the latitude of 45° 14′ 10″, deduced from these determinations, is
39.1154; and it is so equally, whether an ellipticity of 1/288th,
or of 1/304th, or any intermediate ellipticity, be assumed in the
reduction.
We have, then, 39.1154−39.0992 = ·0162 inch., as the [p158] measure
of the difference in the intensity of gravitation at the place of
observation elevated 1943 metres; and at the level of the sea. The
radius of the earth, being 6,376,478 metres, this measure, according
to the duplicate proportion of the distances from the earth’s centre,
should be ·0238 inch. The attraction of the mountain is, then,
equal to ·0238−·0162 = ·0076 inch. Whence it appears that, in this
particular instance, the correction for the elevation is reduced,
by the attraction of the interposed matter, 68/100ths, or to about
7/10ths of the amount immediately deducible from the squares of the
distances.
It is obvious that, if we possessed a correct knowledge of the
density and arrangement of the materials of which Mont Cenis is
composed, so as to enable a computation of the sum of all the
attractions which they exercise on the place of observation, this
result might furnish, as well as Dr. Maskelyne’s experiments on the
deviation of the plumb-line produced by the attraction of Mount
Schehallien, a certain determination of the mean density of the
earth. Professor Carlini considers that the form of the eminence may
be sufficiently represented by a segment of a sphere, a geographical
mile in height, having as its base a circle of 11 miles diameter,
the distance from Susa to Lansleburgo; the attractive force, on
a point placed on the summit, would, in such case, be equal to
2 π δ (1 − (2/3) √(1/11)) or in numbers to 5·020 δ, δ being the
density of the mountain, and 2 π the ratio of the circumference to
radius. The attractive force of the earth, on a point at its surface,
is (4/3) π r Δ, = 14394 Δ, _r_ being the radius of the earth = 3437
geographical miles, and Δ its mean density. Now these two quantities,
14394 Δ and 5·020 δ, should be, to each other, in the proportion
of 39.1154,—the pendulum at the level of the sea, representing
gravitation at the surface of the earth,—to ·0076, the portion of
gravitation at the summit of the mountain due to the attraction
of the mountain. By the observations of M. de Saussure and other
geologists, Mont Cenis is chiefly composed of schistus, marble, and
gypsum; the specific gravities of which substances were ascertained,
from numerous specimens in the possession of M. Carlini, to be
respectively as follows:— [p159]
The schistous 2·81.
The marble 2·86.
The gypsum 2.32.
In the absence of a precise knowledge of the quantity and position
or each of these three component parts, we may take the mean, 2.66,
of their several densities as approximatively the density of the
mountain, = δ. We have then
5.02 δ × 39.1154
Δ = -------------- = 4.77,
14394 × ·0076
a result differing little from that of Cavendish as recently
corrected by Dr. Hutton, and still less from that of the Schehallien
experiments.
The most hypothetical element of this calculation is the width
assigned to the base of the mountain; but by the very nature of the
question, it has but little influence on the final result; since,
by even doubling the assigned diameter, the total attraction would
not be altered a twentieth. In regard to the mean density of the
mountain, if it were taken at 2.75, instead of 2.66, that of the
earth would result 4.94, instead of 4.77, as given above.
E. S.
_Transactions of the Horticultural Society_. Vol. vii. Part 1. 4to.
London, 1827. pp. 208.
I. _Observations upon the Growth of Early and Late Grapes under
Glass_. By Mr. James Acon.
Few gardens are to be found in which bunches of fresh ripe grapes can
be gathered every day in the year: notwithstanding the importance
of the fruit to the luxurious, and the facility with which the vine
submits to the artificial climate of the forcing-house. Nothing is
easier than to secure crops of grapes in a vinery during the spring
and summer months; but it is far more difficult to obtain them in
the last and earliest seasons of the year, when the plants would
[p160] naturally be in state of torpidity. It is well known that
this desirable purpose is attained in great perfection in the garden
of the Earl of Surrey, at Worksop Manor; and the management there
practised is the subject of this paper.
