heat which
were lost per minute by the body which was subject to the
experiment; and, therefore, these numbers represent the velocity
of cooling.

The fact, already adverted to, that the ratio of cooling in
those bodies that radiate least is more rapid at low tempera-
tures, and less at high temperatures, than those bodies that
radiate most, is, perhaps, one of the most remarkable of the laws
of cooling. It was first deduced experimentally by Petit and
Dulong, and it may be mathematically proved from their for-
mula ; but it is unnecessary here to enter into the investigation.
It appears, however, that when the total cooling of two bodies is
compared, the law is more rapid at low temperatures for the
body which radiates least, and less rapid for the same body at
high temperatures ; though separately, for conduction and radia-
tion, the law of cooling is, for the former, irrespective of the
nature of the body, and for the latter, that all bodies preserv^e at
every difference of temperature a constant ratio in their radi-
ating power.

It is not our purpose to enter minutely into detail on the laws
of heal, which will be found in modern works on chemistry,
and which ought to form part of the studies of all young gar-
deners who wish to become acquainted with the principles of
hot-house management. We will now proceed to consider the
specific properties of air and water as agents in the heating of
horticultural structures.

3. Specific heat of air and water. — Very erroneous notions
are entertained by many persons as to the absolute quantity of

162 PRINCIPLES OF HEATING HOT-HOUSES.

heat taken up by different substances. To ascertain, therefore,
the effect a certain quantity of water will produce in warming
the air of a hot-house, there appears to be no better method
than that of computing from the specific heat of gases compared
with water.

Every substance has its peculiar specific heat. Now, one
cubic foot of water, by losing one degree of heat, w^ill raise the
temperature of 2990 cubic feet of air the extent of one degree ;
and, by the same rule, by losing 10° of its heat, it will raise the
temperature of 2990 cubic feet of air 10 degrees; and so with
similar quantities in similar proportions.

In order to know fhe time it will take to heat a certain quan-
tity of air any required number of degrees, by means of hot
water contained in metal pipes, we must calculate the effect
from direct experiment ; and, as the radiating and conducting
powers of different substances differ considerably, it is necessary
that the experiment be made with the same material as the
pipes for which we wish to estimate the effect.

From data obtained by experiments on the cooling of iron
pipes, it appears that the water contained in a pipe 4 inches in
diameter loses '851 of a degree of heat per minute, when the
excess of its temperature is above 125 degrees above that of the
surrounding air. There one foot in length of a pipe 4 inches
diameter will heat 222 cubic feet of air one degree per minute,
when the difference between the temperature of pipe and the
air is 125 degrees.

To calculate from this data, however, the length of a pipe, of
any given size, that will be necessary to warm a house, and to
maintain it at any given temperature under a certain external
temperature, it will be necessary to estimate the heat lost by
the conducting and radiating power of the glass, and of any
metallic substance used in the structure.

Heating horticultural structures is a very different matter
from heating solid opaque buildings ; and here many erectors
of heating apparatus fall into error. They suppose, because an
apparatus of certain power heated a large building, — a church
or a hall, — one of proportionate dimensions should warm a hot
house of proportionate size, without taking into full considera

PRINCIPLES OF HEATING HOT-HOUSES. 163

tion the great difference of the external radiation, and the con-
duction of heat by the materials of the building.

The loss of heat by buildings covered with glass is very great.
It appears, by experiment, that one square foot of glass will cool
down 1-279 cubic feet of air as many degrees per minute as the
internal temperature of the house exceeds the temperature of
the external air; thus, if the difference between the external
temperature and the temperature of the house be 30 degrees,
then 1-279 cubic feet of air will be cooled 30 degrees by each
square foot of glass ; or, more correctly, as much heat as is equal
to this will be given off by each square foot of glass, for, in real-
ity, a very much larger quantity of air will be affected by the
glass, but it will be cooled to a less extent. The real loss of
heat, however, from the house will be what is here stated.

There are various causes likely to affect these calculations,
such as, —

High winds, which are found to reduce the internal tempera-
ture more than actual cold, or even frost ;

Condensation of moisture on the glass, which prevents the
escape of heated air ; and, when a certain temperature is main-
tained within, prevents radiation from the glass to a great
degree ;

The extent of wood in the roof of the house, which also pre-
vents radiation and conduction, as in the case of metallic roofs.

These circumstances will be found to affect, in a greater or
less degree, the air of the house, though, under general circum-
stances, these calculations will be nearly correct.

In estimating the quantity of glass surface contained in a
building, the extent of wood surface must be carefully excluded.
This is particularly necessary in all horticultural buildings,
where the maximum of heating power is dependent upon the
estimate taken. The readiest way of calculating, and suffi-
ciently accurate for ordinary purposes, is to take the square sur-
►faces of the sashes, and then deduct one eighth of the amount for
wood work. In the generality of horticultural buildings, the
wood work fully amounts to this quantity. When the frames
and sashes are made of metal, the radiation of heat will be quite

104

PRINCIPLES OF ILEATING HOT-HOUSES.

as much from the frame as from the glass ; therefore no deduc-
tion is required in such cases.

From the preceding calculations the following corollary may
be drawn : —

The quantity of air to be warmed per mi?iute in habitable
rooms and public buildings, must be 3^- cubic feet for each
person the room contains, and 1^ cubic feet for each square
foot of glass.

For conservatories, forcing-houses, and all buildings of this
description, the quantity of air warmed pe?' viinute must be 1^
cubic feet for each square foot of glass the structure contains.

When the quantity of air required to be heated has thus been
ascertained, the length of pipe to heat it by hot water may be
found by the following table :

Table of the quantity of pipe 4 inches diameter which will heat 1000 cubic
feet of air per minute, any required number of degrees. The temperature
of the pipe being 200^ Fahrenheit : —

Temperature of exter-
nal air.

Temperature at which the house is required to be kept.

Fahrenheit's scale.

45^

50'

55- 1 60- 65- 1 70- 75- 1 80-

85- 1 90°

10^

126:

150

174

200

229

259

292

328

367

409

12°

119

142

166

192

220

251

283

318

357

399

140

112

135

159

184

212

242

274

309

347.

388

16°

105

127

151

176

204

233

265

300

337

378

18°

120

143

168

195

225

256

290

328

368

20°

112

135

160

187

216

247

281

318

358

22°

105

128

152

179

207

238

271

308

347

24°

120

144

170

199

229

262

298

337

26°

112

136

162

190

220

253

288

327

28°

104

128

154

181

211

243

279

317

30°

120

145

173

202

234

269

307

Freezing point 32°

112

137

164

193

225

259

29r) i

34°

104

129

155

184

215

249

28f) \

36°

120

149

175

206

239

276 1

38°

112

138

166

196

229

266

40°

104

129

157

187

220

255

42°

121

148

178

210

245

44°

112

139

168

200

235

46°

103

130

159

190

225

48°

121

150

181

215

50°

112

140

171

204

52°

54 1 77

103 1 131

161

193

To ascertain, by the above table, the quantity of pipe required
to heat 1000 cubic feet of air per minute, find, in the first column

PRINCIPLES OF HEATING HOT-HOUSES.

165

the temperature which corresponds to that of the external air,
which may be the medium (or average) of your locality.
Then, in the other column, find the temperature required in the
house ; then, in this latter column, and on the line which cor-
responds with the external temperature, the required number of
feet of pipe will be found.

Supposing, now^, that a forcing-house is to be kept at 75 de-
grees, and the average of the external thermometer in the
coldest weather, taken at 10° (Fah.) ; then, by the foregoing
table, we find, under the column 75°, and on the line 10°, for
external temperature, the quantity 292, which is the number of
feet of pipe required to heat 1000 cubic feet of air per minute,
the proposed number of degrees. Of course, the volume of air
in the house must be previously ascertained. Any other differ-
ence of temperature may be found in the same way.

It will thus be perceived, that the amount of heat required
for warming a glazed structure is much greater than that re-
quired for warming an opaque building of the same size, in
consequence of the radiation of heat from its surface ; and the
difference is much greater than the allowance made by erectors
of heating apparatuses, under general circumstances.

To ascertain the effect of glass windows in cooling the atmos-
phere of a house, the following experiments were made, with a
vessel as nearly as possible the same thickness as the glass
ordinarily used for glazing. The temperature of the house, in
these experiments, was 65° ; the thickness of the glass was .0825
of an inch ; the 'surface of the vessel measured 34-296 square
inches, and it contained 9*794 cubic inches of water. The time
in which this vessel cooled, when filled with hot water, is showai
as follows : —

Thermometer

cooled.

Observed
time of
cooling.

Calculated
time of
cooling.

Average rate of the

observed time of

cooling.

from 1 to

150^
150
150
150

140-'
130
120
110

6' 40''
14 50
23 30
34 0

& 5i"
14 43
23 40
34 0

1-176^ per minute,
at an excess of 65^
above the tempera-
ture of the air.

From the average rate of cooling here given, the effect of
glass in cooling the atmosphere of a room may easily be calcu

166 PRINCIPLES OF HEATING HOT-HOUSES.

lated, as the specific heat of equal volumes of air and water is
as 1 to 2990. The above average will show that each square
foot of glass will cool 1*279 cubic feet of air one degree per
minute, when the temperature of the glass is one degree above
that of the external air.

But by this we can only find the effect of glass in a still at-
mosphere, and, therefore, to find the effect of glass in cooling
the volume of a hot-house, especially when exposed to the action
of winds, further experiments are necessary, of which we shall
treat in a subsequent part of this work, in connection with " pro-
tection of hot-house roofs during the night."

SECTION III.

HEATING BY HOT WATER, HOT AIR, AND STEAM.

1. The practice of employing hot water, circulating through
metallic tubes, or wooden troughs, for diffusing artificial heat in
horticultural structures, though of recent origin, has now become
so general, that its merits are fully acknowledged as the best
method that has yet been invented, to effect the purpose with
efficiency and economy. Until the last few years, — although
its powers and properties were fully known, — it had been
chiefly confined to a few cases of experiment, rather than to any
general or useful purpose.

The present day, however, has fully revealed its merits, and
shown the great, the unlimited, extent of its practical application
and general utility. When we see such an immense structure
as the great Palm house, lately erected at Kew Gardens, in
London, heated with hot water in preference to all other modes ;
when we see the lately applauded mode of heating by steam
abandoned; when we see the powerful, but unsuccessful, at-
tempt to establish a new system of heating by hot air, called
Polmaise, by some of the first horticulturists of England ; when
we see this system, notwithstanding its powerful supporters,
driven into obscurity, and all but annihilated, by the well-tried
superiority of hot water, which maintains its proud preeminence
over all other methods of heating, and has its superiority ac-
knowledged, even by its enemies.

One of the greatest advantages which this mode of heating
possesses over all others, is, that a greater permanency of tem-
perature can be obtained by it, than by any other method. The
difference between an apparatus heated by hot water, and one
heated by steam, is not less remarkable, in this particular, than

in its superior economy of fuel.

15"

168 HEATES'G BY HOT WATER, HOT AIR, A^'D STEAM.

2. Coviparison of heat in v:ater and steam. — The heating of
horticultural buildings by steam had its day and its admirers,
though both are now numbered among the things that were.
Even if the original outlay were equal, the additional outlay for
fuel, the risk of explosion from neglect, and the want of perma-
nency in the apparatus to maintain the heat for any length of
time, are insuperable' objections to its adoption. Among many
instances that could be given of this method of warming large
houses, we might mention the large Palm house, in the Royal
Botanic Garden of Edinburgh, which was erected when heating
by steam was in the height of its fame. This house is about
fifty feet high and seventy-five feet wide, in the form of an
octagon ; the pipes are laid around the side of the wall. There
is a contrivance, however, resorted to here, in connection with
the system, to which its success in heating the house may be
somewhat, if not entirely, attributed. The steam is thrown into
large iron boxes, loosely filled with stones and pieces of brick,
for the retention and absorption of the heat. These iron boxes
are placed underneath the shelf that surrounds the house, and
close by the side of the wall, and at regular distances from
each other. By this contrivance, the temperature of the house
is kept up for a considerable time longer than would be by the
circulation of the steam alone. Indeed, we believe it was found
perfectly impracticable to maintain the proper temperature, dur-
ing cold nights, until this expedient was adopted, viz., of filling
the boxes with absorbinof materials.

We have known conservatories, in which steam apparatuses
had been erected, taken down, and their place supplied with
others of hot water, merely in consideration of the consumption
of fuel and extra attention required by a steam apparatus, keep-
ing the danger of explosion out of the question.

It seldom happens that the pipes of a hot-water apparatus can
be raised to so high a temperature as 212° ; in fact, it is not
desirable to do so, because it is unnecessary to generate steam,
which would only escape by the air vent, without affording any
available heat. Steam pipes, on the contrary, must always be
above the temperature of 212°, otherwise steam will not be gen-
erated : and here the grand point to be attended to in artificial

HEATIA'G BY HOT WATER, HOT AIR, AJS'D STEAM. 169

heating is nullified, namely, the diffusion of heat at a low tem-
perature. A given length of steain pipe, however, will afford
more heat than one heated by hot water, by the aggregate cal-
culation of its specific heat. But, if we consider the relative
permanency of temperature, we shall find a very remarkable dif-
ference in favor of pipes heated by hot water ; and the calculations
here given are fully confirmed by experience and observation.

The weight of steam, at the temperature of 212°, compared
with the weight of water at 212°, is about as 1 to 1694, so that
a tube that is filled with water at 212° contains 1694 times as
much matter as one of equal size filled with steam. If the
source of heat be withdrawn from the steam pipes, the temper-
ature will soon fall below 212°, and the steam immediately
in contact with the pipes will condense ; but, in condensing,
the steam parts with its latent heat^ and this heat, in passing
from the latent to the sensible state, will again raise the tem-
perature of the pipes ; but, by the withdrawal of the heat from
the boiler, the action of the cold air on the pipes quickly con-
denses the whole of the steam contained in them, which, when
condensed, possesses just as much heating power as the same
bulk of water at a similar temperature. This water now occu-
pies only y^V^- part of the space which the steam originally did
in the pipes.

The specific heat of uncondensed steam, compared with water,
is, for equal weights, as -8470 to 1 ; but the latent heat of
steam being estimated at 1000 degrees, we shall find the relative
heat obtainable from equal weights of condensed steam and of
water, reducing both from the temperature of 212° to 60°, to be
as 7-425 to 1 ; but for equal bulks it would be as 1 to 228 ; that
is, bulk for bulk, water will give out 228 times as nmch heat as
steam, reducing both to the temperature of 60°. A given bulk
of steam, therefore, will lose as much of its heat in one minute,
as the same bulk of water will lose in three hours and three
quarters.

It must be considered, however, that when the water and
steam are both circulated in iron pipes, the rate of cooling will
be somewhat different from this ratio, in consequence of the

170 HEATI^'G BY HOT WATEK, HOT AIR, AND STEAM.

much larger quantity of heat contained in the metal, than in the
steam with which the pipe is filled.

The specific heat of cast iron being nearly the same as water,
the water being 1000 and the iron 1100, if we take two similar
pipes, four inches in diameter and one fourth of an inch thick,
the one filled with water and the other with steam, each at the
temperature of 212°, the one which is filled with water contains
4-68 times as much heat as the one which is filled with steam.
Therefore, if the pipe w4th the steam cools down to the temper-
ature of 60° in one hour, the one filled with water would require
four hours and a half, under the same circumstances, before it
reached the like temperature.

But this is merely reckoning the effect of the pipe and the
fluid contained in it. In a steam apparatus, this is all that is
effective in giving out heat ; but in a hot-water apparatus there
is likewise the heat from the water contained in the boiler, and
even of the brick-work around the boiler, all which tends to
increase the heat of the pipes, long after the fire is extinguished.
In the one, the heat will continue to circulate through the pipes
as long as any heat remains about the fire-place, because the
circulation will continue in the pipes until the whole apparatus
is cooled down. But, in the case of steam pipes, as sooji as the
water in the boiler falls below the boiling point, (212°,) circula-
tion ceases, and the pipes then begin to cool, the remaining heat
in the boiler and furnace goes for nought.

From these causes the difference in permanency of hot water
and steam will be clearly apparent, and the fact of a house
heated with hot water keeping up its temperature at least six
times as long as one heated with steam, will be fully understood
by those interested in the matter. These considerations are of
the utmost importance to those erecting horticultural build-
ings, or, indeed, any other kind of buildings requiring artificial
heat. This admirable property, which water possesses, of re-
taining its heat, of carrying it to any distance, and, without
difficulty, giving it out gradually, or retaining it for many hours,
renders it of vast importance to gardeners, and prevents the
necessity of that constant attention to the fire, which forms so
serious an objection in all other methods of heating.

HEATING BY HOT WATER, HOT AIR, AND STEAJW. 171

We find, by experience, that no system of heating horticul-
rural buildings in all respects answers the purpose so well as a
hot-water apparatus, well constructed, and judiciously arranged,
in regard to the amount of work it has tD do, so that it ii ay not
be necessary to strain it, on exigencies, to its maximum point of
strength. In whatever point of view it may be regarded, it is,
undoubtedly, the best for all practical purposes ; and the best
possible evidence of its utility is derived from the fact, that no
case has ever come under our knowledre, wherein it has failed
to give complete satisfaction, when it has been properly con-
structed, rightly managed, and judiciously arranged, in regard
to supplying a sufficient amount " of radiating surface for the
work it has to do.

3. Comparison of hot air with hot water, as a mode of heating
horticultural structures. — Various erroneous opinions and prin-
ciples have been theoretically and practically promulgated, in
regard to hot-air heating ; and, carrying with them, in general,
some degree of plausibility, and in some cases emanating fromi
men of learning, have led, many, who have not studied the mat-
ter attentively, into very great errors. However invidious,
therefore, may be the task of pointing out such errors, we con-
sider it our duty, when treating on the subject at large, not only
to exhibit what we consider to be the true principles, but to
show where erroneous principles have been adopted. This must
serve as an apology for the freedom with which the advocates
of Polmaise, and other methods of hot-air heating, and the sys-
tems they approve, are descanted on in this section.

We have already observed that the cooling of a heated body,
under ordinary circumstances, is evidently the combined effect
of radiation and conduction. The conductive power of the air
is principally owing to the mobility of its particles, for, otherwise,
it is one of the worst conductors we are acquainted with.

Atmospheric air, in passing into a house over a highly heated
surface, must necessarily lose a large quantity of its contained
moisture ; [see 1. Effects of Artificial Fleat, of the preceding
section;] and, as its capacity for taking up moisture is increased
according to its temperature, it follows that a great demand

172 HEATING BY HOT WATER, HOT AIR, AND STEAM.

must be made upon the moisture of the house, upon the plants,
and upon everj'thing else within its influence capable of giving
off moisture. This is also the case with hot- water pipes. But
here the advantage of the latter is plainly illustrated ; for while
a hot-air stove abstracts the moisture, in excess, from that part
of the house nearest to the aperture of ingress, hot-water pipes
radiate the heat at a loio temperature equally over the whole
surface, and, as the temperature at which the heat is radiated is
comparatively Iova'', little or no moisture is abstracted. Some
suppose that they get a fine moist heat from hot-water pipes.
This, however sound and sensible it may appear, is, nevertheless,
a practical fallacy, the fact of the case being this, — that, instead
of the moisture of the house being taken up by the air, as in
the case of Polmaise, and other stoves, the warm air of the
pipes being so much lower in temperature than that of the
stoves, it cannot take it up, and hence the moisture remains
with the plants and the atmosphere in its original purity. In
fact, there is no difference between the heat radiated from stone,
brick, or iron, unless it be mixed with extraneous gases, b}^ heat-
ing these bodies to a high temperature.

To supply the moisture required by the heated air, water may
be placed in evaporating pans, in connexion with the current
of ingress; but, as we have already shown, though moisture
may be supplied, the hydrogen of the rarefied air still remains
uncombined, and, until the air be replaced by a fresh volume
from the external atmosphere, its impurities still remain.

With regard to the motion and circulation of the atmosphere
of a hot-house, the system of heating by hot air possesses, the-
oretically, some advantages over all others. Strictly speaking,
however, this has scarcely a practical foundation. If hot air be
admitted in currents, the atmosphere will be agitated, certainly,
but the house will be very unequally heated, as the heated air
will pass upward in currents, at the aperture of its entrance,
without diffusing itself over the lower surface of the house.
Air expands, when heated, -^^-^ of its bulk for each degree of
Fahrenheit, and the velocity of its motion is equal to the addi-
tional height which a given weight of heated air must have, in
order to balance the same weight of cold air ; and as all rare

HEATING BY HOT WATER, HOT AIR, AND STEAM. 173

bodies tend to rise vertically, in a dense medium, it follows, that
when heated air enters a house by an aperture at one part of it,
a very large portion of the heated air thus entering, must rise
immediately towards the roof; and in practice we find this to be
exactly the case. For, let any person examine the roof of
a hot-house in a frosty night, heated by a hot-air stove, and he
will perceive the part immediately above the entrance of the
air quite warm by the ascending heat, while all the rest of the
roof may be covered with ice or snow.

But the atmosphere of a house heated artifically, by whatever
means, is always in motion ; with hot-water pipes it may be
less perceptible, for the reasons already stated, but it is not
the less real. The motion given to the atmosphere of a house
depends upon the difference of temperature between the two
bodies .of air, externally and internally; therefore a motion must
continue in the air of a house artificially warmed, so long as the
house requires warming, — that is, as long as any difference ex-
ists between the internal and external atmospheres.

Some advocates of hot-air heating found their arguments upon
the fact that air can be raised to a higher temperature, in a
given time, by a given amount of caloric, than water. This is
probably true, if we calculate according to the bulk, without re-
gard to the density, of the respective bodies ; but, supposing it to
be true, then we know that, by the law already referred to, its
rapidity in warming will just be in exact proportion to its rapid-
ity in cooling, and vice versa. It is, therefore, manifest, that this
property militates against it as an agent in heating horticultural
buildings, as it is well known to be an all-important point, in
warming these structures, to obtain an equilibrium of heat for
the greatest length of time, and with the least possible amount
of attention, and experience has fully concluded that this is most
effectually and most easily obtained by the circulation of hot
water through wooden and metallic radiators and conductors.

Suppose, for instance, that a house, containing 4000 cubic
feet of air, is required to be heated, from 32° to 60°, and
suppose the external thermometer to remain stationary at this
point ; then, by calculation, we find that it requires double the
amount of fuel to heat the atmosphere through the 28 degrees

174 HEATING BY HOT WATER, HOT AIR, AND STEAM.

between these two points, by means of water, that it does
through the medium of air, i. e., by direct communication, in
each case the calorific action being in pretty exact ratio to the
combustion, and both acting under the most favorable circum-
stances. This would, at first view, decide us in favor of hot
air as a means of heating, in preference to hot water ; and the
fact that the heat becomes more rapidly sensible by hot air, has
induced many to come to a premature conclusion on this point.

Let us, however, take another view of the position here
alluded to, and consider the two methods in regard to their per-
manency of heating power. We find also, by calculation, that
while the temperature of the house is maintained at 60° for
3-25 hours by hot air, with the same amount of combustion the
temperature of 60° is maintained for 10 hours by hot ivater, or
three times the period that the equilibrium is maintained by hot
air. The same experiment shows that 2 bushels of coal will
warm an equal volume of air in a hot-house the same length of
time that 5-067 bushels will warm by direct connexion of its
particles with the source of heat.

Now, in a la-rge house, or number of houses, this saving of
fuel would, in a few years, amount to the difference of cost be-
tween the two apparatuses, keeping out of the question the saving
of labor, the cleanliness and neatness of the one compared with
the other. In regard to these numbers, we may remark, that
the calculations of some experienced and intelligent gardeners,
drawn from accurate observation, have made the difference be-
tween the two methods still greater, in regard to the consump-
tion of fuel, — placing this position in still stronger light than by
the calculation here given.

This remarkable difference in the retention of heat is owing
to the following causes.

First. The power possessed by the water [as already ex-
plained, see " Comparison of Water and Steam "] of absorbing
and retaining a large amount of heat, and giving it off gradually,
as the atmosphere requires it.

Secondly, Owing to the body of metal with which the water
is surrounded, which also absorbs and retains a large amount

HEATING BY HOT "VVATf.:-^, HOT AIR, AND STEAM. 175

of heat, and parts with it slowly to the air by which it is sur-
rounded.

Water is a better conductor of heat than air. Every gardener
well knows how rapidly a wet mat, or any other wet substance,
will carry off the heat in a frosty night, if laid over a hot-bed,
or green-house. In fact, the temperature of a frame under such
covering will fall quicker than if fully exposed. Yet the case
is different if the mat be dry, because the apertures of the mat,
and also the space between it and the glass, are filled with air
at rest, — because the latter is a bad conductor of heat, and the
former a good conductor. In a tank of water in a hot-house,
the thermometer will indicate a temperature probably 10° above
the atmosphere, while, by plunging the hand in the water, it will
feel about 10° lower. This arises from the power possessed by
the water of conducting the heat from the hand immersed in it.
The effect in all these cases may appear different, but the prin-
ciple of action is the same. Water conducts heat rapidly from
a body warmer than itself, and conveys it to a colder one.

Let a stream of air be forced through a tube 100 feet in
length, entering at the temperature of 150° ; by the time it has
travelled, by its own specific gravity, to the end of the tube,
it will be reduced to the temperature of the external atmosphere.
A stream of water, under the same circumstances, will travel to
the end of the tube with a very slight diminution of its tem-
perature, probably only a few degrees, and will have heated the
tube, if a good conductor, to nearly the same temperature as
itself during its passage.

SECTION IV.

HOT-WATER BOILERS AND PIPES.

1. She of Boilers, and surface necessary to he exposed to the
fire. — In adapting the boiler of a hot-water apparatus, it is not
necessary, as in the case of steam boilers, to have its capacity
exactly in proportion to the quantity of pipe that is attached to
It. On the contrary, it is sometimes desirable to invert this
order, and to attach a boiler of small capacity to a considerable
length of pipe. We do not mean, however, in recommending a
boiler of small capacity, to propose, also, that it should be of
small superficies; for the efficiency of a boiler very much depends
upon the quantity of surface exposed to the fire. The larger
the surface exposed to the action of the calorific influence, the
greater will be the economy of fuel, and, therefore, the greater
will be the effect of the apparatus.

In proposing the adoption of boilers of small capacity, how-
ever, it is necessary to accompany the recommendation with a
caution against running into extremes, for this error has been
the cause of the inefficiency of apparatus in many instances.
In some boilers, we have seen the space allowed for the water
so ver}^ small that the boiler was thereby rendered completely
useless.

Too small a quantity of water, and too large a surface exposed
to the fire, give rise to various evils, among which are the depo-
sition of neutral salts and alkaline earths by the water which
evaporates, contracting the water-way, and impeding circulation ;
and also preventing the full action of the fire on the exposed
surface of the boiler.

But perhaps the greatest evil arising from this state of things,
IS from the repulsion of heat by the metal of the boiler. The
quantity ot water it contains being so small, and the heat of
the fire very intense upon it, a repulsion is caused between

HOT-WATER BOILERS AND PIPES. 177

the iron and the water, and, consequently, the latter does not
receive the full quantity of heat. The repulsion between heated
metals and water has been ascertained to exist, even at low tem-
peratures, being appreciably different at various temperatures
below the boiling point of water. But as the temperature rises
the repulsion increases with great rapidity ; so that iron, when
red-hot, completely repels water, scarcely communicating to it
an)'- heat, except, perhaps, when under considerable pressure. '

It is obvious that the extent of surface exposed to the fire
should be in proportion to the amount of water contained in the
boiler and the pipes ; and it is easy to estimate these relative
proportions with sufficient accuracy, notwithstanding the various
circumstances which modify the effect. Calculating the surface
which a steam boiler exposes to the fire at 4 square feet for each
cubic foot of water evaporated per hour, and calculating the
latent heat of steam at 1000 degrees, we shall find that the same
extent of boiler surface that would evaporate a cubic foot of
water, of the temperature of 52°, into steam, of which the tension
is equal to one atmosphere, would supply the requisite heat to
232 feet of pipe,. 4 inches diameter, when its temperature is to
be kept at 140 degrees above that of the surrounding air. The
following proportions for the surface which a boiler for a hot-
water apparatus ought to expose to the action of the fire, will be
found useful.

Surface of boiler
exposed to the fire. 4 inch pipe. 3 inch pipe. 2 inch pipe.

3^ square feet will heat 200 feet, or 266 feet, or 400 feet.
5i " " " " 300 '' 400 '' 600 "
7 " " " " 400 " 533 " 800 ''
8^ " '' '' " 500 " 666 " 1000 "
12 '' " '' " 700 " 933 " 1400 "
17 " '' " " inOO " 1333 '' 2000 "

A small apparatus ought, perhaps, to have rather more sur-
face of boiler, in proportion to the length of pipe, than a larger
one, as the fire is less intense, and acts with less advantage, than
in large furnaces. It depends, however, upon a variety of cir-
cumstances, whether it will be expedient to increase the quan-
tity of pipe, in proportion to the surface of the boiler, beyond

178 HOT-AVATER 201LEKS AND riPES.

what is here stated ; for, although many causes tend to modify
the effect, the above calculation will be found a good average
proportion, under ordinary circumstances. The effect very much
depends upon the quality of fuel, the force of draught, the con-
struction of the furnace, &c., which, from what has been already
said on these matters, will show that they will, in a great
measure, influence the intensity of the heat received by the

boiler. It is always safest, however, to work with a larger sur-
face of boiler, at a moderate heat, than to keep the boiler work-
ing at the maximum of its power.

There is another cause, however, that will tend to modify the
proportions which may be adopted. The data from which the
calculation of the boiler surface is made assumes the difference
to be 140° between the temperature of the pipe and the air with
which it may be surrounded ; the pipe, in this calculation, being
200°, and the air 60°. But if this difference of temperature be
reduced, either by the air in the house being higher, or by the
apparatus being worked below its maximum temperature, then,
in either case, a given surface of boiler will suffice for a greater
length of pipe. For, if the difference of temperature between
the water and the air be only 120°, instead of 140°, the same
surface of boiler will supply the requisite degree of heat to one
sixth more pipe; and if the difference be only 100°, it will sup-
ply one third more pipe than the quantity stated in the table.

It will, therefore, frequently occur, in practice, that the quan-
tity of pipe, in proportion to a given surface of boiler, may be
considerably increased beyond the amount which is given in the
preceding table ; because, in forcing-houses, the temperature of
the air may sometimes be above the number of degrees here
given, and frequently the temperature of the water may be below
100°, — the pipe not being required to be worked at its full heat ;
and, therefore, in both these cases, a larger proportion of pipe
may be worked by a given sized boiler.

Ill order to estimate the quantity of surface which is acted
upon by the fire, an allowance must be made for the flues which
circulate round the exterior of the boiler, (and all boilers should
be so erected as to admit of the action of the heat round their
sides.) Thus, suppose an arch boiler (Fig. 35) to be 30 inches

HOT-WATER BOILERS AND PIPES.

179

Fig. 35.

long", there will be about 8|- square feet of surface exposed to the
fire, that is, to its direct action underneath ; and suppose, also,
that there are four external flues, one on each side, — or sup-
posing that the flue went all round the boiler, top and all, — we
may calculate that nearly one half of the effect is produced by
these flues which would have been obtained had the direct action
of the fire been employed on a like extent of surface ; therefore
the flues will be equal to 5 square feet, making altogether 13|
square feet as the available heating surface of a boiler of this shape
and size, which we consider far superior to the old form of boiler,
as shown in the following cut, (Fig. 36.) A boiler of the size

Fig. 36.

here described (Fig. 35) would be sufficient to heat about 800
feet of pipe, 4 inches diameter, when the excess of its tempera-
ture above that of the surrounding air is 140°, as before stated ;
a boiler of the same shape, 24 inches, has about 11 square feet
of surface directly acted upon by the fire ; one 36 inches long
has 164- square feet of surface ; and one 42 inches long has 19
square feet of surface ; the increase being directly proportioned
in the simple ratio to the length.

180 HOT-WATER BOILERS AND PIPES.

A circular boiler, 30 inches diameter, with a 9 inch circular
Hue running round the outside, will expose nearly the same
extent of surface to the fire as the one just described, (Fig. 35,)
both being the same length, and therefore the one will be as
effective as the other ; a slight diminution on the perpendicular
length of the curve makes but little difference to its capacity for
radiating caloric.

The surfaces of any size of this shaped boiler can easily be
calculated by the same rule ; but, instead of varying in the sim-
ple ratio of the length or diameter, it will be found to be propor-
tional to the square of the diameter^ so that the proportion of
surface increases more rapidly than in the arched boiler. Thus,
a circular boiler, 24 inches diameter, has 8| square feet of sur-
face exposed to the fire ; a 30 inch has 13f square feet ; a 36
inch has 19f square feet ; and a 4'2 inch has 26f square feet
exposed to the fire; the small sizes having proportionally less
surface, and the large sizes more than the high -arched boilers.

The rules which are here given regarding boilers, are framed
to suit common occurrence, and intended to guide practical men
who have the manacrement and workinor of common hot-water
apparatus. There are some cases, however, where apparatus
of great magnitude is necessary, in which these rules will not
apply without modification. But as such instances are com-
paratively rare, and, moreover, as no person that is a novice in
the practical application of this principle of warming, will be
likely to undertake, for his first essay, the responsible erection
of an apparatus of great dimensions, it is the less necessary to
enter at length into such cases as may be supposed to render
any alterations of these principles necessary.

It may, however, be observed, that cases may occur where a
peculiar construction of apparatus rnaj^ be desirable ; for instance,
where, from a large quantity of required surface a furnace of
very great power would be necessary ; and, in that case, a boiler
which exposes a large surface, while it possesses but a small
capacity, would obviously be injudicious, because the intense
heat acting on a small body of water would probably generate
steam to a high degree of elasticity in the boiler, and not only

HOT-WATER BOILERS AND PIPES. 181

produce much inconvenience, but neutralize the effects of what
might otherwise be an efficient apparatus.

The nearer the rules here laid down for regulating the size
of boilers are acted upon, the more efficient will be the working
of the apparatus. There is no advantage whatever gained by
using a larger boiler than is necessary to heat the pipes to their
maximum temperature, — even though this temperature may
never be required, — for, as the return-pipe should (if the appara-
tus be working right) bring in a fresh supply as rapidly as the
flow-pipe takes it away, the boiler is . always kept full. It
may be observed, that the circulation vdll be more rapid from a
minimum boiler than from a maximum one, — that is, from a
boiler whose capacity is rather below the proportion ; while a
boiler whose capacity is above the proportion of the pipes, has a
slower circulation ; and for all horticultural purposes, — though
the former has some little advantage in the time of heating —
the latter is decidedly to be preferred.

In the following section, (Sect. V.,) further information will
be found on boilers, etc., where different methods of heating, in
practical operation, are figured and fully described.

We may here state, in regard to the material for boilers for
horticultural purposes, that cast-iron boilers, if properly made,
will last much longer, and be also somewhat cheaper in the first
instance, than malleable-iron ones, be the plates ever so good ;
the principle of durability resting on the former not being
injured by oxydation so much as the latter. Iq both cases,
however, the durability depends very much on the kind of water
used ; that least liable to form a deposition on the boiler being
the best.

2. Size and arrangement of hot-ivater jnpes. — Some contro-
versy has arisen, among engineers, gardeners, and others, respect-
ing the size of tube most suitable for the purposes of heating
hot-houses. 2, 3, 4, 5, and 6 inch pipes have been used, and
experiments instituted respecting the merits of each ; from which
it has been found that 4 inch pipes radiate more heat than any
of the other sizes ; and, consequently, the 4 inch pipes are now
most generally used

182 HOT-WATER BOILERS AND PIPES.

The unequal rate of cooling of the various sizes of pip«s,
however, renders it necessary to consider the purpose to which
they are applied. If it be desired that the heat shall be retained
for a great many hours after the fire is extinguished, then pipes
of larcrer dimensions must be used. Where a conservatory is
very much exposed, and liable to fall below the minimum tem-
perature during a cold night, then 5 inch pipe may be used,
which will retain the heat longer than one of smaller size ; but a
double length of pipe should always be used in doubtful cases.
But, as a general rule, no pipe should be used of more than 4
inches diameter, as the larger the pipe the greater the consump-
tion of fuel, and more heat will be given out by 4 inch pipes, in
proportion to the consumption of fuel, than by pipes of any
other size.

The ordinary method of arranging hot-water pipes is by
placing the furnace and boiler at one end of the house, and lead-
ing them along the front within a few inches of the wall. If
the house be span-roofed, the pipes ought to travel completely
round both sides ; if single, or lean-to house, the pipe should
pass along the front and return the same way; i. e., the flow and
return pipes should be placed beside each other, as will be seen
in the figures in the next section. The pipe ought never to run
by the back wall of a house, except there be some reason to fear
the entrance of frost in that quarter, which, in houses with thin
wa'lls, or those constructed with clapboards, is quite likely. In
general cases, the heat rises with sufficient rapidity from the
front, to prevent the entrance of frost at the back wall, unless it
be near the bottom of the wall.

In general, hot-water apparatus is so constructed that when
the smoke leaves the boiler, it passes immediately up the chim-
ney, by which an incredible amount of heat is lost. I have seen
the thermometer rise to 200° when placed at top of a chimney
of this kind, and an amount of heat thereby lost nearly equa]
to the whole amount radiated in the atmosphere of the house.
This is the case with many heating apparatuses, without tho
smallest notice being taken of the fact. On making this remark
lately, to a most intelligent gardener, he doubted the fact of
losing any heat by his chimney ; while, on trying the thermome

HOT- WATER BOILERS AND PIPES. 183

ter at the top of his chimney, we found it rise in a few minutea
to 137°, after having travelled through 20 feet of flue through
the back wall of the house.

Whatever apparatus be employed in heating a hot-house, the
flue should always be taken advantage of. It must be remem-
bered that smoke will not travel through a flue, — neither up
nor down, — without first being rarefied by heat. The smoke,
as already described, is, in fact, a body of gases emitted from
the fuel by the action of heat, and a portion of this it takes
along with it on leaving the furnace. In its passage, it com-
municates this heat to other bodies, as the flue ; and more so, as
the flue is in a position more or less horizontal. A flue, there-
fore, should, if possible, be carried the whole length before giving
egress to the smoke, by which a great amount of fuel may be
economized.

In laying down hot-water pipes, it is necessary to allow suffi-
cient room for their elongation and expansion when they become
hot. Want of attention to this has caused several accidents ; for
the expansive power of iron, when heated, is so great, that
scarcely anything can w^ithstand it. The linear expansion of
cast-iron,by raising its temperature from 32° to 212°, is -0011111,
or about one nine hundredth part of its length, which is nearly
equal to If inches in 100 feet. Therefore, it is necessary to
leave the pipe's unconfined, so that they shall have freedom of
motion lengthways; and, instead of confining, as has frequently
been done, facilities should be provided for their free expansion,
by laying them on small rollers, or pieces of rod-iron, between
them and the bearers on which they rest ; for the contraction on
cooling is always equal to the expansion on heating, and unless
they can readily return to their original position when they
become cool, the joints are apt to become loose and leaky, as
indeed all cast-iron pipes do, that are exposed to sudden
extremes of temperature.

Every hot-water apparatus should be provided with a supply-
cistern attached to the boiler, or the pipes; the pipe leading
from the supply-cistern should flow either into the return-pipe,
or into the boiler, near the bottom. In no case rihould it entel
the flow-pipe, as it is more likely to emit vapor, and the steam

16^

IS-l nOT-WATER BOILERS AND PIPES.

that may sometimes be generated on the surface of the water in
the flow-pipe, would find egress, unless the supply-pipe were
bent in the shape of an m. to prevent it, which is a very good
plan ; and, as a small lead pipe of about 1^ inch bore is suffi-
cient to supply a boiler of considerable size, the pipe can easily
be bent in any shape to answer the purpose.

3. Impediments to circulation, SfC. -The power which pro-
duces the circulation of the water in the pipes is the specific
gravities of the two bodies in the return and flow-pipes ; whether
this force acts on a pipe 100 feet in length, or on one only 5
feet in length, the result is precisely similar.

Now it is evident that if this unequal pressure is the vis viva,
or motive power, which sets in motion the whole quantity of
water in the apparatus, in order to ascertain the exact amount
of this force, it is only necessary that we know the specific
gravities of the two columns of water, and the difference will, of
course, be the effective pressure, or motive power. This can be
accurately determined when the respective temperatures of the
water in the boiler and in the descending or returning pipe are
known.

As this difference of temperature rarely exceeds a very few
degrees in ordinary cases, the difference of the weight of the two
columns nmst be very small. But, probably, the very trifling
difference that exists between them, or, in other words, the
extreme smallness of the motive power, is very imperfectly com-
prehended, and will, perhaps, be regarded with some surprise,
when its amount is shown by exact computation.

In order to ascertain, without a long and troublesome calcula-
tion, what is the amount of motive power for any particular
apparatus, the following table has been constructed. An appara-
tus is assumed to be at work, having the temperature in the
descending pipe 170°, and the difference of pressure upon the
return-pipe is calculated, supposing the water in the boiler to
exceed this temperature, by from one to twenty degrees. This
latter amount will exceed the difference that usually occurs in
practice.

By referring to the annexed table, it will be found that when

HOT- WATER BOILERS AND PIPES.

185

•Rl

the difTerence between the temperature of the flowing
returning columns is 8 degrees, the difference in weight is
grains on each square inch of the section of the return-
supposing the height of the boiler A (Fig. 36,
B) to be 12 inches. This height, however, is
only taken as a convenient standard from
which to calculate ; for, probably, the height
may, in many instarices, be more thari this,
thoua^h it will seldom be less.

Now, suppose that, instead of 12, 18
inches was the distance between the two
pipes, that is, between the top of the upper
and the centre of the lower pipe, and the
pipe 4 inches in diameter; if the difference of
temperature between the water in the boiler
and the return-pipe be 8 degrees, the pressure
on the return-pipe will be 153 grains, or
about one third part of an ounce; and this
will constitute the whole amount of motive
power of the apparatus, w^hatever be . the
length of pipe attached to it. If such an
apparatus have 100 yards of pipe 4 inches in
diameter, and the boiler contains, say, 30 gal-
lons of water, there will be in all 190 gallons,
or 1900 lbs. weight of water, kept in continual
motion by a force equal only to one third of
an ounce. This calculation of the motive
power will vary under different circumstances;
and, in all cases, the velocity of the circula-
tion will vary s'multaneously with it.

186

HOT-WATEli BOILERS 4.ND I'lFES.

Difference in weight of two columns of water each one foot high, at vcrious

temveratures.

Difference in
temp. i)f the
two coliiiims
of water ia

Difference

in weight of two columns of water contained
in different pipes.

Difference of

a column one

foot high.

degrees of
Fah. 's scale.

1 ill. diam.
grs. weight

1-5

2 in. diam.

'■i in. diam.

4 in. diam.

5 in. diam.

per sq. inch.

gr^.u-eighi
6-3

grs.wei!,rhl

14-3

grs. wei^iht

25-4

grs. weight

33-6

ars. weisrht
2.028

3-1

12-7

28-8

51-1

110-1

4-068

6°

4-7

19-1

43-3

76 7

211-7

6-108

6-4

25-6

57-9

120-5

250-0

8-160

10^

8-0

320

72-3

1281

317-5

10-200

12^

g-6

38-5

87-0

154-1

376-1

12-264

11-2

45-0

101-7

180-1

390-9

14-328

16^

12-8

51-4

116-3

205-9

449-1

16392

18^

14-4

57-9

1310

231-9

522-0

18-456

20^

16-1

64-5

145-7

2580

700-0

20-532

The above table has been calculated by the formula given
with table IV., (see xA.ppendix,) for ascertaining the specific grav-
ity of water at different temperatures. The assumed tempera
ture is from 170° to 190°.

It will be observed, in the foregoing table, that the amount
of motive power increases with the size of the pipe ; for instance,
the power is four times as great in one of 4 inches diameter as
in one of 2 inches, and nearly six times as great in one of 5
inches. The power, however, bears exactly the same relative
proportion to the resistance, or weight of water to be put in
motion, in all the sizes alike ; for, although the motive powder is
four times as great in pipes of 4 inches as in those of 2 inches,
the former contains four times as much water as the latter.
The power and the resistance are, therefore, relatively the same.

These calculations are given with the view of showing how
trifling a cause may impede the proper circulation of the hot
water in pipes, and that, when once obstructed, how impossible
it is for an apparatus to work. Trifling as this power may
appear, yet upon its action depends entirely the efficiency of an
apparatus. Seeing that the motive power is so small, it is not
surprising that, by an injudicious arrangement of its parts, the
motion may frequently be impeded and even destroyed ; for the
slower the circulation of the water, the more likely is it to be
interrupted in its course.

HOT-WATER BOILERS AND PIPES. . 187

There aru two ways by which the motive power may be
increased. One, to allow the water to cool a greater number of
degrees between the time of its leaving the boiler and the period
of its return through the descending pipe. The other, by
increasing the vertical height of the ascending and descending
columns. The efTects produced by these two methods are pre-
cisely similar ; for, by doubling the difference of temperature
between the flow and return pipes, the same increase of power
is obtained as by increasing the vertical height.

There are two methods of increasing the difference of temper-
ature between the flowing and returning pipes. First, by
increasing the quantity of the pipe, so as to allow the water to
flow a greater distance before it returns to the boiler. Secondly,
by diminishing the diameter of the pipe, so as to expose more
surface in proportion to the quantity of water contained in it,
and by this means to make it part with more heat in a given
time.

The first of these methods, although the most practical, is
ncessarily limited, in some instances, to the length of the build-
ing to be heated, to which the length of pipe must be adjusted,
in order to obtain the required temperature ; and, as to the
second, we have already enumerated many objections against
the use of sm.all pipes. Where the motive power, therefore, is
not of sufficient strength, the increase of the height of the col-
umn ascending from the boiler must be depended on for an
additional motive power.

In all cases, the rapidity of circulation is proportional to the
motive power, and, in fact, it is the index and measure of its
amount. For, if, while the resistance remains uniform, the
motive power be increased in any manner, or in any degree,
the rapidity of circulation will increase in a relative proportion.

Now, the motive power may be augmented, as we have seen,
either by increasing the vertical height of the pipe, by reducing
its diameter, or by increasing its length. If, by any of these
means, the circulation be doubled in velocity, then, as the water
will pass through the same length of pipe it did before, in one
half the time, it will only lose half as much heat as in the for-
mer case, because the rate of cooling is not proportional to the

188 HOT-WATER BOILERS AND PIPES.

distance through ivhich the water circulates, but to the tirjie of
transit. If, then, by raising the pipes vertically, the difference
between the temperature of the flow and return pipes be in-
creased, it appears to be the most practical method of increasing
the velocity of motion. The increased velocity, therefore, is
indicative of increased power, and in a hot-water apparatus it is
the velocity of circulation which enables it to overcome any
extraordinary obstructions.

Neither the principle nor the practice of an apparatus is in
the least affected by having an additional number of pipes lead-
ing out of, or into, the boiler; the effect is the same, whether
there be more flows than return pipes, or, conversely, more return
than flow pipes.

4. Level of Pipes. — Some persons have supposed that if the
pipes be inclined so as to allow a gradual fall to the boiler in its
return, additional power is gained. This appears very plausible,
particularly with regard to some forms of apparatus, but the
principle is entirely erroneous. This error appears to arise from
treating the subject as a simple question of hydraulics, instead
of a compound result of hydrodynamics. If the question were
only as regards a fluid of uniform temperature, then the greatest
effect would be obtained by using an inclined pipe ; but the
water in the pipes we are now treating of, is of varying density
and temperature, which very materially alters the results.

Contniiy co rhe ideas of some persons, the circulation of the
water first takes place in the lower pipe ; in consequence of the
water in the boiler becoming lighter by the absorption of heat,
the column of water in the return-pipe, being of greater density,
forces its way into the boiler, when the water in the upper pipe
falls into its place. Now, suppose the distance between the
entrance of the return-pipe and that of the flow-pipe be 12 inches.
This distance is neither increased nor diminished by any incli-
nation of the return-pipe towards the boiler, the effective pressure
being in both cases the same.

Discarding the erroneous hypothesis that the motion of the
water commences in the upper pipe instead of the lower one, —
and the motion commences at the entmnce of the ower pipe into

HOT-WATER BOILERS AND F.PES. 189

the boiler, which we have frequently proved, — it is, therefore,
evident that there can be no advantage by making the pipe to
incline fronri the horizontal level ; for whether the water descends
through a vertical or through an inclined tube, the force of
gravity will only be equal to the perpendicular height ; there
must, therefore, be an equality of pressure on the boiler under
all circumstances, whether the pipe entering the boiler be on a
level, or inclined from its junction with the flow-pipe.

When it is necessary to sink the return-pipe below the level
of the boiler, there must be a sufficient weight of water in the
pipes, above its level, to overcome the perpendicular column that
exists below the level of the boiler, otherwise the tendency of
the lower column will be to a retrograde motion. The only way
is to raise the pipe sufficiently to affisrd a perpendicular return-
ing column of sufficient pressure to raise the water in the per-
pendicular pipe attached to the boiler.

