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1843.] 
THE GARDENERS’ CHRONICLE. 
261 
i SHADES FOR GREENHOUSE; 
J WEEKS & Co., Arcuirects, HorticunruRAL 
7 » Burrpmrs, &c., Gloucester-place, King’s-road, Chelsea.— 
The great simplicity of their improved plan of Sanne, b: 
Which the roof of the largest or smallest house can be instantly 
Covered with a sheet of Canvas, renders the principle an object 
of admiration. To be seen in use at most of the London Nur- 
Chen and at their Horticultural Manufactory, Gloucester-place, 
elsea, 
MEETINGS FOR THE TWO FOLLOWING WEEKS. 
Tuesday, April25 «+ . Zoological ad rx 
Wednesday, April 26 
Entomological»... 8 Pate 
Monday, May 1 Onn Lnenauieni Anniversary 1p. xe 
Horticultural a ace 
Tuesday, May 2 
Friday, May5. 6... 
Counray Snows, April 29 
Lime 
May 5 ae ies Liverpool. 
Wnuen buildings for the shelter of plants in winter 
Were first thought of, large rooms with upright win- 
dows were the means employed ; and hence the old- 
fashioned conservatory (or hibernatory), such as still 
exists at Kensington Palace, Hampton Court, Kew, 
and other old gardens, and as was but a few 
Years since contrived in the ditch of Windsor Castle 
terrace garden. But as gardeners gained a better 
insight into the nature of plants, they found that 
ight was as necessary to healthy vegetation as protec- 
tion from cold ; and then arose the glass sheds with 
lean-to roofs. Afterwards, when Priestley, Senebier, 
and others, had explained the nature of the solar action 
Upon plants, ingenuity was taxed to secure the greatest 
Possible quantity of light in plant-houses; first, a 
Southern aspect was regarded as indispensable ; then 
was caleulated the angle of slope which would enable 
the sunbeams to strike the glass roof most directly at 
all seasons ; next, rafters of wood were regarded as 
too heavy, and iron was substituted ; and then came 
curvilinear roofs, with all that lightness and beauty of 
appearance for which they are so well known. 
But there has long been an opinion in the gardening 
world that span-roofed houses are in some respects 
better than lean-tos; probably because of the impossi- 
bility of turning to good account the back wall of a 
common greenhouse; and buildings of that descrip- 
tion are now becoming common. It has even been 
doubted whether the large quantity of light, which 
modern inventions are specially directed to secure, is 
as advantageous to plants as has been supposed. But 
Common sense tells us that under no circumstances 
can plants in glass houses receive so much light as 
Nature would, with certain exceptions, give them out 
of doors; and experience shows that, with proper 
Management, the health of plants is generally in pro. 
Portion to the amount of light which they receive, 
any plants, indeed, grow naturally in woods and 
Secluded places, and to them bright sun-light is 
Mjurious ; of this kind are Ferns and most Orchidaceous 
Plants. But they form the exception, rather than the 
Tule, and in no degree invalidate the law, thatif plants 
are to be kept in the best possible health, they must 
‘ave the greatest possible natural light. 
t may, however, happen, that strong light is dan- 
Serous to all plants under particular circumstances, 
Ust as the most wholesome food ‘may occasionally be 
Prejudicial to the human system. We know, for 
stance, that plants that have been frozen, and which 
erish, when rapidly thawed by sudden sunshine, 
Will not die if the thawing is slow and gentle, All 
Sardeners are, or ought to be, aware of that fact; it 
Nas been certainly ascertained in so greut a variety of 
abe as to admit of no doubt ; it explains why tender 
*“nts thrive better within the shadow of north walls, 
°F at the north side of a shrubbery, than when they 
ih placed in warm and sunny nooks. The cause of 
ype enomenon has been discussed in a report on the 
pests of the Frost of the Winter of 1837-8, published 
y the Horticultural Society (Z'ransactions, second series, 
the i p. 305.) We find that Mr. James Macnab, 
ay skilful curator of the Caledonian Horticultural 
ae 8 garden, has suggested that, on this account, 
ae toofed greenhouses which run north and south, 
ie Consequently face east and west, are better than 
a “tos with a southern exposure. From an excellent 
Riles: in the Edinburgh Advertiser we extract the 
Wing particulars. 
nthe opinion of Mr. Macnab the span-roofed 
h 3 ‘ : 
Bi running north and south is not only better in 
winer, but is still more advantageous in winter. 
