THE CULTIVATOR. 
a 
146 
who entertain this opinion, certainly maintain a very 
unsound theory , and the sooner they sift all the know¬ 
ledge they possess and have gained by their own in¬ 
dividual and unaided exertions, from what they have 
obtained by reading and conversation with others, the 
sooner they will ascertain the sum total of their igno¬ 
rance ., which it is expected will so alarm them that 
they will see the necessity of rubbing some of the 
roughest of it off. . O. 
Practice vs. Theory, or the Hands vs. the Head. 
[ From the Fanners’ Cabinet .] 
“ No divorce, I beseech you, my friends.” 
Having recently been present during a very inte¬ 
resting and amusing conversation between two farm¬ 
ers, about your “ Farmers’ Cabinet,” I will under¬ 
take to give you some account of it, or at least a 
short abstract of the subject matter of it. They were 
both good, and pretty intelligent farmers, but their 
views of some things, and particularly of matters 
written or printed in regard to agriculture, were as 
different as the two sides of a bake-iron. The one 
was descanting on the benefits and advantages of the 
Farmers’ Cabinet to farmers generally, and now and 
then he read a racy article from it to prove his posi¬ 
tion ; the other contended that any thing printed on 
the subject of farming was mere theory, and of no use, 
but rather calculated to lead people of little experi¬ 
ence astray from the good old way of doing things 
that had been practised from the earliest times. He 
said that these printed things only dissipated people’s 
ideas and withdrew their attention from work, and he 
thought were ruining our young people by keeping 
them thinking all the time instead of working. On 
the other side it was contended, that teaching people 
to think enabled them to work to much greater ad¬ 
vantage, and that all the improvements which had 
been made in the world, were the result of thinking, 
and that thinking was not at all incompatible with ac¬ 
tion, but on the contrary, was the very base and 
foundation of it, and that a discovery or improvement 
being made, the promulgation of it in print was doing 
the greatest good to mankind, as it tended to keep 
up the equilibrium of knowledge, and enabled one 
man to work with the tools of another without cost. 
At last the contest assumed the form of a regular 
combat between the Head and Hands ; a little on the 
plan of that detailed by Esop, of the quarrel that took 
place between the Belly and the Limbs, when the lat¬ 
ter fairly rebelled, and refused any longer to work for 
a fat and indolent Paunch, which they considered as 
entirely useless, and unable to provide for itself.— 
However, after a short trial, at keeping up separate 
establishments, finding it not to answer expectation, 
a truce ensued, and they agreed to go on amicably 
together, and found a mutual advantage in it. Now 
I suspect this contest between the Head and the 
Hands will terminate in the same way, by each re¬ 
turning quietly to the performance of its appropriate 
duty again, as members of the same indissoluble firm 
of “ Head and Hands,” each attending to its own de¬ 
partment, while they are both working for the com¬ 
mon good; for I should like to know what sort of a 
farmer a man would make either without a head or 
without hands. I w r as thoroughly convinced by the 
arguments of the parties, that every man in this free 
country has an undoubted right both to think and 
work, either jointly or separately, as much as he 
pleases, and that there is not much danger of our car¬ 
rying either to excess ; but above all I was confirm¬ 
ed in the conviction, that every intelligent farmer 
should write down the results of his experiments, and 
the cogitations of his mind, on agricultural and rural 
affairs, and forward them for insertion in the Farm¬ 
ers’ Cabinet. X. 
Science of Gardening.— Continued. 
[From the Alphabet of Gardening .] 
LIGHT. 
It is common with gardeners to expose their tender 
frame plants gradually to the open air, by taking off 
the lights from day to day, for the purpose, it is said, 
of rendering them more hardy. Few of those, it is 
probable, who do so, are aware of the principal agent 
which renders the plant more hardy, and which, if I 
mistake not, is generally supposed to be cold or fresh 
air. This, there can be no doubt, assists in the pro¬ 
cess, and is indispensable to its perfection; but there 
can be as little doubt, that light is the main agent, 
as a few facts and a little reflection will prove. 
The process of blanching salads depends chiefly on 
depriving the plant of light, by earthing up a portion 
of the stem, as practised with eelery ; by tying up the 
tops of the leaves, as is done with lettuce; or by co¬ 
vering them with inverted pots, as is done with sea 
kale. In all these cases, the plants are crisp, watery 
and tender, compared with others not thus treated 
but similar in all other circumstances, which are 
stringy and tough in their fibres, less juicy, and there¬ 
fore hardy. No exposure to cold or fresh air would 
produce this toughness and hardiness, if the plants 
were kept in the dark; and no absence of cold and 
fresh air would produce blanching, if a strong light 
were admitted. 
