192 
THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, December 27, 1859. 
should be pruned away, and all wounded roots receive a fresh 
and clean cut. The roots should then be spread equally out, and 
covered with a little richer compost, to facilitate a quick root 
action the first season. This is of much importance as gaining 
time. It will be generally found, that if youn^ trees are some¬ 
what excited the first year or two, and thus forced into size and 
then received a more moderate handling through getting into a 
plainer medium, fruiting habits will be speedily induced. So that 
when the volume of soil is a plain loam, or any plain soil, and 
coaxing material of a more forcing character is placed at first 
in contact with the roots, these matters will be accomplished. 
It remains now to offer remarks on a subsequent process con¬ 
nected with fruit-tree planting—that is, middling. There has 
been some difference of opinion about the propriety of this 
practice. Those reasoning from theory, doubtful; but practical 
men in general attached to the practice. 
The shutting out of the returning warmth of spring has been 
with the former party the doubtful point. But let it be remem¬ 
bered, that in autumn-planting it is well to enclose and protect 
the remaining warmth of summer; and in the return of spring, 
it we lose by the slower admission of returning warmth, we 
gain in avoiding those vicissitudes of dryness which so often 
prejudice newly-planted tiers. But if any one doubts this 
argument, how easy would it be to pay a man a shilling to 
simply fork the mulching aside during the month of April, 
running into May; restoring it by the same fork as soon as 
the ground got warmed, and drought apprehended. I speak 
now of fruit trees planted according to the suggestions here 
offered. If people will make holes nearly a yard deep into 
ungenial subsoils, and plant their trees in “ the’good old way,” 
burying their roots and then stamping on them with all their 
might, why I will say little about mulching. But ordinary 
orchard-standards being of coarse rude habit, will, in general, 
do almost at any time, as compared with a fancy espalier. 
Whilst talking about orchard trees, let me not forget to remind 
our friends of staking immediately trees liable to the winds. 
Wind-waving is a great impeder of that early action of the root- 
fibres so very desirable. R. Errington. 
MANAGEMENT OF ORCHARD-HOUSES. 
"Will some of your readers say what is the best distance 
from the gloss -to train Yine-canes in an orchard-house ?— 
[Nine inches.—Ens.] 
I have read Mr. Erringlon’s remarks on orchard-houses. In 
the first place, I think the gentleman was wrong in purchasing 
plants for an orchard-house which had been prepared for 
forcing. Then, as to ventilation at the apex being fatal, I do 
not agree with Mr. Errington’s remarks, having corresponded 
with Mr. Rivers on that subject, who says, “ I have never yet 
found any particular necessity for ridge-ventilation ; but at the 
sides and ends you cannot have too much.” 
Mr. Rivers says, “ on ventilation Success depends.” I think it 
matters not how careful and particular you are in preparing 
your soils, il you do not*ventilate. He does not say the height 
ot his house, and at, what distance his trees are from the glass. ! 
It parties will occasionally give us their experience with 
orchard-houses, I am sure it will be appreciated, and produce 
much useful information. Consult Rivers's 6th edition, as well | 
as a thermometer, and oblige— Nottingham. 
[See what Mr. Rivers says to-day in his able communication. ' 
—Eds.] 
• I 
ATMOSPHERIC MOISTURE IN GLASS-HOUSES. 
Some subscribers have wished for a few more definite directions 
on this subject as a supplement to the article on heating, Ac., a 
small greenhouse. I wish the matter was in abler hands ; but I 
will tiy and do my best, and leave other friends to supplement j 
my deficiencies. 
On this subject we are apt to fall into one of two errors_the 
opposites of each other, and either have the atmosphere of our 1 
houses too dry or too moist. The first error was the one mainly 
committed in olden times, when heat was more thought of than 
securing the necessary amount of atmospheric moisture; or 
when running pots of water along a heated flue, and thus steaming 
the house with vapour at a high temperature was thought to be 
quite sufficient, though the most of that quickly found its way 
out of the house through every lap, opening, and cranny—part 
ot it only being condensed against the glass and falling in the 
shape of drip, if it too did not escape by the laps. The steam 
thus raised was often too hot to be genial, and often injurious to 
i the fiue from whence it came. The best mode is by moist floors, 
\ stages, and evaporating-pans on the source of heat, to present 
the air with the means of being supplied with moist vapour in 
proportion to the temperature. 