If the flow-pipe be carried on a horizontal level with the boiler,
and the return-pipe carried below the level of the boiler, it is
scarcely possible to obtain any circulation ; and if this depth be
much, no circulation at all can be obtained. We have seen some
costly apparatuses completely useless on this account ; and those
erectors of heating apparatus, unacquainted with the principles
of hydrodj'namics, are very apt to commit similar mistakes.
The velocity of circulation in such apparatus will be just in
proportion to the * difference of weight between the columns
above and below the boiler.

It must not be supposed that water will not circulate iti pipes
below the level of the boiler; and much trouble and expense
have frequently been incurred in consequence of being ignorant
of this position. All that is necessary is to give the upper section
of pipe a sufficient preponderance to raise the water in the lower
one, allowing for the superior density of the water in the lower
pipe. It, however, requires considerable judgment in adopting
any such forms of apparatus as this, for many concurring cir-
cumstances are essential to complete success. It should, there-
fore, never be adopted when a common horizontal working
apparatus can be introduced.

190 HOT-AVATER BOILEUS AND riFES.

5. Accumulation of air in pipes. — It is necessary to make
provision for the escape of air in the pipes, which sometimes so
accumulates as to prevent circulation. This is more especially
the case when the apparatus is complicated, and has many turn-
ings and vertical bends in the pipes. It generally collects at the
upper bends of the pipe, but this will depend very much upon
the mode of supplying the apparatus with water. It frequently
requires the greatest care and the closest attention to discover
where the air is likely to lodge, as the most trifling alteration
in the position of the pipes will entirely alter the arrangements
in regard to the air-vents. Want of attention to this has been
the cause of many failures, and the discovery of the places
where the air accumulates is sometimes a matter of difficulty.
For although it be true, in a general sense, that air will rise to
the highest part of the apparatus, it will frequently be prevented
from getting to the highest part by alterations in the level of
the pipes, and by other causes.

As water, while boiling, always evolves air, it is not sufficient
merely to discharge the air from the pipes on first filling them,
because it always accumulates ; and, in many instances, it is
desirable to have the air-vent self-acting, either by using a valve,
or small open pipe ; but we have generally found a cock most
convenient.

The size of the vent is not material, as a very small opening
will be sufficient to allow the escape of air'. The rapidity of
motion in fluids is inversely proportional to their specific gravi-
ties, as water is 827 times more dense than air ; an aperture
which is sufficiently large to empty a pipe in 14 minutes, if it
contamed water, would empty it, if it contained air, in one
second. Air being so much lighter than water, it is of course
necessary that the vents provided for its escape should be placed
at the highest parts of the apparatus, for there it will alvvaj^s
lodge when no impediment occurs to prevent it ; but it will
sometimes be found necessary to have several in difTerent parts
of the apparatus.

Though it is perfectly easy to provide for the discharge of the
air from the pipes, — as far as the mere mechanical operation is
concerned, — it requires much consideration and careful study to

HOT-WATER BOILERS AND PIPES. 191

direct the application of those mechanical means to the exact
spot where they will be useful. We have frequently seen
mechanics, who, though well acquainted with the practical
details of the apparatus they were erecting, yet were perfectly
ignorant of the principles on which it works ; hence the success
of such an apparatus must be entirely a matter of chance.
Wherever alterations of the level occur, vents should be pr<2-
vided for the escape of air; and, as we have said, a small tap
(or cock) will be the most convenient method of outlet.

In a complicated arrangement of hot-water apparatus, it is
sometimes so very difficult to detect the various causes of inter-
ference, and the impediments which arise are often so apparently
insignificant in their extent, that when ascertained they are
frequently neglected. Those, however, who bear in mind how
very small is the amount of motive power in any apparatus of
this description, will not consider as unimportant any impedi-
ment, however small, which they may detect ; moreover, they
will immediately see the propriety of having the evil in ques-
tion put right. But, in the more complicated forms of the
apparatus, so many causes become operative in impeding the
circulation, that the real cause of impediment may elude the
detection of even an experienced practitioner.

We will now proceed to give a description, in detail, of various
methods of heating, which come within the range of our own
experience, accompanying the descriptions with sketches, by
which their details will be more easily understood.

SECTION V.

VARIOUS METHODS OF HEATING DESCRIBED IN

DETAIL.

The heating of hot-houses, by any of the ordinary methods
of warming these structures, has hitherto been attended with
extravagant expense. The difficulty of obtaining, at a reason-
able price, the means of keeping up the desired temperature,
during long and severe winters, — the expense of the apparatus,
— the annual cost of repairs, — the continual outlay for fuel, —
together with the incidental expenses and trouble of working
them, has, in many instances, proved a barrier to their erection,
and has induced many to abandon the attempt, who had well
nigh carried it into execution. Many lovers of exotic gardening
have thus been diverted from the enjoyment of this pleasant and
healthful pursuit; and hence it is of the utmost importance,
especially to amateurs and others having small establishments,
and who do not keep a regular gardener, that the internal ar-
ran2fements of a plant-house, and, above all, the heating arrange-
ments, should be so constructed as to be dependent upon the
very smallest possible amount of time and attention, and likely
to produce the least injury by neglect.

Among the numerous systems of heatmg lately applied to
horticultural buildings in England, is one called Polmaise, from
its having originated at a place in Scotland of that name, — the
seat of the late Mr. Murray, near Sterling. The principles
upon which this method is founded are not new, and the system
itself, in other modifications, dates from a period much more
remote than any other with which we are acquainted. This
system is applied, in a more practical and perfect form, to the
warming of many public and private buildings in this country.
The very general adoption, however, of this system, does not, in
the smallest degree, give us a warrant against its defects. It

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 193

iias been ascertained that air heated to a temperature of 300 de-
grees, becomes so deprived of its organic matter, and otherwise
changed in its properties, as to be unfit for the sustenance of
either animal or vegetable life, in a state of healthy and vigorous
development, for any length of time ; and hence the admission
of a current of highly heated air into a dwelling room, or into
a well glazed hot-house, if no means are taken to restore its
original properties, must, in a short time, become sensibly in-
jurious to the animals and vegetables that are compelled to
breathe it.

And this we find to be practically the case. Every gardener,
on entering 'a hot-house so heated, is immediately sensible of
the presence of contaminating gases in the atmosphere, whether
arising from the combustion of fuel, or otherwise, and he is too
well acquainted with its effects on vegetative beings to allow
his tender plants to absorb it ; hence he takes immediate meas-
ures of modifying what he cannot possibly prevent. It can
scarcely be doubted, that a vast amount of sickness and diseaees
of the respiratory organs is, in a great measure, attributable tc
the same circumstance, especially in people of sedentary habits,
who confine themselves to close chambers, warmed by currents
of hot air, or highly heated stoves. The latter, in this respect,
is probably worse than the former ; for, in the one, the supply of
air to be heated is drawn from the external atmosphere, and,
consequently, is less likely to contaminate the air of the room,
although, when conducted, into the room at high temperatures,
the atmosphere of the latter, without egress as v/ell as ingress
of air, must ultimately become so. In the case of stoves, how-
ever, it is different, for by them the same atmosphere is heated
over and over again, by convection. The particles of air in
contact with the stove first become heated, these expand with
the heat, and, consequently, becoming lighter, rise, and the
colder particles supply their place, which also expand, rise, and
are in their turn replaced by others. Here the supply of air to
be warmed is drawn directly from the room itself; thus com-
pelling the inmates to inhale the same contaminated atmos-
phere for days together, without mixture or admission of fresh
air, except the small portion that finds an unwelcome entrance

194 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

by the occasional opening of the door ; and in the severe weather
of our winters, with the thermometer below zero, this portion is
frequently small indeed. The pleasure and ability of exercising
our physical functions in cold weather, will be in exact propor-
tion to the frequency of practice ; and it is truly surprising, that
with so much positive proof of direct injury resulting from con-
tinued confinement over highly heated stoves, many will, never-
theless, persist in so pernicious a custom, — a custom which is
truly national, and which renders the influence of these stoves
as baneful as that of the Upas tree, and sends thousands an-
nually to an untimely and premature grave.

I have observed, by some articles that have lately appeared in
an excellent horticultural periodical, (Downing's Horticulturist,)
that this much talked of system of warming horticultural struc-
tures with hot air, called Polmaise, has been adopted by some
individuals in this country. These individuals have been misled
by the extravagant statements, or rather ?7ii5-statements, that
have from time to time appeared in the Gardener's Chronicle,
(of England,) by its talented editor and others under his influ-
ence. Those who have been in the habit of reading that paper
in this country, and noticed the laudatory articles that have so
frequently appeared in it, in favor of this method, yet unac^
quainted with the practical opposition it has received by num-
bers of experienced men, in every way qualified to decide upon
its merits, can scarcely be blamed for adopting a system said to
possess so many advantages over all others ; and when it is con-
sidered that the gardening journal, which represents the opinions
of practical men in that country, is but little read in America, —
in fact, I may say, almost unknown, save by a few individuals, —
it is not surprising that they should have been betrayed into the
system supported by such authority. It is difficult, indeed, to
account for the strong-headed and one-sided policy of the advo-
cates and promoters of Polmaise. The fact is well known, that
the system, and the defects connected with it, were thoroughly
established many years before it was applied at the place from
which it takes its name. In many places it had been tried, ant)
found inferior, and far more fickle than the common smokt

VARIO,U«S METHODS OF HEATING DESCRIBED IN DETAIL. 195

flue.^ It originated at Polmaise Gardens, from the following
circumstances : — A church in the neighborhood of that place
had been warmed by a hot-air furnace, similar to those used in
dwelling-houses in this country. A gardener at that place
examined it, and thought it a good plan to warm his hot-houses ;
accordingly, he applied something of the same kind to heat his
vinery. The thing was entirely new to the worthy gardener,
as well as to his employer, who sent an account of it to Dr.
Lindley, of the Gardener's Chronicle, who forthwith espoused
the system, extolled it to the skies, and induced various individ-
uals to adopt it; and those who would not, he straightway de-
nounced as interested and dishonest men. The gardening com-
munity arose in arms, and waged war against their theoretical
foes, until its so-called originators were confounded at the amount
of opposition excited. No controversy connected with gardening
was ever carried on with so much virulence as this one on Pol-
maise heating ; and no system has been so severely tested, to

* The premature encomiums so liberally lavished upon this system, by
the zeal of its promoters, have neither shamed imposture nor reclaimed
credulity. Deceptions seldom stand long against accurate experiments,
and the mere charm of novelty soon vanishes, when economy and util-
ity are both against it. The desire of notoriety, if nothing else, has too
often induced parties to impose on the credulity of those who have not
science enough to investigate its principles, nor practice enough to dis-
cover its defects. Nothing can more plainly show the necessity of doing
something, and the difficulty of finding something to do, to obtain these
paltry ends, than the getting up of this method of heating hot-houses ;
and this, too, by those who know, or ought to know, better, and who
ought to have rejected it with contempt. When a system has no intrin-
sic value, it must necessarily owe its attractions to theoretical embellish-
ment, and catch at all advantages which the art of writing can supply.
Trifles always require exuberance of ornament ; the building which has
no strength or utility, can be valued only for the novelty of its chara,c-
ter, or the money which it cost. It is certain that the advocate of a
' new system is less satisfied by its failure, than its success, even v.'hen
no part of its failure can be imputed to himself, and when the fruits of
his labor are tested by those who can discover their real worth. No
man has a right, in things admitting of gradation, to throw the whole
odium upon his opponents, and totally to exclude investigation and in-
quiry, by a haughty consciousness of his own excellence.

17^

196 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

pr^ve its worth. Gardeners, amateurs, and all, entered the arena
of experiment and discussion. Still its promoters would not
flinch from their original position, and, right or wrong, would
cram it down gardeners' throats, whether it was digestible or
not ; and that, too, without one tittle of evidence in favor of it,
except ripe grapes in September, — a period when grapes would
ripen themselves, without any artificial heat at all. Yet its
cheapness and simplicity were its recommendation, and for
some successive winters many went to work Polmaising their
hot-houses, tearing down their furaaces, flues, &c., and con-
verting- them into Polmaise stoves, hot-air drains, and other
appurtenances of Polmaise ; but, after a short trial, and a good
deal of plant-killing, they one and all abandoned the sys-
tem with disgust. Still, amidst all this dust and dirt, and
smoke and gas, created by the cracking of plates and the
breaking of tiles, the Doctor maintained his ground, until, like
the conquered hero, he was left alone in his glory, in the
midst of the wreck and ruin he had created. What seems very
strange, he never erected one, or caused one to be erected, at
the Horticultural Society's garden, where he had unlimited con-
trol, and ample opportunity of so doing ; and those who erected
them by his recommendation and advice, were obliged to ac-
knowledge them unqualified failures, notwithstanding all their
alterations and improvements upon the original plan, which was
simply this : — A hot-air furnace is placed behind the back wall,
about the centre of the house; immediately opposite the stove
there is an aperture in the wall, for the admission of the heated
air into the house ; directly in front and above this aperture, a
woollen cloth is suspended, which is kept constantly moist by a
number of worsted skeins depending from a small gutter, fixed
on a frame of wood, which supports both the gutter and the
cloth, the lower end of the latter reaching the ground. The
cloth is made thicker in the middle, in order to equahze the
hent, — an arrangement which is absolutely necessary ; for if the
cloth was an equal thickness all over, the centre of the house
would be heated to a scorching degree, (by the rush of hot air,)
while the ends would be comparatively cold. By means of
drains under the floor, the fire-place is supplied with air from

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 197

Fig. 37.

198 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

inside the house, part of which is used for the combustion of
fuel ; the rest passes over the heated stove and enters the house
through the apertures above noticed.

Fig. 38.

Such is the original system of Polmaise heating, which has
created so much sensation in England, but which is now aban-
doned for some one or other of the many improved methods to
which it gave rise, the most perfect and scientific of which, I
have represented in the accompanying cuts. Figs. 37, 38, and 39.
The arrows marked a, in the three figures, show the entrance of
the cold air from the external atmosphere ; and its passage to
the fire-place, beneath the floor of the house, is further shown
by the arrows b, in Figs. 37, 38, and 39. Its passage over the
hot plate, through the chamber, under the bed, and thence into
the house, is marked by c, attached to each arrow in the three
figures ; ^, the fire-place ; e, a tank containing water, imme-
diately over the cast-iron plate ; /, a small funnel, or tube, for
supplying water to the tank ; g, (Fig. 38,) shows the bed on
which the plants are placed, resting on cross-bars, and filled
with pieces of brick, having a layer of sand or sawdust on top ;
this can be converted into a stage, if desired. This is Mr.
Meek's modification of Polmaise, from whom the drawing ap-
peared in the Gardener's Chronicle, and was there represented
as something very near perfection in heating, if not perfection
itself. The above sketch is somewhat altered and simplified in

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 199

N5)

□

the formation of the drains ; and yet,
in all conscience, it is complex and
compound enough for a heating appa-
ratus, as any person can see by a glance
at the above sketches. It is difficult toC:
discover wherein lies its superiority
over the old smoke-flue, and it is
clearly evident, that it has neither
cheapness, simplicity, nor economy in
fuel, to recommend it ; and, as to its
working, it is infinitely more precarious
than the common flue, and the loss of
heat is certainly much greater. This
loss has been stated, by those who have
tested its merits, to be at least one
fourth of its whole heating power. Mr.
Ayres, one of the most enlightened
gardeners in England, stated, in a paper
on that subject, published in the Gar-
dener's Journal of 1847, that Mr. Meek
wasted more heat from his one house,
than he (Mr. Ayres) did from one fire
that had nine different arrangements to
work; and in a Polmaise apparatus that
Mr. Ayres had erected, the waste of
heat was enormous ; that in ten min-
utes after the fire was lighted, he could
ignite a piece of paper at the top of the
chimney with the greatest ease ; and
when the same gentleman asked one
of its strongest advocates the following
question, " If you had a range of houses
to heat in the best possible manner,
would you abandon hot water for Pol-
maise ? " he was answered, " No, cer-
tainly not."

I have quoted the opinion of Mr. Ayres, because he is well
known to be one of the best authorities on matters of practical

200 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

importance, connected with horticulture, at the present day, and
his opinions are endorsed by almost every gardener of note in
England. Mr. Fleming, of Trentham, and Mr. Paxton, of
Chatsworth, as well as many others, regarded it as a thing ut-
terly unworthy of notice. Mr. Ayres, in the same paper already
quoted, puts to the advocates of Polmaise the following conclu-
sive and unanswerable query. If Dr. Lindley, or any other of
its advocates, can point to one place where the apparatus is at
work, and as efficacious as a hot-water apparatus ; if they can
refer us to any one place, where we can see better productions
than what have resulted from the use of hot water, why, says
he, I am ready to spend five sovereigns to go to see it, and be
convinced of my error in opposing it ; but until then, it is mere
nonsense to suppose that any responsible person wnll adopt it.

As an example of a combination of hot water and hot air,
applied in a practical and scientific manner, the following sys-
tem is superior to any other with which I am acquainted, espec-
ially for small houses. It supplies heat, moisture and air, either
singly or combined. It consists of a cast or plate iron boiler, a,
for containing the water ; in shape it is not unlike a pretty large
inverted flower-pot, with a hollow between its sides, about four
or five inches wide, having one pipe entering near the top for
the flow, and another at the bottom for the return, with a tube
entering quite through to the fire-chamber, as represented at 3,
c, and d ; then there is a hot-air chamber round the boiler and
fire-place, as shown at e, e, e, Figs. A, B, and C ; the boiler
rests on a circular course of bricks, forming the furnace/,/.
Figs. B and C. The whole is enclosed by the hot-air chamber,
from which the air is conducted into the house, at h, and is
supplied with cold air, both for the combustion of fuel, and
drawing off the heated air, at i, i. Fig. C. The fire is fed
through the door in the chamber, y, opposite which is a smaller
door in the furnace, at k. In Fig. C is shown the door of the
ash-pit, Z, through which the ashes are drawn. We know of no
apparatus, where a small green-house or conservatory is required
to be heated, that will do it so cfTef'tually and economically as
this. No particle of heat generated is lost, and in its simplicity
is evervthinof that a novi'!e could desire. Here is nothino; more

VAKIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 801

Fig. 40.

202 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

than a cone of cast or plate iron, with hollow sides, one hole
for a flow, and one for a return pipe, (these pipes can branch
into several directions, if necessary, on leaving the boiler,) and
a channel through it, with a flange, or neck, on which to fix the
smoke pipe ; build the boiler, thus formed, on a fire-place, with
just distance sufficient below the edge of the cone for a door, to
supply fuel ; this door should be quite narrow, in order to let
the edge of the boiler as far down as possible. The hot-air
chamber should be built of brick, and, if exposed to the atmos-
phere, should be at least one foot thick. In fact, the thicker
the wall of the hot-air chamber is made, the better will the
heat be retained. A tank of water is placed over the hot-air
entrance, inside the house, for evaporation. If this system be
not bungled in the construction, it will be found as cheap as
any other, and the expenditure for fuel is but trifling. The cir-
culation of the water is complete, and the air in the chamber is
neither roasted nor burned, as it is chiefly received through the
boiler, and, consequently, is possessed of more natural purity,
which is so essential to vegetable life ; and it requires so little
attention that any amateur can manage it without much trouble.
Even in pretty severe weather, when set fairly agoing in the
evening, it wants no more attention till morning ; set it right in
the morning, and you may safely leave it again till night. Nor
is it liable to accident or derangement. Not the least of its
recommendations is its economy of fuel, — a circumstance of con-
siderable importance, especially where the cost of fuel is high ;
and, therefore, the economy thereof is of double moment to the
proprietor.

We have never seen this system applied to large structures, but
we have no doubt, were the apparatus made in proportion to its
work, it would answer as well in large as in small houses ; at
all events, there is no reason why furnaces and boilers of every
description should not be chambered round in a similar way ;
a very great amount of heat, that is now lost, would be turned to
advantage, and I think it is not too much to say, that hot-houses
could be heated at one half the expenditure of fuel.

The system of heating two, three, or more, houses with one
boiler, is one of those valuable improvements which science,

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 203

combined with mechanical ingenuity has devised, and which
has been carried out in practice with the most gratifyino-
success, — so much so, that in some places, separate apparatuses
have been torn down, and this system adopted instead, merely
on account of the fuel economized thereby. Among the many
systems brought before the public, under the fine-sounding name
of improved, it is doubtful whether any of them have given so
entire satisfaction as the above, where it has been properly con-
structed. The facility so admirably afforded by this method of
heating any of the connected houses in the space of a few min-
utes after it is found neressary, is certainly a great recommen-
dation in its favor. In short, you have only to turn a tap, and
the thing is accomplished. Fig. 41 represents the ground plan
of four houses heated in this vvay, and most efficiently.

It will be seen from the plan, that the two end houses on the
front are heated by the pipes flowing and returning into the
pipes which supply the hot water for the two houses standing on
the back. This is easily accomplished by having a tap on each
pipe where it enters the house, so that either house may t:5
heated, or both together, if required.

In the extensive forcing-establishment of Mr. Wilmot, at L.;-
worth, near London, no less than seven ranges of houses, each
ninety feet in length, are heated by one boiler, and all are heated
effectually, and that too for the purpose of forcing grape-vines.
In man}^ other places, in England, we knov/ that this method
has been adopted with the very best results.

In the plan here given, the box, (Fig. 42,) which is given on a
larger scale, is situated immediately over the boiler. It may,
however, be on the same level, or nearly so, and situated in any
corner out of the way The boiler here used is a common saddle
boiler, and with a large apparatus, is probably the best boiler
for general purposes. The apartments, g g, in the cut (Fig. 41)
are offices for the garden, tool-house, potting-room, fruit-room,
&c., and maybe used as a mushroom-house. As the hot-water
pipes pass through them, they are kept slightly warmed, and
may be made useful as store-rooms and other kinds of garden
offices

In some places in England, no less than eight or ten different

204 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

VARIOUS METHODS OF HEATING DESCKIBEU IN DETAIL. 205

Fig. 42.

departments are heated by one boiler; some of them going at
one time, and some at another, and sometimes all going together,
and each having abundance of heat.^ The convenience of this
system cannot be too highly appreciated, especially when there
are a number of small plant-houses situated near each other.
For instance, suppose the boiler to be at work for one of the
houses, which may be a plant-stove or forcing-house ; well, you

Fig. B.

* Fig. B shows the common method of placing supply-cisterns. They
may be placed in some convenient situation and attached by a small
pipe to the apparatus. To prevent the escape of vapor, it is desirable
to bend the pipe into the form shown at a b, as the water in the part of
the inverted syphon at c, will remain quite cold.

206 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

go out before bed-time, and find the sky clear and frosty, con
trary to your anticipations in the early part of the evening, —
and how often do we find this really to be the case, — you enter
into your green-house, and you find the thermometer travelling
down rather quickly towards the freezing-point. Kindling fires
is generally an unpleasant business at this time of night, and
we are pretty often incnned to let the plants take their chance,
rather than be at the trouble of doing it, even if it should cost
us half a night's sleep through anxiety. Here, this unpleasant
business is dispensed with, and the anxiety too, as well as the
sitting up till the house is heated and safe for the night. You
go to the tank or box, which is generally situated so as to be
easily got at, in a recess made in the wall, perhaps, or immedi-
ately over the boiler, as represented in Fig. A ; but, in any case,
it should be so arranged as to be alwaj'-s of easy access from the
houses. The arrangement of the pipes makes no difference,
providing the accumulating tank be sufficiently elevated. The
moment the water is put on, the circulation commences; in
flows a delightful stream of hot water, warming the pipes as it
proceeds through the flow and return ; a vivifying glow of
warmth pervades the chilly atmosphere of your green-house, and
you can retire to rest without being troubled with anxious
thoughts about your plants, let the weather turn as it may.

It may appear, that, by this arrangement, a larger quantity of
fuel will be required for a single house, than if that house had
an apparatus for itself. Not so, however ; for, by close observa-
tion, it is found that the consumption of fuel is pretty nearly in
proportion to the water heated, and that the heat given off by
the pipes is in direct ratio to .the heat absorbed by the boiler
from the fire. Thus, if one house only be at work, there is only
the water of one arrangement to be heated ; and, consequently,
only one return of cold water into the boiler, the rest being shut
ofT. Now, if the water be shiU ofT into the box, that is, the
mouths of the flow-pipes stopped, there is no circulation ; hence,
there is no return of the cold water into the boiler, and, conse-
quently, no absorption of caloric or combustion of fuel. Of
course, more fuel is required to heat the four houses, than would
be required to heat one, for the reasons stated, that the larger

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 207

the body of cold water flowing into the boiler, and the larger
the body of warm flowing from, it, the more heat is carried
away ; hence, the more specific caloric is required, and the more
combustion of fuel to produce it. But the proportion of fuel
consumed to the proportion of heat generated by the pipes is
found to decrease as the radiating surface is increased. This
decrease amounts to nearly one third ; for it is found that eight
separate houses, or departments of a house, can be heated by the
same quantity of fuel which it formerly required to heat five.
This calculation was supplied to me by an intelligent gardener,
of extensive experience, who made it from strict investigation
into the working of the system under his own charge ; and the
statement is corroborated by the fact, that no case has occurred,
to my knowledge, among many with which I am acquainted, and
have examined, that has failed to give satisfaction.

This system has not the complex character which some have
assigned to it, and which, at first sight, it would appear to pos-
sess ; and, as to its cheapness, I believe little can be said about
it, when placed in comparison with other hot-water apparatuses.
I have had no means of calculating the difference, if any,
between this apparatus and as many single ones as it may be
substituted for. But it certainly appears, that four houses
heated with one boiler and one furnace, would be cheaper than
four houses heated with four distinct boilers and furnaces, the
quantity of piping in both cases being equal ; for then, three
boilers and furnaces, or the cost of them, would be saved. This
difTerence, however, will depend very much upon the distance
the pipes must travel before entering the different houses.
When the houses are situated close to each other, the difference
must be very considerable. Some apparatuses of this kind have
no box attached to them, and work directly to and from the boiler.
I consider the box, however, as a very important appendage ;
not only because it affords greater facility for working the
apparatus, but because any of the other arrangements may be
repaired more easily, and parts may even be taken away with-
out in the least affectinof the working: of the rest.

As I have already stated, pipes, in reality, radiate a vjry dry
heat ; though many think otherwise, because the air of a hot-

18=^

203 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

house, SO heated, is generally less arid than one heated by a hot-
air stove. This arises from the fact, that, by hot-water pipes, a
much larger radiating surface is presented to the atmosphere of
the house than by any other method, and the heat is radiated at
a lower temperature, and more equally diffused ; hence, less
moisture is carried upwards by currents of heated air and
deposited on the glass by condensation. Thus, it is clear, that
the larger the heating surface that is acted upon by the air, and
the lower the temperature of that surface, the less moisture will
be drawn from the plants and the atmosphere of the house. It
is always desirable, however, to provide against aridity in the
atmosphere, as heated air will have its supply of moisture, come
from where it will ; and if it cannot draw it from anywhere else,
it will draw it from the plants, or whatever can supply the larg-
est quantity under its influence. For this purpose, a number
of troughs are made to fit on the pipes, made of zinc or gal-
vanized tin. These troughs may likewise be made of earthen
w^are, and perhaps more cheaply than of zinc, though more lia-
ble to be broken. They may be filled with a syphon from the
pipes, or by a common water-pot. When moisture is required
in the house, an agreeable evaporation will be given off, and
which can be rendered still more healthful, by putting in a few
bits of carbonate of ammonia among the wat^r, or common
pigeon's dung, or guano. As the water warms, ammonia will
be evolved into the atmosphere and greedily absorbed by the
plants.

In recommending this system to the notice of those who may
be entering upon the erection of hot-houses, we would slate that
we recommend it not only upon our own experience, but also
upon that of others, whom we consider much better qualified
to decide upon its merits. Nor do we mean to assert that it is
the ne plus ultra of a heating apparatus, although, under certain
circumstances, it is the nearest approach to it that has yet come
under our observation. In making this statement, we do not
wish to dispute the judgment of those who think differently, and
who have opposed it more from a feeling of groundless distrust,
than from any fact they can bring to bear against it. We have
conversed with many who would prefer heating each house with

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 209

Its own fire and boiler, and be at the additional trouble of attend-
ing them too. This, however, springs from a fear entirely with-
out foundation, and we are convinced that a little experience in
the working of this double system of heating would so prove it.
It is a very singular attachment which some people have for old
methods and customs, that they will unflinchingly adhere to
them, however little merit they may have to recommend them.
Some individuals, with a self-sufRciency altogether incompatible
with knowledge, will smile or sneer at what they are pleased to
call the folly of enthusiasm, and, without seeming to be in any
way sensible of the importance of whatever tends to the im-
provement of horticulture, regard these innovations merely as
idle speculations of men who have nothing else to do but invent
them ; and while we cannot guard too much against the adoption
of methods that will prove inconvenient in practice, although
supported by theory, it is an injury to gardening, as an art, to
give an unqualified opposition to systems that have proved their
superiority, and are still capable of great improvement. This
plan is not introduced under the deceptive cognomen of cheap-
ness. Its cost will very much depend upon the circumstance of
position, and may, after all, be much less than some of the costly
and cumbrous apparatuses that are now in use. The easiness
with which it is worked adds an additional item to its worth,
for, when once set agoing, and understood, the veriest novice
could manage it. "^

* It is the common fate of new systems connected with the art of
horticulture, that they are eulogized beyond their real merits by their
advocates, and decried as strongly by their opponents ; for every new
system has alwaj^s both friends and foes, each of -whom are unAvilling to
adhere to the naked truth, and equally incapable of appreciating its
merits with exactness. "When a person invents, or fancies he has
invented, something new, he is too much inclined to set a high value
upon it ; for, if it has cost him much labor, he is unwilling to think he
has been diligent in vain. He, therefore, magnifies what is merely an
alteration into an improvement, and probably prevails upon the imagi-
nation of others to fall into a false approbation of the system, and to
regard that as a valuable desideratum which, at the best, was only a
novelty. If durability and economy in working be allowed to constitute
any part of excellence in a system, then this one has especial claims to
our notice ; a fact which cannot be said of many others.

210 VARIOUS METHODS OF HEATING DESCRIBED IN DETAlir

Fig. 43.

mm:^^^''

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 211

Fig. 43 shows a house wherein proyision is made for increas-
ing the heating surface, when more thiin a very moderate degree
of heat is required from the pipes. A box or tank, made of wood
or zinc, is placed under the stage, and passes all round it on a
level with the pipes. This tank is supplied by a branch pipe «,
proceeding from the flow-pipe, and is provided with a tap at b, for
shutting oflf and on the water when necessary. This is a most
convenient arrangement ; for, if a moderate heat only be required
from the apparatus, then the pipes will be sufficient, and a very
small fire will be required to heat them, as the quantity of water
is small. When it is found necessary to increase the tempera-
ture of the house, the pipes being then tolerably warm, the
water from the flow-pipe is admitted into the tank by opening
the tap. The heat of the pipes is slightly reduced, but the
radiating surface is increased, and the temperature of the house
rises by an equal distribution of heat. It might be supposed
that a quantity of specific heat is lost to the atmosphere, by
drawing it from the pipes and throwing it into a body of cold
water. Not so, however, as a little consideration will make
sufficiently clear. Thus, if the atmosphere of the house be at
45 degrees, the water in the tank will be at 45 degrees also.
Now, suppose the tank and the pipes to contain equal bodies of
water, then, if the pipes communicate a portion of their heat to
the tank, the temperature of the water in the tank will rise just
as much as the water in the pipes will fall ; for, if two equal
bodies of water, at different temperatures, are mingled together,
the temperature produced by the mixture will be the mean of
their previous temperature. Suppose, for instance, that the
temperature of the water in the pipes was 300, and that in the
tank 45 degrees, and that, by the opening of the tap, the hot
water in the pipes, and the cold water in the tank, were inti-
mately mingled together, then the temperature of both would
be 122*5 degrees. The temperature of both has been equal-
ized, but the atmosphere of the house has lost none by the
change, but rather gained, as the tank being 77 degrees
above the temperature of the atmosphere, more heat will be
diflfused than with the pipes alone at double the temperature,
and the object will be gained, namely, that of preventing the

12 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

j)lants from being subjected to a high temperature, that are situ-
ated in the vicinity of the pipes. In the drawing, (Fig. 43,)
the flow and return pipes are placed together, the other side
being heated by the flue from the fire. This arrangement is
intended to economize heat, and to save the expense of pipes,
which, in some places, might be an object of importance, and
even if they were not so, the plan is decidedly good. As for the
tank, it is an admirable contrivance. Not only is the evil of
having highly heated pipes for weeks and months together,
directly under the roots of plants, prevented, but when the tank
is once heated, a more agreeable and healthy warmth will be
produced, and the equilibrium of temperature be maintained
for a much longer time.

The tanks used may either be wooden or metallic. The lat-
ter are preferable, both on account of durability and radiation
of heat, although wooden ones are much cheaper, and answer
the purpose perfectly. Wooden tanks, if the wood be kyanized,
or otherwise treated with a metallic solution, will last for many
years, and produce a very agreeable warmth. Galvanized iron
and zinc are now in common use for this purpose. The dura-
bility imparted to it by the process of galvanization, which pre-
vents oxidation, is evident from the number of articles made
of this material and exposed to the atmosphere. For horticul-
tural purposes, this article is likely to become exceedingly
useful; as ev^ery one is aware of the injury which ordinary hot-
water pipes, and other metallic substances used in horticultural
erections, are liable to from rust. Tanks made of this material
give out their heat much more rapidly. But it must be consid-
ered that the same circumstances that would render them more
quickly effectual, would also render their effect more transient.
For pits and very small houses, the pipes and tanks might be
made of this material. Its cheapness and lightness are impor-
tant advantages in its favor; for, when heavy-cast metal pipes
are conveyed to a great distance, the cost of carriage will nearly
amount to the same sum as would purchase galvanized iron or
zinc tanks, and convey them too.

In using this kind of tanks, the utmost care ought to be
taken in supplying them with water. They ought never to be

VAUIOUS METHODS OF HEATING DESCRIBEl IN DETAIL. 213

over one third or half full ; the less water that is in them the
better, compatible with safety. To work well, the water ought
never to boil into them, otherwise the force of the steam will
expand the metal, and, if the heat continue, it is liable to burst
Fig. 44 represents a house heated with a tank made of galvan-
ized zinc. Next to the boiler there is a short piece of cast-iron
pipe which prevents the zinc from being affected by the imme-
diate action of the fire. The house from which this sketch was
taken has been in use for some years, and has given perfect sat-
isfaction, while the original cost was very small. The principal
objection to the use of this material for heating purposes, is, as
I have already stated, the rapidity with which it is heated, and
the rapidity with which it parts again with its heat. This cir-
cumstance renders it a good conductor, but a bad retainer, of
heat; useful where speedy and immediate action is required, but
useless where a slow and long-continued radiation is necessary
at a very low temperature, as, for instance, for bottom-heat,
for propagating-beds, and for plant-stoves. In such circum-
stances, we should decidedly prefer wood, particularly for the
first-mentioned purposes. In green-houses, and even in forcing-
houses, it may answer well ; for it must be admitted that the
source of heat must ever be looked for at the boiler, not in the
material of which the tanks or pipes are made. And, although
the advantage of employing a material that will absorb the heat
given off from the source to any extent, and part with it gradu-
ally, must be apparent, at least, when it is an object to take
advantage of the heat so absorbed, store it up, so to speak, with
the view of employing it when the action of the apparatus
becomes enfeebled. The law by which this is effected is the
same as that by which the two bodies of water become equal-
ized in temperature by admixture as described on page 210.
This is the law of equalization, which constantly tends to bring
all bodies to an equal temperature. If, for instance, the hot water
from a boiler be admitted into two separate tanks, one of wood
and the other of zinc, then, by placing the palm of the hand upon
the wooden tank, it will feel agreeably warm, while the zinc oi
tin one would be quite unbearable, if not burn, and this while
the temperature of the water in both tanks was the same. The

214 VARIOUS METHODS OF HEATI^'G DESCRIBED IN DETAIL,

Fig. 44.

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 215

reason is, the metal is a good conductor, and quickly conveys
away the heat from the water by imparting it to a colder body,
while the wood is a bad conductor, and retains it. Again, the
metallic tank will have the same temperature as the water
within, before the wooden one is sensibly warm. In fact, the
wooden tank retains and accumulates the heat, while the metal-
lic one gives it off as soon as it receives it. None of this heat,
however, is lost to the atmosphere of the house ; for though the
wooden tank parts with its accumulated heat more slowly, it as
certainly parts with it, in the course of time, as the metallic one.
It parts with its heat gradually till it is reduced to the same
temperature as the atmosphere around it. A house heated with
a wooden tank will maintain an average temperature with less
expenditure of fuel than a thin metallic one, the other circum-
stances being equal, which is accounted for by the fact that
when a house is suddenly heated, the warm air is forced rapidly
upward, and, coming in contact with the glass, is rapidly cooled,
descends, and is again warmed, till the warming surface is
entirely deprived of its heat ; then the temperature falls. On
the other hand, when the heat is disseminated at a low temper-
ature, the atmosphere is less agitated, and the ascending air
less rapid in its motion. Not so much escapes through the laps
of the glass, or is cooled down by the external cold upon its
surface ; and hence, the same quantity of specific heat maintains
a given temperature for a longer time, when gradually given ofK
than when suddenly given off at a high temperature.

Although the sudden rise and fall of temperature by thin
metallic tanks be apparent, we do not condemn their use for all
purposes. As we have already said, they may be profitably
used in many kinds of erections, and for various purposes ; and
I consider them worthy of more extended trials. But I do not
believe that they will ever supersede cast metal pipes for the
general purposes of heating by hot water; and for a retention-
tank, I would decidedly prefer wood. Fig. 45 represents a
house with a wooden tank, in which the water circulates by
various divisions, after it enters from the flow-pipe. This tank
was erected in a plant-house beneath the stage, as shown in the

end section, Fig. 46, which may be objectionable as regards
19

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 217

its position, but the chief object was to hold and retain a sup-
ply of warm water, which it did admirably, and efTectually
warmed the house besides. The manner in which this tank
retained the heat after the fire had ceased to burn, impressed
me with the idea that heat could be drawn off from the regular
apparatus, and applied afterwards when necessary, or for any
other purpose. I believe the heat generated by wooden tanks to
be most favorable to the structural development of plants, as con-
taining- more moisture than heat radiated from either iron or
brick, because the temperature is lower.

We have already remarked that the tank system of heating
hot-houses has but very lately been brought into general notice,
and still receives much less attention than its utility, simplicity,
and economy claim for it ; and where it has been used, it is
chiefly as a medium of bottom-heat, for which it is undoubtedly
superior to anything that has yet been applied. The efficiency
of tanks in supplying atmospheric heat has been doubted by
some and denied by others, without, however, as far as I can
learn, bringing any practical facts to bear upon the subject. I
am convinced that the system, rightly applied, will prove the
doubts to be entirely without foundation. Simplicity in any
system of heating is a point of incalculable importance ; and
when economy and adapdbility are combined with it^ a claim is
presented which facts only can overthrow. It is very true that
we practicals are, many of us at least, prone to adhere bigotedly
to any method with which we are acquainted, and which we
have already proved safe and simple, and are unwilling to
believe that any other method can be safer and simpler than
itself. Gardeners are proverbially a cautious and thoughtful
class of men ; perhaps seldom directly opposing principles
founded upon theoretical deductions, but frequently slow in
instituting experiments with the view of establishing their truth.
In these days of invention and progress, it is the duty of every
one engaged in horticultural pursuits, and particularly garden-
ers, not only to make themselves acquainted with the views and
opinions of other persons, but to test, by various counter-experi-
ments, the conclusions they have drawn. No man is justified

213 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

ill regarding his knowledge of any system vvell-founded, except
upon experiments and observations of his own.

Gardeners are, of all others, the best qualified to decide upon
the merits of any system of heating hot-houses, and to ascertain
its effects upon vegetable life. They are, by necessity, familiar
with the habits of plants ; and, by an instinctive practical knowl-
edge, (if nothing more,) they are less likely to be deceived by
the peculiarities produced by heat and cold, dryness and moist-
ure, either in deficiency or in excess. The gardener is able to tell
whether his plants be in vigorous health, or the reverse ; whether
they are suffering from atmospheric impurity, aridity, or stagna-
tion; and, besides, the necessities of culture compel him to
study the causes of such changes and conditions. All gardeners
are aware that causes the most dissimilar will produce results in
every way identical, while the self-same causes, repeated with
the greatest care, and under circumstances where it was appar-
ently impossible for them to be at variance with the first, will
nevertheless produce results totally different ; and the universal
axiom, that like causes produce like results, would sometimes
appear to be set at naught.

It has ever been a desideratum, as regards the heating appa-
ratus, especially the hot-water kind, that there should be among
gardeners a perfect knowledge of their details, and of the man-
ner of repairing them. It is true we know when they become
warm, and when they cool ; but, as for the rest, once erected and
the workmen gone, they are like a watch, or a doctor's prescrip-
tion, — they rhay go wrong, and become unworkable, but we
cannot put them right, nor scarcely discover w4iat is the matter
with them, till we send for the tradesman ; and then, after an
hour or two pulling and hammering, dusting and besmearing our
plants, turning everything in the house topsy-turvy, lo ! we are
told that a joint had cracked, a collar had split, or some such
mishap had befallen our apparatus. Facts of this kind will be
in the experience of every one who has had much to do v»ith
heating apparatus. Now what I would urge is, that no part of
a heating apparatus should be under ground, or buried in brick-
work so far as it is concerned with the interior of the house
Not an inch of it ought to be covered up with anything. It

VARIOUS METHODS OF HEATmG DESCRIBED IN DETAIL. 219

ought to be all exposed, as far as possible, and of easy access.
Moreover, let it be simple in its arrangements ; the simplicity
of any system is a plea in its favor. Some people, however,
despise simplicity, and would baptize everything about them with
confusion and complexity. We have met with people who fancjf
that their green-house could not be heated without an array of
pipes, winding here and there, as intricately arranged as the
wheels of a watch, and as useless for the heating of their house
as the pillars that support the portico of their dwelling. One
would think that they admired cast metal pipes miore than their
flowering plants.

One of the chief commendations of hot water, as a heatino-
power, is the facility with which you can bring it in contact
with the atmosphere of the house ; however simple the manner
in which it may be applied, it is not the less effectual ; and how-
ever commendable in other respects the warming of hot-houses
by improved methods of hot air may be, the channels and
chambers, the numerous hot and cold air drains, the under-
ground building of brick-work, and the multifarious intricacies
of its arrangements, are sufficient to deter any person from the
erection of such a complicated affair. This will be apparent
from a glance of the drawing of Meek's improved method of a
hot-air heating-apparatus, given on page 197. Such a concern
may do very well on paper, but it will not do in practice. It
may answer admirably as a plaything for amateurs, who have a
fanc}'- for it, and nothing else to do with their time but to amuse
themselves with the motions of air; but, as a method of warm-
ing a hot-house, no sane person will adopt it, when he can have
the thing done by a simple tank and boiler at half the expense.
As a system, it is good for naught. No person who understands
it will adopt it ; and those who do not know it, but will have it,
let them try.

The tank S) stem may justly be regarded a real improvement
in heating, whether for top or bottom ; and it is the simplest,
and perhaps the cheapest, that has yet been brought under pub-
lic notice. The sketches we have given are probably not the best
that could be adopted. It is yet open to great improvement, and

it would be premature, at present, to hazard an opinion upon
19*

222 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

what may hereafter be effected by it, by the friction of one idea
against another in the course of experience. For small pits,
filled with young stock, it is invaluable, as a pipe may be car-
ried from a boiler, heating other structures, into a pit near by ;
and, these being easily covered at night, a sufficiency of heat
may thus be conducted into them to keep the plants safe
during the winter, without much increase of fuel, or any v»qth-
drawal of heat from the structure for which the apparatus was
originally constructed. Green-houses are generally too much
crowded in winter, and the adoption of dry pits for the conserva-
tion of plants that are somewhat hardy in their nature, is not
so common as it ought to be. Pits might be so arranged
as to obtain the superfluous heating power from other houses.
This, in some instances, has been done, and it is likely that
more will ere long be done in the same way ; for if the vast
amoimt of fuel, consumed by the general methods of heating,
could be economically applied, without waste, it is not exaggera-
tion to say that at least one third could be saved.

The hygrometrical and ammoniacal condition of the atmos-
phere of hot-houses has not received that attention, in connec-
tion with heating, which the importance of the matter evidently
demands. We have books enough teaching us the effects of
certain volatile and subtile fluids upon vegetable life, and exhib-
iting a multitude of facts which no person will venture to dis-
pute ; yet, in this matter, we practicals have, in a great measure,
been deaf to the teachings of science, and blind to the lessons
of nature. Practically, or experimentally, we have made but
little inquiry whether invigorating or contaminating gases
abounded in our hot-houses. Now, nature is either a good or
a bad teacher, just in proportion as our knowledge of her im-
mutable laws is limited or comprehensive. When we confine
plants in a case of glass, as in a green-house, if we give them
soil to grow in and water to drink, we are apt to think they
ought to be contented ; and if they do not thrive well and prove
productive, we call them ungrateful, or very difficult to rear.
Now, we ought to consider that plants feed by their leaves as
well as by their roots, and that the volume of air in which the
leaves are expanded, requires to be as regularly moistened and

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 221

manured, as the body of earth in which they grow. It may
appear vague and visionary to talk of manuring the atmosphere
of a hot-house, but the thing is in reality neither so vague nor
yet so visionary as it seems ; for here science comes to our
aid, and not only defines the vagueness, but converts the vision
into a practical reality. It proves to us, both the benefits of
manuring the air, and the manner of doing it. We know that
plants derive a large portion of their food from the atmosphere ;
and we know, also, that the arid atmosphere of a hot-house is not
always charged to a proper degree with these life-giving gases.
An impoverished atmosphere must have the same effect as an
impoverished soil. This is a well-known fact, and requires no
demonstration to prove it. We are well aware that many
plants will grow luxuriantly for years, suspended in the air, pro-
viding they be kept in a condition calculated to sustain them;
but deprive them of these gases, and they will die, — deprive
the atmosphere of its humidity, and they will quickly cease to
exist as living plants. These vegetables absorb carbonic acid,
ammonia, and water, from the atmosphere, by their leaves, even
more abundantly than by their roots. This is especially the
case with plants cultivated in pots ; their roots being circum-
scribed into a small space, the nourishment is speedily exhausted,
and if the atmosphere be at the same time robbed of its gaseous
elements by artificial heat, the plants must perish, if this defi-
ciency is not supplied to them by artificial means.

We have seen, that plants, even of a ligneous nature, will
grow, form lignin, and proteine compounds, while suspended in
a moist warm atmosphere, much in the same manner as plants
do when growing in the soil. The amount of mineral matter
they contain is indeed very small, and may be derived from the
dust continually floating in the atmosphere, which is dissolved
as it falls upon the leaves, and is absorbed with the atmospheric
fluids. Here, then, we have plants subsisting upon the ingre-
dients of the atmosphere ; and experiments seem to prove that
all plants are nourished by the same substances, in variable
proportions, the chief of which are carbonic acid, water, and
ammonia.

Experience has already proved the beneficial effects of these
substances as fertilizers, not only of the soil, but also of the

222 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

atmosphere. Plants watered with a weak solution of the salts
of ammonia (smelling salts) will, in a few days, show their
invigorating effects ; and plants grown in a hot-house, with
the atmosphere impregnated with ammonia, will exhibit, in
a manner equally as striking, its beneficial influence. Every
gardener is aware that plants, growing in frames or pits
heated with fermenting manure, will, under ordinary circum-
stances, evince a much greater degree of luxuriance than in
any other situation. In fact, dung-beds are considered an an-
tidote for nearly every disease that plants are heir to, and not
without a well-grounded knowledge of their effects ; and
hence, when 4i gardener wishes to invigorate sickly plants, he
straightway plunges them into a hot-bed, and if there be any
vitality left in the plant, it seldom fails in pushing out vigorous-
ly. Now nothing is more obvious than the fact that neither the
heat, nor the moisture alone, produced this result ; for if the
plant had been plunged in a hot-bed warmed with the combus-
tion of fuel, in nine cases out of ten the result would have been
the very reverse. In fact, it is found, by long experience, that
neither heat nor moisture alone will compensate for the removal
of a sickly plant from the congenial warmth of a well-prepared
dung-bed. Now, the question which presents itself for solution,
in regard to this mode of heating, is, What is the cause of this
difference, and how can it be otherwise produced ? If we con-
sider the effects due to the gases already mentioned, to be fully
established, we will find that the secret of all this lies in the
stimulating gases of the manure, which constantly surround the
plants when exposed to the mild heat of a dung-bed. The old,
and now almost obsolete, plan of warming forcing-houses with
accumulated masses of fermenting manure, is well known ; and
the luxuriance of vines, forced by this method, is as well known
as the method itself. This luxuriance was produced by the
amrnoniacal and other gases evolved during the process of fer-
mentation ; and though this method of forcing has been entirely
laid aside, on account of its unsightly appearance, and the incon-
venience of keeping up a constant supply of well-prepared ma-
nure, still the merits it possessed, by its ammoniacal properties
have not yet been secured in any other mode of heating.

