THE COTTAGE GARDENER AND COUNTRY GENTLEMAN’S COMPANION, July 21, 1857. 247 
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bottle and do with it likewise, only keep the woollen 
cloth wet, and you will perceive that ere long you will 
have the water inside as cool as if it had been standing 
in ice. The evaporation produces the cold. “ Why, any 
tyro could tell us all about that, and why encumber 
The Cottage Gardener with such self-evident sim¬ 
plicities?” Why, just because I am so thorough a tyro 
as to have found out that most of our failures arise from 
neglect or contempt of these simplicities. Very likely I 
might have seen you—I should not have had to travel 
far to see some one—turning out early Peas from boxes 
in a beautiful dry day in March, planting them nicely in 
rows, finishing them off with the eye of an artist, and 
then watering them overhead as you would do a Celery 
bed in July, or at least thoroughly moistening the soil 
from the surface downwards; and then again, in the 
middle of May, the same person is turning out bedding 
plants, and he uses the water-can freely over the bed as 
he finishes it, and then there are notes, not of admira¬ 
tion, but the reverse, when the plants do not thrive. 
Such simplicities thought of might have suggested that 
the cooling effects of evaporation might next to freeze 
the stems of the tender plants, while, if the soil was dry, i 
the temperature might have been from 5° to 15° higher; 
and that therefore, though watering such freshly turned j 
out plants would be necessary, it should have been con¬ 
fined to the roots and the soil immediately around them, 
and so managed that the surface of the ground should be : 
left as dry as possible. 
When for several years I allowed the surface of a | 
Vine border to bo covered with a concrete of gravel, 
lime, and tar, so that not a drop of water could get 
through it, and recommended those trying such a plan 
to have pipes fixed that they might water at pleasure, 
I never found this watering necessary, a3 when examin¬ 
ing the border I never found it extra dry, and, of course, 
never wet. It seemed capable of drawing moisture to 
itself from the surrounding ground. Under such cir¬ 
cumstances the Vines were excessively fertile, and the 
ground under the concrete one mass of fine healthy 
roots ; but I thought the Vines were getting weaker, and 
therefore removed the concrete and top dressed. A few 
years’ experience, even though it answered well, would 
not be enough to warrant me recommending a con¬ 
tinuous impervious-to-water concreting, and before our 
correspondent did so I would advise him to wait for 
further evidence from experienced growers. The object 
I had in view, however, was not so much to increase 
heat as to secure dryness. I have already mentioned, 
in a late volume, how Mr. Judd uses a concrete of lime 
and gravel made smooth over early vinery borders 
every winter, and removes it in summer, placing it in a 
heap, adding a little fresh lime and the necessary water 
at the end of the autumn. Such a mode secures the 
desired dryness, and yet permits of mulching in summer. 
The ground here is very retentive of moisture, and 
therefore to keep the borders moderately dry, and 
economically as well, can be done without going to the 
expense of covers or tarpauling. I rake the borders 
smooth before the autumn rains, water them slightly, and 
roll or beat them smooth with a spade, or perhaps spread 
half an inch of fresh, moist cowdung over them, made 
smooth also; on this coal tar at about one penny per 
gallon is spread over thinly, in thickness from a thin 
wafer to a sixpence, and a little dry sand or sawdust is 
thrown over it, and it becomes a firm cake, through 
which not a drop of water will pass. If the sun was 
very hot afterwards this thin covering might be dried 
and cracked, and a sharp frost would heave it up and 
break it; but a little litter thrown over prevents all such 
casualties, adding more litter or fermenting material when 
we wish to excite the roots, and removing the covering 
and tar surfacing in June or earlier as convenient. It 
separates easily from the ground, or at least holds very 
little of it, when moist, and if exposed to the summer’s 
sun for a few days such a thin covering will crack and 
lift easily in cakes. If the tar, gravel, &c., are one inch 
in thickness they will not be much influenced by the sun, 
and the heat in the soil beneath them, if compact and 
firm, will be greatly increased during the day; but on 
the same principle that black not only absorbs but radi¬ 
ates heat, such a black-surfaced border will part more 
quickly with heat in a clear night than a common earth 
border would do. In experimenting with thermometers 
in tubes beneath such borders the extremes, in such 
circumstances, were very great; and to neutralise them 
I tried whitening and stone-colouring the surface, which 
reflected the heat instead of absorbing it. 
It is, therefore, only in an indirect manner that the 
concreting and tar surfacing of borders affect their 
general temperatures. No doubt a black surface will 
become more heated under the influence of the sun’s 
rays; but that heat can only be retained wdien^the sun 
has ceased to shine, and especially in clear nights, by 
covering to prevent the cooling effects of radiation. As 
illustrative of this I will mention what came under my 
observation. A border was covered with leaves, See., in 
which no heat could be perceived in June. A ther¬ 
mometer two inches below the surface, in a tube placed 
longitudinally along the border, indicated 73°. The day 
being very hot, and the sun beating on the hard surface 
of the border, the thermometer rose by four o’clock to 7(3°. 
The night being mild, nothing was doue to the border, 
but next morning the thermometer was 59°. A hot day 
succeeded, and the glass in the border indicated 75° in 
the afternoon. Dry litter was thrown over the black¬ 
surfaced border at a little past four, and, though the 
two nights were as much alike as two peas, the thermo¬ 
meter in the morning was at 70°. The hard, firm cake 
on the surface was removed, and the points of a fork 
used to make the surface of the border a little roughish 
and open, and then the day’s sun had so little power on 
the loose surface that the thermometer fell to 00°, though 
it became a little lower at night by radiation. The 
thermometer gradually rose to 70° and upwards in the 
very hot days, and then, on the change of weather, as 
gradually declined. The rough, open surface lessened 
the absorbing and conducting-of-heat power of the 
border, and at the same time the rough, loose surface 
lessened the radiation of heat from it, and the cooling 
which would have been the consequence of evaporation 
if the surface had been moist. 
The young gardeners who advocated that the more 
open and porous a soil is, the greater will it be heated, 
gave as their most powerful argument that the heated 
air would thus find access to it. And this would be 
true so far, and would exercise a beneficial influence 
as respects warmth when the soil was much colder 
than the air; but the case of our correspondent pre¬ 
supposes a gain of extra heat, and the problem for the 
young gardeners’ solution was the difference, as respects 
getting warmed, between loose soil and firm soil in 
summer; and here, on the principle that bodies, as a 
general rule, conduct heat in proportion to their solidity, 
would they be prepared to say that the firm, unmoved soil 
would become the hottest. Our general practice is in 
consistence with this rule. In these warm days, what¬ 
ever we may like for the tops and branches, we have 
no desire to get much more heat in the soil and at the 
roots, and hence we keep the hoe or the fork stirring 
the surface, to prevent the sun acting on a level, plane, 
firm surface, which would thus at one and the same 
time increase the heat in the soil and carry off’ its 
moisture quickly by a rapid evaporation. The stirring 
just keeps the moisture in and the heat out in much 
the same manner as if we put a mat or other coverlet 
over the ground. 
Then how account for the seeming anomaly in our 
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