The common methods of forcing early grapes are to train the vines
under the roof near the glass, or on small frames against flued
walls; but to both these practices Mr. Acon finds great objections:
to the former because it renders the house too dark, and exposes the
young and tender branches to the pernicious effect of blasts of cold
air rushing through the interstices of the panes; and to the latter,
because the heat of the flues is apt to scorch the branches, and
in consequence to destroy the crop,—excessive heat in the one case
producing the same injurious effects as excessive cold in the other.
The following are the two modes by which Mr. Acon obtains his _very
early_ and his _very late_ grapes. For the early crops a house is
used, of which the back wall is 9.6 feet in height, and the front
wall 3 feet, the roof forming an angle of about 30 degrees. It is
heated, from the absolute necessity of employing an atmosphere of
unusually high temperature, with two flues that pass along the middle
of the house, and return in the back wall; a fire-place being built
at each end of the house. Forcing begins on the first of September,
and the fruit begins to ripen the first week in March. The vines
are trained upon a trellis, fixed over the flues, in the centre of
the house, and also upon the back wall; but none are allowed to
obstruct the light by occupying the roof, until about six weeks after
the forcing has commenced, when some new shoots are introduced and
trained to the rafters. The form of this house gives it a peculiar
advantage, in presenting a greater surface for the growth of vines
than can be derived from any other plan; the trellis which is placed
over the flues is nearly equal to the whole roof, without being in
any degree injurious to the plants trained upon the back wall. The
vines are planted in the inside of the house, but in such a manner
that the mould in which they grow is not heated by the fire-places
of either flue. The usual mode of exposing the main stem of a forced
vine to an extremely low temperature in the external air, while the
branches are stimulated by a very high temperature in an entirely
different atmosphere, is very properly objected to. Nothing, in
fact, can be more injudicious than such a practice, in cases where
very early forcing is required; for it should be borne in mind,
that although the absorption of the elements by which the proper
juices of a [p161] plant are elaborated, and brought into the state
under which they appear in the fruit, and in the secretions of the
plant, is carried on by the leaves alone, yet that all these juices
have, in the first instance, to pass along the vessels of the stem
before they reach the leaves; and that the whole of the bark of a
tree is, rightly considered, a leaf of a particular description,
formed of the same kind of tissue, and exercising the same functions,
and undoubtedly producing a powerful effect upon the motion of the
fluids of the branches, with the vessels of which it is elaborately
and intimately entangled, from the core to the circumference. No
argument can be necessary to show that an equal action of the vessels
of a plant is indispensable to the due maintenance of the vegetable
functions in a healthy state, and that this is not to be maintained
by exposing the main stem and the extremities to an atmosphere and
temperature entirely different. Such irregularities do not exist in
free Nature, and she will not submit to them when in fetters.
In pruning vines for early forcing, as little wood should be employed
as possible. Mr. Acon stops the shoots one joint above each cluster,
and has no joint without a bunch. When the crop is over, and the wood
perfectly matured, the branches should be laid near the ground, and
shaded till the recommencement of forcing. In short, they should be
placed in a condition as nearly as possible resembling the gloom and
cold of winter. If this process be well managed, the vines will alter
their natural habits, and instead of budding with the spring, their
vegetation will naturally commence at the period at which they have
been accustomed to be stimulated.
For late grapes, a house of a different construction is employed.
The back wall is 12 feet high, the front wall 1-1/2 foot, and the
roof lies at an angle of 45 degrees. The heat is supplied by a single
flue passing along the middle of the house. The sorts best adapted
for late forcing are the Muscat of Alexandria, the St. Peter’s, and
the Black Damascus; all other kinds wither prematurely. This house
is generally shut about the middle or end of May, as soon as the
bunches become visible. The vines are trained on a trellis near the
glass. Till they are out of blossom the air is kept very warm, a
point to which much importance attaches, because it is during this
period that all the branches that are to bear fruit in the succeeding
season are produced. In a high temperature, the branches will grow
more compactly, and [p162] will be more regularly matured than in
a low temperature, in which the wood is apt to become excessively
luxuriant, and not to ripen well. Great attention must be paid to
this point. As much air as possible is introduced into the vinery
during the summer; but as the autumn advances, more caution in this
respect is observed. The fruit should be perfectly coloured at the
approach of the dark season; for if the colouring be deferred too
long, the berries will never acquire their proper flavour. Great
care must be observed to remove daily such berries as are inclining
to damp, or the whole crop will soon be spoiled. This should be
particularly attended to; for the contagion of what gardeners call
_damp_, arises from the growth of minute fungi which vegetate upon
the epidermis, and spread during the autumn with alarming rapidity
from bunch to bunch.