VARIOUS METHODS OF HEATING DESCKIBED IN DETAIL. 223

Suppose, then, that we have already solved the first part of
the problem, by attributing these results to the beneficial action
of gases arising from fermenting manure ; let us consider how
we can produce those gases, under other circumstances, i. e., with-
out the presence of manure.

Ammonia is the result of a combination of the two gases,
hydrogen and nitrogen, and has been hitherto known to gar-
deners, and applied by them, chiefly in the state in which it
exists, and is produced by the decomposition rf animal and veg-
etable matter, as in the formation of dung-beds, from which we
can perceive it escaping in an uncombined state into the atmos-
phere. It is easily distinguished from all other gases by its
powerful, penetrating odor. It remains, however, but a short
time in this state, as it is speedily absorbed by porous sub-
stances, and by living plants, and combines with other gases,
forming compounds; with carbonic acid, for instance, forming
the carbonate of ammonia of the shops, from which it can read-
ily be disengaged and evolved into the atmosphere of a hot-house.
Ammonia, in the state of a carbonate, is exceedingly volatile, and
when a small portion is mixed with water, and the temperature
raised to about 112 degrees, a large quantity of ammonia is
evolved. This will be still better efiected by mixing a small
quantity of potash, soda, or lime, with the water in which the
ammonia has been absorbed. The salt which held the ammo-
nia in combination is taken up by these alkalies, and the ammo-
nia, being exceedingly volatile, escapes into the atmosphere.

By dissolving the sulphate or carbonate of ammonia in hot-
water tanks, or in thin troughs placed over the pipes and flues,
an atmosphere may be produced strikingly similar to that of a
dung-bed, and capable of producing nearly similar eflfects.
Dung-beds are probably the most natural methods of applying
artificial heat to plants ; and it is yet doubtful if we shall ever
be able to supersede them in their invigorating influence,
although much may be done to modify the existing evils of arid
and unwholesome atmosphere in hot-houses. The mixture of
guano, pigeon's dung, and various other substances, gives off*
large quantities of ammonia in warm water, and may be used
with advantage instead of its salts. Tanks afibrd an excellent

2Ji VARIOUS METHODS OF HEATING DESCRIBED L\ DETAIL.

means of effecting this purpose, and are, not only on the score
of simplicity and economy, but, also, in an ammoniacal and
hygrometrical point of view, -the best methods of producing heat
with which I am acquainted.

The principal kind of structures to which the tank system of
heating has yet been applied, to any extent, in England, are
what are termed forcing-pits ; and in these it has been exten-
sively used, with much success. In this department of forcing,
it has proved one of the greatest improvements of modern times.
In England it is used on a large scale, in the culture of pines,
vines, melons, cucumbers, &c., during winter ; and, although
in this point of view, it may not be deemed of equal importance
in this country, where early forced fruits and vegetables are less
demanded, it is, nevertheless, calculated to be of immense value
to horticulturists in general, and plant-growers in particular.
There is little doubt, but, ere long, an increasing demand for
early forced fruits and vegetables, fresh from the forcing-house,
will stimulate enterprising individuals to the erection of those
cheap and simple structures, which could scarcely fail of being
a profitable investment. A given space, covered with a glass
roof, and otherwise protected, requires a comparatively small
amount of fuel to maintain a tolerable degree of warmth in the
soil, much less than is generally supposed. It is not my pur-
pose to enter, at present, into the details of this question, and I
merely notice it in connection with the subject of heating. By
many it may be regarded as a mere speculative theory, which
it certainly is, yet I think it worthy of more serious considera-
tion.

In many of the English nurseries, tanks are used for stimu-
lating the growth of their young stock, and in many kinds the
annual growths are indeed remarkable. We have seen camellias,
one year from the graft, as strong and vigorous as plants three
or four years old under the old method of culture. Almost all
kinds of green-house plants are benefited by being kept in tank
pits, and we are inclined to think, if tank pits were more gener-
ally used by the nursery-men of this country, they would have
their plants easier got ready for market, and they would require
much less time to do so than is generally the case.

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 225

For amateurs wishing to " try to grow many things," but
who have little time or money to spare for such purposes, one
of these pits is just the thing he requires. A small pit, of this
nature, with a very little attention, would keep a considerable
number of green-house plants over the winter, and enable him
to preserve a plentiful stock of bedding-out plants, such as ver-
Denas, petunias, calceolarias, heliotropiums, penstemons, and
many other pretty little things for the decoration of the flower-
garden in summer. How much more pleasant and profitable
would it be, for lovers of flowers, to have a little pit erected in
some snug corner of their garden, instead of losing all their
roses in winter, and storing their drawing-room plants, — their
oranges, their camellias, their gardenias, oleanders, (Sec, — into
the cellar, from which, of necessity, they are frequently taken
half dead. Such a pit as I allude to may, or may not, be made
to comprehend a narrow pathway along the back, — this would
certainly be the most convenient, — and this portion might be
covered with boards or shingles. This path would greatly facil-
itate the operations of watering, &c. Whether such a pit ought
to be sunk below the ground, or placed on a level with its
surface, will depend altogether upon the nature of the situation.
Thus, if the position be a dry one, or admits of being made so
by drainage, it should, by all means, be sunk two or three feet
below the surface. But if the situation be very damp, it would
certainly be bad policy to sink it so much ; for whatever advan-
tage it would gain in the way of protection, would be more than
counterbalanced by the dampness which would be unavoidable.
A pit, sunk in a dry situation, requires less fuel, even in the
severest winters, than people generally suppose ; and if covered
from the frost, and kept dry, many plants will live over winter
without fire at all. Plants are very much like animals, in re-
gard to warmth ; when once accustomed to a high temperature,
they must have it continually; but inure them to the cold of
autumn, and thev will do with less heat in winter. This is
not saying that we can change the Tiature of plants, and make
them to endure a lower temperature than they can possibly,
under any circumstances, bear. But we know that plants may
be brought into a condition to enable them to survive a much

2£6 VARIOUS r.IETHODS OF HEATIAG DESCRIBED IN DETAIL. ••

greater amount of cold than they could otherwise have endured,
and this, too, apart from the application of aitificial heat. When
half-hardy plants are destroyed by frost, its effects are most
frequently visible at the collar, or lower part of the stem, arising
from the intense action of the cold at the surface of the ground,
which, in combination with moisture, first contracts and then
expands the principal sap-vessels of the plants.

The annexed cut represents a double range of plant-pits,
heated by wooden tanks. These tanks are supplied from a
small boiler, placed in the centre, between the two pits ; a, end
section, shows the end of the tank, which is about six inches
deep, and divided into two compartments, by placing a slip of
wood up the centre, leaving a space at each end, for the water
to circulate round. The arrows show the course of the water
in its progress round the tank ; the flow and return pipes are
represented by dotted lines. These tanks are merely shallow
boxes of wood, occupying nearly the whole inner area of the
pits, and resting on piers of brick, or posts of wood ; rough
pieces of wood are laid crossways over the tanks, and a laj^er
of broken bricks, (or sawdust, if the pots are to be plunged,
which is desirable,) which forms the bottom, or floor, of the pit.

It is truly surprising how very little fire is required to main-
tain a perceptible warmth in these pits ; and the growth of plants
or vegetables of any description is astonishing. In some nurs-
eries these, pits are kept continually at work. The lights are
entirely thrown off them, and the tops thoroughly exposed to
the air ; this prevents them from being drawn up tender and
etiolated, and while their roots are stimulated with an agreeable
warmth, they have, nevertheless, all the strength and hardiness
of plants grown in the open air.

For the growth of early melons and cucumbers these pits are
admirably adapted ; they are equally efficient, without having
the disadvantages of dung-beds. Their neat and tidy appearance
gives them a place beside the other hot-houses, (which is not
the case with hot-beds of manure,) to none of which they
yield, in point of utility or interest.

If there is any one branch of exotic horticulture that possesses
more extended interest than another, it is, undoubtedly, the cul-

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 227

Fig. 47.

■I
I

•-v

I
I

N'^'i^'">^i^S'^'i- -V ■

'n.^S>^<?-?S^-^>^

I
I

-'>^\<.<::^-$^:^-:>.^^>

•20

22^5 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. '^

tare and early forcing of the grape-vine. The increasing im-
portance of this branch of gardening will justify me in devoting
a few pages to that subject. The culture of this fruit occupies
a very high position in this country ; volumes and pamphlets
innumerable have been written about it, by practicals, theorists,
and experimentalists, each one supposing he has discovered
something, which, for want of more extended information, he
calls " new," in the managing, heating, or ventilating of his
vineries, when, lo ! another starts up and knocks it on the head,
and proposes a new nostrum ; and every one is sure to find
some ignorant enough to follow his advice. It might not be out
of place here, to discuss some of the most important points which
an extended experience has proved to be desirable, in the heat-
incr of structures for the culture of the vine.

And, first, let me remark, that nothing is more creditable than
the use of the readiest and cheapest means at hand for securing
a definite result. Whatever system may be thought of, it is
desirable to understand the principles upon which it rests for
its success. It must be borne in mind, in the outset, that no
care in the culture of the vine, under glass, will compensate for
a contaminated atmosphere, which should, at all times, approach
to the natural summer purity and warmth.

Were we to analyze and bring into view the first principles
of horticulture, and make ourselves masters of the various effects
produced upon the grape-vine under glass, and the causes, we
should often smile at the ludicrous importance we attach to par-
ticular methods of practice. A blind man, by habit, will often
walk along a devious path, with quagmires and pitfalls on either
side of him, and safely too, whether at midnight or noon-day ;
and we often follow the example of the blind. We, in one way
or another, acquire the faculty of performing certain operations
with a life-like certainty, though in the same degree of mental
darkness as regards the power of deviating from the beaten
track without committing egregious errors. In all such cases,
there can be no doubt that it is wise to follow the old trodden
path, till we can more plainly see which is the safest for our
particular case. It does not so much signify which of the best
methods we adopt, provided the science of cuhure has given us

' VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 229

sufficient light upon the nature of the endless variety of means
and methods that are before us, which, however defective they
may seem in the hands of the inexperienced, may be safe and
certain in the hands of the skilful practitioner.

It cannot be admitted, however, that in carrying out this
principle it is unnecessary to scrutinize, with the utmost exact-
ness, the facts for or against any particular system, which the
fancy of gardeners or amateurs may choose to follow. The very
fact that there are so many systems of warming hot-houses,
gives increased force to the call for minute record of experi-
ments. Upon no safer principle can our knowledge of horticul-
ture be based, so that those who are its patrons and votaries
may follow principles, founded upon facts, and not upon specula-
tions. Hence thev would not have to endure the inconvenience
and risk of being dependants upon plausible theories, which
practice may prove to be absurd.

A great deal that might be said on vineries, in regard to heat-
ing them, can have but a local application ; and, in some places,
no application at all, inasmuch as the diversity of climate in the
different states would render the erection of an apparatus at one
place necessary, which would be absolute folly in another. The
erection of a powerful and expensive heating-apparatus is only
required where the forcing of the vine is desired in winter, under
difficulties of intense cold and long-continued frost, as in New
Eno^land. To these latter circumstances the followino- method
will chiefly apply.

Figure 48 shows the plan of a winter vinery, i. e., one for
forcing in winter ; a is the border, underneath which is an
arch of brick, forming a chamber, through which the hot-
water pipes are made to travel, after going round the house
inside for atmospheric heat. The cold water returns again into
the boiler at b.

As far as I can learn — and I have made many inquiries —
this system of applying heat, in connection with vine-growing,
has not yet been adopted in this country; still, it maybe in
use, since the obvious utility of it must have been apparent to
those who are engaged in the culture of hot-house grapes. To
recommend such an expensive system as this, for all occasions

iiHO VARIOUS METHODS OF HEATLNG DESCRIBED IN DETAIJ*

Fig. 48.

\^V-M\v\\\v^ v'\i^'. > A

I
1

i ,

¥■

•I

■\\^\\\\\\\\\\\VSS\^\N

\Mm'\^\\\<;^^^

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. £C]

and under every circumstance, would be folly. But its utility
in winter-forcing, especially where the soil is damp and natu-
rally cold, will be obvious to any one of much experience in
these matters. The greatest success has attended the applica-
tion of border-heating, in England, where an enormous amount
of money and labor is annually expended upon the forcing of
grapes, and where they are produced in great perfection all the
year round.

I have said that where early forcing is practised, and the soil
and sub-soil of a cold, retentive nature, the adoption of some
method similar to the above ia almost indispensable to general
success. I wish, however, to be rightly understood, and not to
mislead, and therefore advert to what every gardener knows well,
that good grapes are sometimes produced under the entire neg-
lect of all the ordinary precautionary measures resorted to by
good gardeners for the purpose of securing success.

In support of this method of heating borders, I will briefly
advert to the opinions of some of the leading gardeners in Eng-
land. Mr. Fleming, gardener to the Duke of Sutherland, at
Trentham Hall, Avrites to the Gardener's Chronicle, four years
ago, to the following effect : — " Shrivelling was common here,
until the system of keeping up a bottom heat in the vine bor-
ders was introduced. Since then there has been no appearance
of it, except in a late house last year. In the month of xVugust
we had a great deal of rain, which penetrated the border, and
the weather was for a few da)^s very cold, and the grapes, which
up to that time were swelling beautifully, received a check, and
shortly after many of the fruit-stalks shrivelled."

In the same paper Mr. F. makes the following statement,
which is the strongest evidence of the utility of the system thaf
has come under our notice : — "I am so convinced," says he,
" of the advantage of this practice, that I would prefer the
introduction of flues under ever}- vine border about the place,
did circumstances permit." This method is also employed at
Welbeck, with the greatest success. There the soil and sub-
soil are heavy, cold, and wet ; and without some such precau-
tion, grape-growing would be but a barren busmess. But by
this method of chambering the borders, and other good manage

23£ VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

menl beside, the most abundant crops are obtained. Mr. Rob-
erts, of Raby Castle, author of a treatise on vine culture under
glass, and a good authority on the subject, says : — " Fault has
been found with me for recommending heat to the roots of vines
by fermenting manure, on account of its unsightliness ; but
practice convinces me that without a corresponding degree of
temperature betwixt the root and top, you cannot produce good
grapes. I intend, however, to do away with the unsightliness
of manure, in my new vine borders, by heating them on another
plan." Such is the testimony of men who stand first in their
profession, — men of undoubted probity and extensive expe-
rience, and who, as authorities on these matters, may be fully
relied on. No one, who once has seen the extensive gardens
which they superintend, will dispute the propriety of the practice
of placing fermenting manure on the surface of a vine border.
But I must differ in my opinion from Mr. Roberts in regard to
its eflfects. It may not be positively injurious, but Mr. Roberts
has failed to prove that it is positively beneficial. Moreover, if
he has succeeded in imparting a temperature to his vine border
equal to the atmosphero at which he keeps his vinery, he must
have a body of manure equal in bulk to the vinery itself. Heat
travels with extreme slowness through the damp, confined air
of dung-beds, and the tMfficulty of getting heat to travel down-
wards is well known. A body of fermenting material may
communicate its heat to the mere surface of the soil on which
it lies ; but the moisture it absorbs from the atmosphere, as well
as its saturation by rains, is connnunicated to the soil in place
of heat, so that in reality the good produced is nearly, if not
altogether, counterbalanced by the evil. The plan Mr. R.
intended to adopt has i.ot, as far as I know, been made public ;
but probably it was some kind of chambered border, with arti-
ficial heat radiating beneath it.

The annexed drawing represents a chambered border, heated
with a hot-water tank, which is supplied with water from the
pipes when it can be spared from the atmosphere of the house,
by a tap fixed on the pipe, as shown at a, in the end section.
If the water is allowed to flow into the tank from the boiler for
the space of an hour, a sufficiency of heat will be communicated

VAEIOrS METHODS OF HEATIXG DESCIIBED IN DETAIL. 233

Fig. 49

234 VARIOUS METHODS OF HEATIXG DESCKIIiED IX LETAIL.

to the chamber, and the border for maintaining- a perceptible
warmth in the latter for twelve or fourteen hours. A division
is made in the tank for the circulation and displacement of the
water, as shown by the arrows in Fig. 49. Pigeon-hole walls
are built across the border, about five feet distant from each
other. Upon these rough pieces of timbepare laid, as a bottom
to the border ; a layer of brush-wood (small branches) is laid
over the timber to prevent the soil from falling through upon the
tank. The rest should be filled, to the depth of two feet, with a
good turfy material, with a plentiful admixture of whole bones
and rough pieces of charcoal, to render the mass as porous as
possible, for the admission of the heat upwards, as well as to
maintain an equality in the moisture of the mass. Shutters are
provided for covering the border, which may lie upon the same
angle as the roof, or otherwise, as the front wall of the house
corresponds to the curb in front of the border. Ventilators are
placed in the front wall, beneath each light, for the admission
of air into the house ; and when air is required by these front
ventilators, the shutters covering the border must be tilted at
the lower side, when the air passes across the border, through
the front, into the house. We consider this mode of arrange-
ment for the border cheaper and better than that of arching the
chamber, as shown in Fig. 48, although both are equally effect-
ual, and may be adopted as circumstances may suggest.

If chambered borders be found so beneficial in England, for
winter forcing, where the frost seldom penetrates more than a
few inches into the ground, and rarely continues for more than
a few days at a time, — a week or two, at the longest, — surely
it must prove equally if not more serviceable in the New Eng-
land states, where the winters are so intensely cold as to render
the forcing of grape-vines at that time next to impossible. Still,
if the forcing of this fruit can be carried on at mid-winter, at a
reasonable cost, there is no reason to suppose that it would be
unprofitable, even at the low prices at which grapes are usually
sold in the principal markets of this country. All cultivators
are aware that the profits of fruit culture are just in proportion
to the economy with which good crops can be produced ; and
this is more especially the case in the culture of exotic fruits,

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 235

there being more room for the exercise of skill in their produc-
tion.

Suppose, for instance, that we take the calculations of Mr.
Allen, in his treatise on the Culture of the Grape-vine, where,
in pp. 69, 70 and 71, he estimates the quantity of fermenting
manure, necessary for the covering and warming of a border
100 feet in length to cost S700; which, together with the
other items of management, — repairs, fuel, interest on cost,
etc., — to amount to $1120. The produce of a house so
heated and managed, according to his calculation, is on an
average 1067 pounds of fruit. I do not intend to dispute the
accuracy of these calculations, although they appear startling
enough. And doubtless Mr. Allen has had data sufficiently
accurate and authoritative, from which to draw his deductions ;
and hence I consider myself justified in making them partially
the data of mine.

And, admitting the beneficial effect of fermenting manure to
be all that its advocates claim for it, let us compare the calcula-
tions above, with the cost and working of chambered borders ;
and, by balancing the two together, we shall be the better able
to estimate the m^erits of each on the score of economy.

In order to effect this, I have been at some pains to obtain the
probable expense of such a border as that represented on page
232, Fig. 49 ; and* in making my calculations, I have placed my
figures rather above than under the estimate; so that, should
[ make any error, it will be on the most favorable side.

To make a chambered border 100 feet long, we have —

For brick work, $200

Timber to form the bottom of the border, .... 60

Tank, ' 50

Extra piping for do., 10

Extra fuel, 15

Excavating the border, 45

Shutters, ficc, for covering do., 100

$480

Now, if we' subtract 480 from 700, (the cost of manure,) we
have a saving of S220, the very first season ; or, in other

'ZcQ VARIOUS METHODS OF HEATING DESCRIBED Df DETAIL.

words, the manure required for one year costs more thaj the
making of this border, by S220. Then, if we estimate the an-
nual expenditure on account of the border, for heating, repairs,
etc., to be .$2b, we have S700, the cost of manure, minus
$25, the cost of the tank border, which gives an annual saving
of no less than $675 by this method of heating.

It may be supposed that a body thus situated over a hot-
water tank, might be too rapidly dried by the ascending heat.
But this is only a supposition ; and in practice it amounts to
nothing more, for the w^armth generated by the tank is so grad-
ual, and spread over so large a surface, that the heat is equally
distributed, and no part of the mass is overheated, or one part
heated above another. And, indeed, one would scarcely believe,
from the small quantity of heat thus generated, that so striking
an effect would be produced ; of course, the border must not be
allowed to get too dry. Nor will this be a matter of so much
difficulty as may appear, as two or three good soakings with
water, — or, what is better, weak liquid manure, — will generally
suffice, until the weather permits you to uncover the border
during the middle of a wet day, covering it up again before
evening. The operation of watering will be much facilitated
by having a hose fitted to the tap of a cistern containing rain-
water inside the house ; and no hot-house of any kind should be
without such an appendage. If the m.echanical texture of the
soil be good, the water soon finds its way through. The larger
portion of the moisture being held in suspension by the lower
stratum of soil, becomes gradually warmed by the tank, and is
again carried upwards by the heated air ; so that the roots of
the vines have the full advantage, not only of the heat, but of
the moisture. The abstraction of heat may be in a great meas-
ure prevented, in excessively frosty weather, ly laying a few
inches thick of straw, or stable litter, immediately over the soil
beneath the covering. This is merely a precautionary expedient,
and, though useful, will seldom be necessary.

In the formation of a chambered border many alterations and
improvements will suggest themselves to the mind of the practi-
cal man, which could not be very conveniently represented in
the accompanying sketches. For instance, as a covering,

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 237

instead of shutters, I would decidedly prefer glass ; and where
there are plenty of spare sashes about the place, they might be
used in this way, with much advantage, just as spare sashes are
used for covering peach and apricot wall-trees in England. But
suppose that sashes of sufficient length were provided for the
purpose ; the expense would probably be counterbalanced by the
advantage gained. For a house 100 feet long, 25 sashes would
be required, which, at 3 dollars each, would be 75 dollars; a
very trifling sum when a desirable object is to be attained by the
judicious expenditure of it. And, in this case, although it may
appear injudicious to some, the object is, in my opinion, suf-
ficiently important to justify this expense. Light absorbed is
productive of heat, especially if the absorbing body be of a dark
color, for then it is absorbed without being again reflected upon
the transparent medium. Hence we see the advantage of hav-
ing the border covered with a body admitting light, and the soil
of which the surface of the border is composed, of a dark color,
that the heat which falls upon it may be absorbed and retained.

For winter forcing, small houses are decidedly preferable to
large ones. Houses about 25 or 30 {eet long are sufficiently
large, and are more easily heated, and more convenient to man-
age. Even in the milder climate of England, small vineries
are preferred to large ones, and are found to be more profitably
worked. Above all things, loftiness should be guarded against,
as being the very worst feature in a forcing-house, as the heated
air continues to ascend upwards; and, unless the external
atmosphere can be admitted at the top, the vines at that portion
of the house will always be in a state of vegetable suffocation;
a fact of too frequent occurrence, in lofty houses, even in sum-
mer, and which is rendered still more injurious by the present
defective methods of ventilation.

A few words more regarding the permanency of these borders.
Assuming that a proper command of heat, both for the atmos-
phere and the soil, is obtained, the question has been asked, How
long will borders, so circumscribed, continue to supply a house of
grape-vines with the requisite nourishment ? This question has
hitherto proved a drawback to the adoption of these borders by
many who have, in every other respect, the highest opinion of

2CS VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

the advantages to be derived from them. In short, they are
afraid the vines will exhaust the soil within the limits of the
range allowed to the roots, and then fail in producing a crop for
the want of food. Now I think a very little consideration will
prove this to be a groundless fear. Supposing the soil to be the
principal repository for the nutriment of the vines, and that it
should contain all the substances in abundance, whether solid
or gaseous, which form their structure and produce their fruit ;
yet it is not necessary to form this border into a mass of nitro-
geneous matter to produce these results. Plants, in this respect,
are as bad as animals; and a vine-border may as readily be
poisoned with excess, as impoverished for the want of proper
elements of nutrition. Now I maintain, and I do so upon expe-
rience, that the grand requisite to be looked to in the formation
of a vine-border is its condition as regards texture, and not its
chemical properties. The first secured, the latter can be added,
not only when it is first made up, but annually afterwards, and
each subsequent time, with as much advantage as at the begin-
ning. The food of vines consists chiefly of the elements, car-
bon, hydrogen, nitrogen, and oxygen, in some state of combina-
tion, together with certain inorganic compounds, amounting to
only about 7 per cent., as silica, salts of lime, magnesia, iron,
potash, soda, and other bases, combined with sulphuric, phos-
phoric, carbonic, silicic, humic, and other acids. These sub-
stances can be supplied, in a liquid state, in quantities more than
sufficient for the actual requirements of the vine. But their
efficacy will very much depend upon the freeness, porosity, and
other mechanical qualities of the soil, favorable to the decom-
position and recombination of these elements. The general
method of renovating a vine-border is by incorporating about
half its bulk of manure, to the manifest destruction of many of
the best roots, — for the best are always on the surface, —
besides incurring a vast amount of labor and expense, which
labor and expense would be sufficient for at least a dozen years.
Salts of ammonia, for instance, in their various states of com-
bination, are known to exercise a powerful influence on the
growth of grape-vines. Now, by adding, say, 10 tons of the
best manure to the borders, we supply them with about 85 pounds

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 239

of ammonia, in the form of sulphate, carbonate, nitrate, and
muriate of ammonia. Now, the same quantity will be fur-
nished by one quarter of a ton of good Peruvian guano, at prob-
ably one half the cost, while its application, in a liquid state, is
more immediately beneficial to the vines. The same salts are
supplied from urine, which ought to be collected in tanks for
that purpose. By the addition of these elements, an impover-
ished border, incapable of yielding one fifth of a crop, has been
enriched and made to produce good crops of fruit. As I have
said, however, I would have a border made, say, 12 or 16 feet
wide, of good open material, not over-rich in nitrogeneous mat-
ter, but abundantly mixed with lumps of charcoal, and plenty of
bones ; a quantity of common lime-stone (carbonate of lime)
might be laid on the bottom, and mixed through the mass.
With a border so formed, about 2 feet deep, and 14 feet wide,
by the regular application of nutritious elements in a liquid
form, and proper management in other respects, the most abun-
dant crops may be produced, for at least a quarter of a century.
We are well aware of the arguments that are brought to bear
against shallow vine-borders in this country, from their greater
liability to become dried up by the parching droughts of sum-
mer. But here this argument can have no application, as the
season of forcing is at that period when the ground is saturated
with wet, and little or no abstraction of it by the atmosphere.
And as the temperature of any piece of ground is nearly in
exact proportion to the amount of water it contains, so it follows
that a vine-border saturated with water must necessarily be
colder, and consequently more injurious to forcing plants, than
a dry one, even without heat ! It is true, a border may be
drained, and all superfluous and stagnant moisture carried off,
but even the driest and most silicious soils have a certain
capacity of suspending moisture in their pores, and as this
capacity is greater in soils containing much organic matter than
in those of a more sandy nature, it follows theoretically, — and
we find it so in practice, — that rich borders are colder and
wetter than the common garden soil. I believe this is a fact
which no one will dispute. But however warm vine-borders
may be by their natural position, or rendered so by artificial
21

^^40 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

drainage, they must still be very far from the internal tempera-
ture of the house, — a fact which requires no calculation to
prove it. And hence, although the vine, of all other fruit-bear-
ing plants, will accommodate itself to circumstances apparently
the most unpropitious, and will stand forcing in mid-winter bet-
ter than any other fruit we can place into a hot-house, still, it
carmot be expected that we shall arrive at anything like perfec-
tion in its produce by winter-forcing, under the present methods
of cultivation. And we know that, whatever can be said in
favor of carrion-borders, no mere aggregation of organic matter
will suffice for the production of grapes, especially in winter,
if the principle of life be impotent, and the functions of the plant
impaired, whether by natural or artificial causes ; and nothing
is more likely to weaken the one, or impair the other, than
placing the roots of vines in an ice-house, and the branches in
an oven.

In close connection with the foregoing subject is a system
which has engaged no inconsiderable share of attention in Eng-
land, and may probably be employed with equal advantage in
this country. The system to which I allude, is forcing by hot
walls covered with glass. It has now become common to build
garden walls hollow, and heat them with hot water, with flues,
or both, and by covering them with temporary roofs, consisting
either of spare sashes on hand, or by having sashes made for
the purpose. By this means, a range of portable houses may
be constructed upon any walls adapted for that purpose, at a
very inconsiderable expense, compared with that of permanent
houses. — (See Part I. Construction of Walls.)

Fig. 50 shows an end section of the wall ; a a, ties across the
wall, at regular distances, for the purpose of strengthening the
fabric ; b, the pipes for hot water, or the situation of the flue, if
that method of heating be adopted ; c, the furnace and boiler,
placed in a recess of the wall, as shown in the ground plan ; d
d, the returning pipes, or the position of the rsturning flue, if
pipes are not used ; e, the projecting support for the sashes
under the coping ; /, the lower supports for t!ie sashes, consist-
ing of timber posts driven into the ground, that no obstruction
may be presented to the roots of the vines by a brick wall ; g

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. » 41

Fig. 50.

•//•////////////-///-I

m^-^^^^j^s^j^^^x^

.^■^-

y//////////////M

^^-^

z-^/.

'■////////////////M

it.

242 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL.

the sashes ; h h h^ are square tubes of wood, penetrating the
soil to the chamber beneath, to let the heat rise up into the
space confined within the sashes and the wall ; the number of
these openings depending entirely upon the weather, and the
season of forcing. They may be closed with a lid when the
sashes are removed. From the foregoing description, it will be
perceived that an erection of this kind has all the advantages
of a house, — at least as far as grape-growing is concerned, —
without the consequent expense, and when once all the mate-
rials are properly adjusted, they can be removed, or replaced, by
almost any gardener, without the aid of a tradesman. The
rafters are merely fastened to a plate of wood, about one foot
broad, and two inches thick, by means of iron pegs, as at e,
in the end section, and also at the bottom to another plate, sim-
ilar to the one above, and fitted into the posts at /; the sashes
are fixed to the rafters by means of a latch, or thumb-screw,
placed within reach of the operator, for the facility of admitting
air. This is effected by letting down the sashes to any distance,
and supporting them by notched brackets, or letting them down
to the ground, if necessary, as shown by the dotted line, at /.

This method may be adopted without having any cavity
beneath the border, and, of course, will be cheaper, although we
would decidedly prefer such a cavity, did circumstances permit.
The advantage of hollow walls, warmed by some method, has
been long well known to gardeners, and so highly are they
thought of in England, that scarcely any garden of consequence
is without them. Indeed, in the majority of seasons, the culture
of the vine, peach, nectarine, apricot, and fig, — even on walls, —
would be a very precarious and uncertain business, although
the method of covering such walls with portable glass has but
very lately been brought into use, and, now that glass is cheaper
in that country, is almost certain to be extensively applied to
this purpose. In one or two cases we have seen this method
adopted with astonishing success, and without any cavity, or
any other preparation than the common border and wall of the
garden. In one place we had forty feet of a wall thus covered
with spare sashes ; the space included some peach and fig
trees, in excellent bearing condition, and well set with buds,

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 243

giving promise of a fair crop. The wall was covered with the
glass on the first of February, but no heat was applied to the
wall until the beginning of March. The sashes were fixed
exactly as we have described in the foregoing sketch. The wall
and fire-place were precisely the same, but no cavity was be-
neath the border. The result was, that the crop ripened five
weeks earlier than those on the same wall, uncovered, without
heat, and nearly four weeks earlier than those on the same wall,
with heat, and covered, in the usual way, with netting. Now
this was merely an experimental result, without much previous
preparation, save the covering up of the wall a month earlier
than the warming commenced, — if, indeed, this can be called a
preparation, — being an absolutely necessary prerequisite to suc-
cess, under any method of forcing. When the warm weather
set in, the sashes and rafters were taken away, and the enclosed
part received, during the season, the same treatment as the
other portions of the wall.

In forming a hollow wall, there will be quite as much saved
by the internal cavity as will suffice to warm it, as only about
one half the quantity of bricks are required ; and even without
a heating apparatus, hollow walls are superior to solid ones, for
horticultural purposes ; for, under all circumstances, they are
found to be both warmer and drier. The addition of a heatins:
apparatus, however, will render the wall a very useful auxiliary
to the forcing-house, and the cost will be amply compensated by
the utility. By looking at the foregoing plan, it will be seen
that the furnace is placed in the foundation of the v/all, with a
few steps to descend to it, the whole being covered with a trap-
door, leaving nothing unsightly open to the view of the visitor.

In many parts of this country, grapes are frequently overtaken
by the autumn frosts, before they are ripened, and in many
others, they do not ripen at all. Now, it is obvious, that it is
neither owing to a deficiency of sun-light, nor a deficiency of
heat, for in Britain the quantity of both are much less, and the
quality of the latter less powerful for the maturation of fibre and
fruit ; and yet it is common enough to have good crops of (what
in America are called foreign) grapes, on the open walls. In
ordinary seasons, the black Hamburg, Muscadine, and Fron-
21^

244 VARIOUS METHODS OF HEATING DESCRIBED I^" DETAIL.

tignacs, ripen well :r. the open air, on southern aspects; and in
all seasons they succeed in ripening their fruit, in tolerable per-
fection, on hollow walls, with a little heat in spring, if the
season be backward, and a little in autumn, if the season
be late, i. e., if cold weather should set in unusually early,
which it frequently does in Scotland ; and yet we have seen tol-
erable crops of grapes produced north of the Tweed, on heated
walls, without any glass at all. This statement may be received
with incredulity by some, W'ho have had poor success in the
cultivation of foreign grapes, in the open air, in this countrj',
under circumstances of climate unquestionably more favorable
than can be found in any part of the British Islands. We believe
this statement will be corroborated by the testimony of every
one who is acquainted with the nature of the climate of both
countries. In fact, so much are people in this country impressed
with the unfavorable nature of an English summer, that in all
journals, magazines, periodicals, and papers, of every descrip-
tion, we, without one single exception, find it qualified with the
words, dull, gloomy, austere, wet, cold, damp, dripping, and
many other appellations of similar import, which it is not my
present purpose either to confirm or confute. But as there has
not, as yet, been (as far as we can learn) any general cause
assigned for the general failure here, there is but one infer-
ence that can be drawn from the above statements, viz., that
there must be, in this country, something wrong, or something
wanting, in the modes of cultivating foreign grapes, in the open
air. It cannot be said that the summers are too hot for the
grape-vine ; for there is hardly another plant in the vegetable
kingdom, that will bear a greater amount of natural or artificial
heat, or greater alternations of heat and cold, under circum-
stances otherwise favorable. There is no degree of heat, to
which natural vegetation is subjected in this country, under
which it will not flourish, provided the intense rays of the noon-
day sun be not concentrated upon its foliage ; and it is a well-
known fact, that grape-vines will not produce fruit abundantly
when they are not in a favorable aspect. There can be little
doubt that we must look to the condition of the plant, during
the spring and autumn, to enable us to reach the cause, and

VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 245

this appears to be substantially proved, b}'- the invariable success
that has attended the culture of foreign grapes in cold houses, as
well as other facts suggested by experii-nce, in the culture of
that noble fruit. The value and importance of the grape-vine
have already induced me to dwell longer on this subject, in con-
nection with heating, than I intended ; I therefore consider it
foreign to my subject to enlarge further on its culture, although
there is great room for speculation, theory, experiment, and
practical improvement. Indeed, it would be difficult for the
practical horticulturist to take hold of a subject affording a wider
field for successful experiment, and holding out brighter hopes
of beneficial results.

Before concluding this chapter on heating, I will briefly notice
another system, more, however, on account of its novelty, than
applicability to the warming of hot-houses, although it has, in
^me instances, been applied to this purpose. I refer to the
method of heating, by which the hot air is carried along by the
power of a steam-engine. This system is applied to the warm-
ing of large factories in England, and has been also applied, with
apparent success, in some large nursery gardens, in Germany.
The following description is from the pen of Mr. Marnock, the
able editor of the " Gardener's Journal," (Eng.,) and drawn from
his own observations of the apparatus, while visiting the gardens
of Baron Hugel, near Schonbrunn, where the system was in
operation at the time.

" The most remarkable feature about this garden is the mode
of heating, which we shall now attempt to describe. In the
first place, there is a large fire-place constructed ; through this
fire-place two or more pipes are introduced ; the pipes are of cast-
iron ; one end of these pipes communicates with the common
atmosphere, the opposite end being introduced into a large box,
or flue ; in this flue is placed a fan, driven by a steam-engine,
which fan is made to revolve in this air-flue, at a short distance
from the fire-place. It will readily be understood, that, when
the fire is in action, with those iron pipes passing through it,
and terminating in the large air-flue, the revolving action of
the fan, in a direction to draw the common atmos|^ieric air
through the iron pipes in the fire-place, will also force the heated

246 VARIOTTS METHODS OF HEATIXG DESCRIBED IN DETAIL.

air onwards to the other end of the flue, and thence through tin,
zinc, or any other kind of pipe placed there to convey it away.
By these means it is conducted {i. e., the heated air from the
box) into the different stoves and green-houses. Each house,
or, rather, each compartment, is provided with a supply-pipe and
a tap, by which heated air is admitted by measure, and of course
regulated according to the requirements of the plants. We
could not clearly ascertain the exact size of the fire-place, but
we saw some iron pipes, which we were told were similar to
those in use in the fire-place for heating the air, and we sup-
posed them to be about six inches in diameter. These pipes,
as they are exposed to the action of a strong fire, become greatly
heated, and the air, in passing through them, becomes intensely
hot and dry, consequently, deprived of its ox^^gen and aqueous
properties. Here, however, no evaporating pans are used for
moistenino- the warm air, as in common hot-air furnaces, and
the method adopted for supplying the heated air with moisture
is quite as novel as the system itself. To effect this, a steam
jet is played into the hot-air flue, immediately before it enters the
different compartments, and Mr. Hooibrink, the gardener to
Baron Hugel, stated that he admitted the steam according to
the nature of the plants cultivated in each apartment. Thus,
he allowed so many feet of steam for his orchards; so many for
his stove plants, and so many for his common green-house
plants ; thus each kind of plants is supplied with steam,
according as it requires a moist or dry atmosphere.

" Thus, if we are rightly understood, there is, first, a large fire-
place ; through this fire two or more cast-iron pipes, six inches
in diameter, are passed ; they are so placed as to be subjected to
the most intense action of the caloric produced by combustion ;
one end of these pipes is exposed to the external atmosphere,
the other ends enter a large oblong box, on a level with the
pipes, in which is placed a fan, similar to those used in small
fanning mills. This fan is made to revolve with considerable
rapidity, by the power of a small steam-engine, drawing the
atmospheric air inwards through the tubes exposed to the fire,
and forcing it onwards through the main conductor, and thence
into the smaller tubes leading to the right or left, up or down,

VARIOUS METHODS OF HEATIXG DESCRIBED IN DETAIL. 247

as the case may be, for the supply of the mansion, and the
several hot-houses, all of which are heated by the same appara-
tus. Here the air is moved and replaced, not only by its own
density, as in the common methods of hot-air heating, but it is
drawn rapidly inwards by the suction of the fan on the one side,
and driven onward by its propulsive power on the other ; and
thus it appears the heat travels with great rapidity, and within
a few minutes after the heated air is turned on the apartment,
and moistsned as may be desired by the jet of steam already
described."^

* Fans are now frequently employed for effecting ventilation, and
are generally connected with the heating apparatus. They have never,
as far as we know, been employed for this purpose in any kind of hor-
ticultural structures, although we can see no reason why they should
not be so. This will be again referred to, when we come to treat on
that part of our subject.

PART III. VENTILATION.

SECTION I.

PRINCIPLES OF VENTILATION.

1. The ventilation of hot-houses, either in summer or win-
ter, constitutes an important, if not the most important, item of
their general management, as it bears more directly upon the
condition of the external and the internal atmosphere. It re-
quires, therefore, the strictest attention of the gardener at all
seasons of the year. For, important as other things connected
with exotic horticulture may be, — light, for instance, — it is,
nevertheless, more under the gardener's control, and more sub-
ject to his will. He places his plants within a transparent
medium, which is, in its general surface, impermeable to the
atmospheric air; and he forms for them an artificial atmos-
phere, which is invigorating, or the reverse, according to his
knowledge of the laws that regulate the atmosphere, or the
general principles of aerometry. Notwithstanding the many
discoveries that have been made regarding the properties of air,
I have been unable to find any work bringing these discoveries
to bear upon the airing of hot-houses. It is true this must be
accomplished by the " practical " man, and the sooner we begin
to think about it the better. Every horticulturalist, no matter
what his department in the vineyard may be, soon discovers the
necessity of maintaining a continual warfare with its different
conditions of purity and impurity, its aridity, and its moisture.
We have, indeed, various theories propounded by physiologists,
regarding the power of plants to withstand these vicissitudes,
some of which have their general principles as yet enveloped in
a mist of shadowy vagueness.

Many remarkable facts, however, might be mentioned relative

PRINCIPLES OF VENTILATION. 249

to the qualities and quantities of certain atmospheric elements
which plants are capable of sustaining in deficiency or in excess.
And the one or the other of these conditions appears to some of
the species a natural and even a necessary circumstance. The
degree in which vitality is sometimes retained by plants, under
the most unfavorable conditions, for a period to which it is diffi-
cult to assign a limit, is one of the most interesting and curious
circumstances in their economy. Instances have been related
of the growth of bulbs, unrolled from among the bandages of
Egyptian mummies. Although there is good reason to believe
that deception has been practised on this point, upon the credu-
lity of travellers, still there is nothing impossible in the asserted
fact. Light, heat, and moisture are the cause of the development
of these curious structures, and their forms become expanded
under the additional agency of atmospheric air. Now, when
removed from the influence of these, there is no reason why a
bulb, if it can remain unchanged for ten years, should not do so
for a hundred ; and if for a hundred, why not for one thousand
years ? The vitality of seeds under similar circumstances
appears quite unlimited. ^

In the first chapter of this treatise, we have ventured to assert
that light is of more importance to plants than air, although we
are aware that this point is open to much discussion, from the
fact of some plants being adapted to thrive under the almost
total deprivation of it. These, however, will generally, if not
solely, be found to consist of plants in the lowest orders of
organization, such, for instance, as the algae, some of which, pos-
sessing a bright green color, have been drawn up from the depth
of more than one hundred fathoms, to which the sun's rays can-
not penetrate in any appreciable proportion ; and also the fungi,
which have been found growing in caverns and mines to which
no rays from the sun, either direct or reflected, would seem to
have access. These facts, however, do not greatly aflect the

* Melon seeds have been known to grow at the age of 40 years, kid-
ney beans at 100, sensitive plant at 60, rye at 40, and there are now
growing, in the garden of the Horticultural Society, raspberry plants
raised from seeds 1600 or 1700 years old. — [Lindlei/s Introduction to
Botany. \

250 PRINCIPLES OF VENTILATION.

accuracy of our assertion, for we find that all the highly devel-
oped organisms, such as we cultivate in our hot-houses, are only
adapted to exist where they can be daily invigorated by the
sun's rays. This fact is very strikingly illustrated in the effect
produced on tropical plants growing in hot-houses in the north-
ern latitudes, where, deprived of the intensity of the sun's rays,
under which they naturally luxuriate, they seem completely
changed by the long absence of the luminary on whose cheering
influence they depend. In such cases, no quantity or quality
of air will compensate for the loss of the sun's vivifying beams.
In the management of hot-house plants, the attentive ob-
server cannot fail to perceive the remarkable effects produced
upon certain kinds of plants by the circumstances in which they
are placed, as to heat, light, and air ; and hence the propriety of
arranging plants in hot-houses, not merely according to their
heights and colors, but also according to their habits and
requirements in relation to these elements.=^ Some plants will
endure an intensity of solar light, without injury, which would
utterly paralyze and suspend the functions of others; some will
luxuriate in an arid temperature, in which others would be
destroyed, and some require daily supplies of fresh air, while
others will exist even in a healthy state for years where the
atmospheric air is, one would think, almost excluded. Even
in nature there are many striking exemplifications of these
facts. A hot spring in Manilla islands, which raises the ther-
mometer to 187°, has plants flourishing in it and on its bor-
ders. In hot springs near a river of Louisiana, the tempera-
ture of which is from 122° to 146°, have been seen growing, not
merely the lower and simpler plants, but shrubs and trees. In
one of the Geysers of Iceland, which was hot enough to boil an

* For example, the common weeds, called chickweed, groundsel and
Pea annua., evidently grow at a temperature very near that of 32^^,
while the nettles, and mallows, and other weeds around them, remain
torpid. In like manner, while our native trees are suited to bear the
low temperature of an English summer, and, in most cases, sutler
if removed into a warmer country, such plants as the mango and coffee-
tree, etc., inhabitants of tropical countries, soon perish, even in our
warmest weather, if exposed to the open air. — [Lind. The. of Hort.]

PRINCIPLES OF VENTILATION. 251

egg in four minutes, a species of chara has been found growing
and reproducing itself; and vegetation of an humble kind has
been observed in the similar boiling springs of Arabia, and the
Cape of Good Hope. One of the most remarkable facts on
record, in reference to the power of vegetation to proceed under
a high temperature, is related by Sir G. Staunton, in his account
of Lord Macartney's Embassy to China. At the island of
Amsterdam a spring was found, the mud of which was far hot-
ter than boiling water, and gave birth to a species of liverwort.
A large squill bulb, which it was wished to dry and preserve,
has been known to push up its stalk and leaves, when buried in
sand kept up to a temperature much exceeding that of boiling
water.

Again, we have observed plants exceedingly tenacious of life
under the deleterious influences of carbonic acid, sulphureous,
chlorine and other gases. We have seen a number of different
kinds of plants placed in a close frame, and fumigated with sul-
phureous gas, the greater part of which were destroyed, though
a few of them were uninjured. This fact has been observed by
many in the fumigating of their green-houses with tobacco, when
some of the tender sorts would be sensibly injured by the smoke,
while others, though receiving a much larger portion, bore it
with impunity.

It is evident, however, that though many plants will live for
a short time under these circumstances, a certain condition of
the atmosphere, as well as a given amount of light and heat, is
necessary to the performance of their functions, and the perfec-
tion of their flowers and fruit. The fact is well known, that if
we take a healthy plant from the light and airy green-house, and
place it in the room of a dwelling-house, it will become sickly,
and ultimately languish and die ; if it be placed in a dark, cold
cellar, its death will be more speedily produced. In like man-
ner, roses grown in a forcing-house in winter are less fragrant
than those grown in the warm sunshine of summer. In gen-
eral, plants grown in the summer months form secretions more
active, in every respect, than the same kind of plants grown in a
hot-house, under the clouded skies of winter; and even in our
finest forced fruits and vegetables this is perceptibly the case.
22

252 PRINCIPLES OF VENTILATION.

2. Much discussion has taken place upon the question
whether or not vegetation is, upon the whole, serviceable in puri-
fying the atmosphere ; that is, whether plants give out most car-
bonic acid or most oxygen. Priestley maintained that the latter
was the only effect of vegetation, and that plants and animals
are thus constantly effecting changes in the atmosphere which
counterbalance one another. Subsequent experiments seem to
show, however, that the carbonic acid given out during the
night, equals or even exceeds in amount the oxygen given out
by day. But this might be owing to the employment of plants
which had become weak and unhealthy, by being kept in an
impure atmosphere, previous to being experimented on, and
which had not been exposed to a fair degree of light. Dr. Dau-
beny, of Oxford, has recently shown that, in fine weather, a
plant, consisting chiefly of leaves and stems, if confined in a
capacious vessel, and duly supplied with carbonic acid during
sunshine, as fast as it removes it, will go on adding to the pro-
portion of oxygen present so long as it continues healthy;
the slight diminution of oxygen and increase of carbonic acid
which take place during the night bearing no considerable pro-
portion to the degree in which the contrary effect occurs during
the day.^

Thus we see that the two great organized kingdoms of
nature are made to cooperate in the execution of the same
design, each ministering to the other, and preserving that due
balance in the constitution of the atmosphere, which adapts it
to the welfare and activity of every order of beings, and which
is quickly destroyed when the operations of any of them become

* Plants decompose carbonic acid during the day, and form it again
during the night, — the oxygen they inhale at that time entering again
into combination with their carbon, — and, during the healthy state of a
plant, the decomposition by day, and recomposition by night, of this
gaseous matter, are perpetually going on. The quantity of carbonic acid
decomposed is in proportion to the intensity of the light which strikes a
leaf, the smallest amount being in shady places ; and the healthiness of
a plant is ccBteris paribus in proportion to the quantity of carbonic acid
decomposed. Therefore, the healthiness of a plant should be in propor-
tion to the quantity of light it receives by day. — [Lind. The. of Hort.]

PRINCIPLES OF VENTILATION. 253

suspended, as is the case in the artificial atmosphere of a hot-
house. And as by artificial means the balance is therein
destroyed, so, also, by artificial means must the elements of the
atmosphere be adjusted, and the balance maintained.

