Various - "The Strand Magazine, Volume V, Issue 28, April 1893"

Washington Irving - "The Life and Voyages of Christopher Columbus (Vol. II)"

W. D. Howells - "Annie Kilburn"

Washington Irving - "The Life and Voyages of Christopher Columbus (Vol. II)"

Annual Bibliography of Commonwealth Literature 2007
This paper argues that discourses of love in Ghanaian market literature for youth offer a view into complex negotiations of agency and empowerment. Drawing on Deborah Durham's notion of youth as "social `shifters'" and Francis Nyamnjoh's conception of the "interconnectedness" of agency, I take Ghanaian market literature as one specific case of how African literature for youth foregrounds questions of continuity and change as African societies enter into increasingly complex global relations. In this literature for youth, received notions of love, often constructed out of impressions from American pop and hip hop music, carry new notions of agency that compete with existing "domesticated" forms. Authors like Ike Tandoh and Evelyn Tay employ discourses of love to offer youth alternative avenues for empowerment in a context of socio-economic disenfranchizement. In a creative process of "straddling", this writing both reveals and reproduces the contradictions that obtain in youth configurations of agency.

The Botanic Garden

E >> Erasmus Darwin >> The Botanic Garden





LAND AND SEA-BREEZES.

The sea being a transparent mass is less heated at its surface by the
sun's rays than the land, and its continual change of surface
contributes to preserve a greater uniformity in the heat of the air
which hangs over it. Hence the surface of the tropical islands is more
heated during the day than the sea that surrounds them, and cools more
in the night by its greater elevation: whence in the afternoon when the
lands of the tropical islands have been much heated by the sun, the air
over them ascends pressed upwards by the cooler air of the incircling
ocean, in the morning again the land becoming cooled more than the sea,
the air over it descends by its increased gravity, and blows over the
ocean near its shores.


CONCLUSION.

1. There are various irregular winds besides those above described,
which consist of horizontal or vertical eddies of air owing to the
inequality of the earth's surface, or the juxtaposition of the sea.
Other irregular winds have their origin from increased evaporation of
water, or its sudden devaporation and descent in showers; others from
the partial expansion and condensation of air by heat and cold; by the
accumulation or defect of electric fluid, or to the air's new production
or absorption occasioned by local causes not yet discovered. See Notes
VII. and XXV.

2. There seem to exist only two original winds: one consisting of air
brought from the north, and the other of air brought from the south. The
former of these winds has also generally an apparent direction from the
east, and the latter from the west, arising from the different
velocities of the earth's surface. All the other winds above described
are deflections or retrogressions of some parts of these currents of air
from the north or south.

3. One fifteenth part of the atmosphere is occasionally destroyed, and
occasionally reproduced by unknown causes. These causes are brought into
immediate activity over a great part of the surface of the earth at
nearly the same time, but always act more powerful to the northward than
to the southward of any given place; and would hence seem to have their
principal effect in the polar circles, existing nevertheless though with
less power toward the tropics or at the line.

For when the north-east wind blows the barometer rises, sometimes from
281/2 inches to 301/2, which shews a great new generation of air in the
north; and when the south-west wind blows the barometer sinks as much,
which shews a great destruction of air in the north. But as the north-
east winds sometimes continue for five or six weeks, the newly-generated
air must be destroyed at those times in the warmer climates to the south
of us, or circulate in superior currents, which has been shewn to be
improbable from its not depositing its water. And as the south-west
winds sometimes continue for some weeks, there must be a generation of
air to the south at those times, or superior currents, which last has
been shewn to be improbable.

4. The north-east winds being generated about the poles are pushed
forwards towards the tropics or line, by the pressure from behind, and
hence they become warmer, as explained in Note VII. as well as by their
coming into contact with a warmer part of the earth which contributes to
make these winds greedily absorb moisture in their passage. On the
contrary, the south-west winds, as the atmosphere is suddenly diminished
in the polar regions, are drawn as it were into an incipient vacancy,
and become therefore expanded in their passage, and thus generate cold,
as explained in Note VII. and are thus induced to part with their
moisture, as well as by their contact with a colder part of the earth's
surface. Add to this, that the difference in the sound of the north-east
and south-west winds may depend on the former being pushed forwards by a
pressure behind, and the latter falling as it were into a partial or
incipient vacancy before; whence the former becomes more condensed, and
the latter more rarefied as it passes. There is a whistle, termed a
lark-call, which consists of a hollow cylinder of tin-plate, closed at
each end, about half an inch in diameter and a quarter of an inch high,
with opposite holes about the size of a goose-quill through the centre
of each end; if this lark-whistle be held between the lips the sound of
it is manifestly different when the breath is forceably blown through it
from within outwards, and when it is sucked from without inwards.
Perhaps this might be worthy the attention of organ-builders.