Peal example, in a span-roofed house, extending 
ee Ne south, during the stormy weather of wipter 
the ay = freely admitted, from whatever direction 
Hite ey blow, there being always a lee-side 
Whee be hes aie be opened. In frames and pits, 
sayy op aix alone can be given, plants suffer greatly 
BA pees but in a span-roofed house, the circula- 
ie air may be constantly kept up so as effectually 
nf ata damp. For such a greenhouse fire-heat is 
atcely at all required ; for if there be a free circula- 
tion of air during the autumn and winter months, 
and if the tables or shelves be carefully kept dry and 
clean, and water be sparingly given to such plants only 
as require it,—cold, even though it should extend to 
the occasional freezing of the surface-soil of the pots, 
willdo less injury to most plants than the application 
of fire-heat. Mr. M‘Nab has found the same kind of 
plants to become soft, spongy, and drawn up, in the 
lean-to house, which continued hard, woody, and 
dwarfish in the span-roofed house. Last season he 
kept a number of fine Cinerarias and Pelargoniums in 
houses of both forms. After a severe frosty night in 
January, they presented in the morning mucl: the 
same appearance in both houses, the leaves drooping 
and being covered with a white rime, resembling hoar- 
frost. By ten o'clock the sun shone forth. The 
plants in the lean-to house were subjected to the full 
influence of the mid-day rays ; and, although air was 
given, they blackened and perished. In the span- 
roofed house. extending north and south, theinfluence 
of the sun was much less felt ; for as he proceeded 
towards the meridian, the intercepting astragals and 
rafters necessarily formed a screen or shade; and air 
being given, the plants survived, and soon recovered. 
“ Amateur cultivators, who like to possess a small 
greenhouse, and to manage it for themselves, ought to 
prefer the span-roof form; and from Mr. M‘Nab 
they may learn this important lesson—that by an 
early and anxious application of fire-heat, in a frosty 
night in the beginning of winter (a common fault), 
they not only incur unnecessary trouble and expense, 
but do real injury to their plants, which would suffer 
little from cold, provided air were made to circulate 
freely among them, and damp were guarded against. 
The beautiful tribes of Erica and Epacris will suffer 
little or nothing in a cold greenhouse, although the 
thermometer in the open air may indicate several de- 
grees below freezing, while the sudden application of 
fire-heat will probably kill them. 
“Mr. M‘Nab mentioned that the superiority of the 
span-roofed form was strikingly exemplified in the 
Society's Garden about the middle of February last 
(1843), when the self-marking thermometer in the 
open air, during different nights, indicated 20°, 15°, 
and even 10°, Fahr. During these frosts no heat 
whatever was applied to the span-roofed house, which 
contained a general collection of soft and hard-wooded 
greenhouse plants. On the mornings of the 17th and 
I9the February, the mercury in the thermometer 
| within the house stood at 25°, or seven degrees below 
freezing ; yet only two or three plants, which were 
standing near the upright glass of the south end of 
the house, and were thus exposed to the mid-day sun, 
suffered from the intense cold to which they had 
been subjected. The temperature in the span-roofed 
house always remained much more equable than in 
the lean-to house. This was signally remarkable at 
1 pm., of the 14th February, when the thermometer 
in the open air indicated 56°, in the lean-to house 70°, 
and in the span-roofed house 43°. In the lean-to 
house, therefore, where the whole glass roof was fully 
exposed to the sun’s meridian rays, the temperature 
thus becoming 14 degrees higher than the open air, 
and 27 degrees higher than in the span-roofed house. 
“ Having enlarged on the advantages of this form 
of greenhouse during winter, we shall only briefly 
state, in conclusion, that, in the warm weather of 
summer, the span-roofed house admits the freest pos- 
sible circulation of air, by means of upright sliding 
sashes on both sides of the house; while the rafters 
and astragals of the glazed roof break and intercept 
the sun’s rays, and help to shade the plants from their 
direct influence; and thatin such a house the plants, 
instead of being drawn up and weakly, continue firm 
and bushy—that they remain much longer in flower 
—and that the colours of the flowers are generally 
brighter.” , 
Although, as is apparent from the observations with 
which we introduced this matter, we do not feel dis- 
posed to assent to the justice of some of the latter 
statements, we freely concede that north and south 
span-roofed houses are very convenient, and that, in 
so far as abating the injury from frost is concerned, 
they are far better than lean-tos. But we must at the 
same time caution our readers against assuming, that, 
because such span-roofs have these merits, they may 
be applied to all purposes with advantage. We do 
not think they can be used at all for early forcing, 
and we much doubt whether they will suit any kind 
of stove plants, except Ferns and Epiphytes, or species 
with similar habits. 