It is impossible for us to contemplate so special an adjustment
of opposite effects, without admiring this beautiful dispensation
of Providence, extending over so vast a scale of being, and
demonstrating the unity of the plan upon which the whole sys-
tem of the organized creation is designed. And yet man, in
his ignorance, has done his utmost to destroy this beautiful and
harmonious plan. It was evidently the intention of the Creator,
that animal and vegetable life should everywhere exist together,
so that the baneful influence which the former is constantly
exercising upon the air should be counteracted by the latter.
Nothing, therefore, can be more prejudicial to the health of a
large population, than the close packing of houses together, as
presented in large cities. Hundreds of thousands of men, with
manufactories of all kinds, — the smoke and vapors of which are
still more injurious than the foul air produced by human respi-
ration,— being crowded together in the smallest possible com-
pass, with scarcely the intervention of an open space on which the
light and air of heaven may freely play, and without any oppor-
tunity for the growth of any kind of vegetation sufficiently luxu-
riant to give pleasure to the eye, or sufficiently energetic to
answer its natural purpose; for the close confined atmosphere
of crowded cities is almost as injurious to vegetation as to ani-
mals; the smoke, which is constantly hovering above them
prevents their enjoyment of the clear bright sunshine which
they require for their health, and the dust, which is constantly
floating in the atmosphere, covers the surface of their leaves,
clogs up the pores, and prevents respiration.

This is the reason why plants thrive so badly in dwelling-
houses in large cities, and also in the external air in the streets
and squares. But lofty trees are so beneficial in such situations
that they have with truth been called the lungs of large cities,
so important is the effect produced by them in purifying the air.
It is true, they may occasion some degree of dampness in the
immediate neighborhood, but this evil is n:or; than counterbal-

254 PRINCIPLES OF VENTILATIO^.

anced by the good they effect. " New Haven," justly called the
City of Elms, is almost embowered in the shade of lofty trees,
and is remarkable for the salubrity of its atmosphere, and the
health of its inhabitants. There, almost every house has its
garden ; and the daily consumers of its deleterious exhalations
stand in the open streets, at once the ornaments of the city and
the scavengers of the air. The cutting down of a healthy tree,
in the midst of a large town, without some very strong reason,
should be regarded as an offence to the community, and an
injury to the public weal. It is much to be wished that other
towns, that are rapidly increasing in extent and population,
would follow the example of New Haven, and bad ventilation
and impure air would, in a very great degree, be deprived of
their injurious effects.

2. Under favorable circumstances, plants are able to appropriate
a larger amount of carbonic acid than that commonly existing
in the atmosphere. The vegetation around the springs, in the
valley of Gottingen, which abound in carbonic acid, is xeiy rich
and luxuriant, appearing several weeks earlier in spring, and
continuing much later in autumn, than at other spots in the
same district. But it is probable that, taking the average of the
whole globe, and at all seasons, the quantity of carbonic acid
existing in the air is that most adapted to maintain the health
of the plants at present inhabitants on its surface, as well as to
interfere as little as possible with the animal creation. In hot-
houses, however, the case is different, especially in winter; for,
although carbonic acid bq not produced by the respiration of
animals, it is produced in abundance b}^ other causes, and these
same causes also depriving the atmosphere of oxygen and its
aqueous vapor, the carbonic remains in excess, and its effect
upon the plants is easily perceived. The presence of oxygen,
in proper quantity, in the atmosphere of a green-house, or hot-
house of any kind, is even more necessary to be artificially
maintained, than carbonic acid, because the oxygen affords the
means by which the superfluous carbon is removed. We know
that plants in a hot-house suffer more frequently from an excess
of carbon than an excess of oxygen, arising from the causesj

PP.INCIPLES OF VENTILATION.

255

above stated. It has been calculated that hot-houses, during the
application of fire heat, contain four times as much carbonic
acid in their atmosphere as is necessary for the health of the
plants.

" Charcoal possesses the property of absorbing some gases to a
great extent, as may be seen by the following table, in which
the numbers indicate the volumes of gases absorbed, that of the
charcoal being taken as unity ."^

Absorption of Gases by Charcoal.

Ammonia, 90

Muriatic acid, 85

Sulphureous acid, 65

Sulphuretted hydrogen, . ... 55

Nitrous oxide, 40

Carbonic acid, 35

Bi-carb. hydrogen, 35

Carbonic oxide, 9.4

Oxygen, 9.2

Nitrogen, 7.5

Carbur. hydrogen, 5

Hydrogen, 1.7"

The above table will show how very useful charcoal may be
rendered as an agent in the absorption of these gases, when
present in excess, either in a plant-house or other places.

3. The evolution of heat by plants is most evident at those
periods of their existence in which an extraordinary quantity of
carbonic acid is formed and given off. This is the case during
the germination of seeds ; and though the heat produced by a
single seed is too soon carried off by surrounding bodies to be
perceptible, it accumulates to a high degree, Avhere a number
are brought together, as in the process of malting, when the
thermometer has been seen to rise 110°. An extraordinary
amount of carbonic acid has been found to accumulate in a hot-
house, in one night, so as sensibly to affect the respiration of in-
dividuals entering the house in the morning ; which shows the
necessity of night ventilation. The disengagement of carbonic
acid has been sensibly found in some plants, by the evolution
of heat in some of their organs. Thus, the flower of a gera-
nium has been found to possess a heat of 87°, when the air
around it was 81°. As in the case of seeds, however, the pro-
duction of heat is most sensible where the flowers are crowded
together, and in those flowers where the size of the fleshy disk ia

22# * Daniel's Introduction to Chemistry.

256 PEINCIPLES OF VENTILATION.

most considerable, the quantity of carbon to be united with the
oxygen is consequently the greatest. And the combination of
this cause with the other, causes the temperature of the clus-
ters to be raised very high. A thermometer placed in the
centre of five spadices has been seen to rise to HP, and one in
the centre of twelve, to 121°, while the temperature of the ex-
ternal one was only 66°.

From what has been stated, we think it may be argued that
plant-houses require to be ventilated at night even more than
during the day ; but the quantity of air then admitted must
be in proportion to the mean of the internal and external
temperatures; but more particularly depending on the con-
dition of the plants.

4. Various theories have been propounded by physiologif.ta
regarding the power of plants to withstand vicissitudes of tem-
perature, and, among others, we have the following from the high
authority of DecandoUe : —

First, in the inverse ratio of the quantity of water they con-
tain ; secondly, in proportion to the viscidity of their fluids ;
thirdly, in the inverse ratio of the rapidity with which the fluids
circulate ; fourthly, in proportion to the size of the cells, so is
the liability of the plants to freeze ; fifthly, the power of plants
to resist the extremes of temperature is in exact proportion to
the amount of confined air which the structure of the plants
enables them to contain. These and other principles are laid
down, and, apart from their practical observation, they are of
themselves sufficient to form the ground, of theory. There is
nothing, however, in the above calculated to be of material ser-
vice to the gardener in the culture of exotic plants. The dis-
tinctions upon which rest their powers to resist changes of tem-
perature are by far too undefined and minute to enable us to
determine the quantity or quality of the organic elements they
contain. Neither can we ascertain the dimensions of the cells
with sufficient accuracy to determine the precise degree of heat
or cold which any given plant will endure. In the management
of tender plants, we must find a firmer foundation on which to
rest our principles of action. We must endeavor to ground our

FRINCIPLES OF VENTILATION. 257

judgment upon broader and safer principles ; and, in order to
reach this point, let us briefly consider the nature of atmospheric
action upon hot-houses.

Before entering upon any illustration of its practical effects
upon these structures, we will give an extract from Dal-
ton's Chemical Philosophy, which will enable us to account
more clearly for some of those results that we have often
observed, and which have so often humiliated our practical pride
and baffled all our boasted experience. In fact, they have been
considered as belonging to that class of unaccountabilities which
our Creator has placed beyond the ken of human discovery.

" It is a remarkable fact," Dahon observes, " and has never I
believe been fully or satisfactorily accounted for, that the atmos-
phere, in all places and seasons, has been found to decrease in
temperature as we ascend, and nearly in arithmetical progression.
Sometimes this fact may have been otherwise, i. e., that the air
was colder at the surface of the earth than above; particularly at
the breaking up of a frost, I have observed it so. But this is evi-
dently the effect of a great and extraordinary commotion in the
atmosphere, and is generally of very short duration. What,
then, is the occasion of this diminution of temperature in ascend-
ing? Before this question can be solved, it may be necessary
to consider the defects of the common solution. Air, it is said,
is not heated by the direct rays of the sun, which passes through
it as a transparent medium, without producing any calorific
effect till they reach the surface of the earth. The earth, being
heated, communicates a portion to the atmosphere, while the
upper strata, in proportion as they are more remote, receive les«
heat, forming a gradation of temperature similar to what takes
place along a bar of iron, when one of its ends is heated." The
first part of the above solution is probably correct. Air, it would
seem, is singular in regard to heat ; it neither receives nor dis-
charges it, in a radiant state. If S9, the propagation of heat
through air must be opposed by its conducting power, the same
as in water. Now, we know that heat, applied to the under sur-
face of a column of water, is propagated upward with great
velocity, by the actual ascent of the heated particles ; it is equally
rertain that heated air ascends in the same way. From these

258 PRINCIPLES OF VENTILATION.

observations, it would follow that the causes assigned above foi
the gradual changes of temperature in a perpendicular column
of atmosphere, would apply to a state of temperature the very
reverse of the fact ; namely, that the higher the ascent, or the
more distant from the earth, the higher would be the tempera-
ture. Whether this reasoning be correct, or not, we think it must
be universally allowed that the fact has not hitherto received a
very satisfactory explanation. We conceive it to be one involv-
ing a new principle of heat ; by which we mean, a principle
which no other phenomenon of nature presents us with, and
which is not at present recognized as such. We shall endeavor,
in what follows, to make out that principle.

The principle is this. The natural equilibrium of heat, in an
atmosphere, is when each atom of air, in the same perpendicular
column, is possessed of the same quantity of heat ; and, conse-
quently, the natural equilibrium of heat in an atmosphere is
when the temperature gradually diminishes in ascending. That
this is a just consequence cannot be denied, when we consider
that air increases, in its capacity for heat, by rarefaction ; and,
therefore, if the quantity of air be limited, it must be regulated
by the density. It is an established principle, that every body
on the surface of the earth, unequally heated, is observed con-
stantly to tend towards an equality. The new principle an-
nounced above would seem to suggest an exception to this law ;
but if it be thoroughly examined, it can scarcely appear in that
light. Equality of heat and equality of temperature, when
applied to the same body, in the same state, are found to be so
uniformly associated together, that we scarcely think of making
any distinction between the two expressions. No one would
object to the commonly observed law being expressed in these
terms. When any body is equally heated, the equilibrium is
found to be restored, when each particle of the body becomes
possessed of the same quantity of heat. Now the law, thus
expressed, is what I apprehend to be the true general law, which
applies to the atmosphere as well as to other bodies. It is an
equality of heat, and not an equality of temperature, that nature
tends to restore.

The atmosphere, indeed, presents to us a strikingly peculiai-

PRINCIPLES OF VENTILATION. 259

feature, in its regard to heat. We see, in a perpendicular col-
umn of air, a body without any change of form, slowly and
gradually changing its capacity for heat, from a less to a greater ;
but all other bodies retain a uniform capacity throughout thei^
substance. If it be asked why an equilibrium of heat should
turn upon the quality in quantity, rather than in temperature, I
answer, I do not know ; but I rest the proof of it upon the fact
of the inequality of temperature observed in the atmosphere in
ascending, which invariably becomes colder as we ascend in
height ; while, in artificial atmospheres, as in the case of a hot-
house, the fact is quite the reverse. If the natural tendency of
air was to an equality of temperature, there does not appear to
me any reason why the lower regions of air are warmer than
the higher, or why the law of equalization held good in one case
and not in another.

To enable us to apply these arguments more clearly to our
subject, it will be necessary more fully to consi'der the relation
of the atmosphere in regard to heat; and the arguments already
advanced in behalf of the principle we are endeavoring to estab-
lish, are powerfully corroborated by the following facts.

We find, by the observations of Bougeur, Sassure, and Gay
Lussac, that the temperature of the atmosphere, at an elevation
where the weight is half that at the surface, (about 1 4,000 feet,
or less than three miles,) is reduced m temperature 50° Fahren-
heit; and, from experiment, it appears that air, suddenly rarefied
from two to one, produces 50° of cold. Hence we might infer
that the stratum of air at the earth's surface being taken up to
the height above mentioned, preserving its original temperature
and suffered to expand, becomes two measures, and is reduced to
the temperature of the surrounding air, and vice versa. In like
manner, we may infer, if a column of air from the higher strata
of the atmosphere were condensed and brought into a horizon-
tal position on the earth's surface, it would become of the same
density and temperature as the air around it, without receiving
or parting with any heat whatever. Another important argu-
ment in favor of the theory here advanced, may be derived from
the contemplation of an atmosphere of vapor. Suppose the pres-
ent aerial atmosphere were to be substituted for one of aqueous

260 PRLNCIPLES OF VENTILATION.

vapor;, and suppose, further, that the temperature of the earth's
surface were uniformly 212°, and its weight equal to 30 inches
of mercury. Now, at the elevation of about six miles, the
weio-ht would be fifteen inches, or one half of that below; at
twelve miles, it would be 74- inches, or one fourth of that at the
surface, and the temperature would probably diminish 25° at
each of these intervals. It could not diminish more ; for the
diminution of temperature 25° reduces the force of vapor one
half. If, therefore, a greater reduction of temperature were to
take place, the weight of the incumbent atmosphere would in-
crease, being converted into water, and the general equilibrium
would thus be disturbed by condensation in the upper regions."
It has been observed, that if the ventilators of hot-houses be
kept close during the day, the internal temperature will rise,
although no artificial heat be applied ; from which it has been
supposed that glass freely admits the calorific rays to pass
through it, in their descent, but arrests it in their upward progress.
Professor Robinson has proved that glass freely transmits the
luminous rays, but stops the calorific rays, till it becomes satu-
rated with heat to a certain degree ; which proves, also, that
light and heat are not identical, although both obey the same
laws of reflection, refraction, and radiation. Although heat may
arise from the same source as light, and possess a great affinity
to it, yet caloric possesses properties peculiar to itself, and diflfers
in its degree of affinity for other bodies ; for, although it has a
tendency to come to an equilibrium, when bodies differing in
quality are exposed to its influence, it has been found thit
these bodies do not all come into an equal temperature at the
same time. Caloric readily enters into some bodies, and freely
combines with them, whereby their temperature becomes in-
creased, and their properties sometimes changed. [See Part I.,
Construction, sec. Glass, p. 106.]

From the foregoing remarks, it will easily be perceived that
many of our operations, in the management of hot-houses, are
not only theoretically wrong, but diametrically opposed to the
laws of nature. Our methods of ventilation are wrong in prac-
tice, because our notions are wrong in principle. We raise t'lo

PRINCIPLES OF VENTILATION. 261

temperature of our houses by artificial means, and drive oiT the
oxygen and aqueous vapor, without returning a supply. We
admit the heat to escape through the laps and fissures of the
glass, of which there is always enough in badly glassed houses
to admit the escape of one fourth the heat radiated in the house.
And, moreover, we allow one fourth more at least to be taken
away by direct radiation from the glass, so that hardly one half
of the heat generated is used for the purpose intended. And,
lastly, we admit the external air into the house, to deprive the
atmosphere of its moisture by condensation. Likewise, in sum-
mer, we admit the external air, in Sirocco currents, to sweep
through the house, carrying away the moisture daily by gal-
lons; and which, if not returned in equal abundance, must
speedily prove injurious to the plants.

SECTION li.

EFFECTS OF VENTILATION, &C.

1. The ventilation of hot-houses, during winter, requires all
the skill which the most experienced gardener has at command.
It is a comparatively easy matter to open and shut the sashes, or
ventilators ; but to do so with benefit to the plants, at all times,
requires an amount of skill which is seldom bestowed upon it.
Admitting large quantities of cold air into a house, many de-
grees below the internal atmosphere, cannot be otherwise than
injurious to the plants growing therein. It has been calculated
that a volume of air, equal to 400 cubic feet, will absorb up-
wards of 36 gallons of water during its rise from 60 to 90°
of temperature ; or, in other words, upwards of a gallon has
been absorbed for every degree of temperature above 60°. This
will, in some measure, show the propriety of keeping the walls
and floors of a plant-house continually saturated with moisture,
especially during the hot days of summer, as well as of pre-
venting currents of air from sweeping through the house. We
have succeeded, in this way, in keeping the atmosphere of a
green-house 10 or 15° below the external temperature, even
when the latter stood above 90° ; and almost every gardener,
who has paid attention to these matters, has experienced the
same results. It is a common error for gardeners to give large
supplies of air, in sultry weather ; but, as it is a practical one,
and one of long standing, it is excusable in those who have not
studied its effects attentively.

By far the larger number of gardeners attach great impor-
tance to the ventilation of their houses abundantly, without per-
haps sufficiently considering the nature of the plants they have
to manage ; and, as has been justly enough said, by supposing
that plants require to be treated like man himself. They con-

EFFECTS OF VEISTILATION. 263

suit their own feelings, rather than the principles of vegetable
growth. There can be no doubt, however, that the effect of
excessive ventilation is more frequently injurious than advan-
tageous ; and that many houses, and especially hot-houses,
would be more skilfully managed, if the power of ventilation
possessed by the gardener were much diminished.

Animals require a continual renovation of the air that sur-
rounds them, because they very speedily render it impure, by
the carbonic acid given off, and the oxygen abstracted by ani-
mal respiration. But the reverse is what happens to plants.
They exhale oxygen during the day, and inhale the carbonic acid
of the atmosphere, thus depriving the latter of that which
would render it unfit for the sustenance of the higher orders
of the animal kingdom ; and, considering the manner in which
glass-houses of all kinds are constructed, the buoyancy of the
air, in all heated houses, would enable it to escape in sufficient
quantity to renew itself as quickly as it can be necessary for
the maintenance of the healthy action of the organs of vegetable
respiration.

It is, therefore, improbable that the ventilation of houses, in
which plants grow, is necessary to them, so far as respiration is
concerned. Indeed, Mr. Ward has proved that many plants
will grow better in confined air, than in that which is often
changed. By placing various kinds of plants in cases, — not,
indeed, air-tight, for that is impossible with the means applied
to the construction of a glass-house, but so as to exclude as
much as possible the admission of the external air, — supplying
them with a due quantity of water, and exposing them fully to
the light, he has shown the possibility of cultivating them with-
out ventilation, with much more success than usually attends
glass-house management.

2. In forcing-houses, in particular, it will be evident from
what is about to follow, that ventilation, under ordinary circum-
stances, in the early spring, may be productive of injury rather
than of benefit. Many gardeners now admit air very sparingly
to their vineries during the time that their leaves are tender
and the fruit unformed. Some excellent hot-houses have no
23

264 EFFECTS Of VENTILATION.

provision at all for ventilation; and we have the direct testimony
of Mr. Knight, as to the advantage of the practice to many
cases to which it has been commonly applied.

" It may be objected," says Knight, " that plants do not
thrive, and that the skins of grapes are thick, and that other
fruits are vrithout flavor, in crowded forcing-houses. But in
these, it is probably light, rather than a more rapid change of air,
that is wanting ; for in a forcing-house, which I have long devoted
to experiments, I employ but very little fire heat, and never give
air till the grapes are fully ripe, in the hottest and brightest
weather, further than is just necessary to prevent the leaves
from being destroyed by excess of heat. Yet this mode of
treatment does not at all lessen the flavor of the fruit, nor ren-
der the skins of the grapes thick. On the contrary, their skins
are always moist, remarkably thin, and very similar to those
grapes which have ripened in the open air." — [Hort. Trans.]

We have experienced the same results, as those recorded by
Mr. Knight, under similar treatment, and that too under a more
powerful sun. We have pursued this method of giving a very
limited supply of air, on an extensive scale, in some large
graperies in Maryland, and under glass of the very worst possi-
ble description. Yet, during one of the hottest summers which
had been experienced for some years, these vines grew beyond
anything we had ever seen, without any indication of injury by
the sun's burning rays. The lower surfaces of the houses, how-
ever, were kept moist, by frequent sprinkling with water during
the day. Many large houses in England are never aired,
except, perhaps, a few apertures at the top of the house, which
are left open, night and day, during the summer. But in all
cases within our knowledge, water is abundantly supplied to the
atmosphere from the floors of the house.

3. The philosophy of this method is easily perceived. The
under surface of the glass is continually covered with a deposi-
tion of the evapomted moisture, which intercepts the calorific
rays, and prevents them from being concentrated on the leaves,
from which cause the leaves are scorched and burned ; the
atmosphere, at the same time, undergoing comparatively little
change, or admixture with the external air.

EFFECTS OF VENTILATION. 265

While, however, the natural atmosphere of a hot-house can-
not be supposed to require changing, in order to adapt it to the
respiration of plants, it is to be borne in mind that the air of
hot-houses, artificially heated, may be rendered impure by the
means employed to produce heat, as will be seen from what has
already been said on the principles of heating, in the preceding
part of this work. Sulphuric acid gas, in variable quantities,
escapes from brick flues, especially old and imperfectly con-
structed ones, and various other unsuspected sources of impu-
rity, an infinitely small quantity of which is sufficient to con-
taminate the air, in respect to vegetable life.

Drs. Turner and Christison found that xtj^tttj of sulphurous
acid gas destroyed leaves in forty-eight hours ; and similar eflfects
were observed from hydro-chloric acid gas. Chlorine, ammo-
nia, and other gases produce the same results, when their pres-
ence is altogether undiscoverable by the olfactory organs. We
also know that the destructive properties of air, poisoned by cor-
rosive sublimate, by its being dissolved and evaporated in the
atmosphere of a hot-house, is not appreciable to the senses.
[See Chemical Combinations in the Atmosphere, sec. IV., for
detailed information on this subject.]

Ventilation is necessary, then, not to enable plants to exercise
their respiratory functions, provided the atmospheric air is un-
mixed with accidental impurities, but to carry off noxious vapors
generated in the atmosphere of a glazed house, and to produce
dryness, or cold, or both. Thus it is evident that air is given
under many conditions, when it is not only unnecessary, but
injurious.

When air is admitted, to produce cold in the house, the
external temperature must be lower than the atmosphere of the
house. This efiect, however, cannot always be produced by
ventilation, as, in summer, if the houses be rightly managed, the
reverse effect will be produced, as the external air is not only
warmer but more drying in its nature than the air of the
house ought to be ; therefore its admission can only prove inju-
rious, rather than otherwise, as we shall afterwards show. On
the other hand, if the external air be cold, its admission will

26Q EFFECTS OF VENTILATION.

produce dryners, which may also prove injurious under certain
circumstances.

4. When the external air is admitted into a glazed house,
below the temperature of the air it contains, the heated moist
air rushes out at the upper ventilators ; or, if it cannot find
egress, it is quickly condensed upon the cold surface, against
which it is forced to ascend ; the latter rapidly abstracts from
the plants, etc., a part of their moisture, and thus gives a shock
to their constitution which cannot fail to be injurious.

This abstraction of moisture is in proportion to the rapidity
of motion in the air. But it is not merely dryness that is thus
produced, or such a lowering of the temperature as the ther-
mometer suspended in the house may indicate. The rapid evapo-
ration that takes place, upon the admission of the air, produces a
degree of cold upon the surface of the leaves, and of the pots in
which they grow, as well as all other bodies around them, of
which our instruments give no indication. To counteract these
mischievous effects, many contrivances have been proposed, in
order to insure the introduction of fresh air, warm and loaded
with moisture ; such as compelling the fresh air to enter a house,
after passing through pipes moderately heated, or over hot-water
pipes surrounded by a damp atmosphere, which have been proved
decidedly advantageous, and to which we will subsequently
refer.

If ventilation is merely employed for the purpose of purifying
the air, i. e., for carrying off extraneous gases and vapors that
may be generated by artificial heat, it should be introduced, by
all means, with great caution ; and some expedient should be
adopted for supplying it with moisture, as well as to warm it
slightly on its passage inwards, more especially in cold, frosty,
or windy weather.

If it is only introduced for the purpose of lowering the tem-
perature, as in mild and genial spring and summer weather, it
may be admitted without any such precaution ; and the freedom
of admission should be in proportion as the external and inter-
nal temperatures approach each other in equality.

In hot, sultry weather, air should be sparingly admitted, as

EFFECTS OF VENTILATION. 267

the same effects are produced by the excessive evaporation as
by the currents of cold air, as will be afterwards shown.

5. Ventilation is also required, in winter, in pits and frames
where soft and succulent plants are grown, especially in pits and
frames warmed with fermenting materials. In this case, much
care and caution are necessary ; the object here being to carry off
the superfluous moisture, in order that the succulent tissue of
the plants may not absorb more aqueous matter than they can
decompose and assimilate. Although these kinds of plants will
bear a high degree of atmospherical moisture in summer, when
the days are long and the sun bright, and when, consequently,
all their digestive energies are in full activity, yet they are
by no means able to endure the same amount in the dark, short
days of winter, when their powers of decomposition, or diges-
tion, are comparatively feeble.

6. The thermometric changes are by no means satisfactory
guides for regulating the admission of air in hot-houses, as the
effect required by the indications of the thermometer may be
produced without resorting to the admission of air. In hot-
houses, we have full control over the state of the atmosphere,
both as regards its moisture and temperature ; and the means
of exercising this power ought to be known and familiar to
every gardener. But there are many circumstances which
ought to be duly considered in the exercise of this power, and
some unsuspected results arise from the unlimited use and exer-
cise of it ; and, as has been already said, by far the greater
number of gardeners attach too much importance to the mere
opening and shutting of sashes, w^indows, etc., without duly
studying the rationale of the practice. We will show that the
practical effects of ventilation are not only different from what
many suppose, but are actually injurious.

During winter we are in the habit of raising the temperature

of our hot-houses, by artificial heat, to 45 or 50° ; then, for six

or seven hours during the day, we open the lights and admit a

large quantity of cold air. This is also a stumbling-block, on

which a great many gardeners fall ; for it is not solely to the
23^

268 EFFECTS OF VENTILATION.

temperature, but rather to the hygrometrical state of the atmos-
phere, we ought to look. We ought to regulate the admission
of air, not solely by the thermometer, but also by the hygrome-
ter ; for, upon the latter condition, the health of the plants, and'
the perfection of their flowers and fruit, very much depend ; —
and, consequently, it is a matter which ought to be studiously
considered. Nothing is more injurious than the admission of
currents of air when the external temperature is lower than the
internal one ; and more especially so to plants that have been
for a considerable time subjected to a high temperature by arti-
ficial heat.

The causes which operate in rendering the atmosphere of
hot-houses unnaturally arid may be said to be two-fold. The
first is the condensation of moisture upon the glass, arising
from the action of the external cold upon its upper surface. The
second is the escape of heated air through the laps and crev-
ices of the glass, and otherwise. This heated air escaping, car-
ries along with it a large quantity of contained moisture, the
loss of air being supplied with cold, dry air, which finds access
by the same means. The loss of heat and moisture sustained
by these means is far more than would be supposed by those
who have not calculated the amount.

7. We have seen that the quantity of moisture a cubic foot
of air will hold in invisible suspension depends on its tem-
perature ; and as the temperature is increased, so is its capacity
for moisture. Suppose, then, that this capacity is doubled
between the temperature of 40 and 60° ; that is to say, every
cubic foot of air that enters the house at 40°, and escapes at 60°,
carries with it just double the quantity of moisture it brought in.
Now, every one must be sensible that these circumstances, con-
tinued for any length of time, must render the utmosphere of
the house too arid for healthy vegetation ; and, consequently, if
the deficiency of moisture so occasioned be not supplied by
artificial evaporation, then the plants must part with their secre-
tions to supply the atmospheric demand, and the soil and other
materials in the house will also be drained of their moisture, to
make up the deficiency. The greater the diflTerence between

EFFECTS OF VENTILATION. 269

the internal and external temperature, the greater will be the
demand for moisture. Thus, if the external air be at the freez-
ing point, (32°,) and the air in the house heated to 50 degrees,
then there is three times more moisture carried away by escap-
ing air than is brought in by the returning quantity; and,
escaping at 90°, it carries away four times as much, and so on,
in proportion to the difference of the two atmospheres ; the ex-
ternal air, however, increasing in ratio as it decreases in tem-
perature.

A'ccording to these calculations, atmospheric air, entering a
house at 32°, and escaping at 100°, carries away nearly six
times as much moisture as it brings in. This, in a short time,
would render the atmosphere of a house deleterious to either
animal or vegetable life ; and in large and lofty houses this is
practically the case. We have managed a lofty plant-house,
where the plants on the side shelves were nearly frozen, while the
thermometer, hung in the angle of the roof, about 45 (eet high,
stood at 100 degrees. Now this heated air, escaping at the top
of the roof, as is generally the case as well as here, carried away
more moisture than the small evaporating surface could supply;
the effects were, consequently, ruinous to the plants. However
imperfect the above calculations may be, they are within the
bounds of truth, and are sufficiently accurate to show the im-
portance of this subject to exotic horticulture ; and it will more
effectually impress upon our minds the amount of care and con-
sideration which the ventilating of hot-houses demands. If air
must be admitted, for the purpose of regulating the internal
temperature, every precaution should be taken to prevent it
from entering in strong currents, and it should be taken in from
the warmest side of the house, and, if possible, over a warm
surface, — as hot-water pipes, or whatever heating apparatus may
be employed, — so that the internal atmosphere may be gradually
reduced ; and, at the same time, the utmost precaution should
be used to prevent the escape of heated air, at least as little as
possible, by direct ascension ; this is easily accomplished by the
improved methods of ventilation now adopted, some of which I
shall hereafter endeavor to describe. Thus the cultivator is
enabled to modify the two atmospheres, previous to their com

210 EFFECTS CF VENTILATION.

bination, and by raising the humidity in the atmosphere of the
house, to compensate for that carried away by the egress of
heated air, the plants \vi\\ breathe an atmosphere more con-
ducive to their healthy development, and will be benefited by
the change.

S. Every gardener has observed the water on the under sur-
face of the glass, in the morning, before the sun has risen,
warmed the glass, and driven it off again, in the form of aqueous
vapor. This affords us a good illustration of the immense quan-
tity of moisture carried upwards by the heated air, and depos-
ited upon the glass, by condensation. This moisture is, of
course, taken away from the plants, and other bodies capable
of giving it off, and is demanded by the air as it becomes warm,
and capable of carrying a larger quantity than when no fire was
applied, — or rather, when the temperature of the house and
the temperature of the external air were alike, for in such case
no condensation on the glass would take place ; and, as I have
remarked, the proportion of water deposited will be in exact
ratio to the intensity of the external cold ; thus, the greater
the difference, the greater the deposition ; for then the action
of the external cold upon the upper surface of the glass being
greater, and the two atmospheres being brought into more rapid
proximity, the particles of heated air are cooled as quickly as
they ascend to the under surface of the glass ; they then fall to
supply the place of others, leaving the contained moisture upon
the cooling surface, in the form of dew, — the same process
being repeated through the whole night, or until an equality of
temperature is established ; the quantity thus deposited amounts
to immense volumes of water.

9. Experiments have proved that each square foot of glass
contained in the roof of a hot-house will cool down 1^ cubic
feet of heated air per minute as many degrees as the temper-
ature of the internal exceeds that of the external atmosphere.
Suppose, for instance, that the external air stands at 40",
and that of the house 60° ; then, for every square foot of
glass containod in tlio bnnso, one and one fourth cubic feet of

EFFECTS OF VENTILATION. 271

air will be cooled down the 20 degrees ; thus, 60 minus 40 gives
the difference, which is 20. If the house contains 800 square
feet of glass, presented to the action of the external atmosphere,
1000 cubic feet of air will lose 20 degrees of heat ; consequent-
ly, the moisture this air held in invisible solution, in virtue of
its 20 degrees of temperature, will be condensed by the external
cold, and deposited on the glass ; and it will also be found, that
the greater the difference between the external and internal
temperatures, the greater will be the amount of condensation.
The quantity of moisture abstracted from plants, at high tem-
peratures, is enormous. This fact is sufficiently de-monstrated
in a hot summer day, when the leaves of the trees are wilted,
and the garden vegetables flag and droop their leaves. The
earth gives out its moisture, and the atmosphere carries it away.
The same thing takes place in hot-houses ; the moisture is ab-
stracted by the heated air, and is carried off in the form of
invisible vapor, till its upward progress is arrested by the glass,
and the cold again reduces it to water.

If we take, for example, the roof of a hot-house, comprising
750 superficial feet of glass, and calculate that every square foot
of that glass will cool down 1| cubic feet of heated air 36°
per minute, and calculating the internal temperature at 65°, we
shall find that 937 cubic feet of air will be cooled down 36 de-
grees per minute. Now air, saturated at the temperature of 65
degrees, contains about 6-59 grains of water per cubic foot, and
at the temperature of 30 degrees, it is saturated with 2-25
grains ; this gives 4'34 grains of water lost, in condensation on
the glass, per minute ; or further, each square foot of glass con-
denses 1| cubic feet, or about 5*42 grains of water, per minute ;
and supposing the atmosphere of a house, such as we have de-
scribed, to be constantly supplied with moisture, by evaporation,
or otherwise, there would be abstracted from it about ^ of a pint
of water per minute, which is about 12 quarts per hour, or at
the rate of nearly 72 gallons in 24 hours. This enormous
amount of water, evaporated into the atmosphere of a hot-house,
when reduced to calculation, and displayed in plain figures,
seems to startle the imagination, and looks very like exaggera-
tion ; although it is much below the mark which, by a more

272 EFFECTS OF VENTILATION.

accurate calculation, it would certainly reach, yet the accuracy
of these calculations will appear sufficiently obvious to any one
who has paid studious attention to the subject. I say studious
attention, because a person may be tolerably observant of atmos-
pheric phenomena, and yet not form anything like an accurate
idea of this extraordinary process going on in his presence, and
the effect thereby produced on the vegetable system. When
we enter a hot-house, on a cold, frosty morning, after a strong
fire has been kept up during the night, we are very apt to regard
the moisture condensed upon the lower surface of the glass
as an evidence of a healthy atmosphere and luxuriant veg-
etation ; and often have I heard it stoutly asserted, that it
was merely the effect of an excess of moisture in the atmos-
phere of the house. This may be partly true, but the conclusions
which are drawn from the fact are founded on misconception,
that the moisture thus deposited on the glass has already per-
formed its purpose of benefit to the plants.

SECTION III.

METHODS OF VENTILATION, &C.

1. If we admit the truth of the foregoing calculations, (and
we cannot justly reject them, until they are disproved by calcu-
lations more accurate, and observations more extended,) then
we must acknowledge, also, that the old methods of ventilating
hot-houses, which are still in common practice, are contrary to
what we know to be right. Hence the question arises. How
are these methods to be improved ? Now, I would remark, that
the mere system on which a house may be ventilated is of com-
paratively little importance, for no method of ventilation will be
good, if the atmosphere be unskilfully managed. Various plans
have been employed to modify the influence of draughts, or
currents of air, many of which can hardly be termed improve-
ments, since the general effect is the same as by the old method
of opening the top and bottom sashes, which admits a current
to rise up beneath the under surface of the glass, and, as it pro-
ceeds towards the aperture made by letting down the upper
sashes, it carries the ascending moisture along with it, without
in the slightest degree mixing with, or purifying, the volume of
atmosphere contained in the lower portions of the house.

2. It has long been an object among gardeners to obtain a
motion in the atmosphere of a hot-house ; and to secure this,
even machinery has, in some instances, been employed, and,
under certain conditions of the atmosphere, these machines may
go on very well. But subject to those vicissitudes of climate,
so prevalent in many parts of this continent, the consequent
result of their adoption is, a complete derangement of all that
equalizing regularity which they were intended to secure. It
appears to us a matter of considerable difficulty to lay down a
definite rule, or propose a particular system of ventilating a
house, since almost every locality has some characteristics pecu-

274 METHODS OF VENTILATION.

liar to itself. It is true, the elements of the atmosphere may be
nearly the same in one place as in another ; but they are influ-
enced by various circumstances, in different localities, and hold
soluble matters in suspension in very different proportions ; and
in places much screened by trees, buildings, and similar objects
of shelter and obstruction, air may be admitted with greater
impunity than in situations exposed to wind from every quarter
of the compass, — the latter condition, as a matter of course, re-
quiring more care, not only in the adjustment of the apertures
of admission, but also in the admission itself. The course of
the current of air, by the common methods of ventilation, — that
is, by opening the front, and letting down the top sashes, — is ex-
ceedingly variable ; sometimes the actual motion created in the
atmosphere is little more than a foot, or fourteen inches, below
the surface of the glass. This motion can be easily determined
by holding the flame of a candle in the current, when the flame
will incline towards the aperture of egress ; lower it gradually
down, till it assumes and maintains a perpendicular position,
being no longer affected by the current, the volume of air being,
in fact, stationary, except there be some aperture of ingress else-
where. We have found this simple operation exceedingly useful
in determining the currents of air in large houses, and, in most
cases, it seldom fails in giving an accurate indication of their
course.

However desirable a motion may be in the atmosphere of a
hot-house, — and I do not doubt but it is beneficial, — yet it is not
necessary that we should run headlong either upon Scylla or
Charybdis. There is a great difference between a motion in
the atmosphere created by the warm particles ascending, and
being replaced by the denser and colder air, and that created by
a tornado sweeping through the house. The former motion is
only perceptible to the eye of the attentive and experienced cul-
tivator, and he can tell at a glance, by the quivering of the
leaves, that they are fanned by' a gentle zephyr. I am aware
that some gardeners have a peculiar fancy for seeing their plants
and vine-leaves bristling about by a good wind, and may be
very successful, too, in their productions; but it cannot be as-
serted that it is compatible with a high state of gardening skill

METHODS OF VENTILATION. 275

or with that perfection in horticulture at which it is our duty to
aim ; inasmuch as the revelations of science are against it, as
has already been shown, and practice has hitherto given no evi-
dence to prove it beneficial to tender plants.

3. In large and lofty structures, and especially in dome-shaped
houses, the management of the atmosphere becomes a matter
of much more importance than in small houses. During mild
and temperate weather, things may go on very well, as at such
times the external air may be allovved to circulate through the
house with greater impunity ; but during the heat of summer,
and the cold of winter, the atmosphere is much more difficult to
equalize. With a frosty air externally, and the temperature at the
surface of the earth down to zero, it is impossible to maintain a
proper degree of temperature, in all parts of the house, without
positive injury to those plants that may be growing, or have
their branches extended into the upper regions of the house. In
fact, without the precaution of covering, or some such expe-
dient, mischief is absolutely unavoidable. What has already
been said, upon the nature and properties of air, will sufficiently
explain the cause ; and, although it has been repeatedly asserted
by theorists, that one part of a house being heated by radiation,
from a body radiating heat, the equalizing law of nature will
heat all parts of the house to the same temperature, and as
speedily, too, j^et we must enter our decided protest against
the practical correctness of such a statement ; at least, in our
own practice, we have never found it so, under any circumstance,
or by any system of heating. And hence, whatever the natural
law of equality may be, the practical effects cannot be mistaken,
or disputed, as far as regards hot-houses. We know that heated
bodies tend to an equality of temperature ; but, as has been
already observed, air, of all other bodies, possesses peculiar
properties in this respect in regard to heat, and in nothing is this
peculiarity more strikingly illustrated than in the case under
consideration.

4. With regard to the motion of the atmosphere in a hot-
house, we know that the greater the difference between the tern-
24

276 METHODS OF VENTILATION.

peratiire of the air entering the house and the atmosphere of
the house itself, the greater will be the movement produced
among the particles. The motion is in exact proportion to the
difference of temperature ; and hence the necessity of admitting
the external air, in small quantities, when the external ther-
mometer is low. The slightest cause that disturbs the equilib-
rium of the air produces a motion. It is more sensible than
the most delicate balance. It is put in motion by the slightest
inequalities of pressure, and by the smallest change of tempera-
ture. It is speedily rarefied by heat, and thereby rendered
specifically lighter than the neighboring portions, so that it
descends, while colder, and consequently denser, flows in, to re-
store the equilibrium. It will be easily seen, from the very
nature of this law, that an equilibrium cannot be maintained in
the artificial atmosphere of a hot-house, since the source of
radiation must necessarily be confined to too small a surface to
equalize the ascending heat ; and, on the other hand, the con-
densation by cold is too irregular throughout the heated vol-
ume. This irregularity, produced by its unequal action on
different parts of the house, must ever render it impossible to
obtain an equality of temperature throughout an atmosphere
heated by artificial means ; and the larger the house, the greater
will be the difficulty of maintaining an equilibrium in its various
parts. So much so is this the case, that, as has been already
stated, the difference has been found to amount to 100°.

" Gaseous bodies expand equally for an equal increase of
temperature, as measured by the thermometer. Gay Lussac
showed that 100 measures of atmospheric air, heated from the
freezing to the boiling point, became 137.5 measures; conse-
quently, the increase for 180° Fahrenheit is \\^^ of its bulk.
Dividing this quantity by 180, we find that a given quantity of
dry air expands ^^-^ of the volume it occupied at 32°, for every
degree of Fahrenheit. New experiments have been made by
Rudberg," within a few years, giving j^y as the ratio of expan-
sion for one degree of Fahrenheit ; and these results are con-
firmed by Regnault. This last number may be adopted as the
true increment.

" If we wish to ascertain the volume which 100 cubic inches

METHODS OF VENTILATION.

277

of a gas at 40° would occupy at 80°, we must remember that it
does not expand ^^y of its bulk at 40° for each degree, but :f^y
of its bulk at 82°. Now, 491 parts of air at 32° become 492
at 33°, become 493 at 34°, and so on. Hence we can institute
a proportion between the volume at 40° and that at 80°. ^

Vol. at 4CP. Volume al 80^. Cubic inch. Cubic inch.

491 + 8

491 + 48

...........^

: : 100 : 108

5. The annexed cuts represent
an improved method of ventilating
lean-to houses, and by which the
Fig. 52.

[

o c^

Fig. 53.

Fig. 51.

* Wyman on Vent.

278

METHODS OF VENTILATION.

whole house may be aired in the space of one minute ; or as
many houses as may be in the range. This is eflected by a rod
passing along the whole length of the house. A pulley is fixed
immediately above each ventilator, and another placed opposite
it upon the rod, as shown in Fig. 51. A piece of chain or cord
is attached to the ventilator at one end ; and passing over the
pulley, as shown at a, Fig. 52, is then fixed to the pulley placed
opposite it upon the rod. A larger wheel, or pulley, is fixed at
one end of the rod, (^,) to which is attached a chain, connected
with a crank, situated within the reach of a person standing on
the floor. This crank is fixed on the back wall, as seen at c,
Fig. 52.

From the foregoing cuts and description it will be perceived
that, by giving the crank (d) a few turns, the whole of the ven-
tilators will be opened. The crank is provided with a racket, so
that they may be opened to any distance, from half an inch to
the full height.

The ventilators in the front wall may be opened and shut by
the same method, and may be, for convenience, brought from the
outside. Any length of house, or any number of houses, may
be ventilated at once by this method, providing the apertures
are in a straight line ; their perpendicular distance from the
horizontal shaft makes no difference in their facility of working.
The pulley cords of the higher ones only require to be length-
ened according to the distance, the diameter of the wheel on
which the cord turns being equal all along the shaft.

6. Figures 54 and 55 represent a method of ventilating
span-roofed houses. It is employed in the houses at Frogmore,

Fig. 54.

METHODS OF VENTILATION.

279

in England. Fig. 54 represents the end section of the house,
with the ventilator in proportion to the other parts. Fig. 55

Fig. 55.

«^

shows the sectional view of the ventilator, enlarged : a a are
openings of admission, and are covered with lattice-work, to
break the force of the current of ingress ; b, the movable shut-
ter, which regulates the admission to and egress from the house.
It is scarcely necessary to observe that these houses have been
ventilated on the most approved principles; and it appears
that several advantages are gained by this method. For in-
stance, the current of heated air is arrested, in its progress
outwards, by the depending glass at c c, and is, in some meas-
ure, thrown downwards, preventing also the escape of its con-
tained moisture. There is no doubt this method is very com-
mendable for span-roofed houses ; and one of its advantages is,
that the house can be aired, at any time, without the plants
being saturated with rain.

It is very possible that these compound systems of ventilation
may excite a smile from some who have, all their lifetime, been
accustomed to pull heavy sashes up and down for the purpose
of giving air. But if we include, in one computation, the
labor, the time, and the advantages of giving a range of houses
three or four hundred feet long, air at the proper time, and all at
the same moment, we will find a value in the system worthy of
something more than the mere smile of passive silence, which
is too frequently all that is at first accorded to such improve-
ments.

In some establishments, instead of pulleys, toothed wheels are

fixed to the shaft, which are made to work in a curved hand] •

24^

'280

I^IETHODS OF VENTILATION.

attached to the front sash by means of a hinge. This curved
rod is toothed on the lower side to answer the wheel, and is
kept in its place by an iron staple, having an eye through which
the sash-handle passes, as seen at a, Fig. 56. A crank and rachet-

Fig. 56.

wheel is provided, at one end of the shaft, by turning which the
sashes are simultaneously opened and shut, to any distance.
This method is simple and efficient. It has been extensively
carried out in the unique assemblage' of horticultural buildings
at Frogmore ; and, as an improvement in the modes of ventilat-
ing hot-houses, is considered, by competent judges, the most
valuable contrivance that has been introduced during the last
half century. By the turning of a small windlass, (which any
child may do,) any quantity of air may be admitted, and in-
creased or diminished at pleasure, throughout the whole range
of buildings.

The ventilation of forcing-houses, by this compound method
of opening the whole sashes at once, is very liable to produce
serious results, before the person in charge becomes fully
acquainted with the management of it. This, like many other
really valuable improvements in gardening, has been adopted, —
bungled in the construction, — mismanaged afterwards, — then,
lo ! it is condemned, with all the pomp and dignity of 'practical
experience ! The present moment affords an ocular demonstra-
tion of this too common fact. Some people suppose, if they
can only get mechanical contrivances to accomplish certain ends

METHODS CF VENTILATION. 281

that all is right. It is certainly desirable to employ mechan-
ical contrivances, whenever they can, as in the present case, be
applied advantageously. But mechanism can never make a
gardener, inasmuch as the chief part of what constitutes a real
gardener springs from mental, not physical, activity. It is a
very easy matter to open and shut the ventilators of a hot-
house ; but it requires something more than mere mechanical
power to do so with certain benefit to the inhabitants within.

This will be rendered clear by a common illustration. Let a
dwelling-room be warmed to a temperature of 60° ; and suppose
it to be tolerably well filled with individuals, by the animal heat
and respiration of whom the room by and by becomes somewhat
raised in temperature, and contaminated in its atmosphere.
Then, all at once, let the windows be thrown open, and the con-
sequence is not only disagreeable, but highly dangerous, as is
manifest by the murmur which very soon pervades the assem-
bled party. Now, the case is precisely similar in a hot-house,
only with this difference, — the unfortunate plants cannot speak
in audible sounds to tell the injuries that are perpetrated upon
them ; yet they bear a language, imprinted on their leaves, no
less truthful, nor less understood by the attentive observer. The
above common occurrence is a plain illustration of what I have
often seen, and have been forced to perform, in the ventilation
of forcing-houses, and which is more likely to be exemplified by
the compound methods which I have described. Science may
enable us to be more watchful of atmospheric phenomena, and
may draw our attention to facts which mere practice might pass
unnoticed. But this is a practical operation which science has
not yet approached, and which, in all her discoveries, she never
can approach, i. e., to tell us the precise quantum of air to
admit at different times and under different temperatures. The
method of mixtures does not come near it, and the combination
of gases gives the gardener little scientific assistance. We 7?mst
know the nature and properties of air at all times and tempera-
tures ; but the quantities and proportions in which we are to
admit it must be learned by experience and strict observation.
We must watch its effects upon the plants, and admit it in

282 METHODS OF VENTILATION.

proportions which appear, by oft-repeated trials, to be most
beneficial.

7. We could describe several other systems of ventilation,
by what we have called the compound method, which have a
greater number of wheels and rachets, and other kinds of ma-
chinery about them, but which possess no advantage over either
of the methods we have described. One system, in particular,
has received some countenance, which consists in opening by
the aid of a spring instead of the toothed rod, as shown in Fig. 56.
We have managed various houses ventilated by this method, but
we must say that it worked badly, although much care had been
taken to have the machinery properly fitted up ; for instance,
where the springs are of unequal strength, — and by constant
use they very soon become so, — you will find a very great irreg-
ularity in the airing of the house, some of them requiring to be
opened nearly full length, before the others will open a few
inches. Again, if some of the sashes be stiff to open, those
that are not so will open freely, while the ones that are hard to
move will not open at all. This has frequently caused us much
annoyance. It can never occur with the toothed wheel, as an
equal force is exerted on each ventilator or sash, and every sash
is opened to a regular distance. But if any of the sashes be
stiff to open, then the whole power applied is directed upon
them alone, until the whole move together. The only supposed
advantage of the springs is, that they do the work silently,
whereas a little noise is made bv the rachet-wheels, — a matter,
in most cases, of so trifling importance, as to be unworthy of
consideration ; but, as drowning men catch at straws, so the most
insignificant circumstance is eagerly seized, and magnified into
momentous import, by would-be inventors, for the purpose of
palming off their so-called invention upon the community, and
sustaining its sinking reputation. The less machinery there is
about a hot-house, the better ; and that system which does its
work in the most efficient manner, with the smallest amount of
labor, and is least likely to get out of order, is decidedly to be
preferred. This is a commendation which cannot be justly
given to some late inventions ; and^ without wishing to throw

METHODS OF VENTILATION. 283

anything in the way of improving our present systems, or
discouraging the application of new mechanical inventions to
aid the practical operations of horticulture, we would say that
some of these methods lately brought into notice may be
justly compared to the putting of extra wheels to a carriage,
increasing the rattling and complexity of the machine, but add-
ing neither to the strength of the structure nor the rapidity of
its course.