Complete blanching is only produced by complete 
exclusion of the light; but its partial exclusion causes 
plants to be pale and sickly, as in the shade of thick 
woods, or plants in a stove or green house acciden¬ 
tally placed so as to be shaded by others. In all such 
cases, plants are popularly said to be drawn, that is, 
they endeavor to push their branches as much as pos¬ 
sible into the light, and being from deficiency thereof 
proportionably feeble, they increase in length without 
at the same time acquiring strength. A potato in a 
dark cellar will in this way send out shoots of some 
yards in length, but not much thicker than a writing 
quill. It is on this account, that the glass frames in 
hot-houses ought to be as thin as possible, and there¬ 
fore iron is preferable to wood. More light also will 
pass through a sloping or level frame than through an 
upright one, and through a domed or curved roof than 
one that is plane; because the rays of light always go 
in straight lines from the sun. 
This singular propensity of plants to turn to the 
light has been supposed to indicate something akin to 
animal instinct; but when the cause is closely exa¬ 
mined, this will not appear to be better founded than 
that of a piece of writing paper bending into a semi¬ 
circle when held to the fire; for both the motion of 
the plant and of the paper depend on the same cause 
—namely, the hardening and stiffening of one side, 
while the other remains soft and flexible. In the case 
of the paper, the side next the fire has its moisture 
carried off by evaporation more rapidly than the other 
side; and in the case of the plant, the side most ex¬ 
posed to the light is in the same way rendered more 
firm, contracted, and shorter than the one less exposed. 
The very long shoots of the potato in the dark cellar 
seem to be caused by the softness of the blanched 
substance offering no resistance by contraction to the 
lengthening out of the parts. 
It will follow that all colour, flavor, smell, and nu¬ 
tritive qualities, depend for their production chiefly on 
the action of light. The red colour of forced rhubarb, 
which seems to be an exception, arises from the red 
matter previously produced by the agency of light be¬ 
ing carried up from the root. 
It hence appears, that the study of the laws and 
action of light is of the first importance to a correct 
knowledge of scientific gardening, as will further ap¬ 
pear when we come to consider the use of leaves. 
HEAT. 
As it has been shown that the food of plants, in or¬ 
der to be available, must be fluid; and as heat is the 
cause of fluidity, its primary importance to vegetation 
must be obvious, for no plant could take up frozen li¬ 
quids. The processes, moreover, of fermentation and 
putrefaction, by which are produced the supply of car¬ 
bonic acid gas, humic acid, and nitrogen, indispensa¬ 
ble to vegetation, cannot go on without warmth. It 
is well known, for instance, that beer cannot be 
brewed in frosty weather, because a due degree of 
fermentation cannot be effected on account of the 
cold. 
The effect of heat on plants is very beautifully 
proved by the experiment of Du Hamel, on the rising 
of the sap in vines in spring. On a frosty day, when 
the sun shone on a cut vine, the sap flowed on the 
south side exposed to the sun, but not on the north 
side where it was in the shade. In Canada, also, 
where the frost recur, though on the south side the 
bleeding goes on, at least during sunshine. It is on 
this account in some northern climates, where the 
long sunny days succeed the thawing of the snows, 
as in Norway and Russia, that the gardeners are said 
to shade their wall trees from the midday sun in the 
spring, to prevent the sap being prematurely raised 
and again checked by the certain cold of the succeed¬ 
ing night, a contrivance which also retards the flow¬ 
ering till there is less danger from spring frosts. Such 
shelter will also be beneficial in protecting from the 
dry winds of spring. 
Did these effects of heat, which must also in part 
be atributed to light, require any proof, it may be 
shown by two wine-glasses, the one filled with hot 
and another with cold water, in each of which is plac¬ 
ed a similar hollow straw so as to discharge the wa¬ 
ter, when it will be seen that the hot water flows 
more rapidly than the cold. 
The soil in this country, below where the frost usu¬ 
ally penetrates, averages a temperature of 48°, or 15° 
above freezing, which is the reason why springs do 
not freeze, and not any quality in the spring water, 
which will freeze readily enough when taken from the 
well. 
It is of the utmost importance to be acquainted 
with what is termed the radiation, that is, the spread¬ 
ing of heat, which arises from heat passing from a hot 
body to a colder one near it, as uniformly as water 
runs down a slope. This spreading of heat takes 
place between the surface of the ground and the air; 
and when the air is cold, though the soil be warm, it 
soon loses its heat, and dew or hoar frost is formed 
on the grass by the moisture diffused in the air, though 
previously invisible, becoming condensed or frozen. 
