210 
THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, Jactabt 4, 1850. 
side. But if, in either house,—the floor of each being 
eight or nine feet from the ridge,—you resolved to have 
large plants standing in pots, or tubs, on the floor, in 
neither case would you succeed so well, as if the sides 
of the house were raised above the ground, and some 
two-thirds of these sides glass as well as the roof, as thus 
you would obtain light all round. Of course, this ad¬ 
vantage is gained at the expense of requiring more arti¬ 
ficial heat in severe weather. When even dwarfish 
plants were not thriving exactly to my mind, in a common 
lean-to sunk pit,—though the plants were pretty near the 
glass,—they soon improved when placed on the stage of a 
house built above the ground, even though that too was a 
lean-to, but with front glass lower than the front of the 
stage. The light thus struck in below the plants as well 
as above them, and the whole air contained within was 
more easily maintained in a state of active motion. 
Where their elegance and utility as to many purposes, 
and the growing large standards on the floor of a house, 
as well as small ones near the glass, or permanent plants 
trained near the glass,—where these are all desirable in 
one house, nothing will beat a span-roofed house, with 
most of the sides glass as well as the roof. When great 
heat is required, as in the case of Pine plants, and 
economy of fuel is a great object; or where, in a green¬ 
house, or pit, it is desirable to cover the glass from 
severe weather, instead of using much fuelsunk houses, 
or pits, will best meet the requirements of the case. 
When in deep sunk pits, with glass merely on one side of 
the top, as pits generally are made, and large plants arc 
ut into them somewhat thickly,—sunk pits should merely 
e looked upon as kybernatories, in which the plants may 
be kept during the winter, but not incited to grow, or the 
lower part of the plants will be injured. 
2. The idea of sinking, or boring, as a means of heat¬ 
ing, is new to me, and I can form no sanguine prospects 
for it; as, even if heat to a small extent might be thus 
attained, it might be so attended with gases, or water, 
&c., as to be a great evil instead of a benefit. The 
E erson who speaks of getting heat up from the earth, can 
avc formed no idea of the depth he would have to go, 
and even that would be varied greatly according to cir¬ 
cumstances. For instance, on the undrained Bed Moss of 
Bolton-le-Moors, even the heat of summer, and the colds of 
winter, pass no further than seven inches. Beyond that 
depth, to that of thirty feet, there is always an uniform 
temperature of 47°, which is about the medium tempera¬ 
ture of the locality fbr the year. In the tropics, a ther¬ 
mometer placed a foot beneath the surface varies little 
in the twenty-four hours. In our latitude, there is hardly 
any difference seen at a depth at from two feet to three 
feet and a half. That depth at which the temperature 
of the earth is uniform, never changing, varies according 
to circumstances, latitude, and climate,—being in some 
cases many feet, and in others only a few. To show the un¬ 
likelihood of getting heat from below (unless in the case 
of hot springs, &c.), I may mention, that, on an average, 
we must get down from fifty to sixty feet, to gain an in¬ 
crease of 1° iu temperature. In some cases it is required 
to go nearly a hundred feet, in other cases little more 
than thirty. This gaining of a degree for that depth 
has reference to that increase over the average medium 
temperature of the place. These facts seem to be proved 
from the depth of artisian w ells, and from noting the tem- 
erature in mines. The heat of the salt spring at Ceyn- 
ausen is 91.04° F. ; the mean annual temperature of 
the atmosphere of the place, a little more than 49° : the 
depth bclow r the sea 2,052 feet; height above, 231 feet. 
Thus an increase of temperature of 1° takes place for 
every 54.68 feet. At Monkswcarmouth, near Newcastle, 
at 1,496 feet below the level of the sea, it would appear 
the heat increased 1° for every 57 feet of depth. In the 
latitude of Paris, 48° 52', where the medium temperature 
of the atmosphere for the year is 51.478°, a thermometer 
placed in the vaults of the Observatory, at the depth of 
88 feet, has stood at 53:j 0 , and has not varied more than 
half a degree for sixty years. Whatever, therefore, may 
be done in deep warm mines, for forcing vegetables that 
are taken there for the purpose, and which are benefited 
by the absence of light, and whatever yet may be ac¬ 
complished on a large scale, by the heat that now escapes 
from large manufactories, I have little hope to see the 
heat from the interior of the earlh made available for 
horticultural purposes. 
3. I will try and finish with a few words, on Position, 
which will be just as applicable to gardens as raising a 
greenhouse. Low level grounds of large extent will 
always be earlier and warmer, than those in similar cir¬ 
cumstances more elevated or varied by undulations. Low 
levels between surrounding heights will be very hot in 
the middle of summer ; but, for all things at all tender, the 
position will not be nearly so good, as an intermediate, 
suitably sloping position between the hollow and the top 
of the height; as we often find the grass crisp from 
the loss of heat by radiation, in such a valley, while 
only a few score of feet higher up we find no traces of 
freezing at all. How often have we seen such a valley 
covered with a dense fog,' whilst fifty feet above its level 
the atmosphere was perfectly clear. That fog may even 
be changed to hoar frost, and yet no trace of fog or frost 
be found on the higher level. Even in the same garden, 
I have often noticed glass on a low level covered with 
hoar frost, whilst some twenty feet higher, on other glass 
in similar circumstances, it had not begun to form. It is 
well known, that, above a certain height, the farther we 
rise, the colder it becomes,— a fact known to every one 
who has climbed a lofty mountain. But for a certain 
height, varying, no doubt, according to many circum¬ 
stances,—say, from 50 to 200 feet,— the heat is greater 
and more uniform, than on the surface of a low level. 
The higher sloping ground not only gains an advantage 
from this heated ail*, but it is not supposed that it can 
radiate so quickly as the lower level ground ; and that 
lower ground is also additionally cooled by the cooler air 
gliding down from the surrounding slopes. On this 
account, I should prefer the medium position, instead of 
one either in the bottom of the narrow valley, or one on 
the top of the hill. A steep slope to the south, or south¬ 
west, should also be avoided for tender things, as the sun 
would be apt to excite them too much early in spring, 
and thus place them more at the mercy of the frosty 
nights. This will not apply to an early-heated house. 
I prefer, therefore, your house to be on the face of the 
rock, instead of over the reservoir of spring water in the 
vale, unless there should be any diiliculty in getting 
water to the former place, as, for everything connected 
with gardening, an unfailing supply of water is a matter 
of first importance. You would gain but little, in the 
way of heat, from your rock wall; but it woidd be better 
than any one you could build, and you would lose but 
little heat, in comparison with having a high w all standing 
fully exposed. If you prefer the lower position, you had 
better content yourself with a moderate reservoir of 
water, as, unless very large, all the heat it will give out 
will not help you greatly in severe weather, and the help 
it would give, on a pinch, w r ould be apt to be counter¬ 
balanced, by placing your plants in a fog bath. On going 
by the side of a stream in a hollow, after a warmish day, 
you must often have noticed a deep mist or fog hanging 
along the neighbourhood of the stream. As the air got 
colder than the water, the vapours that rose from the 
latter got condensed, and more especially if the cold air 
was already saturated with vapour. Supposing, then, 
that on a frosty night the air next your glass got cooled, 
it woidd give place to a warmer stratum of air, to bo 
cooled again in turn, and each would fall to the water; 
and if at all moist previously, the warm vapour that rose 
from the w r ater would be soon converted to fog, and thus 
fill your house. Such fog could only be dispersed quickly 
by artificial heat, changing the visible into invisible 