SECTION IV.

i-dANAGEMENT OF THE ATMOSPHERE

1. Notwithstanding all the discussion which has taken
place upon the abstract question of atmospheric motion, — and
which, under certain temperatures, as we have already seen,
cannot be disputed, — the tnie principles of ventilation still
remain unsettled ; and the mechanical operation of admitting
the air in larger or smaller quantities with facility does not,
in the slightest degree, remove the general objections that have
been urged against its effects on the internal atmosphere. In
considering, therefore, the question, how far the admission of
external air into forcing-houses is practicable and proper, it is
necessary to ask, in the first place. For what purpose is the
admission of external air resorted to under certain circum-
stances ? and, secondly, How does it act upon the atmosphere
when admitted ?

The first of these questions is of comparatively easy solution :
the latter requires more deep consideration, and more close
investigation, before we can find a satisfactory reply.

First. The necessity for ventilation arises from two prime
causes, which are briefly these : to regulate and reduce the
internal temperature ; and to allow the escape of impure air, or
that portion from which some of the .essential constituents have
been abstracted by the plants, or in which the natural equiva-
lents have been changed in their proportions, and consequently
the health-imbuing balance destroyed, — an effect which may
arise from various causes. The first of these points is a distinct
consideration, forming an important branch in vegetable physi-
ology : the others constitute a different branch of scientific
research ; but in relation to our present subject, they both merge
into one.

MANAGEMENT OF THE ATMOSPHERE. 285

The admission of cold air as the sole or principal agent in
regulating the internal temperature of a hot-house during win-
ter, seems to be perfectly unjustifiable. There are, indeed,
times when it can hardly be avoided, during the application of
artificial heat; but these are exceptions, rather than the rule.
Heat, when applied in early forcing, or to maintain the temper-
ature of plant-houses, is artificial, and, therefore, so far unnatu-
ral. And it appears still more unnatural to apply more than is
necessary, for the purpose of admitting the external to cool
down the internal atmosphere, without having secured any
equivalent advantage, but rather lost, by the change. It is much
more reasonable, as well as economical, to apply as much heat^
and no more than is necessary, to raise the temperature to the
minimum point, or, at least, as near this point as is possible. It
may be supposed that it would be unsafe to keep the tempera-
ture so close to the minimum point, lest the sudden external
changes, to which we are subjected in this country in winter,
might have an unfavorable effect upon the internal atmosphere ;
and, under certain circumstances, this would be the case, — such
as an imperfect heating apparatus, a badly glazed house, or a
want of skill in the management of it. The necessity of main-
taining the minimum rather than the maximum temperature
has been already adverted to in the preceding chapter ; and,
instead of being the exception to a general rule, it is rapidly
becoming the rule itself. We must consider that the object to
be kept in view is to improve upon the means at present in use
to obtain these results, and to obviate the risk and inconvenience
which might otherwise ensue by their adoption. It will be
observed, that it is not when the mild and genial weather of
spring is experienced that these remarks have any forcible
eflfect, but when the outward elements are unfavorable to the
development of vegetable life.

2. The atmosphere of a hot-house is very much influenced
in winter by the glazing of the sashes, and the adjustment of its
various parts. When the laps of the glass are open, there is a
continual egress and ingress movement in the atmosphere adja-
cent to the apertures, extending generally over the whole of its

286 MANAGEME^'T OF THE ATMOSPHERE.

interior surface, but not always affecting seriously the internal
volume, except in carrying off the rising particles of heated air,
the greater portion of which is condensed by the cold air imme-
diately as it escapes from the house. The consideration which
refers to the escape of air in a deteriorated state, and the conse-
quent necessity of admitting a fresh volume in its place, does
not appear to offer any insurmountable difficulties to the belief
that the admission of fresh air in the months of winter is very
frequently carried to an injurious excess. Although plants, in
the process of their growth, and in the discharge of their vital
functions, abstract matters from the atmosphere around them,
there is nothing, even in this, to render the admission of cold
air in large volumes at all necessary. In considering the nature
of the atmosphere in its relation to heat and cold, its elastic and
all-pervading properties must not be lost sight of. Under any
circumstances, a considerable effect will be produced by the
external upon the internal atmosphere, by radiation alone ; and
with the evidence before us of the successful growth of plants
in situations so much closed up as in Wardian cases, we cannot
do otherwise than believe that the interchange which takes
place between the volumes by these causes is sufficient to secure
the health and vigor of the plants, so far as the admission of
air alone is concerned. If it be argued that deterioration will
take place by means of evaporation from flues, or pipes, or any
substances confined within the structure, or from the decomposi-
tion of organic matter, the same fact is presented of an inter-
change continually going on, and is sufficient to meet the case,
so far as to show, that, on this ground, at least, the admission
of external air in large volumes is not essential. Besides, with
proper management, the gases that are generated by artificial
heat, or by the decomposition of substances which should find a
place in hot-houses, may be combined with others having an
affinity for them, and thereby not only purifying the atmosphere
by preventing an excess of particular agents, but also turning
those agents to their legitimate purpose, and rendering them
beneficial, rather than detrimental, to vegetable life. And,
therefore, it can only be in cases where misapplication or gross

MANAGEMENT OF THE ATMOSPHERE. 287

mismanagement of some kind or other exists, that they can
possibly be productive of injury, or even of inconvenience.

These considerations, then, would seem to point out the fact,
that the admission of air to any extent in forcing-houses in win-
ter, or at a very early period of the season, cannot be said to be
a matter of urgency, or necessity ; neither can it be grounded on
the plea that many of our practical operations have for their
foundation, viz., an expedient for a better, and probably more
tedious, method of effecting the same results. Whatever impro-
priety may appear in the above statement, it will be fully justi-
fied by its truth, — if a dozen years' extensive practice in the
management of hot-houses, both large and small, and in the
working of forcing-houses throughout the winter, be worth any-
thing, as well as the evidence of many of the best practical
gardeners of the present day. Then we would say that the
influx of large volumes of cold air is decidedly hurtful, even on
other grounds than those advanced in a former part of this chap-
ter. But, on the other hand, the opposite extreme must also be
avoided. The process may not be altogether dispensed with,
although every means ought to be taken to modify its immedi-
ate effect upon the internal atmosphere. It does appear, never-
theless, that the regulation of the internal temperature, i. e., the
prevention of too powerful a degree of heat, when the source of
that heat is the sun, is the only legitimate end to be effected by
the practice. If there are any other real advantages, they are
certain to follovv'. If air is admitted with this only in view, —
and these advantages are not likely to be lost if air is not admit-
ted when not required to effect this primary purpose, — periods
of bright sunshine, then, may be regarded as the only instances
in which a recourse to the practice is absolutely necessary.

3. From a full investigation and consideration of this sub-
ject, the conclusion at v/hich we have arrived is, that, with a
'proper system and routine of management, as regards the
application of atmospheric humidity and heat, the admission of
large volumes of the external air into the interior of hot-houses
is not by any means so essential as it is generally represented

to be. Whatever other differences of opinion may exist with
25

2SS MANAGEMENT OF THE ATMOSPHERE.

respect to this practice, it cannot be denied that a risk is in-
curred, and frequently an injury sustained, when cold air comes
in contact with the active organs of tender plants. And, there-
fore, if no other advantage be gained from the practice than the
regulation of the temperature, then, except in cases where the
heat is increased by the influence of the sun, and therefore
uncontrollable, it would be a much wiser practice to apply a less
amount of heat by artificial means, thus rendering it less neces-
sary to allow the superabundant portion to escape, and conse-
quently exposing the plants in a less degree to the risk to
which we have alluded.

4. Even in those cases in which it is really necessary to
have recourse to the practice of admitting air, much injury will
be sustained, though it may not be apparent at the time, by
admitting it in a rash and improper manner. It should be con-
trived so that the change to be effected may be brought about
gradually, and the cold and heated volumes should be made to
intermingle regularly together, and in a Avay that the internal
volume will be equally affected by it. Thus, if it be desirable
to admit a quantity of air equivalent to the reduction of 20°
of temperature, then the first consideration ought to be the
external temperature ; and the apertures of admission ought to
be regulated according to the calculations given at pp. 164 and
165, and in such a manner that the volume of air within the
house will not be deteriorated thereby, nor deprived of those
gases which are essential to vegetable existence.

Secondly. How does the external air act upon the internal at-
mosphere, when so admitted ? This portion of our subject is of
more difficult solution, and requires a closer investigation, inas-
much as it is influenced by various causes, such as the form of
the structure, the method of admission, and the material of
which the interior part of the house is composed ; for example,
a house presenting a large surface of glass to the morning sun
requires to be sooner ventilated than one whose largest glass
•surface has a western aspect, and a small quantity of air admit-
ted early in the morning will keep the tem|7erature down for a

MANAGEMENT OF THE ATMOSPHERE.

289

longer period, than a larger portion, when the temperature of the
house has increased ten or twelve degrees higher. Again, if
the top sashes be opened first, which is generally done, then a
much larger quantity of oxygen and aqueous vapor is carried
off than at any other period of the day. We believe it is the
practice of nineteen out of every twenty gardeners, to open the
top sashes first; then, when the internal temperature rises, and
more external air is necessary, the top sashes are opened still
more ; and, last of all, the front sashes are opened to make a cir-
culation;— a circulation, indeed! By the time the front sashes
are opened, the two atmospheres are generally equalized. Now,
I would ask, how is this circulation produced, and what are its
effects ? Not by the superior density of either atmosphere, for
both are the same, but by currents of wind, and draughts created
by other causes ; and their effect is to carry off the moisture
already too much reduced. The annexed figure represents a

Fig. 57.

method of admitting fresh air into a house which obviates the
evil here complained of. The air enters through the side-walls
at a a, then passes along beneath the floor, and enters the house
in the centre of the floor, at b. In this instance, no air is
admitted at the top; hence, the air, passing through these drains,
enters the house at a higher temperature than if admitted at
the sides or top, and, becoming gradually warmed as it ascends
through the aperture in the floor, rises until it is again cooled by
action of the external air upon the glass, then falls towards both
sides of the house, producing a motion somewhat similar to thar

290 MANAGEMENT OF THE ATMOSPHERE.

shown by the arrows in the foregoing ficrure. By this method,
air may be introduced into a house at any period of the day, or
even at night; and while every advantage arising from the
admission of external air is gained, the disadvantages are done
away with, save and except by the crevices in the structure.
In winter, if cold air imist be introduced to regulate the internal
temperature, some such method as that given above should be
adopted; but at a more advanced season of the year, when a
larcrer supply of air is necessary, provision nmst be made at the
sides for that purpose. As to opening the top sashes first, and
keeping them open till the last, it is a practice for which we are
unable to obtain any satisfactory reason, and which we think
will not bear a strict investigation. But, it may be asked, how
is the temperature to bs reduced, where, at an advanced period
of spring, the sun shines more powerfully, and when the tem-
perature of a hot-house will suddenly rise ten or fifteen degrees
above the maximum point? To answer this question, it is
necessary to consider whether there be any other method of
reducing the temperature than by expelling the heated air, by
the opening of the top sashes. From what has already been
said on this point, we think we are fully justified in disposing
of this question in the affirmative. Of course, we do not allude
to the ventilation of houses in summer, but in the months of
autumn, winter, and spring. By introducing the external air in
the manner described in the last figure, the atmosphere of a hot-
house will be reduced to any given point as effectually, though
not so rapidly, as if the heated air was expelled through the
sashes at the top of the house. This is accounted for by the
circumstance already explained, viz., that when two columns of
air of unequal temperatures are mixed together, the tempera-
ture of the whole is reduced, while its density is increased ; and-
hence, so long as the atmosphere continues to be heated by
reflection or radiation, this cold air will continue to cool it down,
so that nothing is lost, while all the essentials of vegetation
contained in the atmosphere are retained.

5. The materials of which the internal part of the house is
composed have also a powerful influence on the ventilation of a

MANAGEMENT OF THE ATMOSPHERE.

291

hot-house. Those houses whose internal bases are composed
of open soil require less ventilation than those that are paved
with stone or tiles ; and those that are paved with tiles, or other
soft materials, reqaiie less than those formed of hard and highly
reflecting bodies ; dark-colored walls, also, are longer in raising
the temperature of houses than walls painted white, and for this
reason white is preferred to any other color, as well as for its
clean and light appearance when contrasted with the dark-green
foliage of the plants. But in houses that are perfectly transpa-
rent on every side, and admit abundance of light, there is no
reason to suppose a dark color would not be preferable to a light
one, although we are well aware that some scruples may be
raised against it. Its propriety, however, can only be ques-
tioned as a matter of taste, not of utility ; for, with the advan-
tages above alluded to, in a well-constructed green-house, so far
as the management of its atmosphere is concerned, we would
decidedly prefer a house having the interior painted with a dark
color, although we are very sensible that the effect produced
would be meagre and dull, and but little calculated to harmo-
nize with the floral inhabitants of the house, or the feelings of
those who admire them.

Fig. 58.

6. The above cut represents a house ventilated by the com-
mon method, i. e., the upright sashes at the sides and the top
gashes along the roof, which, in span-framed houses, are gener-
ally about four feet long, or nearly square. In summer this
■nethod answers perfectly ; but in winter and early sp''ing it is

292 MANAGEMENT OF THE ATMOSPHERE.

next to impossible to admit air without injury to the plants, and
incurring" the evils which have been already detailed. Such a
house as this should, by all means, have these sashes made to
open, when requisite, but should also be provided with an
under-c/round method of admittinof air, when the weather is
unfavorable for opening the top and side sashes; and, in this
country, this may be said to be the case for at least three
months out of the twelve, during which time air can seldom be
admitted in anything like a sufficient quantity, without a posi-
tive, though perhaps at the time an imperceptible, injury to
exotic plants.

Various other methods have been adopted for imparting to
the atmosphere of a hot-house all the freshness of the natural
atmosphere, without a reduction of temperature corresponding
to the amount of cold air admitted, and also to effect this with-
out an increased consumption of fuel. The following simple
method has been carried out with pretty favorable results : —

7. Suppose a house already heated by the common flue.
We would propose that a square chamber be built over the top
of the furnace, and embracinof the neck of the flue for two or
three feet, if practicable. This chamber should have a drain,
not straight, but of a serpentine or zig-zag form, laid through
it, one of its ends, communicating with the external air, and the
other communicating with the interior of the house. Into this
latter opening, a pipe, made of tin or zinc, should be fitted, of
sufficient size for the admission of a good volume of air. Let
this pipe be laid along the lateral surface of the flue nearest the
front wall of the house, not in immediate contact with, but sup-
ported by bricks, or some other means, at the distance of a few
inches from the flue. Let that portion of the tube which passes
along the front be perforated with holes, to facilitate the escape
of the warm air, with which it will be filled, into the interior of
the house. This done, let a number of small tubes, — say one
for each light, or one for each alternate light, — be fixed through
the front wall, or otherwise as may be convenient, one end
communicating with the external atmosphere, and the other
entering the perforated tube. These smaller tubes should be

MANAGEMENT OF THE ATMOSPHERE. ' 293

provided with valves to open and shut at pleasure, to any extent
within the limits of their diameter, so that the apertures of
ingress for the cold air may be regulated by the operator accord-
ing to the state of the weather and the quantity of air required.
The size of these tubes will depend upon the size and situation
of the house. For instance, if the house contains a large inter-
nal volume of atmosphere, the perforated tube would require to
be at least eight inches in diameter, and the smaller about one
half the size of the large ones. And now for its mode of action.
It will be evident, that when fire is applied to the furnace, its
cover (which forms the floor of the chamber) will become heated
to a considerable degree. As soon as this takes place, the
external valve of the drain, which communicates with the main
tube, should be opened, when the external air will immediately
rush in ; and, by having to traverse the heated floor of the
chamber aforesaid, will expand along the large tube connected with
it, which, from being in contact with the heated air, will itself
become warm. The radiation of heat, too, from the surface of
the flue directly beneath it, will assist in maintaining the tem-
perature of the tube ; so that, although a portion of the heated
air will escape through the perforations in its upper surface,
enough will be retained to effect the purpose intended, which is,
to neutralize the effects of the cold air that will be admitted
through the medium of the small lateral tubes, and which may
be admitted in any quantity, to the full volume of their admis-
sion. As the warm air rushes along the tube, it will mingle
with that admitted by the small tubes ; and the cold air, enter-
ing by the latter, will thus be modified, while a supply of fresh
air will at the same time be circulated through the atmosphere
of the house.

S. The advocates of what has been called a " free system of
ventilation" have, like many others, in practising and advocat-
ing a favorite theory, in their excess of zeal, completely defeated
the objects they sought to secure. The sole object of some of
the advocates of the free system appears to be the prevention
of a stagnant atmosphere. They admit an unlimited quantity
of atmospheric air, at all seasons, to prevent this most terrible

294 MANAGEMENT OF THE ATMOSPHERE.

evil they call stagnation, and denounce the system of sealing up
plants (as some of them have termed it) from all atmospheric
influence but that exerted over them by their own tainted arti-
ficial atmosphere. Now, a stagnant atmosphere, or any con-
dition in the atmosphere of a hot-house approaching to stagna-
tion, certainly cannot be otherwise than injurious to vegetation.
This is a statement the truth of which will scarcely be called in
question. But, although the prevention or removal of it has
always been the chief object of every scientific gardener, it can-
not be said that every gardener, having this aim in view, has
taken the right way to effect his purpose ; for, certainl^^ what
is called " free " ventilation is very far from being the proper
mode of obvip.ting the evil ; and, in questioning the propriety
of the system upon these grounds, it may be deemed necessary
to enter into an explanation of the results attributed to this sys-
tem of ventilation, which is said to be requisite in order to
adapt an artificial air to the circumstances of the plants growing
in it, and which is supposed by some to be in exact harmony
with the laws of vegetable physiology, and with all that science
has unfolded to us respecting the effects of the atmosphere upon
vegetable life.

The direct effects of ventilation, of any description, are two-
fold, mechanical and chemical. The former embraces the influ-
ence which motion possesses over the growth of plants ; and this
influence has never yet been accurately defined or explained —
whether it be injurious or beneficial, and in what particular
degree it ceases to be so. The latter comprehends the effects of
the various gases, and their influence upon the vital functions
of vegetable beings. To illustrate the effects of the first of
these agents, viz., motion, we may refer to the circumstance
that is well known, that trees trained upon a wall, in ordi-
nary circumstances, do not grow to such size as those standing
in isolated places ; but their fibre is sooner matured, and also
their fruit earlier, as well as larger and more saccharine. It has
been asserted that wall trees do not arrive at so great an age as
others standing in exposed situations, — an assertion as founda-
tionless as it is absurd ; for it is a well-known fact, that wall trees
have outlived others of the same kind, planted in similar soil,

MANAGEMENT OF THE ATMOSPHERE. 295

and at the same period with themselves. And yet this assertion
has been made the basis of an argument in favor of free ven-
tilation. [Experiments of Knight, i/i Fkilosopkical Transac-
tions.]

Surely a system must be in a tottering condition when such far-
fetched arguments are resorted to for its support. Nor is this a
solitary instance of irrelevant arguments being brought to sup-
port untenable systems, when in a sinking condition. When a
plant is in a healthy and vigorous state, its sap is propelled
through its various tissues by its own vital principle, aided by
the combined influence of light, and heat, and moisture. And
while its vital principle remains unimpaired, and these essentials
of its existence unexhausted, its functions will continue in a
state of activity, until some cause, known or unknown, occur to
destroy them.

Let us rehearse an argument which has been advanced to
overthrow the above theory. " When a plant is young and suc-
culent, through all its parts, then all goes on very well; but
when the plant becomes more matured, and its vessels less per-
vious to the flow of sap, from its increased hulk, its approach to
maturity and probably its deade7ied susceptibility to the action of
light and heat, it is evident that to prolong the existence of such
a plant, a new impulse must be communicated to its sap, by a
different species of agency from that which was necessary in the
case of the young plant. This impulse is imparted by motion,
and that motion is created by the winds and currents of the
atmosphere."

Such is the sum and substance of an argument which involves
the solution of a most important problem in vegetable physiol-
ogy ; and, to the merely superficial reader, it has something
very plausible in its appearance, but, unfortunately, it will not
stand to be strictly investigated, for then the very breezes that
are brought to support it, would sweep it away. This is more
especially true when the illustration is applied to the atmos-
phere of hot-houses, upon which point enough has been already
said in this chapter, regarding the mechanical effects of currents,
to render further enlargement on this subject unnecessary.

SECTION V.

CHEBIICAL COMBINATIONS OF THE ATMOSPHERE.

1. With respect to the chemical effects of ventilation, upon
an artificial atmosphere, there are two important things to be
kept in view, in providing an artificial atmosphere for plants in
a glazed structure; namely, the nourishment they ought to
receive from it, and how to maintain it in this nutrient state.

It is needless, in this place, to enter upon the minute detail
of the various substances which enter into the composition of
plants, or of the various elements which combine to form the
different bodies of which they are composed, — bodies, in them-
selves so different in their qualities, yet so identical in their for-
mulae, and consisting of the same elements, united together in
the same proportions. This is one of those facts in chemical
science which appear so very remarkable to those who have not
directed their attention to chemistry", but are scarcely capable of
being clearly comprehended and explained, even by those who
have profoundly studied this branch of natural science. Starch
and sugar — how different their properties ! — how unlike their
uses! — how unequal their importance to the human race!
Yet they consist of the same weights, of the same substances
differently conjoined. The skilful architect can put together
the same proportions of the same stone and cement; and
the painter can combine the same colors, to produce a thou-
sand varied impressions on the sense of sight. But in the hand
of the Deity matter is infinitely more plastic. In his hands,
and at his bidding, the same particles can unite in the same
quantities, so as to produce the most dissimilar impressions, and
on all our senses at once.

A knowledge of the above close relations, in composition
among a class of substances occurring so abundantly in plants,
imparts a degree of simplicity to our ideas of this otherwise so
very complicated subject. It does not appear so mysterious that

CHEMICAL COMBINATIONS. 297

we should have woody fibre, and starch, and gum, and sugar,
occurring together in variable quantities, when we know that
they all are made up of the same materials, in the same pro-
portions ; or that one of these should occasionally disappear
from a plant, to be replaced in whole or in part by another.

A further question arises in our minds, in connection: Are
these elements formed in an artificial atmosphere, such as that
of a hot-house, from the same combinations of matter as in
the natural atmosphere ? A reply, though probably not a satis-
factory one, may be drawn from the following considerations:

During the day plants assimilate carbonic acid, and evolve
oxygen ; and during the night this system is reversed, although
we have no accurate data from which to conclude that the rela-
tive proportions of these gases are, at all times and under all
circumstances, the same. From the latest experiments, we are
induced to suppose that, in an artificial atmosphere, oxygen is
the most important element to be attended to, in the regulation
of its elements ; and from the fact that its presence, to the
amount of 21 per cent, in common atmospheric air, is essential
to the existence of animals and plants, there can be little
doubt that it is more frequently in deficiency, than in excess,
in an artificial atmosphere, and that hot-house plants are more
frequently injured by the want of a proper supply, than by an
excess of it in the atmosphere, when we consider the quantity
of this substance which nature has stored up for the use of
plants and animals. Nearly one half of the solid rocks which
compose the crust of our globe, — of every solid substance we
see around us, — of the houses in which w^e live, and of the
stones on which we tread, — of the soils which we daily culti-
vate, — and much more than one half by weight of the bodies of
all living animals and plants, — consist of this elementary body,
oxygen, known to us only in the state of a gas. It may appear
surprising that any one elementary substance should have been
formed, by the Creator, in such abundance as to constitute nearly
one half by weight of the entire crust of our globe. But this
is not so surprising, when we consider that it is on the presence
of this element that all animal and vegetable life depends ! Nor
is it less wonderful that a substance, which we know only in a

29S CHE3IICAL COMBINATIO>'S

State of thin air, should, by some extraordinary mechanism, by
bound up and imprisoned, in such vast stores, in the solid m.oun-
tains of the globe, — be destined to pervade and refresh all na-
ture, in the form of water, and to beautify and adorn the earth
in the solid parts of animals and plants. But all nature is full
of similar wonders, and every step we advance in the study of
the principles of our art, w^e cannot fail to perceive the united
skill and bounty of the same great Contriver.

2. It has been stated by some philosophers, that when the
leaves of plants are in a state of rest, their respiration is reduced
to its minimnm point, and that it increases within certain limits,
as motion is communicated to them by the action of a current
of air. Now this may be perfectly correct, and very likely is
so ; although, under natural conditions, the suspension of respi-
ration has never been accurately ascertained. Various physiol-
ogists have attempted to discover the minimum of respiratory
suspension, under certain atmospheric conditions, but without
any satisfactory results. But it does not require the discovery
of this delicate point, to decide on the propriety or utility of
atmospheric motion. That a certain motion in the atmosphere
is beneficial, we know; but then, it becomes a question of degree.
We know that the gentle zephyr is favorable to vegetation, and,
even in a hot-house, we have some reason to suppose it is so,
under certain circumstances, and to a certain extent. Now it is
under the uncertain circumstances, and the uncertain extent to
which this practice is carried, that we have any objections ; for
such circumstances, and such indiscriminate abuse of the prac-
tice, we know to exist ; and hence the chemical effects of venti-
lation, in the majority of cases, instead of promoting respiration,
rather tend to prevent it, by depriving the atmosphere of the
principal element that nature has designed to carrj'^ on the work.

The mechanical and chemical influences are intimately con-
nected with each other, so that to secure the chemical ad-
vantage of ventilation, I presume consists in maintaining the
proper equivalents of the atmosphere, which nature has deter-
mined as essential to the development of vegetation. If this
view be correct, the grand and important practical question

OF THE ATMOSPHERE OF HOT-HOUSES. 299

suggests itself, whether, in the atmosphere of hot-houses gener-
ally, these essentials to the growth of plants be suitably provided.
By chemical research, we find that nitrogen forms only a
small portion of plants, but it is never entirely absent from any
part of them ; even when it is not found in any particular organ,
it is found to be present in the fluids that pervade it. Many
experiments have been instituted, with the view of ascertaining
expressly, by what particular organs nitrogen entered into the
plant, and in what form it enters. Indeed, this is a question
which at present occupies much attention. It is well known
that the leaves of plants absorb gaseous elements largely from
the atmosphere, both free and in a combined state, and we might,
therefore, expect that some of the nitrogen of the air would, by
this channel, be admitted into their circulation. This view,
however, is not confirmed by any of the experiments heretofore
made, with the view of investigating the action and functions of
the leaves. We are not at liberty to assume, therefore, that
any of the nitrogen which plants contain, has in this way been
derived directly from the atmosphere. It may be the case, but
it is not yet proved. There is little doubt, however, that nitro-
gen enters the roots of plants, in a state of solution ; but the
quantity they thus absorb is uncertain ; it is supposed to be
small, and must be variable. Therefore, by whatever organs it
finds an entrance into plants, and in whatever quantity it may
be present, the question still remains, that it is the ammonia of
the atmosphere that chiefly furnishes nitrogen to plants.

3. In a former part of this treatise, while treating on the
subject of heating, by means of fermenting manure, we have
alluded to the extraordinary effects of ammonia upon plants. It
is unnecessary^ at present, to recapitulate what has already been
said on that interesting point. It has, we think, been clearly
established, that the difference between a hot-bed of manure, and
that heated by any other means, does not lie. in the quality of
the heat generated ; as we know full well that a hot-bed of
manure, warmed beyond a certain point, will burn the roots
of plants as quickly as one heated by any other method to the
same temperature ; nor does it consist in any life-giving proper-
§6

300 CHEMICAL COMBINATIONS

ties, possessed exclusively b}^ stable manure, for we know, also
that by placing living plants in a hot-bed, newly made, even if
the heat of the bed be kept from injuring the roots, they will
soon cease to exist as living beings, purely from an excess of
those very gases which, in proper proportions, add so much to
their natural luxuriance. Plants are more sensitive, and more
easily affected, with regard to life and health, than many living
animals. Many persons, who have paid little attention to A'eg-
etable physiology, may be dubious of this fact, but it is, neverthe-
less, true. The atmosphere of a hot-house may be impregnated
with ammoniacal and other gases, beneficial to vegetable life,
without being offensive to the ordinary visitor, or even detected
by him in the atmosphere of the house. Besides, it is so quick-
ly absorbed by the plants, that it has to be saturated almost to
excess before much smell is sensibly felt. We have carried on
the practice daily, of impregnating the atmosphere of a green-
house with carbonate of ammonia, by dissolving it in w^ater and
sprinkling through the house, without the ammonia being de-
tected, except by the acute olfactory organs of the experienced
chemist, except, perhaps, wdien the atmosphere was impregnated
to an excess, which, by way of experiment, was sometimes the
case.

4. This subject now resolves itself into the following consid-
erations : —

(1.) Which gases is it necessary to generate artificially, for
the purpose of increasing the capacit)^ of the atmosphere of a
hot-house to sustain vegetable life in a state of vigor and health-
fulness ?

(2.) How are we to determine the precise proportions of each,
so that we may keep as near as possible to that point of health-
fulness, which lies midway between deficiency and excess ?

In replying to the first question, it is not necessary to enter
into an elaborate detail of the various volatile gases which
arise from the combination of the prime elements of the organic
world, in different proportions, and which are absorbed by plants.
It may be sufficient for my present purpose, to notice that grand
stimulus of vegetation already alluded to, viz., ammonia, which,

OF THE ATMOSPHERE OF HOT-HOUSES. 301

as we have already seen, plays such an important part in the
progress of vegetable life. This gas, though composed of
hydrogen and nitrogen, is very unlike these, or, indeed, any
other gases with which the chemist is yet acquainted. It is
possessed of a most powerful penetrating smell, which is familiar
to almost every one as hartshorn and smelling-salts. In excess,
it suffocates living animals, though it requires a very considera-
ble preponderance in the atmospheric volume to destroy either
animal or vegetable life. Illustrations of this fact we have fre-
quently observed in fumigating a pit, or house, for the destruc-
tion of aphides, and other insects ; but it destroys both, much
more rapidly, when evolved at a high temperature, as we fre-
quently find it in hot-beds of dung, when plants have been
placed in them before the gas and heat had somewhat subsided,
as well as in vineries, which we have seen filled with ammoni-
acal gas, when the atmosphere was near 100 degrees, when the
edges of the tender leaves appeared as if they had been nipped
with frost, but the insects were not entirely destroyed. In
fumigating frames and pits with this and other gases, we have
seen some kinds of tender-leaved plants completely destroyed,
while many of the insects, tenacious of life, were uninjured,
which has fully satisfied me of the truth of the statement already
made, i. e., that the generality of tender plants are more sensi-
tive of noxious gases than living animals, although few may be
inclined to believe it, and their disbelief is too often manifested
in the treatment their plants receive. There can be little doubt
that it is this gas, in a certain proportion of atmospheric air,
that produces the luxuriance of plants, when combined with the
mild heat of a dung-bed. Were we to ask a chemist. What are
the manures which, in a fluid or gaseous state, can in these
forms be presented to the atmosphere, and diffused among living
plants, in a hot-house? — he would answer, "Ammonia, obtain
it from whatever source you may, either in a simple or combined
state ;" and as hitherto our chief supply of this substance, which
we have had to deal with in the common operations of garden-
ing, has been found in our hot-beds of stable manure, resulting
from the decomposition of vegetable matter, principally the nitro-
geneous substances contained in corn and other matter on which

302 CHEMICAL COMBINATIONS

the horses have been fed, with the compounds of salts and ani-
mal matter, all of which contain within themselves a tendency
to rapid putrefaction, and necessarily evolve a large amount of
ammonia. This is the principal source which gardeners have
had to draw upon for a supply of this agent ; and, although
exercising the most striking effects, it is rather remarkable that
the cause of these effects should, until lately, remain a mystery
to gardeners in general, and that the same elements, in a more
concentrated state, should not, in other circumstances, be applied
to produce the same results.

The second question is, perhaps, of more difficult solution.
Plants are living, organized, beings, and acted upon, atmospher-
ically, chiefly by the glands that cover the surface of the leaves ;
and abundant evidence exists, that they are as susceptible of
either injury or benefit, through the medium of the atmosphere
to which they are exposed, as animal life, and our ignorance of
the effect of houses artificially heated, upon the delicate organ-
ism of plants, is only accounted for from the fact, that com-
paratively little attention has yet been paid to this branch of
horticultural science by practical gardeners, and still less has it
been applied to the culture of exotic plants. If, for instance,
we take a plant from the open ground, where it is fully exposed
to the pure air, plant it in a pot, and place it in a close living
room, or in a hot-house, the effect will be rendered obvious by
the altered appearance of the plant. Again, if we take a plant
newly potted, and otherwise disturbed in the roots, and set it in
an arid situation, and fully exposed to the air, the leaves will
be withered and dried up in a few hours, and probably the death
of the plant will be the issue. But if the plants are placed in
a close, moist atmosphere, the results will be very different.
Now these illustrations are common, and, in themselves, exceed-
ingly simple, so much so, that we frequently observe them, and,
if asked the cause, we give a kind of generalizing reply, by
attributing it to the sun, or some such cause, which is well
known to be the principal origin of heat, yet they serve to show
how susceptible plants are of influences which, strictly speak-
ing, are neither dependent upon heat nor cold, although these
two latter elements are almost the only ones which .ve are in

OF THE ATMOSPHERE OF HOT-HOUSES. 303

the habit of supplying to our plants by measure, and that, too,
in the most unnatural proportions, while the ammoniacal and
hygrometrical condition of the atmosphere is generally left to
uncontrolled transmutations of chance.

5. It may be asked, " What guide have we to ascertain the
condition of the atmospheric gases ? "

In the present state of our knowledge of gaseous bodies, their
presence or preponderance in the atmosphere of hot-houses must
be little else than a matter of conjecture. An experienced gar-
dener, on entering his hot-house in the dark, can tell pretty
accurately what degree of temperature the atmosphere of the
house is standing at, by the sensation produced upon. his face,
or by the wave of his hand in the air. Now, in regard to the
excess of volatile gases floating in the atmosphere, the organs of
smell are much more delicate indicators than the sense of feeling.
This is more especially the case when the house is close, and the
temperature pretty high; for then the ammonia, being little more
than half the weight of the common atmosphere, [more nearly
three fifths, its specific gravity being 0.59, that of air being ],]
hence, w^hen liberated on the floor, or on the flue, pipes, tank, or
other heating apparatus, it readily rises and mingles with the
atmosphere ; and although it requires a considerable proportion
of it in the atmiOsphere to be injurious, or even offensive to the
senses, it is, nevertheless, easily detected by those acquainted
with this gas, even when present in small quantities, and the
experienced organs of the practical man have no difliculty in
deciding whether or not it is present in excess. On entering a
hot-house, when oxygen and aqueous vapor are deficient in the
atmosphere, this fact is at once detected by the oppressive burnt
smell which pervades the house. Saturate the atmosphere with
water, oxygen is generated, and the smiell ceases. The carbonic
acid, which previously existed in excess, combines with the oxy-
gen, and is transformed into carbonic acid gas, in which state it
is assimilated by the plants. In the state of vapor, water exer-
cises a wonderful influence over the atmosphere of a hot-house,
ind ministers most materially to the life and growth of plants.
It is in the form of water, indeed, that nature introduces the

304 CHEMICAL COMBL\ATIONS

greater portion of the oxygen which performs so important a
part in the numerous and diversified changes which are contin-
ually taking place in the interior of plants. Few changes are
really more wonderful, in chemical physiolog}", than the vast
variety of transmutations which are constantly going on through
the agency of the elements of water.

It rarely, perhaps nei^er, happens that we find the same
unhealthy and disagreeable smell in the external atmosphere,
which we frequently perceive in forcing-houses after a strong
fire has been kept up during the night. Sometimes this condi-
tion may occur in the confined streets of closely-built cities, and
in the vicinity of chemical works, where the heavier gases rise
into the air in a rarefied state, and, on cooling, fall again to the
surface of the earth, producing sometimes injurious conse-
quences. The combustion of fuel for the production of artificial
heat produces also carbonic acid gas in great abundance. And
to form this gas the oxygen is drawn from the plants to form
the combination ; and in this way the deficiency of oxygen, so
much felt in forcing-houses, may partly be accounted for. Oxy-
gen must exist in the atmosphere to the amount of 21 per cent,
of its bulk to be capable of supporting animal and vegetable life
in a state of vigorous development ; and when this proportion is
reduced, the plants under its influence must suffer accordingly.
The most convenient method of supplying the atmosphere with
oxygen is by saturation with water, which latter element con-
tains a very large amount of this gas, — every nine pounds of this
liquid containing no less than eight pounds of oxygen. In the
interior of plants, water undergoes continual decomposition and
recomposition. In its fluid state it finds its way and exists in
every vessel and in every tissue ; and so slight, it would appear,
in such situations, is the hold v/hich its component elements
have upon each other, or so strong their tendency to combine
with other substances, that they are ready to separate from each
other at every impulse, yielding now oxygen to one, now hydro-
gen to another, as the production of the several compounds
which each organ is destined to elaborate respectively demands.
Yet with the same readiness do they re-attach themselves, and
rling together, when new metamorphoses require it.

6. In the const/ tution of the natural atmosphere we are at

OF THE ATMOSPHERE OF HOT-HOUSES. 305

no loss to discover its beautiful adaptation to the Avants and
struct, iral development of animal and vegetable life. The excit-
ing efiect of pure oxygen on the animal economy ^ diluted by
the large admixture with nitrogen ; the quantity of carbonic
acid present is sufficient to supply food to the plant, while it is
not so great as to prove injurious to the animal; and the watery
vapor suffices to maintain the flexibility of the parts of both
orders of beings, without being in such a proportion as to prove
hurtful to either.^

The air, thus charged with these gases, by its subtilty diffuses
itself everywhere. Into every pore of the soil it make its way.
When there, it yields its oxygen, or its carbonic acid, to the
dead vegetable matter existing therein, or to the living roots.
When the soil is heated by the sun, the gases that are impris-
oned therein expand and partially escape, and. are as before
replaced by other particles of air when the heat of the sun is
withdrawn.

By the action of these and other causes, a constant circulation
is kept up, to a certain extent, between the atmosphere on the
surface, which plays among the leaves and stem.s of plants, and
the air which mingles with the soil and ministers to the roots;

* The mutual influence of animal and vegetable life is well illustrated
by the following experiment. Into a glass vessel, filled with water, put
a sprig of a plant and a fish. Let the vessel be tightly corked, and
placed in the sun. The plant, under the influence of solar light. Mill
soon commence the process of liberating oxygen. This being absorbed
by the water is respired by the fish, which, in its turn, gives out car-
bonic acid to be decomposed by the plant. Remove the vessel from the
sun-light ; the plant will cease to give out oxygen, and the fish will
soon languish, and revive when placed in the light. The moving power
of this beautiful system is the solar light. The balance is thus pre-
served ; and the atmosphere, even if of limited extent, cannot be sensibly
changed through all time.

It is not intended to intimate that it is in the removal of carbonic acid
from the atmosphere that plants are most essential to animals, — the
supply of organic matter ready for assimilation is of more immediate
importance than this, — but to show that their influence is mutually
conservative, preventing that change in the constituents of the atmos-
phere which would evenhially be faal to organic life. — [IVyman on
Ventilation. 1

306 CHEMICAL COMBLNATIOXS

and will also suffice to show the absolute necessity of maintain-
ing an adequate supply of aqueous vapor in the atmosphere of
our hot-houses, as well as the imperative necessity of studying
and making ourselves acquainted with the nature and qualities
of the atmospheric elements. Science has already done much,
and is still doing more, for the art of horticulture. We have
the thermometer, by which we can deal out heat and cold by
the measure. We have the barometer, by which we can ascer-
tain to a decimal the weight or density of the air. We have,
also, the hygrometer, by which we can tell the precise amount
of its contained moisture, — although this latter instrument is
but little used in practical horticulture, — and we hope the time
is not distant when it will find a place side by side with the
thermometer in our hot-houses, to which it does not yield one
iota of importance, of interest, or of utility. When shall we have
an instrument, equally simple and efficient as these, with which
we may ascertain the proportions of its gaseous elements, so
that we can regulate the constituents of an atmospheric volume
as easily as we can do its heat and moisture ? Such an instru-
ment is much wanted by exotic horticulturists, and we trust
something of the kind will be yet brought into use. Such an
instrument could be applied to excellent purpose, and would be
an incalculable boon conferred on gardening, — one almost un-
equalled in importance at the present day, and would be of
immense utility in all the higher and more difficult branches
of exotic horticulture.

7. There is, probably, no individual branch of natural science
so useful in itself to the practical gardener as a knowledge of
the various atmospheric phenomena which occur in hot-houses,
as well as out of doors; and without we study the one, we can
have but little knowledge of the agencies which regulate the
other. That a practical foreknowledge or intuitive perception
of the ordinary changes of the atmosphere is an acquirement
which may certainly be obtained, to a very considerable extent,
without the aid of science, is beyond a doubt. We find that the
untutored savage, taught only by his own observation, or instinct-
ively, is regulated in his movements by an unerring perception

OF THE AXnOSPHERE OF HOT-HOUSES. 307

of the coming changes of his own peculiar climate, and many
of the lower animals are also highly sensitive of changes ap-
proaching, especially the feathered tribes. Every person is
more or less familiar with these facts. We reason, therefore,
from the lesser to the greater; and if, in the absence of compara-
tive calculation, or the comparison of the results of one season
with another, — if, in fact, we consider what are the attainments
of instinctive knowledge alone, we are justified in believing
that, from established principles, the result of learned inquiry
and deep investigation, and the application of science extending
over many successive years, many useful facts are already
known and clearly explained for our practical guidance. Aided
b)?" these researches, man's ingenuity has already turned these
elements to a useful account, and made them subserve his pur-
pose, powerful though they be. But, in rendering these pow-
erful and all-pervading elements subservient to our will, the
object of that will must be undeviatingly directed to the imita-
tion of nature. To exceed, or even reach, in every case, the
perfection of the pattern, is impossible ; but the more closely it
is kept in view, and the more nearly it is attained in our artifi-
cial performances, the more perfect will that performance be,
and the more exactly will our own ends be answered. Any
departures from the principles suggested by the exam.ples set
before us in nature, throuo-h an over-hastv desire to arrive at
the object by a nearer road, not only defeats the intended pur-
pose, but also makes the ultimate attainment of that object
much more troublesome and expensive. The subject of this
treatise affords too many examples of this fact ; and, though
these examples may remain unnoticed by some, and uncared
for by others, their baneful influence on the progressing art
of horticulture is neither distant nor obscure. The various
structures for cultivation are, indeed, much improved of late
years ; so, also, are the methods of applying heat, air, vapor,
and water. All are so easy, and so much improved, that we
sometimes hear practical men observe, that this or that principle
or system cannot be beaten or improved ; yet the very best con-
structed apparatus, and the most perfect methods of applying
heat, vapor, air, and light, are capable of astonishing improve-

308 COMBINATIONS OF THE ATMOSPHERE.

ments. And no doubt the next twenty years will brin^ many
a hidden treasure to light, and, in that time, even our most
approved systems of applying heat, etc., will be altogether
economized and reformed.

SECTIOJT VI.

PROTECTION OF PLANT-HOUSES DURING COLD

NIGHTS.

1. Before concluding this brief treatise on horticultural
buildings, we will just cursorily advert to one more topic con-
nected therewith, which we are inclined to think is of far more
importance than is generally credited, at least, it certainly is so,
if we are to judge from the degree of its practical application,
viz., the protection of plant-houses, and, more especially, forcing-
houses, during cold nights, both with a view to the economizing
of fuel, and the equalization of heat. If duly considered, the
advantages of such covering are obvious. The low degree of
night temperature, which the best cultivators of the present day
agree in regarding as being most favorable to the healthfulness
ind general welfare of their plants, would depend upon the com-
bustion of fuel, so much less, in proportion, as the escape of
the internal heat, by radiation and otherwise, was prevented by
means of a covering exterior to the conducting surface of the
glass.

The manifest advantage of such a protecting body does not
wholly consist in the economizing of fuel. In such n variable
climate as we have in the New England States, with the exter-
nal atmosphere acting on the glass at a temperature of 25 or 30
degrees below the freezing point, it is, then, almost under any
system of heating, unavoidably necessary to apply an excess of
artificial heat, to ensure the safety of the plants against injuri-
ous depressions of temperature. Now, if a covering of non-
conducting materials be employed to intercept the action of the
changing atmosphere upon the surface of the glass, the plants
will be as ^afe at a much lower internal temperature, as if no
such protection were afforded them, with a high t€mperatur3.
The plants, therefore, will, under these circumstances, be in v

3iO PROTECTlOxN OF PLAKT-HOUSES DURING COLD IslGHTS.

condition more conducive to their health, than if their safety from
excess of cold had involved their submission to a higher degree
of artificial heat durinor i)^q ni<rht.

Night coverings, moreover, seem to afford facilities for night
ventilation, — a time when ventilation, of all others, appears to be
most necessary; for then, deleterious gases are generated in
the greatest abundance, and the agitation and circulation of
the atmosphere is most required. We have seen that motion
and interchange of atmospheric particles are, to a certain extent,
beneficial to the health of plants; and as their functions are in a
state of activity during the night, motion and circulation are as
necessary during that time as at midday. If a close confined
atmosphere be injurious to plants in the daytime, it must be
more so during the night, especially when artificial heat is in
process of generation. This fact is now beginning to be recog-
nized by the sounds, which are echoing in our ears — though as
yet but faintly, — the injunction, to keep a little air on all night ;
and which is responded to by the practice of the best cultivators
of the present day.

Under ordinary circumstances, where artificial heat is neces-
sary, there is some risk in following these recommendations.
A chilly blast, which cannot be refused admission when the bar-
rier to ingress is removed, would deal death and desolation
around ; and if this would be liable to happen in the daytime,
when attendants are at hand, the risk would be still greater at
night, when none were present to guard against it; and, under
the most favorable circumstances, night ventilation, if carried to
any extent, would involve a great loss of heat. It becomes,
therefore, a question, if the motion and circulation of the inter-
nal atmosphere during the night could not be so far facilitated
by other means, as to secure the chief advantage of an actual
interchange of air, without the internal heat being carried oflf by
the cause that produced it ?

Whatever prevents the radiation of heat from the interior to
the exterior atmosphere through the conducting agency of glass,
decreases in the same ratio the amount of required, heat, and
hence, saves the plants from being subjected to unnecessary
excitement. The principle upon which a covering acts effi-

PROTECTION OF PLANT-HOUSES DURING COLD NIGHTS. 311

ciently, is that of enclosing a complete stratum of air between
it and the glass, this body of air being entirely shut off from the
surrounding outer atmosphere, as far as may be practicable to
do so; and as air is a bad conductor of heat, the warmth of the
interior is prevented from passing to the exterior atmosphere, by
means of direct radiation from the glass ; or, in other words, the
exterior atmosphere, being prevented from coming in contact
with the glass, cannot absorb from the interior any sensible por-
tion of its heat. To secure this advantage, it will be evident
that the covering must be kept some distance from the glass,
and should be on every side where the structure is formed of
glass ; the coverings, in fact, should form a complete case to all
the glazed portion of the structure.*

So far, so good. As a matter of protection, and nothing else,
this is all very well. The advantages of such a covering will
be obvious to every one ; and, as a matter of protection alone, it
deserves every word that can be said in its favor. Whether it

* In the different experiments, it appears that the cooling effect of
wind at different velocities on a thin glass surface, is very nearly as the
square root of the velocity. In these experiments, the velocity of the
air Avas measured by the revolutions of the vanes of a fan. The tem-
perature of the air was 68^, the time required to cool the thermom^eter
20^ was noted for every different velocity, and the maximum tempera-
ture of the thermometer in each experiment was 120^. In still air, it
equired 5' 45'' to cool the thermometer this extent, and Table VIII. in
the Appendix shows the time of cooling by air in motion.

In consequence of the large quantity of glass used in the construction
of horticultural buildings, the cooling effect of wdnd is of considerable
importance. We find, however, that, with an increased velocity, the
cooling effect is considerably less in proportion, on glass, than on metal,
and it will be very much less on window-glass than even what is stated
in the table. As glass is an extremely bad conductor of heat, the
increased thickness which vrindow-glass possesses over that which
forms the bulb of a thermometer, will make a material difference in
the quantity of heat lost by the abduction of the air, there will be, as in
this case, a greater difference between the temperature of the external
and the int^ernal surface. The cooling effect of wind, therefore, is not
near so considerable as is generally supposed ; and the effect of wind in
hot-houses is very much increased by open laps and accidental fissures
in the glazing of the sashes.
27

312 PROTECTION OF PLANT-HOUSES DURING COLD NIGHTS.

can practicably be made the means of admitting the external air
into the house at an increased temperature, and thereby creat-
ing a motion in the internal atmosphere, is a question which, as
yet, we are unable to prove from experience, although we mean
to take an early opportunity of testing the plan which we are
about to describe.

