160 
trees rise on a small hill than on a spot equal to its base, 
though this will not apply to strawberries, New-Zealand 
spinach, and other creeping or spreading plants. 
EXPOSURE AND SHELTER. 
The degree of light, and of exposure, has a great me¬ 
chanical effect on plants. In the interior of forests and 
crowded orchards, the wind produces much less effect 
than on solitary trees in a garden or park. When 
crowded, the tops push up into the light above, and not 
being agitated by the wind, their trunks do not thicken, 
or become stunted, to prevent the blast making a greater 
pull against the roots. 
On the other hand, when standing in an open situa¬ 
tion, trees, being freely exposed to every storm, give 
every advantage to its violence, by the wide-spreading 
of their branches. 
In accordance with this, solitary trees become greatly 
larger than those which are crowded, while their system 
of roots is always proportional to the branches, in order 
to afford a heavier ballast and a stronger anchorage for 
counteracting the great spread of sail displayed in the 
wider expansion of the branches. The same is true of 
all or most garden plants, which extend in proportion 
to their room. Hence the necessity of wide planting 
when it is required to have plants with large spreading 
heads, as in the instance of New-Zealand spinach; and 
on the other hand of planting closely when plants are 
required to be tall, and at the same time slender, a case 
which more rarely occurs than the other. 
[Fig. No. 58.] 
A tree taken from an open exposure to show that the roots 
spread out proportionally with the branches. 
Recent writers on botany have endeavored to show 
that the tapering tuber of the carrot, the beet, and other 
simpler plants, are not properly roots, or at least that they 
have more the characteristics of stems than of roots; in 
other words, as every plant grows in two directions, one 
downwards, the other upwards, the spindle-formed tuber 
of the carrot is alleged to belong to the upper or ascend¬ 
ing portion of the plant, rather than to the downward or 
descending portion. Independent of structure, however, 
this would appear to be equally rational as to allege 
that a man’s feet belong to the upper portion of his body, 
but it appears to be correct enough to say that the part¬ 
ly horizontal portions of the iris, though under ground, 
are not roots but stems; and it must be very obvious 
that the creeping runners of strawberries are not stems. 
[Fig. No. 59.] 
A tree taken from a crowded plantation to show that the 
roots are equally small with the brandies. 
Weak stems which cannot rise high in a perpendicu¬ 
lar direction by their own rigidity, are furnished with 
several means for effecting this. Some straggle up ir¬ 
regularly amongst other thick-growing plants, as the 
bramble and bitter-sweet; others, like the hop, the kid¬ 
ney-bean and convolvulus, twine closely around others 
stronger than themselves, and when they cannot meet 
with such, several shoots will twine around each other, 
to give mutual support. 
THE CULTIVATOR. 
It is important to remark, that different species, in 
twining for support, follow different laws, one going 
from right to left, of which there are twenty genera, and 
another from left to right, of which there are ten gene¬ 
ra. A hop-plant, for instance, directs its course round a 
pole with the sun; but if untwisted and forced to take 
an opposite direction, it will injure or perhaps kill it.— 
If a honey-suckle do not meet with support, it twists in¬ 
to a spiral from right to left. It is of importance to at¬ 
tend to these circumstances in training. 
MECHANICAL TEXTURE OF SOILS. 
Though it has been stated above, that the roots, at 
least of trees, are generally proportional in extent to the 
branches, this must be taken with some limitation, inas¬ 
much as it will in part depend upon the texture of the 
soil. The perpendicular extent of roots, for example, is 
greatly influenced by the looseness or compactness of 
the soil; and hence l)u Hamel found the tap-root of an 
oak, which had been sown in a rich deep soil, to be four 
feet in length, while the stem rose only six inches high. 
Carrots and similar deep penetrating roots, when they 
meet with a stiff soil, not easily divisible, are not only 
dwarfed, but split into branches or twisted into a spiral. 
When certain roots, also, such as those of timothy grass, 
are planted in the moist soil natural to the plant, they 
are fibrous; but when on the top of a dry wall, they be¬ 
come tuberculated; for the purpose, it would appear, 
of laying up a store of nourishment incase of accidental 
drought. An alder root was found amongst gravel, 
marked all over with the contour of small stones. 
