3 >9 
THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, Eebhuaky 15, 1859. 
talents, and, combined as these were, with perhaps too 
much of an unobtrusive retiring modesty. I know of a 
dozen subscribers at least who would not have been 
likely to take the work, had they not been informed that 
this member of foreign horticultural and pomological 
societies was, after all, our own Turnham Green Thomp¬ 
son. Let the publishers look to it. 
Well, pardoning this digression, you will there find what 
I referred to the other week—that the Led Moss at Bolton- 
lc-Moors, at seven inches below the surface, could neither 
be heated by the warmthof summer, nor cooled by the frosts 
of winter, beyond or below 47°, and that it retained that 
temperature to at least the depth of thirty feet. When 
drained, the temperature in June at seven inches below 
the surface rose to 66°. The regular temperature of the 
undrained part approached the medium atmospheric tem¬ 
perature of the place, though the extremes between the 
hottest and the coldest ranged from 24° to 25°. To show 
still moro conclusively how little heating power can be 
transmitted downwards from the surface of a liquid—or 
even through a solid, such as earths saturated or covered 
with liquid—an experiment was made which our young 
friends may repeat for themselves. A square box was 
formed, eighteen inches deep, eleven inches wide at top, 
and six at bottom, furnished with a tap at bottom. This 
box was filled, to the depth of twelve inches and a half, 
with earth saturated with water, and covered with the 
same. A thermometer was secured in the centre of the 
mass, the bulb being within one inch and a half of the 
bottom of the box. The heat indicated was 39^°. A 
gallon of boiliug water was poured on the top, and in five 
minutes the thermometer rose to 44°. This rise was 
owing, however, not to the conduction or absorption of 
heat by the water-covered and saturated soil; but to the 
heat getting down by means of the tube and the case of 
the thermometer. To prove this, another thermometer 
was let in at the same level through an opening in the 
side of the box, and therefore having no direct communi¬ 
cation with the hot water at the surface ; and thus placed, 
no variation took place in the height of the thermometer, 
even after one gallon of boiling water had cooled, and 
another, and another in succession had been poured on 
the surface. Of course, when all the liquid was allowed 
to drain through the tap-hole at the bottom, and the tap 
again replaced, and hot water poured over the unsaturated 
soil, the temperature of the whole was quickly raised, so 
as to secure something like an equilibrium from top to 
bottom. Such a simple experiment will show the impos¬ 
sibility of heating wet lands, until the redundant moisture 
is dispelled ; the inability of warm rains getting an 
entrance into a soil already saturated with cold water; 
and the consequent futility of trying to heat a border to 
any depth, by any amount of fermenting matter, if that 
border is saturated with water. 
As to the transmitting of heat downwards by fermenting 
material or otherwise, denied to be possible by some, 
because heated air, vapour, &c., naturally ascend—they 
leave out of view the constant tendency to an equilibrium 
of temperature in bodies, going on constantly, however 
slowly. Thus, it is no uncommon thing to find in severe 
weather, even in our climate, frost penetrating downwards 
to the depth of four or six inches; but beyond that, if 
the ground is only moderately dry, and so long as the 
frost continues, the earth next the frozen part will de¬ 
crease in temperature, and that decrease will go down¬ 
wards gradually to a number of feet; though, the lower 
we go, we shall generally, in such circumstances, find the 
temperature the highest. For instance: if, at a foot 
below the surface, we found the temperature at 34°, at 
two feet we should find it about 36°; at three feet about 
39°; and so on, higher as we got deeper : and the greater 
the heat retained in the soil before the frost came, the 
more woidd that heat tend to modify its intensity, and 
the depth to which, in straight lines, it could reach. 
There is no want of evidence that cold gets downward 
easily enough, merely from the loss of heat upwards by 
radiation; and in the summer months there is just as 
much proof that heat gets down slightly by radiation, 
and chiefly by absorption and conduction. Here, how¬ 
ever, we find the position of the temperature of the earth 
reversed to what it is in winter; for the surface, or near 
the surface, is generally the warmest, and the heat de¬ 
creases as we descend. Thus: supposing that in July we 
found the heat two inches below the surface to be 70°, at 
the depth of a foot we should expect to find it about 67° ; 
at two feet 64°; and so on. As a general rule, from the 
end of May to the middle of September, the soil near the 
surface is highest in temperature, and gets lower as we 
descend. From the middle of September to the middle 
of May, it will generally be found that the lower ive 
descend the higher we shall find the temperature. For 
instance: when the surface has been frozen two inches 
deep in December, a thermometer at a depth of three 
feet has indicated 45°; when the frost lasted some weeks, 
though not penetrating much farther, the thermometer, 
plunged to that depth, gradually fell to 41°. In a similar 
place, where the border was protected with some six to 
nine inches of dry litter, the sunk thermometer scarcely 
varied at three-feet depth from 46° to 48°; showing what 
even a surface-littering could do to keep heat in. Sea- 
kale beds, covered slightly in the autumn, wanted little 
heat comparatively to start them into growth in the 
spring. Since seeing and reading of the experiments of 
Mr. Drummond, at Culross Abbey, with thermometers in 
soils and borders, I have made many experiments in the 
same direction, corroborative alike of Mr. Drummond s 
facts, and of the interesting tables and conclusions as 
given in p. 267 of the current volume, (No. 539). 
Notwithstandmg, then, the demonstrated fact, that 
heat always rises so much more naturally than it can bo 
made to descend—and that earths and soils, even when 
aired and free from stagnant water, are some of the 
poorest and slowest of heat conductors—the above ob» 
servations will sufficiently show that their radiating and 
conducting powers are sufficient to make them much 
cooled in winter and much heated in summer; and my 
limited experience leads me to the conclusion, that any 
other heating medium would exert a similar, though less 
natural and less powerful, influence than the sun. By 
means of the sun’s rays striking the surface of the earth 
in summer, it becomes heated, and that heat is trans¬ 
mitted to a considerable depth in well-drained land By 
means of the heated air finding its way into every opening 
and cranny in well aired soil (for here we should find 
that the strong natural tendency to equilibrium would 
conquer the mere laws of gravity as applied to cold and 
hotter strata of air)—by means of absorbing the rays of 
heat faster or more slowly as the colour was more clark 
or light; and then transmitting that heat by conduction, 
according to its density and solidity. Manage to keep a 
heated medium close to the surface of the soil; and, not¬ 
withstanding the tendency of the heat to rise, it will also 
raise the temperature of the soil beneath it, decreasing in 
power just like sun-heat as it descends. I regret I cannot 
lay my hands upon some experiments that would tend to 
show this more clearly. The results, however, seemed to 
indicate that absorption and conduction were the chief 
means in such circumstances for transmitting heat down¬ 
wards. I had proved satisfactorily to myself that a ther¬ 
mometer, with its bulb six inches below the surface of a 
hard gravel-walk, was raised higher and more quickly by 
sun-heat than a similar thermometer, sunk to a similar 
depth in a surface-stirred border. The walk, when freely 
exposed, also parted with its heat the soonest. I have 
generally found that a border rather close, especially at 
the surface, was more quickly heated by conduction 
downwards, than one more open and stirred at the sur¬ 
face. If the frost be excluded by a litter-covering by the 
middle or end of October, so as to prevent the stored-up 
heat of summer freely escaping, I have found that from 