2. The best material which we have seen used for this pur-
pose is canvas, or any other kind of strong coarse cloth, painted
with two or three coats of pitch, wax, and oil boiled together, and
applied in a warm state to the cloth ; this makes an efficient
and durable covering. Asphalte felt is also used extensively
in England and Germany for this purpose. This latter mate-
rial is fixed on light. wooden frames, about the size of a sash, or
larger, as may be found convenient ; and for covering frames
and pits it answers admirably, as it is quite impervious to wet,
and if taken care of, will last for some years. But for covering
the roofs of large houses, we would decidedly prefer the cloth,
which can be more easily drawn ofT and put on, and, if well
painted, will be as impervious to air and wet, as wooden shut-
ters, or asphalte frames, and will be cheaper than either.

Suppose, then, that a glazed cloth, of the requisite dimensions,
is prepared. We would provide means for securing it against
wind, by loops, etc., and fix on parallel strips of wood over each
rafter, about nhie inches from the glass. The cloth should be
made to fit quite close at the top, and to reach the ground on
all sides of the house, which, formed of conducting materials, or
side-pieces, must be made to fit closely over the over-lapping
edge of the upper one, and the lower edge secured against the
admission of air. The house is now in a case, impervious both
to air and water, and enclosing a stratum of air, which gradu-
ally becomes warmer than the external atmosphere, and efiectu-
ally prevents the latter from abstracting the heat from the inte-
rior of the house. Then let there be square holes made along
the cloth, near the bottom, say one for each alternate light, each
aperture made about ten inches square, and provided with a
shutter of the same material, to close it when necessary. All
these apertures, or any number of them, may be opened, accord

PROTECTION OF PLANT-HOUSES DURING COLD NIGHTS. 313

in^i^ to the wind, or other circumstances likely to affect the inter-
nal atmosphere. Then small apertures may be left open in
different parts of the house, during the night, whereby an inter-
change of the atmospheric volume would take place, without
exposing the plants to immediate contact with the cold air. By
this plan, we conceive that direct benefit would accrue to the
plants, because the air between the covering and the glass,
although not cold, would nevertheless be of greater density than
that of the house, and would consequently find its way into the
interior, by the ventilators left open for that purpose. This
would also enable us to maintain a much lower night tempera-
ture than could possibly be otherv/ise done, with regard to the
safety of the plants, which the fear of sudden changes during the
night, and consequent injury from frost, prevent from being
realized in this changeable climate.

It is truly remarkable how very slight a covering is required
to exclude a pretty severe frost. " I have often," observes Dr.
Wells, " in the pride of half-knowledge, smiled at the means fre-
quently employed by gardeners to protect tender plants from
cold, as it appeared to me impossible that a thin mat, or an}'
such thin substance, could prevent them from attaining the tem-
perature of the surrounding atmosphere, by which alone, I thought
them liable to be injured. But when I had learned that bodies
on the surface of the earth, become, during a still and serene
night, colder than the atmosphere, by radiating their heat to the
heavens, I perceived immediately a just reason for the practice
which I had before deemed useless. Being desirous, however,
of acquiring some precise information on this subject, I fixed
perpendicularly in the earth of a grass plot four small sticks, and
over their upper extremities, — which were six inches above the
grass, and formed the corners of a square, the sides of which
were two feet long, — fixed a thin cambric handkerchief, so as
to cover the included space. In this disposition of things, there-
fore, nothing existed to prevent the free passage of air from the
surrounding grass to that which was sheltered under the hand-
kerchief, except the four small upright sticks supporting it, and
there was no substance to radiate heat downwards to the grass
beneath but the cambric handkerchief. The temperature of the

314 PROTECTION OF PLANT-HOUSES DURING COLD NIGHTS.

grass, which was thus shielded from the sky, was, upon many
nights afterwards, examined by me, and was always found
higher than the neighboring grass which was uncovered, if this
was colder than the air. When the difference in temperature
between the air several feet above the ground and the unshel-
tered grass did not exceed 5°, the sheltered grass was about as
warm as the air. If that difference, however, exceeded 5°, the
air was found to be somewhat warmer than the sheltered grass.
Thus, upon one night, when fully exposed grass was 11° colder
than the air, the latter was 3° warmer than the sheltered grass,
And the same difference existed on another night, when the air
was 14° warmer than the exposed grass. One reason for this
difference, no doubt, was, that the air which passed from the
exposed grass, by which it had been very much cooled, had
passed through that under the handkerchief, and deprived the
latter of part of its heat. Another reason might be given, —
that the handkerchief, from being made colder than the atmos-
phere, by the radiation of its upper surface to the heavens, would
remit somewhat less to the grass beneath, than what it received
from that substance. But still, as the sheltered grass, notwith-
standing these drawbacks, was, upon one night, as may be seen
from the preceding account, S°, and upon another, 11°, warmer
than grass freely exposed to the sky, a sufficient reason was
now obtained for the utility of a very slight covering, to protect
plants from the influence of frost or external cold."*

* As the elevation of temperature, induced by the heat of summer, is
essential to the full exertion of the energies of the vital principle, so the
depression of temperature, consequent upon intense cold nights, has been
thought to suspend the exertion of the vital energies altogether. But this
opinion is evidently founded on a mistake, as is proved by the example
of such plants as protrude their leaves and flowers in the winter season
only, as well as by the dissection of the yet unfolded bud, at diflerent
periods of the winter, which proves regular and progressive develop-
ment ; even in the case of such plants as protrude their leaves and
flowers in the spring and summer, and in which, as we have said, there
is a gradual, regular, and incipient development of parts, from the time
of the bud's first appearance, till its ultimate opening in the spring. The
sap, it is true, flows much less freely, but it is not wholly stopped. Du
Hamel planted some young trees in the autumn, cutting off all the

PROTECTION OF PLANT-HOUSES DURING COLD NIGHTS. 315

We have instituted numerous experiments with the view of
ascertaining the capacity of various substances for the protection
of plants and horticultural structures, by which we find that
bodies of soft and open texture, — as woollen netting, thin cloth,
&c., — will, on dry, clear nights, afford an amount of protection
equal to 7° of frost. But if the covering should become wet
before the frost sets in, it will afford very little protection to the
plants beneath it.

Coarse cloth, which had been coated with paint, kept out 10'^
of frost, and several kinds of plants, which, at the freezing point,
would suffer injurj-, were kept alive during the whole winter,
with the thermometer occasionally indicating 22^ of frost. These
plants were frequently frozen, but the covering was never removed
during several months, although the air circulated freely under-
neath the glass.

In protecting plants, or glazed structures of any description, it
is essential to observe that the covering should always be placed
so that a stratum of air may always be confined between the
covering and the objects to be protected ; this is an important
part of he matter, as, if the covering be laid immediately on the
glass of a frame, or green-house, which it is wished to protect,
the cold will be conducted by the covering to the glass, which
in turn will cool the air beneath it. The covering should never
touch the object to be sheltered, though, from what we see around
us, this point appears to be very little attended to.

A covering of thin cloth, or woollen netting, when suspended
in a vertical position over trees, &;c., will afford better protection
than the same substance laid horizontally over the surface. In
this manner, wall trees are protected in the British Isles from
spring frosts, and we have frequently seen the blossoms of peach,
apricot, and pear trees completely uninjured under woollen or
hair netting, when the hardiest trees of the woods were nipt
with frost, and the tender vegetables of the garden were entirely

smaller fibers of the roots, with a view to watch the progress of the for-
ination of new ones. At the end of a fortnight he had the plants all
taken up and examined, with all possible care, to prevent injuring them,
and found that, when they did not actually freeze, new roots were alwav.s
uniformly developed.

316 PROTECTION OF PLANT-HOUSES DURING COLD NIGHTS.

destroyed. Peaches and other fruit tress might frequently be
protected in this way, and the crop, at least, partly saved, instead
of being, in one single night, blasted for the season.

Common bass mats afford the best and cheapest protection for
frames and small pits ; but they have the fault of absorbing
moisture very readily in wet weather, and then become very bad
protection. They should never be laid on the glass in a wet
state, as they are sure to do more injury than good. We have
found it an excellent method, in covering frames and small
houses with mats, to have a thin water-proof covering to lay
over the mats, which not only prevents the escape of the con-
fined air, but also keeps the mats always dry, and thus, one of
the very best protectors is obtained.

Large structures are more difficult to cover than pits, and the
difficulty which thus presents itself has, in general, prevented
every attempt to overcome it. We have seen various plans put
in operation, besides that which we have already described; all
more or less effectual. The difficulty of getting common rollers
to work in frosty weather has made them all but useless, in the
protection of hot-houses by rolling blinds, or screens of oil-cloth.
Nevertheless, this plan is not only an effectual one, but one
which is cheap and easily adopted. And the cloth can be drawn
off, in the mornings, and spread out to dry on the snow, or hung
on a fence, during the day. When the time comes for covering
at night, it might be so arranged as to be drawn up by cords
passing through a pulley at each end of the house. We have
succeeded in arrangements of this kind ; and the saving of fuel
in a severe winter, with the certainty of the plants being safe
from injury, either from frost or from fire, is ample compensation
for the trouble which it costs.

Whatever kind of object it is wished to protect, whether a
house or a plant, the protector should always be at least one
foot from it. A considerable difference of temperature is always
observed, on still and serene nights, between bodies sheltered
from the sky by substances touching them, and similar bodies
which were sheltered by a substance a little above them. "I
found, for example," says Dr. Wells, " upon one night, that the
warmth of grass sheltered by a cambric handkerchief, raised a

PROTECTION OF 'T.A.NT-HOUSES DURING COLD NIGHTS. 317

few inches in the aif, was 3° greater than a neighboring piece
of grass, which was sheheied by a similar handkerchief, which
was actually in contact with it. On another night the difference
between the temperatures of the two portions of grass, sheltered
in the same manner as the two above mentioned, from the infiu*
ence of the sky, was 4°. Possibly," says he, " experience has
long ago taught gardeners the superior advantages of defending
tender plants from the cold of clear and calm nights, by means
of substances not directly touching them, though I do not recol-
lect ever having seen any contrivance for keeping mats, and such
like bodies, at a distance from the plants which they were meant
to protect." We know 'this to be a fact; for gardeners seldom
take any thought whether the plant is protected or not, provid-
ing it be covered, with mats or something else, from the external
atmosphere. •

Straw, and corn stalks, afTord good protection to trees and half
hardy shrubs, when properly arranged, so that the covering may
be water-tight. The air that lodges among the straw, and in
the interstices of the stalks, keeps the plant within, always at a
regular temperature, and prevents sudden freezing and thawing,
which prove the destruction of tender plants.

Bodies, however, capable of absorbing heat during the day,
and parting with it at night, when the temperature of the atmos-
phere falls, are also useful as a means of protecting plants, $zc.
Among such bodies may be classed the walls of houses, which
may be regarded useful in two waj^s ; namely, by the mechani-
cal shelter they afford against cold winds, and by giving out
the warmth, during the night, which they had absorbed during
the day. It appears, however, that on clear and calm nights,
those, on which plants frequently receive much injury from cold,
walls must be beneficial in another way; namely, by preventing,
in part, the loss of heat, which the plants would sustain from
radiation, if they were fully exposed to the sky. The following
experiment was made by Dr. Wells, for the purpose of deter-
mining the justness of this opinion. A cambric handkerchief
having been placed, by means of two upright sticks, perpendicu-
larly to a grass plot, and at right angles to the course of the air,
a thermometer was laid upon the grass close to the lower edge

IS PROTECTION OF PLANT-HOUSES DURING CGI NIGHTS.

of the handkerchief on its windward side. :ie thermometer
thus situated was, for several nights, compared with another
lying on the same grass plat, but on a part of it fully exposed
to the sky. On two of these nights, the air being clear and
calm, the grass close to the handkerchief was found to be four
degrees warmer than the fully exposed grass; on a third night
the difference was six degrees. An analogous fact is men-
tioned by Gersten, who says that a horizon tcl surface is more
abundantly dewed than one which is perpendicular to the
ground.

Snow forms an excellent covering, and seems to be a provis-
ion of nature for the protection of many tender roots and plants
which would otherwise perish. Its usefulness as a plant-pro-
tector may be disputed, from the fact of their tops being exposed
to the influence of the atmosphere, while their roots and lower
parts only are protected. In reply to this, however, we may
observe, that it prevents the occurrence of the cold, which bodies
on the earth acquire in addition to that of the atmosphere, by
the radiation of their heat to the heavens, in still and clear
nights. The cause, indeed, of this additional cold, does not
constantly operate, but its presence during only a few hours,
might effectually destroy plants which now pass unhurt through
the winter. Again, as things are, while low-growing vegetable
productions are prevented, by the covering of snow, from becom-
ing colder than the atmosphere, in consequence of their own
radiation, the parts of trees and tall shrubs which rise above the
snow are little affected by cold from this cause ; for their outer-
most twigs, now that they are destitute of leaves, are much
smaller than the thermometer suspended by us in the air, which,
in this situation, seldom became more than two degrees colder
than the atmosphere. The large branches, too, which, if fully
exposed to the sky, would become colder than the extreme parts,
are in a great degree sheltered by them, and, in the last place,
the trunks are sheltered both by the larger and smaller parts,
not to speak of the heat they derive by conduction through the
roots, from the earth kept warm by the snow. In a similar man-
ner is partly to be explained the v/ay in which a layer of straw

PROTECTION OF PLANT-HOUSES DURING COLD NIGHTS. 319

or earth preserves vegetable matters in the fields from the inju-
rious influence of cold during severe winters. ^

When frames and such places are covered with snow, it
should be allowed to remain on till it melts away by the influ-
ence of the atmosphere. In like manner, trees and shrubs
should never have the snow drawn from their branches, during
snow storms, except where the branches are likely to be broken
down by the weight of snow lying upon them. Snow is not
only the best, but also the most natural, covering during the
winter months.

* That the warmth of the soil acts as a protection to plants may be
easily understood. A plant is penetrated in all directions by innumera-
ble microscopic air-passages and chambers, so that there is a free com-
munication between its extremities. It may, therefore, be conceived
that, if, as necessarily happens, the air inside the plant is in motion, the
effect of warming the air in the roots will be to raise the temperature
of the whole individual, and the same is true of its fluids. Now, when
the temperature of the soil is raised to 50^ at noonda)'-, by the force of
the solar rays, it will retain a considerable part of that \varmth during
the night ; but the temperature of the air may fall to such a degree, that
the excitability of a plant would be too much and too suddenly impaired,
if it acquired the coldness of the medium surrounding it. This is pre-
vented by the warmth communicated to the general system, from the
soil through the roots, so that the lowering of the temperature of the
air by radiation during the night, is unable to affect plants injuriously
in consequence of the antagonist force exercised by the heated soil.

SECTION VII.

GENERAL REMARKS ON THE ]MANAGEMENT OF THE
ATMOSPHERE OF HOT -HOUSES.

1. One of the most prevalent errors, and one of very consid-
erable importance, consists in reversing the natural condition
of the atmosphere in regard to the artificial regulation of the
temperature during the night. The artificial climate is not
rendered natural by adjusting it to the heat and light of the sun.
In cloudy weather, and during night, the artificial atmosphere
is kept hot by fires, and by excluding the external air; while, in
clear days and during sunshine, fires are left off, or allowed to
decline, the external atmosphere is admitted, and the internal
atmosphere is reduced to the temperature of the air without.
As heat in nature is the result of the shining of the sun, it fol-
lows that when there is most light there is most heat ; but the
practice in managing hot-houses is generally the reverse.

"A gardener," observes Knight, "generally treats his plants as
he would wish to be treated himself, and consequently, though
the aggregate temperature of his house be nearly what it ought
to be, its temperature during the night, relatively to that of the
day, is almost always too high.

•' It is very doubtful if any point in exotic horticulture is less
attended to than that wliich is involved in this question. We
are too apt to forget that plants not only have their periodical
rest of winter and summer, but they have also their diurnal
periods of repose. Night and its accompanying refreshments
are just as necessary to them as to animals. In all nature, the
temperature of night falls below that of day, and thus, the great
cause of vital excitement is diminished, perspiration is stopped,
and the plant parts with none of its aqueous particles, although
it continues to imbibe by all its green surface as well as by its
roots. The processes of assimilation are suspended. No diges-

THE ATMOSPHERE OF HOT-HOUSES. 32]

tion of food and conversion of it into organized matter takes
place, and instead of decomposing carbonic acid by the extrica-
tion of oxygen, they part with carbonic acid, and rob the atmos-
phere of its oxygen, thus deteriorating the air at night. It is,
therefore, most important that the temperature of glass-houses
of every kind should, under all circumstances whatever, be
lower during the night than the minimum temperature of the
day ; and this ought to take place to a greater extent than is
generally imagined among practical gardeners.

" Plants, it is true, thrive well, and many species of fruit attain
their greatest state of perfection in some situations within the
tropics, where the temperature in the shade does not vary in
the day and night more than seven or eight degrees; but in
these climates the plant is exposed during the day to the full
blaze of the tropical sun, and early in the night it is regularly
drenched with heavy wetting dews, and, consequently, it is very
differently circumstanced in the day and night, though the tem-
perature of^the air in the shade, at both periods, be very nearly
the same. I suspect," continues Knight, " that a large por-
tion of the blossoms of the cherry and other fruit trees in the
forcing-house often prove abortive, because they grow in too high
and too unit'orm a temperature. I have been led," he says,
*' during the last three years, to try the effects of keeping up a
much higher temperature during the day than during the night.
As early in the spring as I wished the blossoms of my peach
trees to unfold, m.y house was made warm during the middle of
the day, but, towards night, it was suffered to cool, and the
trees were then sprinkled, by means of a large syringe, with
clear water, as nearly at the temperature as that which rises
from the ground as I could obtain it, and no artificial heat was
given during the night, unless there appeared a prospect of frost.
Under this mode of treatment, the blossoms advanced with very
great vigor, and, when expanded, were of a larger size than I
had ever before seen on the same varieties.

" Another ill eflTect of high night temperature is, that it exhausts
the excitability of the tree much more rapidly than it promotes
the growth, or accelerates the maturation, of the fruit, which
is, in consequence, ill supplied v>-ith nutriment at the period of

322 GENERAL REMARKS ON THE BIANAGEMENT

its ripening', when most nutriment is probably wanted. The
Muscat of Alexandria grapes, and some other late grapes, are
often seen to wither upon the branch in a very imperfect state
of maturity, and the want of richness and flavor in other forced
fruit is, we are very confident, often attributable to the same
cause. There are few peach houses or graperies in this coun-
try in which the night temperature does not exceed, during the
months of April and May, that of the warmest valleys of
Jamaica, in the hottest period of the year. And there are prob-
ably as few hot-houses in which the trees are not more strongly
stimulated by the close and damp air of the night, than by the
temperature of the dry air of the noon of the following day.
The practice which occasions this cannot be right ; it is in
direct opposition to nature.'"^

We have fully satisfied ourselves that a high night temperature
is injurious to plants of any description, kept under glass, and
that green-house plants not only expand their flowers more per-
fectly, but continue much longer in bloom, when the temperature
of the house is reduced at night by the admission of air or other-
wise. In like manner, fruits are not only better flavored, — a
fact generally adniitted, — but also better colored, and more per-
fect in form, by a low temperature at night. On the other
hand, too much air is generally admitted during the day.

There is no doubt that gardeners frequently err in admitting
the external air into their hot-houses, etc., during ihe day, par-
ticularly in bright weather; and this error is so common as to
form a portion of regular practice. We have seen graperies
and green-houses fully exposed to the parching winds of a sum-
mer day, without screen or shelter; while the plants subjected
to this treatment plainly indicated, by their appearance, its inju-
rious effects. The climate of this country is so different in
respect to its atmosphere during the day, from that of Britain,
we are too apt to follow the practice of that country, where this
practice is also carried to too great extent.!

* Loudon's Encyclopedia of Gardening.

f The climate of the British Isles, relatively to others in the same lati-
tude, is temperate, humid, and variable. The moderation of its temper-
ature and its humidity are owing to its being surrounded by watei;,

OF THE ATMOSPHERE OF HOT-HOUSES. 323

The striking difference which is exhibited between our con-
servatories and green-houses in this country, and those of Eng-
land, is not so much owing to the existing peculiarities of cli-
mate, as to the methods of practice adopted by the gardeners
themselves in the management of the atmosphere of their
houses. However costly and faultlessly a conservatory, a hot-
house, or a grapery, may be constructed, the whole success of
the structure depends upon the subsequent management of its
atmosphere.

The imitation of warm climates in winter, for the purpose of
preserving tender plants, must not be confounded with the arti-
ficial climate created in a hot-house for the purpose of forcing
or accelerating foreign or native productions. As two different
objects are sought for, different courses of procedure must be
adopted. All that is necessary for the preservation of green-
house plants, is to keep the atmosphere at night a few degrees
above the freezing point ; and, indeed, if a proper attention be
paid to the plants, so as to avoid an excess of moisture, there is
scarcely any kind of w^iat are generally termed hot-house plants,
that will not thrive well enough under similar treatment. We
have often allowed our plant-houses to fall below the freezing
point in very severe nights; and when long and continued frosts
set in, the plant-houses should be gradually inured to bear even
a few degrees of frost below 32° ; and this the plants will do
without injury, if they be kept in a proper condition. When
the external atmosphere is dry and mild, air should be admitted
freely to the green-house during winter, but closed early in the

R'hich, being less affected by the sun than the earth, imbibes less heat

m summer, and, from its fluidity, is less early cooled in winter. As the

sea on the coasts of Britain never freezes, its temperature must ahvays

be above 33^ or 34° ; and hence, when air from the polar regions, at a

much lower temperature, passes over it, that air must be in some degree

heated by the radiation of the water. On the other hand, in summer,

the warm currents of air from the south necessarily give out part of

their heat in passing over a surface so much lower in temperature.

The variable nature of its climate is chiefly owing to the unequal

breadth of watery surface which surrounds it, — on one side a channel

of a few leagues in breadth, on the other, the broad Atlantic Ocean. —

iLoudon's Encij. of Gard.]

324 GENERAL REMARKS ON THE MANAGEMENT

afternoon, so as to preserve a portion of the warmth generated
by the sun's rays within the house, to maintain a slight degree
of heat in the house before the heating apparatus is set to work.

The accelerating, or forcing, of the vegetables and fruits of
temperate climates into a state of premature production is some-
what different, and more difficult, than the preservation of plants
durins: winter. The constitutions of the various fruit-bearin"
plants, as vines, &c., require atmospheres of different tempera-
ture and moisture, and their success is dependent upon many
contingent circumstances, which never occur in the mere preser-
vation of green-house plants.

The two principal methods of accelerating fruits in hot-
houses are, by planting them permanently in borders prepared
for them, and by planting in tubs and large pots ; and keeping
a succession of plants thus prepared, every year, to supply the
places of those which had become unfruitful by the effects of
forcing and producing a heavy crop of fruit. ,

The first of these methods has long been practised, and is,
undoubtedly, the best for permanent crops, as more fruit can be
produced in a house by this method than by the potting system.
When once planted out, however, and growing under the glass,
they cannot be removed from the house, and, consequently, arc
dependent upon the cultivator for the elements of consumption,
air and water. The grand effect is produced by heat, and the
great £(im is to supply just as much as will harmonize with the
light afforded by the sun, and the peculiar condition under which
the plants exist. All the operations must be natural and grad-
ual, and a good cultivator will always follow the dictates and
example of the natural world. He will never be anxious to force
things on too rapidly, — a very common error, and a frequent
cause of failure ; he will likewise be careful to guard against
sudden checks, either by a sudden decrease of temperature, or
the reverse ; but he will endeavor to continue the natural course
of vegetation uninterruptedly through foliation, inflorescence, and
fructification.

The skilful balancing of the temperature and moisture of the
air, in cultivating the different kinds of fruits in forcing-houses,
iind the just adaptation of the various seasons of growth and

OF THE ATMOSPHERE OF HOT-HOUSES. 325

maturity, constitute the most complicated and difficult part of
the gardener's art. There is some danger in laying down any
general rules on this subject, so much depends upon the pecu
liarities of the kind under cultivation, and the endless train of
considerations connected with the process of forcing.

The following rules, however, may be safely stated-, as deserv-
ing especial attention from the gardener in charge of hot-houses :

1. Moisture is most required in the atmosphere by plants
when they first begin to grow, and least when their periodical
growth is completed.

2. The quantity of atmospheric moisture required by plants
is, ccBteris paribus, in inverse proportion to the distance from the
equator of the countries which they naturally inhabit.

3. Plants with annual stems require more than those with
ligneous stems.

4. The amomit of moisture in the air most suitable to plants
at rest, is in inverse proportion to the quantity of aqueous matter
they, at that time, contain. Hence the dryness required in the.
atmosphere, by succulent plants, when at rest.

Moisture in the atmosphere, then, is absolutely necessarj'' to
all plants, when they are in a state of rapid growth, partly be-
cause it prevents the action of perspiration becoming too violent,
as it always does in a high and dry atmosphere, and partly
because, under such circumstances, a considerable quantity of
aqueous food is absorbed from the atmosphere, in addition to
that drawn from the soil by the roots.

Excessive moisture is injurious to vegetables in winter, when
their digestive and decomposing powers are feeble, and evapora-
tion from the soil should rather be intercepted than otherwise,
except when the atmosphere is dried to an unhealthy degree,
by the use of fire heat.

One of the causes of the Dutch method of winter-forcing is,
undoubtedly, their avoiding the necessity of winter ventilation,
by intercepting the excessive vapor that rises from the soil, and
would otherwise mix with the air. For this purpose they inter-
pose screens of oiled paper between the earth and the air of their
houses; and in their pits for vegetables, they cover the surface
of the ground with the same oiled paper, by which means vapor

326 GENERAL REMARKS ON THE MANAGEMENT

is effectually intercepted, and the atmosphere preserved from
excessive moisture.

The difficulty of keeping- succulent plants in damp cellars,
during- winter, is also owing to the same cause. Moisture,
without a sufficiency of light to enable plants to decompose it,
quickly destroys them.

On the other hand, the difficulty of keeping up that necessary
degree of humidity in the atmosphere of a dwelling room, dur-
ing the summer months, is the cause of the unhealthiness of
plants kept in them ; and the fact of their position being gener-
ally in the window, where there is always a current of air from
without, during the day, contributes, in a great measure, to
exhaust the plants of their contained moisture, and then they
gradually decline. Could the atmosphere around them be kept
sufficiently moist, wnth plenty of light, there is no reason why
they should not thrive as well as in the green-house.

We have already alluded to the injurious effects of maintain-
ing a high temperature in green-houses and conservatories dur-
ing winter. If we look over the different climates of the world,
we shall find, that in each there is a season of growth, and a
season in which vegetation is more or less suspended, and that
these periodically alternate with the same regularity as our
summer and winter. I do not know that in nature there is any
exception to this rule ; for even in the Tierra Templada of Mex-
ico, where, it is said, that, at the height of 4000 to 5000 feet,
there constantly reigns the genial climate of spring, which does
not vary more than 8° or 9° of temperature, — intense heat and
excessive cold being alike unknown, — the mean temperature
varjdng from 68° to 70°; we cannot suppose that, even in
that favored region, a season of repose is wanting; for it is
difficult to conceive how plants can exist, any more than animals,
in a season of incessant excitement. Indeed, it is pretty evident
that these countries have periods when vegetation ceases, for
Xalapa belongs to the Tierra Templada, and we know that the
Ipomea purga, an inhabitant of its woods, dies down annually,
like our native Convolvuli.

Fiom what has already been said on this subject, it is evident
that the natural resting of plants from growth is a most impor-

OF THE ATMOSPHERE OF HOT-HOUSES. 327

tant phenomenon, of universal occurrence, and that it takes place
equally in the hottest and in the coldest regions. It is, there-
fore, a condition necessary to the well-being of a plant, not to
be overworked under any circumstances whatever ; and there
cannot be any good gardening where this is not attended to, in
the management of plants under glass. Rest is effected in two
ways ; either by a very considerable lowering of temperature,
or by a degree of dryness under which vegetation cannot be
sustained.

In treating on the various conditions of the atmosphere, and
its effects on vegetation, we have already sufficiently explained
these influences ; which renders it unnecessary to recapitulate
them in this place. In practice we find that the effects of a
very dry atmosphere are, necessarily, an inspissated state of the
sap of the plant, and this, in all cases, — if not carried to an
injurious extent, — leads to the formation of blossom-buds, and
of fruit. This influence, however, must be controlled by the
cultivator, otherwise it will lead to inevitable failure, as the sap
of the plant may be so much dried up as to prevent its accumu-
lation in sufficient quantity, in the smaller branches, to form
fruit buds. It is, nevertheless, true, that a low temperature,
under the influence of much light, by retarding and diminishing
the expenditure of the sap in growing plants, produces nearly
similar effects, and causes an early appearance of fruit.

All the operations may be very essentially influenced by these
facts, vvhen they are fully understood to the cultivator, and, by
a skilful alteration of the periods of rest, we are enabled to
break in upon the natural habits of plants, and to invert them
so completely, that the flowers and fruits of summer may be
brought to perfection at the opposite season of the year.

By carrying out these principles, we have, for several years,
succeeded in fruiting grape-vines in the months of March and
April, without any extraordinary degree of excitability being
exercised at any period of their growth. The whole secret of
success consists in preparing the plants the preceding season,
by ripening their wood at an early period of the season, and ex-
posing them to such an amount of heat and dryness as can be ob-
tained by presenting them, un watered, to the influence of the sun,

28-^

328 GENERAL REMARKS, ETC.

at an early period of summer ; then, after the leaves have ripened,
keep them as cool as possible for some time ; thus causing a
sufficient accumulation of excitability by the end of October,
instead of the following month of May, at which period the fruit
will be ripe.

SECTION VIII.

VENTILATION WITH FANS.

In a preceding part of this work, [see Part II., Sec. V.] we have
described a method of warming hot-houses practised in Ger-
many, in which a fan is used as a means of propelling the
heated air into the apartments required to be warmed, and by
which the volume of air to be heated is drawn from the external
atmosphere. As an auxiliary to a heating apparatus, however,
the complicated arrangements of this machine, the cost of its
construction, and the expense and trouble of working it, must
ever continue to prevent its adoption as a method of warming
horticultural buildings, however extensive they may be. But as
an auxiliary of ventilation, and as a means of creating that con-
tinual motion in the air, which some cultivators so much admire,
it is undoubtedly superior to all other methods.

Fans are so common as to require very little description. The
kind of machine generally used for this purpose is merely a
light circular kind of wheel, composed of as many vanes or blades
as the size will admit. By the constant revolution of this w^heel,
a movement is created in the atmosphere, which causes a change
in the position of the atomic particles of the atmosphere of the
room in which it is at work ; but does not, as some suppose,
tend to its equalization.

Fans are of t\vo kinds, and have different methods of action.
The one is termed blowing fans ; the other, exhausting^ or suction
fans. In the first case,, the air in the house is driven outwards
from the fan, or blown away ; in the other, it is drawn towards it.
It will appear evident, however, that, in applying this machine
to the creation of a movement in the atmosphere of a hot-house,
various requisites must be had, namely, a moving powder, con-
stantly and steadily acting, and completely under control ; and
when it is to be applied to night ventilation and motion, which
appears to us the most adaptable use to which it can be applied

330 VENTILATION WITH FANS.

in relation to any kind of horticultural structures, then a supply
of warmed air must be kept up by means of the heating appa-
ratus, and a channel of conduction for the vitiated air to
escape by.

In places where the mechanical power for moving- a fan can
be easily obtained, this machine may be turned to excellent
advantage. The question, therefore, is not as to the adaptability
of the machine, but as to the means of working it so as to bring
it within the reach of hot-house adaptation, at a cost which
would justify us in recommending it.

There are various points to be considered in relation to draw-
ing in fresh, and'expelling foul, air from a hot-house, namely, that
we must not only expel the vitiated air from the house, but we
must introduce pure air into its place ; and that pure air must
be warmed before it is introduced. We have heard and read a
good deal about this and the other method of introducing warm
air into a hot-house ; and, in theory, many of these notions are
very plausible, but when we come to apply them to practice,
they are entire failures.

The principal objects to be obtained by an efficient system of
night ventilation may be classed as follows : —

1. The expulsion of a certain quantity of vitiated air, in a
certain time, from the whole volume contained in the house ;
and, as the impure air rises by rarefaction to the upper regions
of the house, means must be provided to carry it away, with-
out creating counter-currents, or admitting any cold air, by the
channels of conduction thus made.

2. A quantity of air must be introduced to the internal vol-
ume equal to the quantity expelled ; otherwise the remaining
internal volume will expand, by its increased temperature, and
fill the space occupied by the decreasing volume, and thus the
air becomes more vitiated than if none had escaped. The air
thus broucfht in must be introduced without acting- in a direct
current upon the vegetable productions within the house.

3. The air thus introduced must be warmed to a certain tem-
perature, before it enters the house. This temperature should
be regulated by the temperature at which it is desired to main-
tain the internal atmosphere. If the desired temperature be

VENTILATION WITH FANS. 331

50°, the air entering should not be under that temperature, but
rather a few degrees above it.

4. If the house be heated by pipes laid round the side of the
house, the air thus admitted should be introduced so as to pass
upward, by the side of the pipes, on entering the house. This
air should pass regularly and consentaneously upwards ; not in
sudden blasts and currents, which have always an injurious
influence on the internal atmosphere.

To effect this, a hot-air chamber should be placed in connec-
tion with the heating apparatus, from which must be laid air
channels, or conduction tubes, all around the house, having
apertures for the egress of the air, at distances of six or eight feet
apart. Within this chamber a fan might be used for drawing
in the external air and driving in the warmed air through the
tube. This fan might be driven by a small windmill con-
structed for the purpose.

When air is under the control of a moving power, it will take
any direction that is desired. It will move horizontally, or ver-
tically, either upwards or downwards, and even in both direc-
tions, at the same time.

It is essential, however, that the supply to be warmed should
be drawn from the external atmosphere ; and here the fan may
be used to great advantage. In no case should the supply of air
be drawn from the interior of the house. The vitiated air, as it
passes upward, should be allowed to pass off freely into the
atmosphere.

In this country, however, the fan cannot be so advantageously
applied in the ventilation of horticultural buildings, as in north-
ern Europe, and only at night, the period when ventilation is
most needful. The large amount of artificial heat necessary in
our New England climate, in severe nights, is more injurious to
green-house plants than the excessive heat of summer. There
is no impossibility, however, in producing a constant and equa-
ble motion in the atmosphere of green-houses, at night ; and
this may be effected by the means which we have just ex-
plained.

Fans may also be beneficially employed in producing a cool-
ing effect in the air at the top of the house. The injurious

332 VENTILATION WITH FANS.

eflTect of the liighly-heated air in the upper regions must be
obviou:>. W'^ have measured the temperature of a house 45
feet in heighi.and have found the temperature at the floor of the
house to be 3S°, while the temperature of the upper stratum was
103°, showing a difference of 65°. In many other cases, we
have found the temperature of the upper stratum of air in a
house, above 120°, while the water cistern, at the floor of the
house was covered with ice. The application of a fan may be
beneficial in reducing this temperature, and expelling the foul
air collected in the upper portions, at apertures lower down the
house.

Various other mechanical contrivances, besides the fan, have
been used for producing motion in the atmosphere of houses.
Among these may be mentioned common windmills, of which
we have already spoken. The windmill ventilator is a very
adaptable machine, and may be constructed very simply, in con-
nection with a hot-house, and applied in moving the atmosphere
of the house, or in propelling the warmed air through the con-
duction tubes with greater velocity than it would acquire by its
own specific gravity. The windmill, of course, is turned by
the force of the wind outside the house, and is entirely depend-
ent upon the motion of the external air, for the power it exer-
cises over the internal atmosphere. In hot-houses, with dome-
shaped roofs, it is well adapted for drawing ofl" the highly-
heated air at the top of the house, and may be made something
like the screw propeller of the steamboats, and situated directly
in the apex of tho roof.

Pumps have also been used for drawing off the foul air from
buildings, although we are not aware that they have ever been
employed for ventilating hot-houses, for which they are not at
all adapted.

Chimney shafts are well adapted for producing motion in the
air, by the draughts. None of these methods, however, are so
useful as the fan, when mechanical means are to be applied ;
though, for the practical purposes of ventilation, in horticultural
structures, the common process of spontaneous ventilation must,
in general cases, suffice ; — and, therefore, the question is, as to
the means of admitting the air, and the temperature at which it

VENTILATION WITH FANS. 333

iS to be admitted. The movements of the atmosphere, caused
by the difference 6f temperature between the external and inter-
nal volumes, have been already considered ; and we now leave
the subject to the consideration of those who are engaged in the
practical operat'ons of exotic horticulture.

APPENDIX.

TABLE I.

TABLE of the Expansive Force of Steam, in Atmospheres, and in lbs.
per square inch ; for temperatures above 212^ of Fahrenheit.

N. B. The steam is supposed to be in contact with the water from which it is formed,
and the water and steam to be alike in temperature.

bits:

Pressure.

Pres

3sure.

Degrees
•enheit.

Pressure.

•—

— sS

X <=■

a,
m

s
<1

lbs.

Heat in
of Fahi

Xi
Q,

o
£

lbs.

x:
a.

lb.s.

212

431

345

646

150

2250

251

436

360

, 655

160

2400

275

439

375

663

170

2550

294

457

450

671

180

2700

308

473

525

679

190

2850

320

487

600

686

200

3000

332

105

499

675

! 694

210

3150

342

120

511

750

700

220

3300 1

351

135

521

825

707

230

3450

359

150

531

900

713

240

3600

367

165

540

975

719

250

3750

374

180

549

1050

i 726

260

3900

381

1^5

557

1125

J 731

270

4050 i

387

210

565

1200

737

280

4200 I

393

225

572

1275

742

290

4350 i

399

^40

579

1350

748

300

4500

404

255

586

1425

753

310

4650

409

270

592

100

1500

758

320

4800

414

285

605

110

1650

763

330

4950

418

300

616

120

1800

768

340

5100

423

315

627

130

1950

772

350

5250

427

330 1

i 636

140

2100

*i^* The above Table is deduced from the experiments of MINI.
Dulong and Arago. Their calculations extend only as far as 50 atmos-

336

AtTZyDlX.

pheres ; from thence the pressures are now calculated to 350 atmos-
pheres by their formula, viz. : —

t=A/e

•7153

where e represents the pressure in atmospheres, and t the temperature
above 100^ of Centigrade. In this equation each 100^ of Centigrade is
represented by unity.

In reducing these temperatures from Centigrade to Fahrenheit's scale,
where the fractions amount to -5, they have been taken as the next
degree above, and all fractions below -5 have been rejected.

TABLE II.

TABLE of the quantity of Vapor contained in Atmospheric Air, at
different Temperatures, when saturated.

.2 " i

•2-

3 .

■-Sw

ofo

3 ^

Uy,

I. 'a

t^ 1

I. '3

t- 73

c «

o 2

£?

£•■5

Ii4

C-.5

« 2

v.- ^

£l

c .-

o -

O /-

X .»

x'~

>v—

.t; ^

.-> •-

•^ ' **

a 1

20^

1-52

48-'

3-98

76^

9-53

1-64

4-24

10-16

1-76 1

4-52

10-78

1-90 i

4-82

U-49

2-03 :

5-13

12-20

2-25 i

5-51

12-91

232 ;

5-83

13-61

2-48 1

6-21

14-42

2-64 ;

6-60

15-22

2-82

7-00

16-11

302

7-43

17-11

3-24

7-90

98 ■

18-20

3-48

L 74

8-40

100

19-39

3-73

8-95

*4^* The above Table is computed from Dr. Dalton's Experiments on
the Elastic Force of Vapor.

ATFE- D:x.

337

TABLE III.

TABLE of the Expansion of Air and oilier Gases b}' Heat, when per-

lectly free from Vapor.

Temperature

Fahrenheil's
Scale.

Expansion.

Fahrenheil's
Scale.

Expansion.

32^

1000

100°

1152

1007

110

1178

1021

120

1194

1032

130

1215

1043

140

1235

1055

150

1255

1066

160

1275

1077

170

1295

1089

180

1315

1099

190

1334

1110

200

1354

1121

210

1372

1132

212

1376

1142

*^* The above numbers are obtained from Dr. Dalton's experiments
which give an average of j^j part, or -00207 for the expansion b)^ each
degree of Fahrenheit. Gay Lussac found it to be equal to ^|^ part, or
•002083 for each degree of Fahrenheit ; and that the same law extends
to condensable vapors when excluded from contact of the liqnids which
produce them.

APPENDIX.

TABLE IV.

TABLE of the Specific Gravity and Expansion of "Water at different

Temperatures.

ex.-

1
1

Weight !

, Fah-

cale.

Wei gin

5j=

Specific

1 Cubic

£71

.2 '

Specific

of
1 Cubic

E 3

^ ,1

30^

Gravity.

Inch,
ingrains.

c-S
S 5

12P!

Gravity.

Inch,
ingrains.

•00017 1

•9998

252^714

•01236

•9878

249^677

•00010 '

•9999

252-734

124 1

•01319

•9870

249-473

•00005 '

•9999

252-745

127 1

•01403

-9861

249-265

36 '

•00004

•9999

252-753

130 !

•01490

•9853

249-053

•000002

•9999

252-758

133

•01578

•9844

248-836

•00000

1-0000

252-759

1.36

•01668

•9836

248 615

•00003

•9999

252-750

139

•01760

•9827

248-391

•00010

•9999

252-734

142

•01853

•9818

248-163

49 :

•00021

•9997

252-704

145 '

•01947

•9809

247-931

52 i

•00036

•9996

252-667

148

•02043

•9799

247-697

55 !

•00054

•9994

252-621

151

•02141

•9790

247-459

•00076

•9992

252-566

154

•02240

•9780

247-219

61 ;

•00101

•9989

252-502

157 1

•02340

•9771

246-976

64 i

•00130

•9986

252^429

160 ;

•02441

•9760

246-707

67 '

•00163

•9983

252-349

163 '

•02543

•9751

246-483

•00198

•9981

2.52-285

166

•02647

•9741

246-233

73 1

•00237

•9976

252-162

169

•02751

•9731

245-982

•00278

•9972

252-058

172

•02856

•9721

245-729

•00323

•9967

251-945

175

•02962

•9711

245-474

•00371

•9963

251-825

1 178

•03068

•9701

245-218

•00422

•9958

251-698

181

•03176

•9691

244-962

88 :

•00476

•9952

251-564

184

•03284

•9681

244-704

•00533

•9947

251-422

187

•03392 i

•9671

244^446

•00592

•9941

251-275

190

•03501 '

•9660

244^187

•00654

•9935

251-121

193

•03610

•9650

243-928

100

•00718

•9928

250-960

i 196 ,

•03720

•9640

243-669

103

•00785

•9922

250-794

199

•03829 :

•9630

243-410

106

•00855

' -9915

250-621

202

•03939 1

•9619

243-151

109

•00927

•9908

250-443

205

•04049 j

•9609

242-893

112

•01001

•9901

, 250-259

1208 ;

•04159

•9599

242-635

115

•01077

•9893

250-070

212 !

•04306

•9585

242-293

118

•01156

. ^9885

249-876

*^* In the above Table the expansions are calculated by Dr. Young's
formula, 22 /'^ (1 — -002/) in ten millionths. The diminution of specific
gravity is calculated by this equation: •0000022/-^ — •00000000472/3.
In both equations, / represents the number of degrees above or belo-w
39^ of Fahrenheit. The absolute weight of a cubic inch of water, at
any temperature, may be found by multiplying the weight of a cubic
inch at 39^, by the specific gravity at the required temperature.

APPENDIX.

339

TABLE V.

TABLE of the Specific Heat, Specific Gravity, and Expansion by Heat

of different Bodies.
Barometer 30 Inches. — Thermometer 6(P.

Apjhon

Air (atmospheric)
— (dry) ....
Aqueous vapor .

Azote

oxide of . .

Carbonic acid
oxide .

Hydrogen .
defiant gas
Oxygen . .
Water . . .

Water . .
Bismuth .
Brass . ,
wire

Specinc Heal.

•— si

o ^

s g

3 CO

o •-

•2669
■2767
•S470
•2754
•2369
■2210
2884
3^2936
•4207
•2361

rooo

Specific
gravity.

rooo

•0288

Cobalt
Copper . .
Gold . . . .
Glass (flint)
(tube)

Iron (cast)
(bar)

Lead

Nickel

Pewter (fine)

Platinum

Silver

Solder (lead 2 -f tin 1)
Spelter (brass 2-|-zinc 1)
Steel (untempered) . .

(yellow tempered)

Sulphur

Tellurium

Tin

Zinc

■1498
•0949
0298

1100
0293
1035

1-000

•633

•9722

b5277

1.5277

•9722

•0694

•9722

Mill

rooo

9^880
7-824
8^396
S^OOO
8-900

19250
2^760
2^520
7^248
7^788

11350
8^279

0314 2r470
05571 10^470

Weight of

lOU Cubic

Inches.

"o §

_ o
CO aj
>- S

0) o

<a S

Grains.

30^519

r9-32l*

29^65

46-596

29-65

2-118
29-65
33-888

-1880
-0912
•0514
0927

7-840

7-816

1-990J

6-115|

7^291

7^191

Ounce.-;.

57-87
571-7
452-77
485-87
497-6
515-0
1114-0
159-72
145-83
418-9
450-2
656-8
478-5

1242-4
605-8

453-7

452-31

115-1

353-5

421-9

416 0

Li near Ex-
paii.sioa by
ISOOofheal,

from
320 to 2120.

00186671

00193000

00172244
00U6606
000S1166
O00S7572
00111111
U0122045
00284836

00228300
00099 ISO
00208260
00250S00
00205S00
00107675
00136900

•00217298
00291200

*4s=* Air is taken as the standard for the specific gravity of the gases,
and water as the standard for the solids.
♦ Specific gravity of steam at 212o = -431. Weight of 100 cubic inches, 14-630 grains.

29^

340

APPENDIX.

TABLE VI.

TABLE of the Effects of Heat.

' Wedgwood's
I _ Scale.

Greales; heat observed

Hessian crucible fused

Cast iron thoroughly melted

Greatest heat of a smith's forge

of a plate-glass furnace ....

of a tiint-glass ditto

Derby porcelain vitrifies

Welding heat of iron (greatest)

a u a u (least)

Fine gold melts

Fine silver melts

Swedish copper melts

Brass melts

Diamond burns

Red heat fully visible in daylight

Iron red-hot in the twilight ,

Charcoal burns

Heat of a common fire

Iron bright-red in the dark

Zinc melts (680- Davy)

Mercury boils (Black"' 600-) (Secondat 644-) Petit and

Dulong)

" " (Crichton 655) (Irvine 672-) (Dalton) .

Lowest ignition of iron in the dark

Lead melts (Guyton and Irvine 594) (Crichton) . . .

Steel becomes darlc blue, verging on black

" " a full blue

Sulphur burns

Steel becomes a bright blue

*' " purple

brown, with purple spots

brown

Bismuth melts

Steel becomes a full yellow

" " a pale straw color

Tin melts

Steel becomes a verv faint yellow

Tin 3 4- lead 2 4- bismuth 1. melts

Tin and bismuth, equal parts, melts

Bismuth 5-j-tin 3 -|- lead 2, melts

Water boils (barometer 30 in.)

Water freezes

INTilk freezes

Vinegar freezes

Sea water freezes

Strong wine freezes . . •

Quicksilver congeals

Sulphuric eether congeals

Natural temperature at Hudson's Bay

Great artificial cold

Fahrenheit •
Scale.

u
(I

656

660

635

612

600

560

550

530

510

490

476

470

450

442

430

334

283

212

—39

—47

—51

—91

APPENDIX.

341

TABLE VII,

TABLE of the Quantity of "Water contained in 100 feet of Pipe of dif-
ferent diameters.

Diameter

Conlenls of 100 Feel

of Pipe.

ill leaglli.

Inches.

Gallons.

•84

3-39

u .

7-64

13-58

21-22

30-56

54-33

. 5

84 90

122-26

TABLE VIIL

TABLE, showing the Effects of "Wind in Cooling Glass.

Velocity

of the

wind

in miles

per liour.

Time of cooling the Thermometer 20^, from 12CP to lOCP,

Fahrenheit.

Observed
time of
coolin.ij.

Time re-
duced to
decimals

of a
minute.

Corrected time, being the inverse of the square
root of the velocities, in decimals of a minute.

3-26

5-18

6-54

8-86

10-90

13-36

17-97

20-45

24-54

27-27

2' 35'
2 10
1 55
1 40
1 30
1 15
1 5
1 0
0 55
0 48

2-58
2-16
1-91
1-66
1-50
1-25

ro8

1-00
•91
•81

2-5S
2-04
1-82
1-56
1-41
127
MO
103
•94
•88

342

APPENDIX,

TABLE IX.

Experiments on the Cooling Effect of Windows.*

These experiments were made in a wooden house, double plastered,
with a space between the two plasterings ; walls 6 inches thick. Heat
introduced from a hot-air furnace, heated air being shut off when the
room was heated to a proper temperatui'e. Thermometer four feet from
the floor. When the windows were closed, two thicknesses of blankets
were fastened closely to the window-frame internally.

Three windows, equal to 33-21 square feet ; walls, 531 square feet ;
cubic contents of room, 1930 feet, being 9 feet high, 165 feet long, 13
feet wide.

The room was kept as nearly as possible under the same circum-
stances.