Since then the mere texture of a soil, independently 
of the food of plants which it contains, produces such 
remarkable effects, it must be of great importance for 
the gardener to attend to this circumstance. 
CIRCULATION OF WATER IN SOILS. 
It is no less necessary for the due nourishment of 
plants, that the water by which soils are moistened have 
a proper movement or circulation, than it is for the ani¬ 
mal food, when digested, to pass through the stomach 
and have a proper movement through the bowels. In 
the case of the animal, when this movement in the bow¬ 
els is too rapid, as in cholera, the food is hurried off be¬ 
fore it can be conveyed into blood, and when it is too 
slow, as in costiveness, the mouths of the minute tubes 
are pressed upon and obstructed, so that the food* can¬ 
not obtain admission. It is much the same with plants, 
when the soil is so loose and porous as not to retain 
moisture, or so stiff and compact as not to allow what 
water it imbibes to circulate. In the latter case, indeed, 
plants are more precisely like animals affected with 
costiveness, in that the rejections of the digested food 
are retained so near the mouths of the nutrient vessels, 
as to greatly hinder their getting at the proper materials. 
The difference in plants arises from their having to 
lengthen their rootlets to get beyond the rejections thrown 
out, which they obviously cannot do in a stiff hard soil. 
Even independently of having thus to continue their 
roots amidst a mass of such rejections, the water, in 
consequence of stagnating, and of course preventing a 
fresh supply from above, becomes soon exhausted of the 
nutritive materials with which it may have at first been 
mixed. 
This [s not mere theory, as some may be apt to con¬ 
sider it; for it has been proved by numerous facts, that 
the most fertile soils are those which are so compound¬ 
ed so as to admit of the greatest, most minute, and most 
immediate distribution, diffusion and circulation of wa¬ 
ter, or rather moisture; for when water is found in such 
portions as to be distinguished from the soil which it 
moistens, this will form, in most points of view a watery 
and bad soil. 
The chief causes of the circulation of water may be 
traced to the principle which makes a stream run down 
a slope. When rain accordingly falls on the level sur¬ 
face of a loose porous soil, it will sink into it; and if 
this, instead of being level, is sloping, the water will 
both sink partly into the soil, and also move slowly 
through it towards the bottom of the slope. If the soil 
is so loose to any depth as to cause this water to drain 
nearly all away, the first warm day will expand the wa¬ 
ter nearest the surface into vapour, and raise it into the 
air; and as soon as by this means the surface becomes 
dry, the moisture below will gradually rise, in the same 
way as water may be seen to rise into a bit of blotting 
paper, or a piece oflump sugar. 
It hence becomes obvious, that though the surface 
soil be sufficiently porous to permit the due circulation 
of water both upwards and downwards, if the under 
soil at some little depth, (say from less than a foot to two 
feet or more,) be a stiff clay, a hard marl, or a levelrock 
of any kind, the rain water, instead of circulating whole¬ 
somely, will settle there, from being out of the reach 
of the sun’s influence to raise it; and in the case of the 
level rock, having no declivity to run off by. It is in 
such cases that draining becomes useful; or, where it 
can be effected, forming a gentle slope of the whole 
surface, which would farther operate on the circulation 
of the water by obtaining a more powerful influence of 
the sun, and thereby increasing the heat. The fancy 
staled in books, that the runs of earth-worms or dew- 
worms are important for draining off water, is without 
any foundation. 
TESTS OF THE TEXTURE OF SOILS. 
One of the best methods of ascertaining the capability 
of any soil, to take up and retain moisture, is that de¬ 
scribed by Mr. C. Johnson, for which purpose he employs 
the following apparatus. 
* Technically, Chyle. 
[Fig. No. 60.] 
Analysis of soils, a a small lamp; b. a stool, with a hole 
in the seat for receiving c, a shallow tin vessel, closely cover¬ 
ed, but having a pipe, d, for the escape of steam; h, a pair of 
accurate scales, such as are used by apothecaries and gold¬ 
smiths. 