But when the sky is covered by clouds, this spreading 
and loss of heat is in a great measure prevented, and 
hence there is no dew or hoar frost formed on a calm 
cloudy night, as was first remarked by Aristotle. 
It is on this principle, that garden plants are pro¬ 
tected by matting, which stops the heat of the soil 
from spreading about and being lost in the air. Dr. 
Wells proved this principle by stretching a very thin 
cambric handkerchief two feet square, six inches above 
a grass plot; and he found on one night that it was 
five degrees warmer under the handkerchief than the 
rest of the grass plot; and on another night there 
were eight degrees of difference. Hence, great thick¬ 
ness does not seem to be so important in such cases, 
as the interposition of any screen whatever between 
the soil and the sky, provided always that the screen: 
does not touch the soil or the plants to be protected. 
In this case it might carry offbeat by conduction. 
It is on the same principle that snow affords a pro-: 
tection from the severity of frost, the plants under 
snow having been found by Dr. Darwin to indicate 
forty degrees, that is eight degrees above freezing; 
hence some Alpine and Siberian plants, such as auri¬ 
culas, do not bear exposure to frosts when unprotect¬ 
ed by snow, so well as those which are natives of a 
warmer clime, and require artificial shelter. 
It may be remarked, that hoar frost is never seen 
on a sloping hedge bank, on the side of an earthed-up 
row of celery, nor close to a garden wall, unless when 
the surface is already frozen, and that such places are 
always the first to thaw, beginning with the summit 
of a slope, evidently because the slope is unfavorable 
to the spreading of heat, while the garden wall stops 
it, in the same way as Dr. Wells’s handkerchief did. i 
Hence broad coping stones on walls are excellent foi 
protecting wall trees. 
Another reason for a slope or a hill being warmei i 
than a valley, is that cold air being heavier than warn’: 
air, the coldest air, always rolls down to the lowest 
situation ; but if there be a brisk running stream in iii 
valiey it wall prevent, in some measure, the stagnation! 
of cold air; injurious, because the greatest cold alway! 
occurs in air having the least motion. Prof. Daniel 
says he has seen a difference of 30 degrees on th< 
same night, between two thermometers, one placet, 
on an elevated situation and another in a sheltered: 
valley. The shelter of walls may, therefore it would: 
appear, be so arranged as to prove injurious rathe: 
than beneficial, by causing the air to stagnate and be: 
come cold, as it does in sheltered valleys during the! 
night. 
The evaporation of water is so strongly productive 
of cold, from the water requiring much heat to ex: 
pand it, which it of course carries off into the air, than 
in the hot climate of India, ice is, for the purposes c : 
luxury actually procured in considerable quantity, bt 
exposing unboiled pump water in broad shallow ean 
then pans placed on dry straw on calm cloudles! 
nights, to the open sky. 
It is from the rapid increase of cold by evaporation: 
that we account for the injury produced by watering, 
plants when a warm dry wind blows, or during brighn 
sunshine,which is popularly termed scorching, thougj 
it is not the heat that affects them, but the col:! 
caused by the water carrying off tl.e heat as it arise; 
in form of vapor into the air. Miller is undoubted 
ly wrong in supposing it to be occasioned by th 
sun’s rays being brought to a focus, as in a burninjii 
glass, by the small globules of water, for these glch 
bules, from their touching the plant, cannot brin,:i 
the rays to a focus. 
The injury caused by the melting of hoar-frost o 
frozen ram on plants arises from a similar cause, th 
carrying off a portion of heat from the plant in ordel 
to render the frozen water fluid. 
The amount of evaporation depends on the quaE! 
tity of moisture in the air, and the rapidity of its ms 
tion; or, in other words, on the velocity of the winn 1 
Over the first the gardener has little or no contro.i: 
but he can, by means of walls, palings, hedges, an 
other screens, obstruct or stop the current of th 
wind; or natural, she I ter may be found in unevei 
ground. Professor Daniell states that the same su; 
face which, in a calm state of the air, would give c ’ 
100 parts of moisture, would yield 125 in a moderar 
breeze, and 150 in a high wind. The dryness of tl 
air in spring renders the effect most injurious to tl 
tender shoots of this season, when it is desirable : 
shelter gardens from the easterly and norther: 
winds in particular, by means of high walls placit 
not too far asunder. 
I need scarcely allude to the extensive use whii 
is made of artificial heat in rearing the plants a 
warm climates, as well as in the various modes a 
forcing, for proof of its being of the first important: 
for every gardener to study the laws by which its d f 
tribution is regulated, and the means by which til 