External Internal Tinip

Thermom. Thernioni.

o o h. m.

74 ^ ^ i Weather calm, windows

64 10 15 / uncovered.

March 19, i843. 26
25

March 20.

March 21.

22
18

74
59

11 41
2 5

Windows covered with
blankets.

144

74
64

8 8

9 24

Windows uncovered.

)

24
22

74
61

10 17
12 22

Windows covered with
blankets.

125

24
19

74
64

8 51
10 19

Calm, windows covered.

17
16

11 26

12 16

Windows uncovered,
calm.

The experiments were also made in other rooms, with wooden shut-
ters internally.

The results are as follows : —

1st, room cooled 10^ in 74' = P in 7-4', windows open.
" '' 15' in 144' = P in 9-6', windows closed.

2d, room cooled 10 in 76' = 1" in 76', Avindows open.

* \Vvni^;i on Ventiialior*.

j\ppExDix. 343

2d, room cooled 13^ in 125' = P in 9-6', windows closed.
3d, room cooled 10^ in 88' = 1° in 8-8', windows closed.
" " 10= in 50' = P in 5-0', windows open.

Experiment with wooden shutters : —

Room cooled 10= in 93' = 1° in 9-3', shutters closed.
" " 10= in 58' = 1= in 5-8', shutters open.

From the above, the eflect of glass is very evident, and also the advan-
tage of curtains and .shutters. We shall not attempt to form any gen-
eral rule, since it could be applied correctly only under circumstances
which differed very little from the above.

The preparation for covering white cotton for interior windows is
composed of 4 oz. of pulverized dry white cheese, 2 oz. of white slack
lime, and 4 oz. of boiled linseed oil. These three ingredients having
been mixed with each other, 4 oz. of the white of eggs, and as much of
the yolk, are added, and the mixture then made liquid by heating.
The oil combines easily with the other ingredients, and the varnish re-
mains pliable and quite transparent. It is applied with a brush.

344

APPENDIX.

TABLE X.

Weights of Watery Vapor in one Cubic Foot of Air, at Dew-points from

0° to 100^ Fahrenheit.

c ^
O

i'l
26

Grains in a
fool.

c —

Grains in a
fool.

" 'a

« -::

o -
•J

Grains in a
loot.

0-186

1-915

4-382

9-523

0 810

1-986

4-524

9-813

0-836

2-054

4-671

10-111

0-864

2- 125

4-822

10-417

0-893

2- 197

4-978

10-732

0-925

2-273

5-138

11-055

0-957

2-350

5-303

11-388

0-992

2-430

5-473

11-729

1-028

2-513

5-648

12-079

1-065

2-598

5-828

12-439

M03

2-686

6013

12-808

1-143

2-776

6-204

13-185

1-184

2-870

6-400

13-577

1-226

2-966

6-602

13-977

1-270

3-066

6-810

14-387

1-315

3-168

7-024

14-809

1-361

3-274

7-243

15-241

1-409

3-382

7-469

15-684

1-459

3-495

7-702

16140

1-510

3-610

7-941

16-607

1-563

3-729

8-186

17-086

1-618

3-851

8-439

17 577

1-674

3-979

8-699

18-081

1-733

4-109

8-966

18-598

1-793

4-244

9-241

100

19-129

1-855

APPENDIX.

345

TABLE XL

Dalton's Table of the Force of Vapor, from 32^ to 80^

Tempe-
rature.

Force of va-
por ill inches

Tempe-
rature.

Force of va-
por in iuc'ies

Tempe
rat u re.

Force of va-
p-ir ill inches

of mercury.

32^

0-2000

49-

0-3483

1 65

0 6146

0-2066

0-3600

66
67

6355

0-2134

0-3735

6571

0-2204

0-3875

6794

0-2277

0-4020

i 69

7025

0-2352

0-4171

i 70

7260

0-2429

0-4327

! 71

7507

0-2509

0-4489

\ 72

7762

0-2600

0-4657

8026

0-2686

0-4832

8299

0-2775

0-5012

8581

0-2866

0-5200

8873

0-2961

0-5377

9175

0-3059

0-5560

9487

0-3160

0-5749

9809

0-3264

0-5944

0120

0-3372

Note to Table '^ll.—{Setnext'pagt.)

To determine the dew-point, take two thermometers, the scales of
which agree, cover the bulb of one with thin muslin, and wet it with
water j swing both thermometers in the air, that they may be exposed under
similar circumstances, and note the height of the mercurial column in
each, after it has become stationary. Ascertain the difference between the
heights of the two columns. In the following table, find a number at the
top corresponding to the difference of heights, and in the left hand
column the degree answering to the temperature indicated by the dry
bulb thermometer ,• the figure at the intersection of the two lines is the
dew-point.

Suppose, for instance, the dry bulb indicated 70=, and the wet bulb
6P ; 70 — 61 = 9, which is found at the top of the table ; in the column
beneath, and against 70=, is bb^, the dew-point.

■6

APPENDIX.

TABLE XII.

Table for ascertaining Dew-point by

I euip

"90-
89
88
87
8G
85
84
83
82
81

80
79
78
77
76
75
74
73
72
71

70
69
68
67
66
65
64
63
62
61

~W
59
58
57
56
55
54
53
52
51

50
49
48
47
46
45
44
43
42
41
40

2 3

88-7
87-7
86-7

87'
86-

85 •

S5-7 84

84-7
83-7
82-7
81-7
80-7
79-7

78^
77-6
76-6
75-6
74-6
73-6
72-6
71-5
70-5
69-5

68^
67-4
66-4
65-4
64-4
63-3
62-3
61-3
60-3
59;2

58-2
57-2
56-1
55-1
54-0
53-0
51-9
50-9
49-8
48-8

46-6
45-5
44-4
13-4
12-2
!M
40-1
3^9
3-f^
i36-7

83'
82

80
79

78-3

7T3
76-3
75-3
74-2
73-2
72-2
71-1
70-1
69-1
68-0

67
66
64
63
62
61
60
59
58
57

56-
55-
54-
53-
52'
50-
49'
48'
47'
46'

86
85
84
83
82
81
SO
79
78
77

76
75
73
72
71
70
69
68
67
66

65
•i4
03
o2
61
60

:i8

•57
56
55

45-2
44- 1
42-9
41-7
10-5
39-3
38-1
^6-8
15-6
■!1-r
33 0

54
53
52
51
49
18
47
46
15
13

42
41
40
38
37
36
34
33
31
30
28

85-1
84-0
83-0
81-9
80-9
79-8
78-8
77-8
76-7
75-6

74-6

73-5

72-5

66-0

64-9

83
82
81
80
79
78
77
76
75
74

63
62
61
60
59
)S
57
55
51
53-

52-
51-
50-
48-
47-
46-
45-
43-
42-
41-

72
71
69
68
67
66
65
64
63

62
61
59
58
57
56
55
54
52
51

50
49
47
46
45
43
42
41
39
38

37-0

35-51

34 0

32-5;

30-9

29-3

27-6

:25-8:

23-9

36
35
33
31
30
28
26
24
22
20
18

82
81
80
79
78
77
76
75
73
72

71
70
69

68
67
66
65
64
62
61

60
59
58
56
55
54
53
52
50
49

48
46
45
44
42
41
39
38
36
35

33
31
29
27
25
23
21
19
16
14
11

581
4 80
4 79
3 78

76
75

174
0 73
972

8,71

7|70
7j69
5 68
4'66
3:65
2164
l|63
0 62

8;61

6'59

5'58
3;57
1156
9 55
753
552
2'51
0:49
7,48
4,47

1|45
844
442
0141
639
138
6|36
1134
633
0!31

3'29
6'27

7!25
923
7i20
9,18

715
4il2
9! 9
3l 6
4i 2

68
67
66
65
64
63
61
60
59
58

79"

56
55
54
53
51
50
49
47
4(5
41

43
41
40
38
36
35
33
31
29
27

25
5123
5 20
17
14
12
8
4
0
-5

9,78'
8,77-
7|76'
6 75-
5 74-
4,73-
3 71-

70-
69-
68-

8 67
6 66

5 65
3 63

2 62
061
8 60

6 58

3 57
1'56

9 55
6 53
352
051
7:49
4 48
0'46
6:45
2'43
7'42

2 40
7,39
137
5 35
8 33
131

3 29
327
7 25
4|22

320
0,17
614
9!ll

8
0
5
6
0

-1

-7

10 11

77-2,75-8

12 13 14

/ /
76
74
73
72
71
70
69
68
66

65
64
63
62
60
59
58
57
55
54.

53
51
50
48
47
45
44
42
41
39

37
35
34

6
0
2

5 32

6 30

8 27
725
4j23
3,20

9 17

14
11

-2-6

74-4

74-6|73-2
73-5,72-l
72-470-9
71-2:69-7
70-o:68-5
68-9!67-3
67^7;66-l
66-5|64-9
65-3 63-7

64-1 62-4
62-8:6M
61-659-8
60-3'58-5
59-1 57-2
57-7|55-9
56-454-5
55-153-1

7 53-7 51-7
4'52-450-3

73-0
71-8
70-6
69-4
68-2
67-0
65-7
64-5
63-2
62-0

60^7
59-4
58-1
56-7
55-3
540
52-5
51-1
49-6
48-1

71-5
70-3
69-1
67-9
66-6
65-4
64-1
62-8
61-5
60-3

510,48-8
49-547-3

2 48-0,45-7

46-5|44-l
45-042-4
43-4:40-7
41-739-0
40-1 37-1
3S-335-2
36-4 33-2

46-5
44-9
43-2
41-5
39-7
37-9
36-0
34-0
31-9
29-7

58-9
57-6
56-2
54-8
53-4
52-0
50-4
49-0
47-3
45-7

7 34-6 31'
9 32-6 28'
0 30-5 26-
28-3 24-
26-0,21-
23-4 18-
^^0-8 15-

44-1
42-4
40-5
38-8
36-8
34-8
32-7
30-5
28-2
25-7

6 22

1 19

416

412

31 8

0 17-8,11-5| 3

7-8-1

3-3

127-3 23-0

9 24-8|20-l
0

1117-

14-8
11-3

71 7-4
2 2-9
3'-2-4
1

-20

13'
9-
4-

-0-

APPENDIX.

347

TABLE XII. — Continued.
Observations on the Wet and Dry Bulb Thermometer.

Temp,
of air.

90-

81_

80
79
78
77
76
75
74
73
72
71

69
68
67
66
65
64
63
62
61

60
59
58
57

70-0

68-8
67-5
66-3
65-0
63-7
62-4
6M
59-8
58-5

57-1
55-7
54-2
52-8
51-3
49-8
48-2
46-6
45-0
j43-3

lITB
J39-7
I37-8
135-8
|33-7
131-5
;29-2
J27-6
24-0
21-2

iiM

114-6

10-8

6-4

68^
67-2
65-9
64-7
63.-3
62-0
60-7
59-4
58-0
56-6

5"5^2

53-

52-

50'

49'

47-

46'

42'

40'

38-7

36-8

32-5

30-2

27-8

25-2

22-3

19-3

15_;9

12^
7-9

66
65
64
63
61
60
59
57
56
54

53
51
50
48
46
45
43
41
39
37

35
33
31
29
26
23
20
17
13
9

65
63
62
61
59
58
57
55
54
52

51
49
48
46
44
42
40
39
36
34

32
30
27
25
22
18
15
11

19 1 20 21

63
62
60
59
58
56
55
53
52
50

49
47
45

43
42
40

38
0i36
933

8|31

5l29
2|26

23
20
17
13

61
60
59
57
56
54
53
51
50
48

4^
45
43
41
39
37
35
32
30
27

25
22
18
15

9;60
5 '58
1!57
7(55
2154
7i52
2{51
6149
47
46

44
42
40

38
36
34
•0131
-8!29
-4|26
-8,23

"o!20

58
56
55
53
52
50
48
47
45
43

39
37
35
33
30
28
25
22

23 24

56-4
54-9
53-3
51-7
50-1
48-4
46-6
44-8
430
41-0

25 26 27

54-4 52 4 50 3i48-0
52-9 50-8'48-5!46-2
51-2 49-0:46-7 44-3
49-6 47-3'44-9'42-4
47-8 45-5;430|
46-1143-6 410!
44-2i41-6 38-9
42.339-6
40-337-4
38-2 35-2

39-0 3601
36-8 33-7
34-6 31-2
32-2
29-7
27-0

28
45~6

:;■)

343

APPENDIX.

£
0

ft)

.-I
0

3
0

pira-
ven-

tr.

1
1

•a
ft)

03
0

.1"

0
0

£^To

■5.

ft)

3 ^ -Ci

03
ft)

l-H

u
"0

0
0

S
0

-3

c
ft)

C
ft)

rt
0
03
ft)

2^ 2 to

ft) C ::
boo 3) ■ =

== " " 9"

•- a X »

3
0

ft)

£
ft)

ft)

3
•A
0

a;
^ 03

c c

ft)

5
ft)

£
£

rt -T ")

S-?)3

*>*

§ bo

.2 c

« 0

-3 ft)

ft)

§■■§

ft) C ft)

S-2 = S

"= .5

~c'l

.y^sS

03 73

S S3

fco

^■S.

3 m £ 0)

- 3 ft) C

^'" i.i

GO --^
^ 2 "

-5 u ii 0
0 K 3 — "

rr Li ** J— r

boS

•

"3
«

o
a.
i<
W

♦J

bo
c

.^
X
V

c
c

ft)

0 3 <U „
— 0 S i;

= !n 2 = „„

C ..J

ft)

~ 33

•n

■5 0:

- 0

1 2
Q t: c

-5 « ^
0 rt _

.2 =.?

ft)
bfl

£'5

3 =

bc^f

= la

■S"^ 3
0 — -

— -r ft)
5 = "

'■<

'5.
2

iiejs

2 rt

Z; re"-

d ft) 0 ci;
0) — "i: "3 •-

03 nS -^ 0 -^

rt » <=

— >- C3

£
0

C ° ^

0
0

•§ C

o=i 0

._ 0 ft)

W<1

O"^

^< 12;

'•<o-<

^•-v-V.

/%k^%<^

/ w^"V"V.

^ • •-

S-. . >^

^ . ^

^ ' ^

o t „ c

.■^ o S i; =

= ^ ; 3 -2
> =; o. -

00 T»<

•^

t>. ip

w- . ^ _ .

.7-00

*«•

^.(>J

.^~ 2 o ?r -

•— 0 0

h-<N

C/3

3.b: ~ S'- =?

TT< r:)

..^

COO

> s a ^-r

-J

J.'3'=.^ = = =■

0 0

O»-0

c _•= u 5- S

—

CO CO

C0-<5"

-5

— '00 <N

CO Tf

T?< ■*! C^

(N t>.00

, ^

* +-

*■* .-♦

•«^

= O i K

0 IN -^

Mi^

0 0

000

0 ''s *^

0 w

= '^ j; s

— 1 CO

ra CO 0

TJ<

1-^ •— <

« — 0

.J.

- 'i'

l;«

poo

p 0

0 p p

p u- p

rt'o S

" n

0 •—» rn

0 ^

.^ — 0

OCiO

^i>§

-• «>.

»^

000 0

»— •

n (N

<N <N 0

0« QO

"5 d

0 05

*-M

01 i^

t^ l^ 0

oco oj

o "-

»— •

•—1 f— •

•-H

_2l_

1-5

1.0 o<

O — O M

ny CO

^ i

t;. b, 0

= - -i

060

OJ _o

Tp 00 <N

■^ — c^

O ■'::: = =-

1—4

gs«

■— t— 1

tp -rf ^

-H n'

in N

fcti£ c

* 6

6i ci a

^ s

^°5

>-• a

>. CO

— (N (M

£J2i

5 = -

^ ■>»

(NIN CM

(M (N

<N (N

r^^.A^^

»^>.^s^

ft)

rSi

«)

"S-

.-1

03
^^ 3

. -3 1

« 0 >

C
ft)

E £

£ ''""'^ ^

cu 0
>^ 0

1-8

0; •_;
ill

is
c

•a

O
c

3) "

£ 1

0 ft)

D —

3 = S 'J
— ■;: £ ftj

•- C ft) 9)
'~ I- c ^-'

"2!
'C

.->

J2 "o n"
.— . ft)
w >% —

S £ 2

- ^ e

ft)' <u~ ®
= 3 J)

»■■ 05 P ft)

0) 0 " =

£
c

rt
■5

0 !z

E- 3

rt ftj^jj
i jr3

10.

1- ci

<- ^^

c-s

ri "w/

C v'

C 'i. —

— ^ ir ^

a. rt rt

o
7.

■<

Hk:?

s^a.

H r- -J

^-*.

orcz:

— •

>>~

'^^

'^p;

^- ^ ^

x^>

■^•^ 1

APPENDIX. 349

TABLE XIV.

Constitution of the Atmosphere.

Dumas and Boussingaiilt analyzed atmospheric air by fixing its oxygen
on copper, which was weighed ; the azote was also collected and
weighed.

1000 parts of air at Paris contained by weight : —

Oxygen. Azote.

April 27, fair weather, 229.2 770-8

" " " " 229.2 770.8

" 28, " " 230.3 769.7

" " " " 230.9 769.1

" 29, '' " 230.3 769.7

" " " " 230.4 769.6

May 29, rainy, 230.1 769.9

July 20, mid-day, rainy, 230.5 769.5

« 21, midnight, clear, 230.0 770.0

" 26, mid-day, clear, 230.7 769.3

Mean, 230.2 769.8

By volume, 208 792=1000

Consumption of Oxygen and Formation of Carbonic Acid.

From experiments of Dumas on himself, it appears that about twenty
cubic inches were received into the lungs at each inspiration,- and from
fifteen to seventeen inspirations per minute. The expired air contained
from three to four per cent, of carbonic acid, and had lost from four to
six per cent, of oxygen. These data, for each day of twenty-four hours,
give,

16 insp. X 20 cubic inches = 320 cubic inches expired per minute.

19,200 " " " hour.

460,800 " " " day

C53

APPKNDIX.

TABLE XV.

A Table of Mean Temperatures of the hottest and coldest months.

.Mr-aii

l'<;in(j. .<!

Authorities.

Latitude.

Long-itude.

Warm-

CoMe.<l

est
Alon'li

IMonili.

St. Pelersburgh,

59 56 N.

30 19 E.

65-660

8-60-

Humboldt.

Moscow,

55 45 N.

37 32 E.

70-52

6 03

J Melville Island, \

74 47 N.

1 10 43 W

39-03
42-41

-35-52
-32-19

Hugh Murray.
Ed. Phil. Journal.

Ciipeiihagen,

.55 41 N.

12 35 E.

65-66

27-14

Humboldt.

Edinburgh,

55 57 N.

3 10 W.

59-36

33-30

Geneva,

46 12 N.

6 8 E.

66-56

31 16

Vienna,

43 12 N.

16 22 E.

70-52

26 60

Pari.s,

43 50 N.

2 20 E.

65-30

3614

London,

51 SON.

0 5 \V

64-40

37-76

Pliiladelphia,

39 56 N.

75 16 \V.

77-00

32-72

New York,

40 40 N.

73 53 W.

30-70

25-34

Pekin,

39 54 x\.

116 27 E.

■^4-33

24-62

i Milan,

45 23 N.

9 11 E.

74 66

36-14

; Bordeaux,

44 50 N.

0 34 W.

73 04

41-00

Marseilles,

43 17 N.

5 22 E.

74-66

44-42

Rome,

41 53 N.

12 27 E.

77-00

42-26

Funchal,

32 37 N.

16 56 W.

(5 oo

64 04

Algiers,

36 43 x\.

3 1 E.

32-76

60-0

: Cairo,

30 2N.

30 IS E.

35-82

56-12

Vera Cruz,

19 11 x\.

96 1 W.

31-86

71 -06

Havanna

23 ION.

S2 13 W.

33-34

69-93

Cumana,

10 27 N.

65 15 W.

34-33

79-16

Canton,

23 10 N.

113 13 E.

34-50

57-00

Anglo-Chinese Calendar

Macao,

22 10 N.

113 32 E.

36-00

63-50?

11 11 <i

Canaries,

2S 30 N.

16 00 W.

78-90

63-70

Brande's Journal.

Lohooghal (5800 ^
feet above the >

29 23 N.

79 56 E.

69-34

43-57

; Trans. Med. Phya.
f Calc.

Soc.

sea.) )

Fattehpiir,

25 56 N.

80 45 E.

74 94

58-74

Gleanings in Science.

Gurrah Warrah,

23 ION.

79 54 E.

37-45

60-23

(( (( (t

Calcutta, <

22 40 N.

88 25 E.

35-70

66.20

It (( i<

36-86

70-10

Journal As. Soc.

Ava,

21 51 N.

95 98 E.

33-15

64-12

Gleanings in Science.

Bareiily,

23 23 N.

79 23 E.

91-91

56 50

11 II II

Chunar,

25 'J N.

82 54 E.

90-00

58-00

Ed. Ph. Journ.

Cape of Good ")

1 Hope (Feld- >

34 23 S.

18 25 E.

74-27

57-43

Herschel (MSS.)

' liausen.) )

Bahamas,

26 30 N.

78 30 W.

83-52

69 07

Hon. J. C. Lees (MSS.)

Swan River,

32 00 S.

115 50 E.

78-00

64-84

Miliigan.

Bermuda,

32 15 N.

64 30 \V .

76-75

57-90

Col. Emmett.

APPENDIX.

351

TABLE XVI.

The following proportions between the Mean Temperature of the earth,
as indicated by springs, and that of the atmosphere, have been collected
from various sources.

Names of Places.

Berlin, . . . ,

Carlstrom, . .
Upsal, . . .

Paris, . . . .
Charleston,

Philadelphia, .

Virginia, . . .
Massachusetts,
Vermont,

Authority.

"Wahlenberg,
((

(Catacombs,)
Volney,

Dewey,
Volney,

Raith, (Scotland,) ! Ferguson,

Gosport, (England,)
Kendal, (do.)
Keswick, (do.)
Leith, (Scotland,)
South of England,
Torrid Zone, . .

Watson,

Rees' Cyclo,
Volney, . .

Temp.

of
Earth.

49
47

43
53
63
53
57
47
44
47
52
47
46
47
48
63

•28^ i
•30 ,
•70
■00
•00
•00
00
•21
•00
•70
•46
•20
•60
•30
•00
•00

I Mean
Temp, of
Atmns-
I phere.

4640-
42^03

42-08
51-00
68-00

5?-

.0-12
57-00
44-73
56-00
47-00
51-42
47-04
48-00
48-36
50-62
81-50

30^

352

JlPPENDIX,

TABLE XVII.

Showing the Specific Gravity of different kinds of timber.

Box, . . .
Plum-tree,
Hawthorn,
Beech, . .
Ash. . . .

Yew, ....

Elm,

Birch, ....
Apple, ....
Pear, ....
Yoke-elm, . .
Orange-iree,
Walnut-tree, .
Pine, ....
Maple, ....
Linden-tree,
Cypress, . . .
Cedar, ....
Horse chestnut,
Alder, ....
White poplar, .
Common poplar,
Cork, ....

ir.

942

872

871

852

845

670

807

744

800

568

738

733

734

732

728

705

660

657

763

645

604

559

598

561

551

538

529

383
2.i0

387

*:j^* The column I., in the above table, exhibits the specific gravity
of different woods, adopted by the Annunire du Bureau des Longitudes
The second column contains the results obtained by M. Kafrmarsch.

APPENDIX.

353

TABLE XVIII.

Solutions for the impregnation of wood which is exposed to the atmos-
phere, for the purpose of preserving it from decay.

Tar.

Sulphate of Copper.

Sulphate of Zinc.

Sulphate of Iron.

Sulphate of Lime.

Sulphate of JMagnesia.

Sulphate of Barytes.

Sulphate of Soda.

Alum.

Carbonate of Soda.

Carbonate of Potash.

Carbonate of Barytes.

Sulphuric Acid.

Acid of Tar, (pyroligneous acid.)

Common Salt.

Vegetable Oils.

Animal Oils.

Coal Oil, (Naphtha,)

Resins.

Quick-lime.

Glue.

Corrosive sublimate.*

Nitrate of Potash.

Arsenical Pyrites water, — (water
containing arsenical acid.)

Peat JMoss, (containing tannin.)

Creosote and Eupion.

Crude Acetate, or pyrolignite of iron.

Peroxide of Tin.

Oxide of Copper.

Nitrate of Copper.

Acetate of Copper.

Solution of Bitumen, in oil of tur-
pentine.

Yellow Cromate of Potash.

Refuse Lime-water of Gas-works.

Caoutchouc, dissolved in naptha.

Drying Oil.

Beeswax, dissolved in turpentine-

IChloride of Zinc.

* Corrosive sublimate is one of the most efficient of all these antiseptic applications.
It was proposed by Mr. Kyan as a preventive of dry rot, under the idea of its acting
as a poison to the fungi and insects, wliich were the supposed cause of the disease.
But this explanation of the action of corrosive sublimate is no longer tenable, as ii is
generally admitted that the fungi and insects are not to be considered the origin, but
the result, of the dry roi. It has been suggested that its action depends en the forma-
tion of a compound of lignum, or pure woody fibre, with corrosive sublimate, which re-
sists decomposition in circumstances where pure lignum is liable to decay. But pure
lignum possesses no tendency to combine with corrosive sublimate. The action of
this substance is in reality confined to the albumen, with which it unites to form an
insoluble compound, not susceptible of spontaneous decomposition, and, therefore, in-
capable of exciting fermentation. Vegetable and animal ipatters, the most prone to
decomposition, are completely deprived of their property of putrefaction and fermenta-
tion by the contact of corrosive sublimate. It is on this account advantageously em-
ployed as a means of preserving 3.nimal and vegetable substances. Its expensiveness
in this country is a great obstacle to its extensive employment on timber used for build-
ing purposes, for fences, bridges. Ice. There is scarcely any antisceptic application
BO effectual. By Mr. Kyan's process, the timber to be impregnated, is sawed up into
planks, and soaked for seven or eight days in a solution containing one pound of cor-
rosive sublimate to five gallons of water. The Impregnation may be easily effected in
an open tank ; though the best way is to impregnate the timber by placing it in an
air-tight box, from wiiich the air has been exhausted as much as possible by a pump.
The solution then enters the pores of wood freely, being pressed into them by a force
equal to about one hundred pounds to the square inch. — ParneWs Applied Chemistry.

354 APPENTJIX.

TABLE XIX.

Table showing the Heating Power of different kinds of "Wood, drawn
by iM^I. Peterson and Schodler, from the quantity of Oxygen required
to burn them.

Names of Trees. Oxygen required to burn lliein.

Tila Europea, lime, 140523

Ulmus suberosa, elm, 139-408

Pinus abies, fir, 138-377

Pinus larix, larch, 138-0S2

jEsculus hippocastanum, horse-chestnut, 138-002

Buxus sempervirens, box, 137-315

Acer campestres, maple, 136-9ti0

Pinus sylvestris, Scotch fir, 136-931

Pinus pinea, pitch pine, 136-886

Populus nigra, black poplar, 136-628

Pyrus communis, pear tree, . 135-881

Juglans regia, walnut, 135690

Betula alnus, alder, 133 956

Salix fragilis, willow, 133-951

Quercus robur, oak, 133-472

Pyrus malus, apple-tree, 133-340

Fraxinus excelsior, ash, 133-251

Betula alba, birch, 133.22'J

Prunus cerasus, cherry-tree, . 133-139

Robinea pseudacacia, acacia, 132-543

Fagus sylvatica, white beach, 132-312

Prunus domestica, plum, 132-088

Fagus sylvatica, red beach, 130-834

Diospyros ebenum, ebony, n8-178

APPENDIX.

355

TABLE XX.

Difference in Weight of two columns of Water, each one foot high, at

various Temperatures.

Diiference in

temperature

of ihs two

coluirins of
water iii

Difference in weight of two columns of water,
contained in different sized pipes.

Difference of a

column one foot

high.

decrees of

Fahreahiil's

Scale.

1 inch d a.
"rs. weigiit.

2 inches dia.

3 inches dia.

4 inches dia.
i;rs. weight.

per square inch.

grs. weight.

grs. weisfht.

1-5

6-3

14-3

25-4

2-028

12-7

28-8

51-1

4-068

4-7

19-1

43-3

76 7

6-108 -

6-4

25-6

57-9

102-5

8-160

8-0

32-0

72-3

128-1

10-200

9-6

SB-')

87-0

154-1

12'264

11-2

450

101-7

180-0

14-328

12-8

51-4

116-3

205-9

16-392

14-4

57-9

131-0

231-9

18-456

16-1

64-5

145-7

258-0

20-532

*^* It will be observed in the above table that the amount of motive
power increases with the size of the pipe ; for instance, the power is
4 times as great in a pipe of 4 inches diameter as in one of 2 inches.
The power, however, bears exactly the same relative proportion to the
resistance, or weight of water to be put in motion in all the sizes alike ;
for, although the motive power is 4 times as great in pipes of 4 inches
diameter, as in pipes of 2 inches, the former contains 4 times as much
water as the other. The power and the resistance, therefore, are rela-
tively the same.

INDEX TO THE ILLUSTRATIONS.

PART I.

SECTION I.

Fio. Paob.

1 Elevations of hot-house roofs, 35

2 Difference of elevation of the sun's rays at Philadelphia and London, . . 36

3 End section of a forcing pit, 39

4 Ground plan and elevation of forcing pit, 41

5 End section of a stove, 42

6 Polyprosopic forcing house, 43

7 Cambridge pit, 43

8 Saunders' pit, 48

9 Curvilinear cold pit, 46

10 Dung bed with frame for forcing, 46

11 Portable glass frmne, 48

12 Portable plant prolector, 48

13 Ground plan of an extensive framing ground, 51

.14 Riin^e of graperies at Clifton Park, 53

15 Single-roofed grapery, 55

16 Span-roofed house on the same scale, '55

17 Single-roofed curvilinear grapery, 57

18 Double-roofed house of the same plan, 57

19 Polyprosopic grapery, 61

20 Ground plan of do., 61

21 Ridge and furrow roof, 65

22 Range of small houses, 69

23 Ornamental grapery, 71

24 End section of green-house, 76

25 Perspective view of span-roofed green-house, 77

26 Range of plant-houses, 78

27 Ornamental plant-house, 80

SECTION II.

28 Roof trellises, • . 85

29 Interior trellises, 86

30 Upright trellises, 87

31 Roof trellises and open border planting, 87

32 Interior ground plan of a conservatory 9S

ILLUSTRATIONS.

357

PART II.

Fio. PJ^gb.

33 Williams' furnace for prevention of smoke, 149

34 Jeffreys' smoke-precipitating furnace, 151

35 Improved arch boiler, 179

36 Common t)oiler, • • •. ^^^

36 A Circular boiler and pipes, 185

37 Ground plan of polmaise heated green-house, 197

38 End section of do., 193

39 Longitudinal section of do., 199

40 Combination of hot water and hot air, 201

41 Four houses heated with one boiler, 204

42 Boiler and supply box, 205

B Supplv cistern, 205

43 Tank 'method of heating, 210

44 Tank of galvanized zinc, 214

45 Wooden tank for retention of heat, 216

46 End section of do., 216

47 Plant pits heated by wooden tanks, 227

48 Arched borders heated with hot-water pipes, 230

49 Chambered border heated with tanks, 233

50 Covered hot wall, 241

PART III.

52 Method of ventilating lean-to houses by pulleys, 277

53 End section, showing the apertures for ventilation through the walls, . 277

54 End section of span roof, showing ventilation at top, 278

55 Showing the ventilator enlarged, 279

56 Front ventilation by racliet wheel, 280

f7 Movement of the atmosphere from the floor of the house, 289

iS Comiuon methods of ventilation SSI

TABLES.

I. Table of the expansive force of steam in pounds per square inch, for tem-
peratures above 212° Fahrenheit, 335

II. Table of the quantity of vapor contained in atmospheric air at different
temperatures, when saturated, 336

III. Table of the expansion of air and other gases by heat, when perfectly
free from vapor, 337

IV. Table of specific gravity and expansion of water at different temper-
atures, 338

V. Table of specific heat, specific gravity, and expansion by heaiof difierent
bodies, '. 339

VI. Table of the eflects of heat, . . . 340

VII. Table of the quantity of water contained in 100 feet of pipe of difierent
diameters, 341

VIII. Table showing the effects of wind in cooling glass, 341

IX. Experiments on the cooling efl'ect of windows, 342

X. Weights of watery vapor in one cubic foot of air, at dew points from 0° to
100° Fahrenheit, 344

XI. Dalton's table of the force of vapor, from 32" to 80°, 345

XII. Table for ascertaining dew point by observations on the wet and dry
bulb thermometer, 346

XIII. Table of the anal3-sis of confined air, 343

XIV. Constitutiou of the ptmosphere ; consumption of oxygen, and formation
of carbonic acid, 349

XV. Table of mean temperatures of the hottest and coldest months, 350

XVI. Mean temperature of the earth and of the atmosphere, 351

XVII. Specific gravity of different kinds of timlier, 352

XVIII. Solutions for the impregnation of wood which is exposed to the at-
mosphere, for the purpose of preserving it from decay, 353

XIX. Heating power of different kinds of wood, drawn from the quantity
of oxygen required to burn them, 364

XX. Difference of weight of two columns of water, each one foot high, at
wious temperatures, 465

INDEX.

PART I. -CONSTRUCTION.

SECTION I.

SITUATION.

Site and position, — What is to be understood by site and position. — Cir-
cumstances to affect the position of a hot-house.— Avoid bare, elevated spots. — ■
Reasons for so doing. — For shelter. — For beauty and effect, . . , . \ . . 13

Terraces. — Their origin, and use round horticultural buildings. — The un-
sightliness of turf terraces. — Architectural terraces. — Description of a terrace
at a gentleman's residence. — Effect of trees. — Effect without trees. — Choice
of position decided by other circumstances, 15

Aspect. — Best aspect for lean-to houses. — Reasons for choosing a south-
eastern aspect. — Aspect for span-roofed houses. — The aspect oi conserva-
tories. — Unsuitable conservatories, 20

SECTION II.

DESIGN.

General principles. — Object of hot-houses. — Agents of vegetative growth. —
Reasons why had structures arc so generally erected in this country. — Mansion
architects. — Their incapacity for erecting horticultural buildings. — Fitness for
the end in view. — Solid, opaque conservatories. — Conservatory at Brookline.
— Absurdity of spending large sums on conservatories. — Observations of an
architect. — Massive conservatories, 25

Light a primary object. — Wonderful effects of light on vegetables. — Theory
of the transmission of light. — Rays of light reflected from transparent sur-
faces. — Action of light upon plants. — Effects of different rays. — Light which
has permeated yellow media. — Light which has permeated red media. — Light
which has permeated blue media. — Difficulty of obtaining pure colors. —
Amount of assimilation and perspiration in plants. — Necessity of making plant-
houses transparent on all sides, 29

Slope of hot-house roofs. — Much depends on the angle of elevation. — Prin-
ciples to guide the inclination of hot-house roofs. — Elevations of roofs in
England. — Figure representing different elevations. — Figure showing the dif-
ference of latitude between London and Philadelphia. — Application of these

360 L\UEX.

principles. — Error committed in laying hot-houst roofs too flat. — Table show-
ing the number of rays reflected at different angles. — Circumstances on which
the slope of roofs depends, ' 34

SECTION III.

STRUCTURES ADAPTED TO PARTICULAR PURPOSES

Forcing-houses, culinary-houses, &c. — Purposes of their erection. — Section
of a forcing-pit figured and described. — Large forcing-pit figured and described.
— Dimensions of winter forcing-houses. — Skill required in the forcing of fruit
in winter. — Polyprosopic forcing-houses figured and described. — Advantages
of polyprosopic roofs, 39

Pits. — The Cambridge pit. — Saunders' forcing-pit figured and described. —
Curvilinear roofed cold pits. — Dung beds. — Temporary frames. — Plant pro-
tectors.— Figures and descriptions of them, 43

Framing ground. — Its purposes. — General condition of this department. —
Appropriate site for it. — Ground plan and disposition of framing ground, . 49

Orangeries, graperies, &c. — Latitude 2:iven in their construction. — Repre-
sentation of a range of cold-houses at Clifton Park. — Size of cold-houses. —
Figures of lean-to and span-roofed houses. — Figures of double and sinsle-
roofed curvilinear houses, 54

Objections raised against curvilinear houses in England. — Properties pos-
sessed by curvilinear houses. — Reflection and refracCiori of light liy them. —
Their adaptability for grape-growing. — Gable ends. — Objections to them. . 58

Polyprosopic houses. — Figures and descriptions of do. — Double-roofed
houses of this kind. — Cold vineries. — Disadvantages attending them. —
Front wall of hot-houses. — The height of do. -r- Objections to upright fronts. —
parapet walls, 60

Ridge and furrow-roofed houses. — Figure and description of a house of this
kind. — Directions for building rirlges and furrows. — Glazing of do. — Aavan-
lages of do. — Principle of their construction, 64

Cold vineries. — Range of small houses figured and described. — Advantages
of small houses over large ones, 67

Green-houseSj conservatories, &c. — Distinction between green-houses and
conservatories. — Amalgamation of the two together. — Appropriation of green-
houses in summer. — Span-roofed green-houses preferable to single-roofed ones.
— Beauty of well-grown plants. — Impossibility of growing plants well in opaque
houses. — Proportions of a green-house, 73

Plan of green-house, and description. — Prospective view of green-house. —
Range of green-houses. — Height of plant-houses. — Errors in making them too
high. — Conservatory at Regent's Park Botanic Garden. — Principles of design
and taste displayed. — Advantages of low-roofed plant-houses, 76

SECTION IV.

INTERIOR ARRANGEMENTS.

Arrangements for forcing-houses, culinary-houses, &c. — Trellises and meth-
ods of fixing trellises. — Roof trellises. — Centre trellises. — Cross trellises.
— Trellises for double houses, 84

Interior of greenhouses. — Slope of ijreen-house stages. — Green-houses for
promiscuous plants. — Width and height of green-house shelves. — Stages for
small plants* 6lc., 87

Conservatories, Orangeries, &c. — Houses for growing large plants. — Con-
servatory beds. — Level of do. — Objections to the general form of conserva-
tory beds. — Irregular method of laying out the interior of conservatories. —
This method illustrated in the conservatory at the Royal Botanic Garden, Re-
gent's Park. — Ground plan of a conservatory laid out in the irregular style. —
Advantages resulting from this method, 89

INDEX. 381

SECTION V.

MATERIALS OF CONSTRUCTION.

Workmanship. — Bad foundations, &c. — Temporary nature of horticultural
erections. — Conseouence of bad constructed houses. — Superior workmanship.

— Economy of building substantial houses, _ 99

Materials of construction. — Most suitable materials for building hot-houses.

— Metallic houses — Superior to wood. — Opposition to iron hot-houses. —
Objections raised. — Ot)jections answered. — Expansibility of copper — Of
iron. — Power of metals to conduct heat. — Electricity an objection. — Cost
of iron hot-houses. — I\Ir. Ressor's iron vinery. — Horticultural structures in
Europe of iron. — Transportability of materials, &c., 101

SECTION VI.
GLASS.

The physical properties of transparent bodies. — Glass of the palm-house ai
Kew. — Report of Mr. Hunt, from Silliman^s Journal of Science. — Calorific
influence of the glass chosen. — Action of the non-luminous rays of light. —
Green glass of Melloni, 106

Evils consequent on employing bad glass in hot-houses. — Knotted and
wavy glass. — Its effects. — Resources against bad glass. — Painting and shad-
ing the glass. — Inconveniencies attending both these methods. — Utility of
using good glass. — Propriety of manufacturers of glass making good mate-
rial, 109

Glazing. — Size of laps. — Glazing roof-sashes. — Objectionable nature of
broad laps. — The most approved method of making laps. — Curvilinear glaz-
ing. — Reversed curvilinear glazing. — Puttying the laps. — Glazing ridge and
furrow roofs. — Anomalous surfaces, 110

Color of walls. — Considerations in favor of a dark color. — Influence of
reflected light on dark walls. — Retention of heat by dark-colored walls. --
Color of the rafters. — Painting of the wood-work of the house with an anti-
corrosive solution, 113

SECTION VII.
FORMATION OF GARDENS.

Form of the garden and disposition of the ground. — Considerations neces-
sary for fixing on the site. — Walks. — Entrance-walk. — Formation of walks.

— t)ifl"erent kinds of walks. — The durability and comfort of walks. — Materials
for the surface of walks. — Form of the surface. — Edges of walks, . . . .116

Borders and compartments. — Width and size of do. — General ri.le for lay-
ing down borders. — Size and number of compartments. — Bad efl'ects of small
walks, 119

Walls — their msc. — Forms of walls. — Their height. —Gardens of Mr.
Cushine, at Watertown. — Hot and flued walls. — Wooden fences. — Com-
parative ♦•conomy (A walls and fences, 121

862 INDEX.

PART II. -HEATING.

SECTION I.

PRINCIPLES OF COMBUSTION.

TLe nature and properties of fuel. — Considerations on the subject. — Char
acteristics yi the use of coals pointed out. — Result of the application of heat
to coa.. — Disengagement of gas. — Gases endowed with the power of giving out
heat. — Combustibility. — What is combustion. — The heating pow^er of gas, 125

Inquiry into the combustion of coal gas. — Doctrine of equivalents. — Ob-
servations of Mr. Parks. — Disproportion between the volumes of the constituent
parts. — Different kinds of gases generated. — Bulk of gases represented by
figures, 132

Atmospheric air. — Its constituents represented by diagrams. — The com-
ponent parts of different gases represented by diagrams. — Union of the con-
stituents. — Chemical law in relation to these gases. — Carbon vapor, . . .137

Formation of carburetted hydrogen. — Excess and deficiency of heat-producing
ingredients. — The union of oxygen with smoke. — Q-uantity of air required to
supply the requisite quantity of oxygen. — How ordinary furnaces are incapable
of consuming coal perfectly. — The complete combustion of bodies, . . . -145

Argand lamp. — Williams' smoke-preventing furnace figured and described.

— Jeffries' smoke-precipitating furnace figured and described. — Their value
considered. — Application of these inventions in Europe. — Methods of burning
smoke, 148

Construction of furnaces. — For heating large boilers. — For making the
fuel last a long time. — Considerations necessary to be noticed in building the
furnace. — The kind of fuel to be consumed. — Size and width of bars. —
Table for ascertaining the area of furnaces, 153

SECTION II.
PRINCIPLES OF HEATING HOT-HOUSES.

Effects of artificial heat. — Changes produced by it. — Animal and vegetable
matter decomposed by it. — Hydrogen eliminated by the decomposition of
water. — Experiments on the effects of heated air. — Heat from brick flues. —
Iron radiators more injurious than others, 156

Laws of heat. — Radiation and conduction. — Combined effects of radiation.

— Proportion they bear to each other. — Table showing the velocities of cooling
at different temperatures. — Experiments on cooling of iron pipes. — Specific
heat of air and water. — Horticultural structures different from opaque build-
ings.— Causes of loss of heat, 153

Table showing the quantity required to heat given volumes of air. — The
effects of glass windows ascertained. — Experiments on glass surfaces. — Table
showing the results. — Specific heat of air and water. — Application to hot-
nouse buildings, 1 G4

SECTION in.

HEATING BY HOT WATER, HOT-AIK,AND STEAM.

Practice of heating by hot water. — Its merits considered. — Temperature
of hot-water pipes. — Weight of steam. — Calculations showing the supeiiority
of hot-water pipes. — Permanancy of heat by hot water, 167

INDEX. 363

Comparison of hot air with h \l water, as a method of heatiug horticultural
buildings. — Air a bad conductoi. — Evaporating pans for supplying moisture.

— Considered in respect to motion in the atmospnere — in respect to perma-
nency of heating power. — Water a better conductor. — Experiments on air and
water as modes of conducting heal, 171

SECTION IV.

HOT-WATER BOILERS AND PIPES.

Size of boilers, and surfaces necessary to be exposed to the fire. — Adapta-
tion of the boiler to the apparatus. — Of the boiler and the quantity of water
contained. — The repulsion of heat by the metal of the boiler. — Table showing
the proportion the surface exposed to the fire must bear to the quantity of pipe, 176

Causes tending to modify the proportions to be adopted. — Figures of boilers.

— Estimated action of the fire upon the boilers. — Material for boilers, . . 179
Size and arrangement of hot-w^ater pipes most suitable for the purposes of

heating. — Unequal rate of cooling in tne various sized pipes. — The ordinary
methods of arranging hot-water apparatus. — Advantage of taking the flue
through the house. — Laying down hot-water pipes. — Expansion of pipes
when heated. — Supply cisterns, 181

Impediments to circulation. — Causes of circulation. — Amount of motive-
power. — Table showing the weight of water at different temperatures. —
Trifling cause renders an apparatus inefficient. — Methods of increasing the
motive-power. — The rapidity of circulation in proportion to the motive-
power 184

Level of pipes. — Errors committed in the level of pipes. — Circulation takes
place first at the boiler. — Methods of making water circulate in pipes below
the level of the boiler, 188

Accumulation of air in pipes. — Provision necessary for the escape of air. —
Want of attention to this the cause of failures. — The size of air vents. — Diffi-
culty of finding the proper place to place the air vents, 190

SECTION V.

VARIOUS METHODS OF HEATING DESCRIBED.

Expense attending the ordinary methods of heating. — Polmaise method of
heating. — Its adoption in houses in this' country. — Its origin. — Means em-
ployed to promote it in England. — Description and figures of this method, . 192

A method of combining hot air and hot water together. — Figured and de-
scribed. — Advantages of this method in the generation of heat and saving of
fuel, • 200

Compound method of heating. — Seven ranges of houses heated by this
method. —Figure representing four houses heated by this plan. — Figure of
boiler and box. — Of supply cisterns. — Advantages of this mode of heating. —
Saving of fuel by it. — Simplicity of working, 203

Tank methods of heating. — Methods figured and described. — Wooden and
metallic tanks. — The merits and properties of each. — Utility and simplicitv
of do., . 211

Fertilization of the atmosphere by tanks. — Dissolving volatile gases in tanks.
Their use in English nurseries for growing young stock. — Their adaptation to
amateurs, in small pits, '. 223

Representation of plant pits and description. — Uses of these pits. — Protec-
tion of plants during winter in them, 226

Chambered vine borders. — Argument in favor of them. — Their utility
under certain circumstances. — Figure and description of a chambered border.

— Evidence in favor of them, 228

Cheap method of forming a chambered vine border. — Comparison of cost of

it with manure. — Economy of their adoption. — Method of managing them. —
Coverings of borders 234

31^

364 ITs'DEX.

Construction of hot walls. — Figure and description of hot wall. — Varions
methods of building hot walls. — Trial of hot walls, covered and uncovered. —
Foreign grapes may be grown on hot walls. — Grapes produced on hot walls in
England, 210

New method of propelling heated air liv means of machinery — described ty
Mr. Marnock in Gardeners' Journal. — The air propelled by means of a fan, 246

PART III. -VENTILATION.

SECTION I.

PRINCIPLES OF VENTILATION.

Attention required from gardeners, &c. — Its practical importance. — Power
of plants to withstand the changes of climate. — Power of vitality possessed
by seeds. — Power of plants to bear high temperatures. — Of bearing delete-
rious gases. — Effect of winter-forcing on the odor of flowers — and on the
flavor of fruits, 248

Whether vegetation purifies the air. — Opinions of Priestley — of Dr. Dau-
beny, of Oxford — of Dr. Lindley, of llonaon. — Natural adjustment of the
atmospherical elements. — Atmosphere of cities. — Benefits of large trees in
the streets. — New Haven, the effect of trees in it, 252

Power of plants to absorb carbonic acid. — Gottingen springs. — Property of
charcoal for absorbing gases. — Table of gases and the quantities absorbed by
charcoal, • 254

Power of plants to withstand the vicissitudes of temperature. — Theories of
physiologists. — Dalton's chemical philosophy. — His theory of the relations of
the atmosphere to heat. — The properties possessed by caloric, 256

SECTION II.

EFFECTS OF VENTILATION.

Effects of admitting cold air into a hot-house. — Moisture carried away, —
Necessity of keeping the ffoors damp. — Plants unlike animals in respect to
ventilation. — Ventilation not necessary as regards respiration. — Air-tight
glass cases for plants, • ' * * ^^^

Knight's experiments on grape vines. — The philosophy of this system. —
Evaporation of moisture on the glass. — Contaminating gases in the atmos-
phere.— Experiments of Drs. Turner and Christison, . .264

The abstraction of moisture in proportion to the rajtidity of the motion of the
air. — Methods of counteracting this loss. — Thermometric changes not sat-
isfactory rules for the admission of air, ; • • ^^^

Ouantity of moisture contained in the air. — Its capacity for moisture. —
Estimated quantity of air escaped. — Estimated quantity of moisture escaping
in the air.- - Lofty plant-houses. — Difliculty of managing the atmosphere in
them, ' 269

SECTION III.
METHODS OF VENTILATION.