Ir the intersection of a country by good roads, 
formed upon correct principles, be—as it surely is— 
one of the greatest means ot rendering the resources 
of a country available, and of civilising its inhabitants, 
so, on the other hand, is a universal and consistent 
construction of water-courses, to drain the land, second 
only to the former in importance. If the first enables 
the inhabitants to move their produce freely from point 
to point, the second places within their reach the 
means of, obtaining the greatest attainable amount of 
produce to be moved : if the one softens their manners 
by the facilities it gives to the spread of metropolitan 
refinements, the second no less efficiently contributes 
to their, comforts by the removal of insalubrious 
vapours. The drainage of a country, however, not 
being attended by such self-evident advantages as its 
high-roads, is much more slowly appreciated ; and it 
is only when the exhausted soil refuses to yield the 
tenant and the landlord their accustomed profits that 
its real importance begins to be felt. That people are 
now aware of it in this country is sufficiently shown 
by the many drainage associations which are rising 
into vigorous existence. 
But in an old and densely-peopled country like 
England, it will always be found that the very best 
measures are thwarted by conflicting wishes or per- 
sonal prejudices. If one man is enlightened enough 
to understand his real interests, his neighbours may 
not have arrived at the same point of information, and 
their opposition will then thwart his measures wher- 
ever co-operation is required of them. We have no 
right to do men good against their will, still less are 
we entitled to compel others to enter into plans which 
they dislike, however advantageous they may be to 
them. And hence a great difficulty in carrying out 
any general measure of public utility: so great, indeed, 
that nothing short of legislative interference can re- 
move it. 
The general drainage of the country is exactly such 
acase. A man who chooses to sow his garden with 
Blackberries can do so if he likes, and his crop will be 
neither better nor worse for his neighbours’ acts. If 
he succeed, their assistance was not necessary to 
enable him to do so; if he fail, his ill success is 
nothing to them. Cropping, then, and all the general 
details of cultivating the soil, are without the pale of 
legal interference. But drainage is a very different 
affair. A may be anxious to drain his garden, but 
his neighbour B cares nothing about the matter, or 
perhaps has a spite against him, and will neither help 
him nor allow him to do so. A’s land is a little higher 
than B’s, or B lies between A and the outfall, and 
then the opposition of B putsa stop to A’s plans. 
A is an honest man, working hard for his living, and 
perhaps with a family suffering in health from the 
swampy nature of the soil. B, on the other hand, is 
alazy careless fellow, and does not know the look of a 
doctor's bill ; but_B’s acts compel A to put up with 
scanty crops and perpetual sickness. This is so mani- 
festly unjust, and so frequent of occurrence, that the 
law has long since attempted to provide a remedy— 
with what ill success the state of the whole country 
can tell. 
It is, then, to a general Drainage Bill that we should 
look for that assistance which the circumstances of the 
case demand—to some enactment of a comprehensive 
character, which should merge all private and petty 
interests in the greater exigencies of the state, and 
which, compensating those who suffer, and trenching 
unnecessarily upon no man’s right, should secure the 
effectual intersection of the country by water-courses, 
that Should be as much public property as the turnpike 
roads, Without pretending to go into the details of 
such a Bill, we may be permitted to state what we 
conceive should be its general features. 
engineers should be appointed, to direct simultaneously 
all the works that are to be executed; they should 
determine the lines of new water-courses, and the im- 
provement of old ones ; they should have power to take 
up land wherever required for their operations, com- 
pensating the owners ; and to compel commissioners of 
sewers, and other town authorities, to adjust their 
drains, wherever practicable, to those of the country. 
No applications from persons desirous of promoting 
drainage should be waited for ; no deposits of money 
should be required: but the work should be carried 
on by public officers, for public interests, and at the 
public expense. No surveys would be required, for 
the Ordnance maps would supply all the data that are 
wanted. The cost of the operations might, in the 
first instance, be defrayed by Government, and be 
repaid by county rates, or by taxes levied upon those 
who make use of the public water-courses for their 
own advantage. The district surveyors might be 
charged with the duty of keeping all the water-courses 
in repair ; and the cost of the operation might be de- 
frayed upon the same principle as that now pursued 
with the high roads. If this were done, the whole 
island would be cut into a net-work of efficier 
water-courses; and then the p 
drain his land might do so, while 
live in a quagmire would have the advai 
joying it without interference, and without the dis- 
agreeable compulsion of exchan ring his own 30 bushels 
ef Wheat-an acre for his neighbour's 40. 
It may, at first sight, appear unreasonable to levy a 
county rate to defray the expense of works which are 
only advantageous to those who have farms or gardens; 
but the benefit of general drainage would not be thus 
narrowly limited. Its inevitable effect would be to 
render all the drained districts more healthy, and to 
improve their climate: now this is a great advantage, 
A board of. 