All plants when young, and in a healthy, active, growing 
state, like the atmospheric moisture to be proportionate to the 
temperature. Thus tropical plants require more than those from 
more temperate latif udes or loftier elevations. Thus, also, plants 
; of a succulent nature need more than those of a woody nature— 
as in winter and spring it might be necessary to sprinkle shelves 
for Cinerarias, Calceolarias, and even free-growing Geraniums, 
when it might be necessary to dry the air a little for Heaths, 
| Epaci’ises, and hard-wooded plants. An exception here may be 
made for true succulents, such as Cacti, Aloes, Haworthias, 
Mesembryanthemums, Ac., which, if grown in summer and not 
; kept in a high temperature in winter, will need very little moisture 
I in the soil or in the air, as they have laid up a sufficient stock to 
last until the bright days come round. If even they, however, 
are exposed to a high temperature, then the atmosphere must be 
fairly supplied with moisture, in order that their stems may 
j absorb as well as perspire. Thus it will be apparent, after making 
, these allowances, that less atmospheric moisture will be necessary 
in a greenhouse at from 45° to 50° than in a vinery in March 
ranging from 65° fo 75°. 
T he power of air to contain moisture in the shape of insensible 
j vapour just increases with its temperature. That power is 
! doubled between 44° and 66°, trebled at 80°, and quadrupled at 
90°, and so on. Free uncorfined air, at a temperature of 50°, 
will generally contain about one-fiftieth part of its volume of 
i vapour; and, as the specific gravity of vapour to air is as 10 to 
15, the vapour will constitute one-seventy-filth part of its weight . 
The air at 100°, and with access to dampish surfaces, will contain 
i one-fourteenth ot its volume in vapour, and one-twenty-one part 
j in weight. The higher the temperature, therefore—provided the 
air has access to damp surfaces—the greater will be the quantity 
of vapour suspended in it, and the lighter will a column of air be ; 
because moist air is so much lighter than dry air, and from the 
i diminished pressure the column of mercury in the barometer will 
be lower. Thus in the open air in summer the debilitating 
effects of continued dry weather are so far counteracted by the 
amount of invisible vapour in the air during the day, and the 
refreshings of heavy dews during the night; a clear sky and a 
sinking of from 5° to 10° in the shade being sufficient to enable 
the fine points of the leaves of plants to condense the moisture in 
the air near them. If the air were very dry and heavy, as it 
often is in our spring months, then a greater proportionate fall 
of the thermometer would be necessary before wliat little vapour 
that was in it. could be converted into pearly dewdrops. 
W lien a gardener, therefore, speaks of an atmosphere in one of 
his houses being nearly saturated with vapour, he means that 
there is so much vapour that a few degrees less temperature, say 
from 5° to I 3 , would enable the plants to condense it in the form 
of dew for their own benefit. When a philosopher speaks of the 
air being so little or so much above the dew-point, he means 
much the same tiling—namely, the difference in the degree of 
beat between a thermometer with dry cotton muslin wrapped 
round its bulb, and another thermometer with a piece of similar 
muslin wrapped round its bulb, but kept constantly wet by 
means of a syphon of woollen or silk thread connected w ith a 
bottle of water. The cold produced by evaporation will form 
what is called the dew-point; and the difference between the 
two thermometers will give an idea of how much or how little 
vapour there is in the atmosphere. In a close, muggy day or 
night in summer or autumn there will belittle difference between 
the two thermometers. In bright, sunny, dry, frosty days in 
March, the difference is often astonishing even in the open air. 
Hence early-growing and early-blooming plants suffer so much 
from being alternately excited, and scorched, and nipped. Thus, 
too, plants against walls are more liable to suffer than those in 
the open ground: the sun beating against the wall not only 
excites the branches before the roots, but the dry heated air 
shrivels up and parches the early blossoms. Hence the import¬ 
ance of shades and glass in front of such walls, where heat and 
dryness can be moderated by air and moisture during the day. 
To ascertain the quantity of vapour in the air various instru¬ 
ments called hygrometers have been invented ; but it is not our 
purpose to allude to them, the principle in all is the same. A 
body is chosen that expands and contracts by dryness and 