Improvements af the present methods of ventilation. — Plans adopted \o
modity the influence of draughts. — Motion in the atmosphere. — Machinery
employed for this purpose. — Detection of currents by a common candle. —
Propriety of a rauid mntinn disuuled, 273

INDEX. 365

Difficulty of managins^ the atmosphere in large, dome-shaped houses. —
Covering necessary. — To equalize the temperature. — The natural law of
equality ineffectual. — The slightest cause disiurlis the equilibrium of the air.
— The extreme sensibility of the air. — Irregularity of its temjjerature in hot-
houses. — The causes of this irregularity. — Experiments of Gay Lussac —
of Rudberg, 275

A new method of ventilation. — Adapted to lean-to houses. — Figured and de-
scribed.— Facility with wliich this method may be wrought, 277

Method of ventilating span-roofed houses. — Adopted in the new hot-houses
at Frogmore. — Figures and description of this method, . 279

Methods of airing by the rachet wheels. — By springs. — Superiority of the
former. — Necessity of having the machinery for ventilation properly erected. —
Its liability to get out of repair. — Method applauded without merit. — Neces-
sity of guarding against the applauded inventions of any one, 230

SECTION IV.

MANAGEMENT OF THE ATMOSPHERE.

Atmospheric motion. — Admitting large quantities of cold air. — The results
of this method. — Questions arising out of these considerations. — The quantity
of air to be admitted. — Motion affected by various circumstances. — The
atmosphere of a hot-house influenced by the glazing of the sashes. — Effect
produced by radiation. — Growth of plants in Wardian cases. — Deterioration
of air by flues, &c., 234

Method of airing without opening the sashes. — Figured and described. —
This method recommended for houses during cold weather in winter, . . . 238

Common method of ventilating figured and described. — Evils resulting from
this method — Action in cold weather, 290

Contrivance for admitting warmed air into the house over the heating appa-
ratus. — By a serpentine conductor. — Size of the tubes necessary. — Radiation
of heat from the surface of the flue. — The effects of the external air neutral-
ized by this method, ^ 292

The system of ventilation, — Its object being to prevent a stagnation in the
atmosphere. — Evils of this method shown and explained. — Mechanical and
chemical effects of ventilation, 293

SECTION V.

CHEMICAL COMBINATIONS IN THE ATMOSPHERE

OF H OT-HOUSES.

Nourishment plants ought to receive from the atmosphere. — How to receive
it. — Starch and su^ar. — Their different properties. — Questions arising from
considerations of their properties. — Experiments on the atmosphere. — The
importance of oxygen to vegetable life, 296

Atmosphere from fermenting manure. — Quality of heat generated by it. —
Impregnation of the atmosphere with ammonia. — Experiments on the atmos-
phere of a green-house with ammouiacal gas, 299

Composition of ammonia. — Excess of ammonia. — Its suffocating influence.
— Illustrations of its effects. — Fumigation of plant-houses and pits with
ammonia. — The cause of luxuriance in plants. — Produced largely from fer-
menting manure, &c., 1 300

What guides we have to ascertain the various changes in the atmospheric
elements. — Disagreeable smell on entering a hot-house. — The cause, and how
to remedy it. — The important part played by oxygen in this process. — Pro-
portion of oxygen necessary to vegetables. — Amount contained in atmospheric
cir and water. — .4ffinitv of its elements 303

366 INDEX.

Beautiful adaptation of the atmosphere to plants and animals, — Effect of
pure oxygen. — Property of watery vapor in vegetable economy. — Subtlety of
the air. — Necessity of maintaining au adequate supply of aqueous vapor in the
atmosphere. — Instruments for guiding us in regulating the atmosphere. — In-
struments much wanted for measuring the respective quantities of the gaseous
elements, 305

SECTION VI.

PROTECTION OF PLANT-HOUSES DURING COLD

NIGHTS.

Advantages of protecting bodies. — Conditions of the plants at low temper-
atures.— Light coverings otherwise useful. — Experiments on the cooling
effects of wind. — Materials for protecting glazed structures. — Methods of
protection, 309

Slight covering that is required to protect plants from frost. — Experiments
of Dr. Wells on coverings. — Method of covering. — Distance to keep the cov-
ering from the object protected, ... 313

Effects of vertical coverings. — Horizontal coverings. — Coverings of straw,
etc. — Protection afforded by walls. — Protection of snow. — Warmth afforded
by the soil to trees in winter, 317

SECTION VII.

GENERAL REMARKS ON THE MANAGEMENT OF
THE ATJIOSPHERE OF HOT-HOUSES.

Adjustment of the artificial to the natural atmosphere. — Observations of
Knight. — Rest necessary to plants during night. — Cause of the imperfect
maturation of fruit-tree blossoms. — High night temperatures exhaust tne ex-
citability of the trees. — Plants continue longer in bloom in low night temper-
atures.— Admission of external air during day. — Difference of climate be-
tween this country and England, 320

Rules to be observed by the gardener in charge of hot-houses. — Dutch meth-
od of forcing. — Excessive moisture — its effects. — Necessity for pei-iods of
rest to plants. — Changing the period of fructification, 325

SECTION VIII.

VENTILATION WITH FANS.

. Construction of ventilating fans. — Methods of using them. — Their adapta-
tion to horticultural purposes. — Different kinds of fans. — Objects to be ef-
fected by them. — Requisites to the use of fans. — Windmill ventilators. —
Their employment in horticultural buildings. — Pun p ventilators. — Ventila-
tion by means of chimney shafts, &c 329

AU the Bools on this Catalogue smt ly mail, iaj any par^ of the Cmon,fru

of postage, upon receipt of Price,

CATALOGUE OF BOOKS

AGRICULTURE AND HORTICULTURE,

PUBLISHED BY

A. . O . M O O H E ,

(LATE C. 1[. SAXTON & COAIPANY,)
No. MO PULTON STREET, NEW YORK,

SUITAJJLE FOB

8CflU0L,T0WN, AGRICULTURAL, AND PRIVATE LIBRARIES.

THE AMEHICAN FAKMER'S ENCYCLOPEDIA, - - - ^4 00

Embracing all the Recent Discoveries in Agriultural Chem-
Istry, an-l the use of Mineral. Vegetable and Animal Mannres, with Descriptions and
Figures of American Insects injurious to Vegetation. Being a Complete Guide for the
cultivation of every variety ol Garden and Field Crops. Illustrated by numerous Ec-
eravings of Grasses, Grains, Animals, Implements, Insects, &c. By GorvERNEua
Emekpon, of Pennsylvania, upon the basis of Johnson's Farmer's Encyclopedia.

DOWNING'S (A. J.) LANDSCAPE GARDENING, - - 3 50

A Treatise on the Theory and Practi'-?' ' ^ ^NDSCAPE Gar-
dening. Adapted to North America, with a view to the impi^vement ol Country
Residences; comprising Historical ZS^otices and General Principles of the Art. direc-
tions for Laying out Grounds and Arranging Plar.tatiiins. the Description and Cultiva-
tion of Hardy Trece, Decorative Accompaninjents to the House and Grounds, the
Formation of Pieces of Artificial Waters, Flo^s'er Gardens, &c., with Remarks on
Kural Architectore. Elegantly Illustrated, with a Portrait of the Author. By A. J.
Downing.

DOWNING'S (A. J.) RURAL ESSAYS, . - - - 3 00

On Horticulture, Landscape Gardening, Rural Architecture,
Trees, Agriculture, Fruit, with his Letters f;om England. Ediied, with a Memoir oj
the Author by Gkorge "Wm. Ccrtis, and a letter to his friends, by Fkeukeika Brb-
lOsE, and an elegant steel Portrait of the Author.

DADD'S ANATOMY AliD PHYSIOLOGY OF THE HORSE, Plain. 2 00
Do. Do. Do. Do. Colored Plates, 4 00

With Anatomical and Questional Illustrations ; Contain i no-,
also, a Series of Examinations on Equine Anatomy and Philosophy, with Instnictiona
In reference to Dissection, ^nd the mode of making Anatomical Preparations ; to whicL
is added a Glossary of Veterinary Technicalities, Toxicological Chart, and Dictionary
of Veterinary Science.

DADD'S MODERN EORSE DOCTOR. .... 1 00

Containing Practical Observations on the Causes. Nature
tnd Treatment of D sease and Lameness of Horses, embracing the most recent and ap-
jroved methods, ac<;ording to an enlightened .«ystom of veterinary tberap*i; tics, fof

preservation and restoration « health. With Illufltrfttlona.

2 Books Published hy A. 0. ^roORE.

DAED'S (GEO. H.) AKIRICAN CATTIF DCCT( K, - - §1 CO

CONTAININO TIIK N KCK.'-SA F! V ] NKORMaTION FOR PRrf:KnVIN(; TUF.
Bcilth and Curing the Diseases of Oxen, Cows, Sheep, and Bwlne. with a great \oriety
of Orif.'lnii! Kecipps and VjiiuaMe Inloniiaticr in rt^-Vrence to Fiirman;'. I)iiiry niana^e-
rnent, w'uerehy every man ran be his own ("attle I»oei<'r. Tlie princiiries laupht in
thla work are. that all Medication shall be ^nl.-ervient to Natuiv— ihat all MedicirniS
Diust be sanative in their operation, and adniinisti red with a view «>1 ai'ling the vitJtl
powtrs, inc-tead of dojiressintr. a.-^ heretofore, with the lancet or by i-cleoB. Uy G JL
1)AUD, M. D., Veterinary Practitioner.

IKE DOG AND GUN, 50

A Few Loose Chapters on Shooting, amono: which will be found

some Anecdotes and Incidents ; also, Instractions for Dog Breaking, and Interesting let-
ters from Sportsmen. By A Bad Shot.

KOKGAN HOKSES, 1 00

A Premium Essay on the Origin, History, and CnARACTERTPTirs

of this remarkable American Breed of Horses; tracing the Pedigree from the original
Justin Morgan, through the most noted of Ids progeny, down to the present tiiuc.
With nnuicrous jKjrtraits. To which are added hints for Breeding, BioakiuLr. and
General I'sc and Manfiiremont of Horses, with practical Directions for training them fi.r
exhibition at Agricultural Fairs. By D. C. Li>8i.ky.

60RGE0 AND IMPHEE, THE CHINESE AND AFRICAN SUGAR

CAKES. 1 00

A Complete Treatise upon thf.ir Origin and Varieties. Culture

end Uses, their value as a Forage Crop, and directions for making Sugar, Wo!as«cs,
Alcohol, Sparkling and Still Wines, Beer, Ciilcr, Vinegar. Paper, Stareli. end Dye
Btuffs. Fully Illustrated with Drawings ol Approved Machinery : Witli an Appendix
by Leonard Wrat, of C'aflraria. and a descriiition of his j)atented process of crystalliz-
ing liie juice of the Iniphee ; with the latest American experiments, including those of
1657, in the South. By Henry S. Olcott. To which are added translations of valu-
able French Pamphlets, received from the Hon. Johk Y. Mason, American Minister
at Paris.

THE STABLE EOOZ, 1 00

A Ireatise on the Management of Horses, in Relation to
Stabling, Groom'" " '' f ding, Watering and Working, Construction of Stables, Ven<i a
tion, Appendagco ,« isiables. Management of the Feet, and of Diseased and Defective
Horses. By JonN Stewakt, Veterinary Surgeon. With Notes and Additions, adapt-
ing it to American Food and Climate. By A. B. Allen, Editor of the American
Agriculturist,

IHE HORSE'S FOOT, AND HOW TO KEEP IT SOU^D, - 50

AViTii Cuts, Illustrating the Anatomy of the Foot, and contain-
ing valuable Hints on Shoeing &nd Stable Managemest, In Health and In Disease. By
William Miles.

'•HE FRUIT GARDEN - 1 25

A TrEATLSE, intended to PIXPLAIN AND ILLUSTRATE THE PlIVSI-
ology of Fruit Trees, the Theory and Practice of all Operations connected with the
Propagation, Transplanting, Pruning and Training of Orchard and Garden Trees, an
Standards, Dwarfs, Pyrauiids, Esi)alier. &c. The Layii.goutaml Arr.-inL'ing ditFerent
kinds of Orchards and Gardens, the selection of suitable varieties for different |),irposei
and localities. Gathering and Preserving P'ruits, freatnient of LMseases, Destruction o|
Insects, Description and Uses of liii]ileiiient8, Ac. Ilhisvrated with uj.wards <!f IM]
Figures, representing Different Parts of Tree.% all Practical Operations, forirs ofTrecs,
Designs for IMantatious, Implements, <kc. By P.Barrt, of the Mount KoncNur:>eriJS,
Rochester, N. Y.

FIELD'S PEAR CULTURE 75

The Pear Garden : or, a 'iVeatise on tlie Propao-ation jnid
Cultivation "f the Pear Tree, wUh Instructions for Its Management from tbc 8pf-^Ui.§F
to the Bearing Tree. By Tuomas \\ . Field.

Books Puhlislied by A. 0. Moore. 2

BRIDGEMAN'S (THOS.) YOUNG GARDENER'S ASSTSTANT. %l 50

In Three Parts, Containing CataloLaies of (iarden ami Flower

8«oi.\, wil'u /'radical Directions unJcr each head for the Cultivation of Culinary Vcge-
taoi'^s ••nd V'iowers. Also directions for Cultivating Fruit Trees, the Grape Vine, Ac,
ti.> which is tdde<i, a Calendar to each part, showing tlie work necessary to be done \M
tLt) Vkrioud departments each month of the yea;. One volume octavo.

BRIDGEMAH'S KITCHEN GARDENER'S INSTRUCTOR, i Cloth, 50

Cloth, 60

URIDG-EMAN'S FLORIST'S GUIDE, ... - i Cloth, 60

" '• - - - Cloth, 60

BRIDGEMAN'S FRUIT CULTIVATOR'S MANUAL, - i Cloth, 50

Cloth, GO

COLE'S AMERICAN FRUIT BOOK, 50

Containing Directions for Raising, PRorAGATiNo and Manag-

ing Fruit Tr^jes, Shrub8 and Plants ; with a description of the Best Varieties of F»~!t
Including New and Valuable Kinds.

COLE'S AMERICAN VETERINARIAN, - - . . 60

Containing Diseases of Domestic Animals, their Causes,
Syraptomo and Kemedles; with Eules for Restoring and Preserving Health by good
management; also for Training and Breeding.

BCHENCK'S GARDENER'S TEXT BOOK. - - - . . 50

Containing Directions for the Formation and JNIanagement
of the Kitchen Garden, the Culture and Use of Vegetables, Fruits and Medicinal Herbs.

AMERICAN ARCHITECT, - - - - - - 6 GO

The American Architect, Comprising original Designs of Cheap

Country and Village Residences, with Details, Specifications, Plans and Directions,
and an'Estimate of the (,'ost of Each Design. By Joun W. Eitch, Architect. First
and Second Series, 4to, bound in 1 ''oL

BUIST'S (ROBERT) AMIRICAJN FLOWER GARDEN DIRECTORY, 1 £5

Containing Practical Dtre-cttons for the Culture of Plants,
In the Flower-Garden, Hot-House, Green-House, Rooms or Parlor Windows, for every
Month in the Tear ; with a Descriptiun of the Plants most desirable in each, the nature
ot the Soil and Situation best adajjted to their Growth, the Proper Season for Trans-
planting, &c.; with Instructioiis for Erecting a Hot-House, Green-House, and Laying
out a Flower Garden ; the whole adapted to cither Large or Small Gardens, with In-
structions for Preparing the Soil, Propagating, Planting, Pruning, Training and Fruit-
ing the Grape Vine.

THE AMERICAN BIRD FANCIER,

Considered with reference to the Breeding, Rearing, Feed-
Ing, Management and Peculiarities of Cage and House Birds. lUustrated with Engrav-
ings. By D. Jay Bkowne.

aEEMELIN'S (CHAS.) VINE DRESSER'S MANUAL, - - 60

An Illustrated Treatise on Vineyards and TVine-Makino,

containing Full Instructions as to Location and 3oil, Preparation of Ground, Selection

and Propagation of Vines, the Treatment of Young Vineyards, Trimming and Training

the Vines, Maniires, and th>^ Making of Wine.

DANA'S MUCK MANUAL, FOR THE USE OF FARMERS, - 1 00

A Treatise on the Physical and Chemical Properties op
• Bolls and Chemistry of Manures" Including, also, the subject of Compost*. Artiflcial
Manures and Irrigation. A new edition, with a Chapter on Bones and Superphos-
phates.

CHEiniCAL FIELD LECTURES FOR AGRICULTURISTS, - 1 00

V-y Dr. Julius Adglphus Stockhardt, Professor in tlie Royal
Aeademy of Agriculture at Tharant Translated from the German. Edited, with

botes, bv J Ail 8 E. TKOBEUA.CBXS.

4 Books FuLlus/tcd hy A. 0. Moorp

BTJIST'S (FIOIET) FAMILY KITCEIK G/iIIIKIE, - - CO Is
Containing Plain and Accurate DEFCinPTiONP op at/. rr<F Dtf-

ferent Species and Vrtrieties of Culinary Vegetables, wltb their Botanical, Kiigiish,
French and GcrniMn names, alphabetically arranjred, VNith tbe Best Iilo.'.o of Oul.tva'ing
thern in the Garden or under trlass; also iDescrij/tions and Character of the iiiv)St Pelect
J^ruitv their Miuiagernent, Propagation, Ac, By Kobiet Buist, author of the " Am-
erican Flower Garden Directory," &c.

DOMESIIC AKD or.N AMENTA! POTJLTHY. Plain Plates, - 1 00

Do. Do. Do. Colored Plates, - 2 00

A Treatisj^: on the History and Mangement of Ornamental

and Domestic Poultry. By Eev. Kdmusd Ba"ji. Dixon, A.M., with large addiMona b/
J. J. Kerk, M.D. Illustrated with sixty-five Original Portrait*, engraved exprefltly fol
this work. Fourth edition revised.

HOW TO EUILD MiQ VENTILATE EOT-HOUSES, - - 1 W

A PiACTicAL Treatise on the Construction, Heating and

Ventilation of Hot-Houses, including Conservatories, Green-Houses, Graperies an4
other kinds of Honicultural Structures, with Practical Directions for their Manage
ment, in regard to Light, Heat and Air, Illustrated with numerous eagravings. By
P. B. Lextcuacs, Garden Architect.

CHOSLTON'S G?t APE-GROWER'S GUIDE, .... 60

Intended P]specially for the American Climate. Beinir a

Practical Treatise on the Cultivation of the Grape Vine in each department of Hot
House. Cold Grapery, Eetarding House and Out-door Culture. With Plans for tl/'*
Conatruction of Jie iiequisite Bui'dlngs. and giving the best methods for Heating the
same. Every department lieing fully illustrated. By WiLLiAii Chorlton.

NORTON'S (JOHIf r.) ELEMENTS OF SCIENTIFIC AGRICULTURE, 60
Or. ths Connection between Science and the Art of Practicai,

Farming. Prize Essay of the New York State Agricultural Society. By John P.
Norton. M.A., Professor of Scientific Agriculture in Yale College. Adapted to tba
use of Schools.

JOHNSTON'S (J. F. W.) CATECHISM OF AGRICULTURAL CHEK-

ISTRY AND GEOLOGY, 25

By James F. W. John.'^ton. M.A., F.R.SS.L. and E,, Honorary

Member of the Royal Agricultural Society ol England, and author of "Lectures on
Agricultural Chemistry and Geology." With an Introduction by John Pitkin Nor-
ton, M.A., late Professor of Scientiiic Agricu!tt:re in Yale Colk-ge. With notes and
additions by the author, prepared expressly for this edition, and an Appendix com[)iled
by the Superintendent ol Education in Nova Scotia. Adapted to the use of Schools.

JOHNSTON'S (J. F. W.) ELEMENTS OF AGRICULTURAL CHEM-
ISTRY AND GEOLOGY, 1 00

With a Complete Analytical and Alphabetical Index and an
American Preface. By Hon. Simon Browk, Editor of the "New England Farmer.'

JOHNSTON'S (JAMES F. W.) AGRICULTURAL CHEMISTRY, 1 25

Lectures on the Application of Chemistry and Geology to
Agriculture. New edition, with an Appendix, containing the Author's Experiment*
In r radical Agriculture.

TEE, COMPLETE FARMER AND AMERICAN GARDENER, 1 25

IvUKAL ICCONOMIST AND NeW AMERICAN GaRDENER ; Conffv'lling
a Compendious Epitome of the most Important Branches of Agriculture and Inraj
Ecor.nmy ; with Practical Directions on the Cultivation of Fruits and Veiretables, iti-
clu.'.liig Land.H'ape and Oraamcntal Gardening. ByTnoMAB G. Febsekden. 2 \o!h.
In oiio.

?Ef SIN DEN'S (T. G.) AMERICAN KITCHEN GARDENER, - 50

''oNTAiNiNG Directions for the Cultivation of Vegetables and

Garden Fru<t8 Cl:>th.

Boohs FuhUshed by A. 0. Moore. 5

KASH'S (J. a.) progressive farmer, - - - . £0 60

A SCIENTIFIC Treatise on Agrtcut.tural CnEMisTKY, the (Je-
ology of Agricultare, on Plants and Animals, Manures and Soils, applied to Practioal
Agriculture ; with a Catechism of Scientific and Practical Agriculture. By J. A. Is aeh

EEECK'S BOOK OF FLOWERS, 1 00

In which are Described all the Various Hardy Herbacfious
Perennials, Annuals, Shrubs, Plants uid Evergreen Trees, with Directions for their
Cultivation.

I VTITH'S (C. H. J.) LANDSCAPE GARDENING, PARKS AND PLEASURE

GROUNDS, 1 25

"With Practical Notes on Country Residences, YnxAS, Public

Parl^3 and Gardens. By Charles TT. J. Smith, Landscape Gardener and Garden
Architect, <fec. With Notes and Additions by Lxwis F. Alues, author of "liural
Architecture."

fHE COTTON PLANTER'S MANUAL, - - - - 1 00

Being a Compilation op Facts from the Best Authorities on
the Culture of Cotton, its Natural History, Chemical Analysis, Trade and Consumption,
and embracing a History ol Cotton and the Cotton Gin. By J. A. Tubnej^.

t'OBBETT'S AMERICAN GARDENER, .... 50

A Treatise on the Situation, Soil, and Laying-out of Gardens,
and the making and managing of Hot-Beds f(nd Green-Honses, and on the Propagation
and Cultivation of the several sorts of Vegetables, Herbs, Fruits and Flowers.

ALLEN (J. FISK) ON THE CULTURE OF THE GRAPE, - I 00

A Practical Treatise on the Culture and Treatment of tiir
Grape Vine, embracing Its History, -with Directions for its Treatment in the Uiiited
States ol America, in the Open Air and under Glass Structuree, with and without
Artificial Heat. By J. Fisk AtLEN .

ALLEN'S (R. L ) DISEASES OF DOMESTIC ANIMALS, - 75

Being a History and Description of the Horse. ]\ruT.E, Cattle,

Sheep, Swine, Poultry, and Farm Dogs, with Directions for their Management, Breed-
ing. Crossing. EeJ^ring, Feeding, and Preparation for a Profitable Market ; also, their
Dise.ises and Remedies, together with full Directions for the Management of the Dairy,
and the comparative liconomy and Advantages of W orking AnimaJs, the Horse, Mule,
Oxen, &c By E. L. Allsn.

ALLEN'S (R. L.) AMERICAN FARM BOOK, - - - 1 00

The American Farm Book ; or, a Compend of American Agricul-
tnre, being a Practical Treatise on Soils, Manures, Draining, Irrigation, Grasses. Grain,
Kools. Fruits, Cotton, Tobacco, Sugar Cane. Rice, and every Staple Product of the
(Inited States; with the Be-st Methods of Planting, Cultivating and Preparation for
Market. Illustrated with more than 100 engravings. By K. L. Alleh.

ALIEN'S (L. F.) RURAL ARCHITEOTURE; . - - 125

Being a Complete Description of Farm Houses, Cottages, and
(»ut Buildings, comprising "Wood Houses, "Workshops, Tool Houses, Carriage and
Wagon Houses, Stables, Smoke and Ash Houses, Ice Houses. Apiaries or Bee Ilccscs,
I'oultry Houses, Rabbltry, Dovecote, Piggery, Barns, and Sheds for Cattle, <fec., A-o,
together with Lawns, Pleasure Grounds, and Parks; the Flower, Fruit, and Vege«
table Garden ; also useful and ornamental domestic Animals for the Country Resident,
Ac, Ac Also, the best method of conducting water into Cattle Yards and Hou^eac
Beautifully Illustrated.

*'ARTNG'S ELEMENTS OF AGRICULTURE; ... 75

A Book tor Young Farmers, with Questions fob the use o?

StihooU.

6 Boohs FuUisJied by A. 0. Moore.

PAKDES (3. G.) ON STRAWSEERY CULTITRE ; - - SO 60

A CoMiT.ET?: Manual for the Cl"LTIvation of the Stkawbkkky ;
with a dtscrijition of the hest varieties.

AiM>, uofrcas of the Kasfibt-rry, Blackberry, Coirant, Gooeebe y, and Grape; with
directions lor tlieit cultivation, and the selection ot the best vaiieties. "Every prucet*
here recommended has been proved, the plans c( others tried, and the result is ber»
given." With a valuable appendix, containing the observations and expeiieiic cA
Bome of the moat successful cultivators of these fruits in our coantry.

OUENON CN MILCH COWS ; CO

A Treatise on Milch Cows, whereby the Quality and Qnnnfity of
Milk which any Cow will give maybe accurately determined by obaerving^ Natiira'
Warksor External Infiications alone; the length of time she will continue to give
Milk, ifcc. «kc. Byil. Fi:ANCis Gl'eson, of Libourne, France. Translated by Niciio-
/.A3 r. Tkist, Esq ; with Int oductlon, Remarks, and Observations on the Cow and
the Dairy, by John S. Skinkejb. Illustrated with numerous engravings. Neatly
done up in paper covers, 37 cts.

AMERICAN POULTRY YARD ; 100

Comprising the Origin', History and Description of tlie dilTerent
Breeds of Domestic Poultr.v, with complete directions for their Breeding, Crossing,
Bearing. Fattening, and I'reparation for Market ; including specific directions for
Cai'iiui/iug Fowls, ami for tl.e Treatment of the Principal Diseases to which they are
eubject. drawn from authentic sources and personal observation. lUustreted with
nuuierous engravings. By D. J. Bbowne.

BROWNE'S (D. JAY; FIELD BOOK OF MANURES ; - - 1 25

Or, American Mltk Book ; Treating- of the Nature. Properties,
Sources, History, and Operations of all the Priccipal Fertilizers and Manures in Com-
r.iiin L'se, with specific directions for their Preservation, and Application to tiie Soil
and to Crops; drawn from authentic sources, actual ezj'erience, and persona! observa-
tion, as combined with the Leading Principles of Practical and Scientific Agriculture*
By D. Jay Bkowse.

EANDALL'S (H. S.) SKEEP HUSBANDRY; - - - 125

"With an Account of the Different Breeds, and ceneral direc-
tions in regard to Summer and Winter Management Breeding, and the Treatment c/
Diseases, with Portraits and other Engravings. By Hexrt S. Eandall.

THE SHEPHERD'S OWN BOOK ; • - - - - 2 00

With an Account of the Different Breeds, Diseases and Man-
agement of Sheep, and General Directions in regard to Summer and Winter Man.
ageixient, Breeding, and the Treatment of Diseases ; with Illustrative Engrav ngs, by
■\ ou ATT «fe Band all; Embracing Skinner's Notes on the Breed and Management of
."^ h«ep in the Unit^id ^ tates, and on the Culture of Fine Wool

YOUATT ON SHEEP , - 75

Their Breed, Management and Diseases, with Illustrative En-
gr»vinfi'^; to which ara added Remarks on the Breeds and Management of Sheep la
the Unit*! .-tates, and on the Culture of Fine "Wool in Silesia. By Wuxiam Yocatt.

'f OUATT AND MARTIN ON CATTLE ; - - - - 1 25

Bking a Treatise on their Breeds, Management, and Diseases,
comprising a full History of the Various Races; their Origin, Breeding, and Mojils;
(.heir capacity for Beef and Milk. Vj W. Youatt and "W. C. L. Martcn. The whoI«
forming a Complete Gui<1e for the Farmer, the Amateur, and the Veterinary Surgeon,
with UjO Illustrations. Edited by Ambkose Stevens.

f n-JATT ON THE HORSE ; 1 25

Youatt on the Structure and Diseases of the Horse, willi

tfielr Rcmedi<^. Also. Practical Rules for Buyers, Breeders, Smiths, <fec Edirt^d by
"/f. C. Spooxer, M.R.O V 8. With an account of the Breed* In the United tates, bj
tliHST 2. Randall

Books PuUished by A. 0. Moore.

JOTJATT AND MARTIN ON TEE IICG; - - - . §.0 75

A "i'RFlATISE OX THR BkEEDS. IM AN.AnEMENT. AVD MeDIOAE Ti EaT-
nient of Swine, with Directions for Salting Pork, and Curing ' aeon and Haitis ' y
U.M VovATT. V.S . and W C L. Maktin Edited by Ambkosk Stevens. Illiisirat«i
wiUi Et-gravings drawn from life

S LAKE'S (SEV. JOHN L.) FARMER AT HOME; • 125

A Family Text Book for the Counti^y ; bcinj? a Cyclopodia of
Agricultural Implements and Productions, and of the more Important topics in liio-
meslic Economy, . cience, and Literature, adapted to Rural Life. ly Eev. Joun L

blAKK,DD

mTJUH'S (B.) PRACTICAL LAND DRAINER ; - - - 50

Being a Treatise ox Draining Land, in which the mof^t approved

systems ol Drainage are explained, and their differences and comparative merits dis-
cussed; with full iJirection; for the Cutting and Making of Drains, with Remarks upon
the Various materials of which they may be constructed. With many illustrations, i y
h. Ml'.nn, Landscape Gardener.

ELLIOTT'S AMERICAN IRUIT GROWER'S GUIDE IN ORCHARD

AND GARDEN ; 1 25

Being a Compend of the History, Modes of Propagation. Cul-
ture. ifec of Fruit Trees and Sh ubs, with descriptions of nearly all the varieties of
> ruita cultivated in this country ; and Notes of their adaptation to localities, soi's, and
a complete list of i ruits worthy of cultivation. 1 y F. R. Elliott, Pomologist.

IRACTICAL FRUIT, FLOWER, AND KITCHEN GARDENER'S COM-
PANION; - - - - - - - - 1 GO

"With a Calendar. By Patrick Neill, LL.D., F.R.S.E., Score
tary of the Royal Caledonian Horticultural Society. Adapted to the United States
from the fourth edition, revised and improved by tlie author. Edited by G. Emebson-,
M D.. Editor of '-The American Farmer's Encyclopedia." With Notes'and Additions
by E. G Paedee, author of '"Manual of the Strawberry Culture." With illustrations

STEPHENS' (HENRY) BOOK OF THE FARM; - - 4 00

A Complete Guide to the Farmer, Steward, Plowman. Cat-
tleman. Shepherd. Field Worker, and Dairy Maid. By Henry Stephens. With Four
Hundred and Fifty Illustrations; to which are added Explanatory Notes, Remarks,
&c., by J S Skinner. Really ons of the best books a farmer can possess.

PEDDERS' (JAMES) FARMERS' LA.^"D MEASURER; - - 53

Or, Pocket Companion ; Showing- at one view the ConteDts of any
Piece of Land from Dimensions taken In Yards. With % set of Useful Agrlculturiy
Tables.

WHITE'S (W. N.) GARDENING FOR THE SOUTH; - - 1 25

Or. the Kitchen and Fruit Garden, with the best methods for

their Cultivation; together with hints upon Landscape and Flower Gardening; con-
taining modes of culture and descriptions of the species and varieties of the Culinary
Vegetables, Fruit Trees, and Fruits, and a select list of Ornamental Trees and Plants,
four>d by trial adapted to the States of the Union south of Pennsylvania, with Garden*
ing Calendars lor the same. By Wu. N. Whitb, of Athens, Georgia.

EASTWOOD (B.) ON THE CULTIVATION OF THE CRANBERRY ; 50

"With a Pescription of the best Varieties. By B. Eastwood,

"Septimus"' of the New York Tribune.

iMERIC AN bee-keeper' S MANUAL ; . - - - 100

Being a Practical Treatise on the History and Pomestio
Economy of the Honey Bee, embracing a full Illustration of the whole subject, w ith
the most approved methods of managing this Insect, through every branch of iti
Lultu e; tbe r^snlt of many years' experience. Illustrated with ma-ay engraving*
By T. B. MiNKB.

Books Fuhlished by A. 0. !Moore.

THAES,'S ^ALBERT D.) AGRICULTURE - - . £2 CO

'J'liE Principles of Agriculture, Dy Alrtet D. Tij \f,r ; tnms-
laf.ed by William Shaw and Cuthbebt W. Johksow, Esq , F.E.3. With a Memoir
ol the Author. 1 vol 8vo.

This work is regarded by those who are competent to judge as one of the \no*\
beau ti fill works that has ever ajtpeared on the subject of Agriculture At the samo
time lliat it is euiinentiy practical, it is philoso, hicai, and, even to the general reader,
reinarkabiy eutei taining.

BOUSSINGAULT'S (J. B.) RURAL ECONOMY, - - 125

Lv its Relations to Chemistry, Physics, and Meteorology :

or, Chemistry applied to Agriculture. By J. B. Boussixqault. Translated, with
notes etc., by George Law, Aorriculturist.

" The work is the fruit of a long life of study and expe'lment, and its perusal ivlU
•id the farmer greatly in obtaining a practical and scientific knoieledge of his proles
felon.''

MYSTERIES OF BEE-KEEPING EXPLAINED ; - - - 100

Being a Complete Analysis of the Whole Subject, consistint^
of the Natural History ot Bees; Directions for obtaining the greatest amount of Pure
Surplus Honey with the least possible expense; Remedies for losses iriven, and the
Science of Luck fully illustrated; the result ol more than twenty years' expedence in
extensive .piaries. By M Qdinbv.

THE COTTAGE AND FAEil BEE-KEEPER ; - - . 50

A Practical Work, by a Couutry Curate.
WEEKS (JOHN M.) ON BEES.-A MANUAL ; - - - 60

Or, an Easy Method of Managing Bees in the most profitapi.e

manner to thei owner; with infallible rules to prevent their destruction by the Moih
"W ith an appendix, by Woostkb A. Flanukks.

THE ROSE ; - 50

Being a Practical Treatise on the Propagation, Cultivation,

and Management «f the Rose in all Seasons; with a 15=1 of Choice and Ai^proved Varie-
ties, adapted to the Climate of the United States; to A-hich is added full directions lor
the Treatment of the Dahiia. Illustrated by Engravings.

MOORE'S RURAL HAND BOOKS, 1 25

First Series, containing Treatises on —

The TTofse, The Pests of the Farm,

The Hog, Domestic Fowls, and

The Honey Bee, The Cow,

Second Series, containing — _ . . . 1 25

£vERT Ladt her owk Flowee Gardenkb, Essat on Manueeb,
/lements of Aorioulttjre, Am ekican Kitchen Gardener,

•JiBD Fanci.;b, A-mekican Rose Cultueist.

Third Series, containing — 1 25

Miles on the Horse's Foot, Vine Dresser's JIanital,

The Rabbit Fancier, Bee-Kee ir's Chart,

Weeks on Bees, Cuemistey made East. •

Fourth Series, containing — - . . - 1 25

Persoz on the Vine, Hoopf.r's Dog and Gtrii,

LiKBio s Familiar Letters, Skillful Hoi'sf.wifb,

Bkowne's Memoirs of Indian Corn.

aiCHARDSON ON DOGS: TREIR ORIGIN AND VARIETIES. . 50

Directions as to their General Maxa(;e.\ient. AViil) minKrnii?
orlcrinal anecdotes. Also. Complete Instructions as to Treatment under Disease. By
II D. Richardson. Illustrated with numerous wood engravinffs.
This is not only a cheap work, but one of th« b*8t ever iubiished on the Dog

Boohs Published by A. 0. Moore.

IIESIG'S (JUrTIIS) FAMIIIAH LECTTJEES ON CHEHISTEY. SO 50

And its ll?:i,AT«>\ t<» {Jommkkce, i'uvriiOLooY, and Aquiculture.
Edited by John GAButJs'ER, M.D.

BEMi NT'S (C. N.) EABBIT FANCIER; - - . _ 50

A Trratise on tiik 1)RKEdino, Rearing, Fredino, and General
ManugPinent of Kabhits, with remarks upon their diseases and emedles, to which are
adiled lull directions fur ilie constiuction of llutdies, Kablitries, &.c., together with
recipes for cooking and dressing tor the Table. Beautifully Illustrated. .

.THOMPSON (K. D.) ON THE FOOD OF ANIM.ULS - . 75

Experimental RESEARriiEs on the Food of Animals and the

Fattening of ("attle; with remarks on the Food of Man. Hasod iry,on Erp<'rim<'nts
uiid.rtakin by "r-Kr ol tin- i>ritisti flovernriifnt, l>y Houkrt Dundas TuoJi son, M D.,
Lecturer uu rractical (. heuiisiry. University of Giasgow.

THi:. WEsTEKl^ FEUIT BOOK; 125

I?E1N(; A r^'^MPEND OF THE RiSTORY. MoOES OF PrOPAOATION, ClL-
ture, Ac, of Fruit Trees and Shrubs, &c., Ac By F. ll. Elliott.

THE SKILLFUL KG t' SEW FE; 50

Or (.'omim.etk U'tihe to Domf=tto CorKFRV. Taste. Comfort, and
Efonnmy, enibradriir Oo'.i n*ci[i«s [.frtainlng to Ilonseliold Duties, the care of Health,
Ginli'Uiug, Birds, tdutaiion 01 Cliildrcn, Ac, Ac By Mrs L. G. Abkll.

THE AMERICAN FLCRISTS GTJIBE; 75

CoMPRI=:iNO THE AMERICAN RoSE Cci.TCRIST AND EvERY LaDY TIER
own Flower Gardener.

EVERY LADY HER N FLfW^'R GABDrNER; - - 50

AnoREssEn TO the lynr.^Triorp and Fro.vovioALONLY : ront;)niMi.r

Blniple and practif.il nirertiiT.sfor Cu!ti\ atini: P!antj>:»nd F'owers: a'so, Firts fur tue
Mana^'ometil of I'lowers; in Un. ms, with l.rii'f Botanical Dcscrljitinii'^ '/ Plants and
Flowera The whole In plain ana sinipie language. By Loli&a . ouns /«.

FI3:;i CULTOR-:; 1 00

A Trrxttse on the Artificial Propaoation of certain ktnd=! op

Fish, with the description and h^bit? of suf"h kinds as are most suitable for piscicu't'iro.
iM.so directions for tlie most succosfful methods of Ansriins, illustrided witii numerous
en?ra inffs By Theouatus Gaelick, M.D., Vice I'reciident of Cleveland Academy
of Isatural Science.

FLiNr ON Gii ASSES; 1 25

A Practical Treatise on Grasses and Forage Plants, compris-

Ins their natnral history, comparntive nutritive value, methods of cultivating, nit-ing,
and rurinii^. and the manairement of grass lands. By Cuas. L. Flint, A.M., Secretary
of Mass. State B:);trd of Agricallure.

W.-P.;k:> ON uEOvJE AN!) EVERGREENS; - - - 3 00

A Vanttat. on T.tvf Fences, with paptpplar D'Tjecttons pcp Ti-r ir

p'anMns, culture and trinwiiini.', es[>ecially with regard to t!ie >'achiia liciljrcs. ;)!:!
bi>w niTnake it. Also an essav on Kvergreens, their varieties. j>rop;i-ifi.>ii. 'r-.n-ii .-I'lt-
ii^ir a:rl -uir'tre in the Uni ed States. By John A. WARUEl^ M.D., Pr. si. lent o!
Ciueinnati Horticultural Society.

l(f Books PuhlisJied hy A. 0. Moore.

]\I 0 0 11 E ' 3

AU arranged and adapted to the Use of American Farnit/rn.

PRICE «5 CEIVTS EACH.

HOGS;

Tttftr Oktotn, Yarifttfs axd ^fAXAOKMEXT. ■u'ltli E Tif-TV to Pro-
fit, fln<l Tr«>iitn)ent un*1i-r Disease; also I'lnln Din-ctions relative totlif»uj«»M apprnved
nodt'Sot jiri-.-erviiijr thfir FU->h. Pj- II. D. Un nAi;DbO>, author of "Tue iiive and tLa
lioney Bee,'" &c^ vVc. "Wiib illustiaiiuns — I'imo.

THE HIVE AND THE HONEY BEE ;

AVrrn Plain l^iKiUTioNSFop. ()btatxtxga Coxftdf.rari.f, Axxual

Income from tliis hr.inrh of Rura! KcnoTny ; also an Account of tlie Diseases of Beea
^noi '.>nir IN'int'dics. ami iJeinaiks a> (otlifir Kiiemies. ari'l lin- list iiKn'e of [';oteciiiig
tLe lUves iVuin ilicir attacks. By 11. 1) ILicuajj^son. AVitb illustratioLS.

DOMESTIC roWLS ;

TrEik Natural TTtstory, Brffdixo. Efartxg. axd Gfxfral
Marttritnent By II. I). RiruARueoN, author of "The Natural History of the Fossil
D."*f,' xc. With iilustrutlons.

THE HOlvSE;

Thitr Ortotn axd Vartfttk.s; tttttt Plaix Dirfctioxs as= to the

Br<>edin;» Rearinjr. and General Mana-.'oment, with Instructions as to tbe Treatment of
Diseiiss. Handsomely illustrated — 12iuo. By H. D. IUcuasd6un.

THE ROS I \

The Amfrtcax Rose ruLTURisT ; beino" a Practical Treatise on tho
Propaunti >n. Cultivation, and Management in all Seasons, Ac Vtth fsU directions for
the Treat aent ol the JMhlia.

IKE PESTS OF THE FAEM ;

AViTii IxsTRLTToxs FOR THFTR ExTTRPATTOx ; bcinGT a l^fauiial of
Plain D^r. ctions for the certain Destruction of every description of Vermin. With
nnmero'i? Illustrations on Wood.

iLN ESSAY ON MANURES;

RlT;M)rTFD TO THE TRrPTFER OF TTTE MAPSAOnUSFTTS SOCIETY FOR
Prorr.oang Agriculture, for their Premium. By Samuel H. Daka.

THE /IvlEitiCAN EIKD FANCItE;

Covs^inEiJED WITH IIkferexce TO TTiE Prfedixo. Peartxo. Ffed-
In?, Man^sjnaent. and Perul!arities of Cage and House Birds. Hlustrated wjth Engia?
ii-ijit;. By 1). Jav Bkownk.

CHcMISTEY MALE EASY;

Fop. the Use op Farmers. By J. Topham.
ELEMENTS OF AGRICULTURE ;

Tr-.AN.'^LATFD FROM THE French, and Adapted to the use of American

FarraaTS. By F. 0. Skimjik

Boolcs PuUisJied hy A. 0. Moore. 11

TFE HO~SE'S FOOT AITT) HCW TO 3:ES? IT Sr;TJ"D ;

W'irii ("I'ls. ii'ustrjriii <i- ilic A 1 > " iny f t tit- !-^i)*.n:Ml (•■ t;":';)' lu
F8li<al>!f Hints on .shoeing and stal/e uianageDiLUU bulb Iii lit-ailh aLii diitaf e. By V.'iL-

THE oKiLLeUL HOUSEWIFE;

Or. C('inj)K'T(' (juide to Di'iriti^tic Cool<erv. Taste. CoTTifort.nnfl Ef'on-
Oiiij'. euibracirnr 5.".9 n cipt-s ptTtaining to House hold Duties, tlie care of Health, Gai-
dcriiiig, Ijirds, Education of Children, •kc, &c. By Mrs. L. G. Auell.

THE AMERICAN KITCHEN GAEDENEE ;

CoxTAixixG Directions for the Cultivation of Yegetables and

Gtrden Fruits. By T. G. Fessenden.

CHINESE SUGAR CANE AKD SUGAR MAKING:

Jts ITi.<tory, Cllturk, and ADArxATittN TO THE Soil, Climate,
and Economy of the Jnitod States, ^vith an accoant of various proces.«e8 of Manufac-
turing Sugar. Drawn troin autlK-niie soJirces by Charles F. Sta^sbuuy, A.M.^ hite
Coiiiiuifsionur at the Exiiil.iiion ol all Isatiousat London.

PERSOZ' CULTURE OF IH£ VINE ;

A Xkw Process for the {^'lturf, of the Tine, by Persoz. Pro-
fe.ssor to the Facnlty of Snences of Strasbourg; dirt-cting Proressor of the St^.hooi
of I'barinuey of the same city. Trantlaieil by J. OG. Bakclay, Surgeon U.S. N.

THE BSt: KEEFiiR'ii CHAiiT;

BEfNG A IJIMEF rRAf'TirAL TrEATISE ON THE InSTTNCT. TTa BITS, find
Maiiai'i'mi'Mt of the Il>>noy Bee. in all Jts various brancJies. the result of m.iny years'
prai.Lie:il e.vperien<f. win re!>y the au:bor b:ij lut-n cnal'led to divert the siibii-ctoi
uuicli tliat has 1 etn c<>M>i'!»ed mypli-rious and JillicnU to ovvriome. and lender ii
more sure, prortial'lc, anil interesting to every one, than it bos heretofore been. By

E. W. i'llELl-b.

EVERY LAliY HER OWN FLOWIR GARDENER;

Addrf-^^eo tottie IxDrsTRiofP and EcoNCoiTr-AL only: coiitninin?
Simple and Practical Direotjons for Cultivating Plants mid Flowers; also. Hints foJ
the Mitiiagement of Flowers in lidoms, with brief IJotanical Deseri|itions of Plants and
Flowers. The vbole in j>lain and simple language. By Locisa Jounsom.

THE COW; DAIRY HUSBAKIRY AND CATTLE BREEDING.

By M. M. MiLRunx. and revised by H. D. Richardson and Ambrose

Btktbss. With Illustrations.

WILSON ON THE CULTURE OF FLAX ;

Tt.«! 1'reatment. Agrictltfral and TEfTTNTrAL ; delivered before

the New York State Ajnicultnral Socit-fy, at the Anr.nal Fair »t Saratojia, 1t> Septem-
ber last, by .loiiN Wilson, late President of the Uoyal Agriculiur^l College at Ciren
oester, England.

ATEEKS ON BEES: A MANUAL.

Or. an Easy Method of Manaotno Bees in tfe most proftta •
Me manner to tlieir owner, with infa!li))le rules to prevent Ihtir d'j/^tractiop by t'i«
Moth; with an Appendix by ^Voo9TKR A. Flamiers.

U££iOLIN"3 (CHA3.) VINE DRESNER'S MANUAL;

CovTA!NTN(i FULL Instrfctions hs to LOCATION and Soil : Prepara-
ti'>n of Ground: Selection and ProfmL'ation of Vln-s; the Treatm-o'/t of a Toung
Vimvard : triiiimlng and training the Tines ; manures and the making cf M lee, Eve'"y
department illustrated.

HYDE'S CHINESE SUGAR CANE;

CONTAIXTNO ITr. TTlSTORY. MoDE OF CuLTURE. MANUFACTrEK of ths
Sugar, Jcc. ; with Reports of Ifj success in differen*. parts of the United &rj\t4M»

12 Boohs Published by A. 0. MoORE.

BSI^FNT'S (C. M.) EABBTT FANCIER ;

A 'i'f^EATisF: ox THE Breeding. REAnixo, Feeding, and Genepal

Mannc»>i-o-rit ol" R.ilbits, with remarks npim tli ir diseases and remedies; to wliich
are added lu.I directions for tiie constructinn of Hutches, Kabbitries, &c., together with
recipes for cooking and dressing for ihe table.

EICHAKD30N ON DOGS : THEIR ORIGIN AND VARIETIES ;

Directions as to their General Management. With mimcrons
originai anecdotes. Also Complete Instructions as to Treatment under Disease. By
H. D. RtcnA!;DSON. Illustrated with numerous wood engravings.
This is not only a cheap, but one of the best works ever published on the Dog.

LIEBIG'3 (JUSTUS) FAMILI: R LETTERS ON CHEMISTRY ;

And its Relation ro Commerce, Physiology, and Agriculture.
Edited by John Gardener, M. D.

THE BOa AND GUN ;

A FEW I/^osE Chapters on Phooting. amonir Avliirli will be fonnd
some Anecdotes ond Incidents. Also Instructions for Dog Breaking, and interesting
letters fWmi Sportsmen. By a Bad Shot.

THE PRESERVATION OF FOOD ;

The various methods of preserving Meats. Fruits. Vegetables.
Milk, Butter, Grain, <kc, by drying, smoking, pickling, and other processes. Bj £2.
GoouEica SUITB.

-f : i

:i\''<.;'^,-: '-'4

-•.fif

.■■:-'if/:>,- '-

: -r . i;

t ^ :

.' . t - .

""'■Ml.

nmmm

ill

! <

'^^H

•^

. ^ 'ifIT

'-" . c

■« \. '

} .

{ ;

f 1 -•.:.,

■^

.\ ■»

/ V .

; 1 ' •"<.

"^- ' "^ •■

■ V y\

% :

'' ■ ''

'>.<"

\ \

.^ i .

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "A practical treatise on the construction, heating and ventilation of hot-houses; : including conservatories, green-houses, graperies and other kinds of horticultural structures..."

See other formats