The pruning of vines for late forcing is the same as has been already
explained. When the crop is gathered, the house is unroofed for a
short time, in order to expose the branches to a low temperature,
and to the degree of humidity necessary to replenish their vessels,
which have been drained by the dryness of the climate in which, when
forced, they were necessarily kept.
By the means above described, a regular supply of grapes is secured
through the year. The late-house crop lasts from the middle of
January to the end of March; it is succeeded by the first crop in
the early-house, which carries on the supply into May, and it is
continued by the grapes on the rafters in the same house until the
vines in the pine stoves, which are forced early in January and
February, produce their crops. These continue bearing through the
summer, when a vinery, of which the forcing commences about the end
of March, furnishes the supply till the late-house fruit is ready in
January.
Upon the whole this may be considered a most instructive and valuable
communication.
II. _On the Varieties of Cardoon, and the Methods of cultivating
them_. By Mr. A. Mathews.
Who does not wish to read of the cardoon; of that prince of
vegetables, whose praises have been sung or said by all cooks and
gourmands, from the fastidious Périgords and Cardellis of the
French _cuisine_, down to the more homely Rundells and Glasses
of our English kitchens; whose virtues are so marvellous as to
be credible upon no less authority [p163] than that of the sage
gastrophilists aforesaid. To restore unwonted vigour to old age,
and new elasticity to youth, are the most modest of its attributes;
the magical broth with which the veins of Æson were replenished by
the cunning Medea, was doubtless prepared from the cardoon; and the
story itself is probably a sort of figurative record of the skill
of the fair enchantress in cooking this delicious vegetable, which
was well known to the Grecian gastronomes under the name of κακτος;
but this we throw out merely as a suggestion. Upon preparing herbs
thus potent for the table, cookery has exhausted all its skill; to
dress a cardoon is declared, by the highest authority in the art, to
be the surest test of a skilful cook; and one of those invaluable
acquirements which, to borrow the words of a writer not less
celebrated for his powers of composition than of cooking, “raises
cookery to the rank of the _sciences_, and its _professors_ to the
title of artists.” Our good forefathers, indeed, “could not find the
true manner of dressing cardoons,” and were content to eat them raw
“with vinegar and oyl, pepper and salt, all of them, or some, as
every one liketh for their delight;” which, considering that this
vegetable is both bitter and astringent in a high degree, does not
argue much for the delicacy of palate of our ancestors; little did
they dream of the savoury preparations that modern art has devised by
the aid of Espagnole, consommé, blancs, tammies, marking, masking,
and all the mysteries of the stew-pan.
Four varieties are here described, of which the Spanish cardoon is
the most common, and the cardon de Tours the best.
They are cultivated, like celery, in deep broad trenches, well
manured and watered. When the plants are nearly full-grown, which
will be about the end of October, a dry day is to be chosen for
performing the operation of blanching them, which is thus effected:—
“The leaves of each plant are carefully and lightly tied together
with strong matting, keeping the whole upright, and the ribs of
the leaves together. The plant is then bound closely round with
twisted haybands, about an inch and a half in diameter, beginning
at the root, and continuing to about two-thirds of its height. If
the plants are intended for winter store, they must be earthed up
like celery; but if to be consumed before the frosts set in, the
operation of earthing up may be omitted.” [p164]
III. _Accounts and Descriptions of the several Plants belonging
to the genus Hoya, which are cultivated in the garden of the
Horticultural Society at Chiswick_. By Mr. James Traill.
The beauty of one species of Hoya, viz., H. _carnosa_, has long
caused it to be a favourite with collectors. The object of the writer
of this paper is to call attention to such others as are known to
exist in gardens, or as are preserved in the records of the botanist.