In order to employ this apparatus, put a small quan¬ 
tity of the soil to be tried upon the top of the tin vessel, 
in which water is kept briskly boiling for about half an 
hour, so as to thoroughly dry the soil by expelling its 
moisture. Take ten grains accurately weighed of this 
dried soil, and add to it, by means of a quill, a drop or 
two of pure water; if distilled water can be had, so 
much the better. Weigh the whole a second time, 
which will now be a few grains above ten. Take out 
the weight of the water from the scale, leaving in the 
weight of the dried soil, and suspend the beam, so that 
the scale e may rest on the lid of the tin vessel, the 
water in which is still kept boiling; then with a stop 
watch note the exact time which the added water 
takes to evaporate, as will be shown by the beam of the 
balance becoming level. Mr. C. Johnson found, that 
soils requiring less than twenty-five, or more than fifty 
minutes, to evaporate the added water, and bring the 
balance to a level, were always proportionately unpro¬ 
ductive ; the first, from having too much flinty sand, and 
consequently no texture fitted for retaining water; and 
the second, from having too much clay, and consequently 
too few interstices to allow the water to escape. 
Rich soil, treated in this way, required thirty-two 
minutes to bring the beam to a level; chalk twenty-nine 
minutes, poor flinty soil, twenty-three minutes, and 
gypsum, only eighteen minutes. 
A very fertile soil from Ormiston, Haddingtonshire, 
containing, in one thousand parts, more than half of 
finely divided materials, among which were eleven 
parts of limestone soil, and nine parts of vegetable prin¬ 
ciples, when dried in a similar way, gained eighteen 
grains in an hour, by exposure to moist air, at the heat 
of sixty-two degrees Fahrenheit; while 1000 parts of a 
barren soil, from Bagshot Heath, gained only three 
grains in the same time. 
Mr. C. Johnson farther found that one hundred parts 
of burnt clay, when exposed in a dry state for three 
hours to air saturated with moisture at sixty-eight de¬ 
grees, took up twenty nine parts of water; that gypsum, 
in similar circumstances, took up only nine parts ; and 
chalk only four parts. 
Another method of testing the texture of soils is, by 
taking what is termed their specific gravity; that is 
comparing what they weigh in air with what they 
weigh in water. Sufficient accuracy for practical pur¬ 
poses may be obtained by drying two different soils, at 
an equal distance from a fire, or in an oven, at the 
same time, and then weighing in the air a pound of 
each in a thin bladder with a few holes near its top, or 
neck. When the weight has thus been obtained in the 
air, the bladder may be put into water, letting it sink 
low enough to permit the water to enter through the 
holes in the neck, in order to mix with the dried speci¬ 
men of the soil. The weight in water, divided by the 
difference of the two weights, will be the specific gra¬ 
vity, and the less this is, the greater will be the capacity 
of the soil to take up and retain water. Muschenbroek 
thus found rich garden mould to be 1630 compared to 
1000 of water, and Fabroni found a barren sand to be 
2210 compared to 1000 of water. 
Or fill a wide necked pint or quart bottle half full 
with water, and add the soil to be tried till the wa¬ 
ter rises to the brim. Then if the bottle can contain 
one pound of water, and gains half a pound addition¬ 
al when filled in this way, half with water and half 
with soil, the soil thus tried will be twice as heavy as 
water, and its specific gravity will be two. If it only 
gain a quarter of a pound, its specific gravity will only 
be one. 
M. Giobert ascertained that a pound of fertile soil 
contained, of flinty sand, about 4400 grains, of clay 
about 600 grains, of lime about 400, besides seventy of 
water, and about twenty-five grains of inflammable ma¬ 
terials, chiefly carbon. On a comparative trial of a bar¬ 
ren soil, M. Giobert found that a pound weight contain¬ 
ed about 3000 grains of flinty sand, about 600 grains of 
clay, about 400 grains of lime, and little or no inflam¬ 
mable materials. Mr. Grisenthwaite directs an equal 
portion of two soils perfectly dry, to be introduced into 
two tall glasses, in the midst of each of which a glass 
funnel has been previously placed. The soils are to be 
put in so as to retain, as nearly as possible, their natu¬ 
ral state when in the ground, and are consequently not to 