The following species form the subject of the paper, viz.:
1 Hoya carnosa, _R. Brown_. 2 Hoya crassifolia, _Haworth_. 3 Hoya
pallida, _Lindley_. 4 Hoya Pottsii, (Tab. I.) 5 Hoya trinervis.
These five are all the species at present cultivated in gardens;
others are known to exist in the warmer regions of Asia, where they
should be assiduously sought for by travellers, as they are not only
very ornamental, but easily to be transported to Europe.
From such materials as he has been able to procure, the writer
enumerates the following as completing the genus Hoya, as far as at
present ascertained:
6 Hoya chinensis. 7 Hoya viridiflora, _R. Brown_. 8 Hoya lanceolata,
_D. Don_. 9 Hoya linearis, _D. Don_. 10 Hoya australis, _R. Brown_,
_MSS_. 11 Hoya nicobarica, _R. Brown, MSS_. 12 Hoya augustifolia.
The paper concludes with a detailed explanation of the best manner of
cultivating Hoyas.
IV. _On acclimatizing Plants at Biel, in East Lothian_. By Mr. John
Street, gardener to the Honourable Mrs. Hamilton Nesbitt.
Perhaps there is no point whatever, connected with Horticulture, of
greater interest than that which forms the subject of this paper;
it is the distant goal towards which we all are striving, but of
which, alas! we have not as yet even caught a glimpse. The gardener
is in possession of the powers by which he can bend the seasons to
his will; he can dispel the frozen gloom of winter with the rich
warm glow of the vintage; at his call the flowers of spring and
summer start up beneath his feet, and his hothouses are filled with
the luscious fruits of the torrid zone. All this he knows how to
effect with an artificial climate; but he has no influence over the
natural climate of his country, nor can he impart to the vegetation
of warmer latitudes the least additional power of resisting cold, for
which they have not been prepared by nature. Acclimatizing is still
a secret to be discovered. To [p165] this day not a single instance
can be adduced of any exotic plant whatever possessing greater powers
of withstanding cold, than it had when first introduced. It has been
hoped that if the seeds of given plant could be procured, for many
generations, in a climate severer than its own, the offspring so
obtained would gradually accommodate themselves to their new country;
but no such result has followed from the experiments that have been
tried. Let us take a few familiar examples:—the common nasturtium,
(Tropælum majus,) a native of Peru, is said to have been introduced
about the year 1686. At the time at which we are writing, it must
have descended through about 140 generations; and yet it has not
become in the smallest degree capable of resisting cold. Of the
mignonette (Reseda odorata), the date of introduction is not well
ascertained; it has probably been a favourite border annual for sixty
or seventy years, and yet it has in no degree shaken off its annual
character, which is unnatural to it, and resumed the suffrutescent
habit which it possesses in its own milder climate. The potato,
too, which has for two centuries and a half been increased in every
conceivable manner, by seeds as well as by offsets, bears cold in
no degree more readily than it did in the sixteenth century. Nor
does it appear to us probable, that acclimatizing, if practicable,
is to be brought about by sowing seeds in northern latitudes
through successive generations. We do not believe that plants will
bear their seeds at all in a temperature much lower than that in
which they have been located by the hand of Nature. The heat of a
northern summer sufficiently approximates to that of the tropics,
to be considered, with reference to vegetation, as the same, and
it is during that season that the seeds of all plants are ripened;
the conditions, therefore, under which the seeds of Tropæolum, for
example, are produced in England, do not materially differ from those
under which the same seeds are produced in Peru; if the season proves
unpropitious in any considerable degree, they are not produced at
all. How then can it be expected that seeds ripened under similar
circumstances, but in different latitudes, should give birth to a
progeny differing in any remarkable particular from their parents?
In fact, in power of resisting cold, they do not differ at all. If
such a capability were to obtained, it would be by inducing plants to
ripen their seeds in winter.
But if it is certain that nothing is to be gained in acclimatizing,
by raising plants from seed through successive generations, [p166]
it is no less true that many trees, which have been supposed to be
incapable of surviving a northern winter, are now ascertained to be
perfectly hardy, and that the power of enduring cold may be increased
in others, by a judicious management of soil and situation.
The phenomenon of vegetable life being destroyed by cold, probably
arises from the vessels, through which the circulation and secretion
of the fluids of plants take place, being ruptured by the expansion,
from cold, of the fluid they contain. In proportion, therefore,
to the tenuity of the vessels, and the abundance of their fluid,
will be the danger to which they are exposed from frost; and to the
strength of the vessels, and the paucity of their fluid, the power
of resisting cold. Thus vigorous shoots of the oak, walnut, and many
other trees, which are formed with rapidity, imperfectly matured,
and highly charged with fluid, are extremely impatient of cold, and
are even destroyed by a few degrees of frost; while the twigs and
branches of the same trees, which are formed slowly, fully matured,
and incompletely filled with fluid, bear unharmed the utmost rigour
of our winters. In acclimatizing, therefore, this law should be
carefully remembered, and the situations in which tender plants are
stationed, should be those in which their growth is restrained, and
an excessive absorption of fluid prevented.
This appears to have been the true secret of the success that has
attended the attempts at acclimatizing, which form the subject of
Mr. Street’s communication. By planting in situations well drained
from superfluous moisture, under circumstances where rapid growth
was rendered impracticable, and, as we understand, in a garden
admirably adapted to the object, from its position, he has succeeded
in naturalizing, in latitude 56° N., plants which have not yet been
known to endure the winters even of the parallel of London.
V. _Upon the Culture of Celery_. By Thomas Andrew Knight, Esq.,
F.R.S., President.
“That which can be very easily done, without the exertion of much
skill or ingenuity, is,” Mr. Knight observes, “very rarely found
to be well done, the excitement to excellence being in such cases
necessarily very feeble.” This remark is in the present case applied
to the cultivation of celery, which, being a native of the sides
of wet ditches, might naturally be expected to demand an abundant
supply of water when cultivated. Accordingly, Mr. Knight found that
by keeping the ground, in which celery was planted, [p167] constantly
wet, it grew by the middle of September to the height of five feet,
and its quality was in proportion to its size. Mr. Knight also
recommends planting at greater distances than is usually the case,
and covering the beds, into which the young seedlings are first
removed, with half-rotten dung, overspread to the depth of about two
inches with mould; under which circumstances, whenever the plants are
removed, the dung will adhere tenaciously to their roots, and it will
not be necessary to deprive the plants of any part of their leaves.
VI. _Report upon the New or Rare Plants which flowered in the Garden
of the Horticultural Society at Chiswick, between March, 1825, and
March, 1826_. Part 1. _Tender Plants_. By John Lindley, Esq.
The subject of this paper consisting of botanical details which do
not bear curtailing, we shall only extract the names of the new
species described in it, as a guide to our botanical readers. In the
whole, thirty-three species are noticed; of which the following are
published for the first time:—
2 Passiflora obscura. 7 Solanum dealbatum. 10 Tabernæmontana
gratissima. 13 Tephrosia? Chinensis. 15 Hellenia abnormis. 16
Gesneria Douglassii. 21 Gynandropsis pulchella. 23 Rodriguezia
planifolia. 26 Brassavola nodosa. 33 Phycella corusca.
VII. _Account of a Protecting Frame for Fruit-Trees on Walls_. By
Mr. John Dick.
In order to protect the fruit upon walls from the ravages of bees,
wasps, flies, and other winged enemies, a frame is contrived fitting
close to the face of the wall, and having a moveable sliding canvass
front, which can be readily removed when the fruit is to be gathered,
and replaced again afterwards. A plan of the frame accompanies the
paper. From what we have seen of this contrivance, we know that it is
well adapted to its purpose, and that no garden in which fine fruit
is required, should be without one or more of such frames. For the
mode of making them, we must refer to the paper itself.
VIII. _On the Esculent Egg-Plants_. By Mr. Andrew Mathews.
In this country, the egg-plant, brinjal, or aubergine, is chiefly
cultivated as a curiosity; but in warmer climates, where its growth
is attended with less trouble, it is a favourite article of the
kitchen-garden. In the form of fritters, or farces, or in soups, it
is frequently brought to table in all the southern parts of Europe;
and forms a pleasant [p168] variety of esculent. This paper describes
the only two kinds that are worth cultivation in England.