5. A stop is put to this new generation of air, when about a fifteenth
of the whole is produced, by its increasing pressure; and a similar
boundary is fixed to its absorption or destruction by the decrease of
atmospheric pressure. As water requires more heat to convert it into
vapour under a heavy atmosphere than under a light one, so in letting
off the water from muddy fish-ponds great quantities of air-bubbles are
seen to ascend from the bottom, which were previously confined there by
the pressure of the water. Similar bubbles of inflammable air are seen
to arise from lakes in many seasons of the year, when the atmosphere
suddenly becomes light.

6. The increased absorptions and evolutions of air must, like its simple
expansions, depend much on the presence or absence of heat and light,
and will hence, in respect to the times and places of its production and
destruction, be governed by the approach or retrocession of the sun, and
on the temperature, in regard to heat, of various latitudes, and parts
of the same latitude, so well explained by Mr. Kirwan.

7. Though the immediate cause of the destruction or reproduction of
great masses of air at certain times, when the wind changes from north
to south, or from south to north can not yet be ascertained; yet as
there appears greater difficulty in accounting for this change of wind
for any other known causes, we may still suspect that there exists in
the arctic and antarctic circles a BEAR or DRAGON yet unknown to
philosophers, which at times suddenly drinks up, and as suddenly at
other times vomits out one-fifteenth part of the atmosphere: and hope
that this or some future age will learn how to govern and domesticate a
monster which might be rendered of such important service to mankind.


INSTRUMENTS.

If along with the usual registers of the weather observations were made
on the winds in many parts of the earth with the three following
instruments, which might be constructed at no great expence, some useful
information might be acquired.

1. To mark the hour when the wind changes from north-east to south-west,
and the contrary. This might be managed by making a communication from
the vane of a weathercock to a clock; in such a manner, that if the vane
mould revolve quite round, a tooth on its revolving axis should stop the
clock, or put back a small bolt on the edge of a wheel revolving once in
twenty-four hours.

2. To discover whether in a year more air passed from north to south, or
the contrary. This might be effected by placing a windmill-sail of
copper about nine inches diameter in a hollow cylinder about six inches
long, open at both ends, and fixed on an eminent situation exactly north
and south. Thence only a part of the north-east and south-west currents
would affect the sail so as to turn it; and if its revolutions were
counted by an adapted machinery, as the sail would turn one way with the
north currents of air, and the contrary one with the south currents, the
advance of the counting finger either way would shew which wind had
prevailed most at the end of the year.

3. To discover the rolling cylinders of air, the vane of a weathercock
might be so suspended as to dip or rise vertically, as well as to have
its horizontal rotation.


RECAPITULATION.

NORTH-EAST WINDS consist of air flowing from the north, where it seems
to be occasionally produced; has an apparent direction from the east
owing to its not having acquired in its journey the increasing velocity
of the earth's surface; these winds are analogous to the trade-winds
between the tropics, and frequently continue in the vernal months for
four and six weeks together, with a high barometer, and fair or frosty
weather. 2. They sometimes consist of south-west air, which had passed
by us or over us, driven back by a new accumulation of air in the north,
These continue but a day or two, and are attended with rain. See Note
XXV.

SOUTH-WEST WIND consists of air flowing from the south, and seems
occasionally absorbed at its arrival to the more northern latitudes. It
has a real direction from the west owing to its not having lost in its
journey the greater velocity it had acquired from the earth's surface
from whence it came. These winds are analogous to the monsoons between
the tropics, and frequently continue for four or six weeks together,
with a low barometer and rainy weather. 2. They sometimes consist of
north-east air, which had passed by us or over us, which becomes
retrograde by a commencing deficiency of air in the north. These winds
continue but a day or two, attended with severer frost with a sinking
barometer; their cold being increased by their expansion, as they
return, into an incipient vacancy.

NORTH-WEST WINDS consist, first, of south-west winds, which have passed
over us, bent down and driven back towards the south by newly generated
northern air. They continue but a day or two, and are attended with rain
or clouds. 2. They consist of north-east winds bent down from the higher
parts of the atmosphere, and having there acquired a greater velocity
than, the earth's surface; are frosty or fair. 3. They consist of north-
east winds formed into a vertical spiral eddy, as on the eastern coasts
of North America, and bring severe frost.

SOUTH-EAST WINDS consist, first, of north-east winds become retrograde,
continue for a day or two, frosty or fair, sinking barometer. 2. They
consist of north-east winds formed into a vertical eddy not a spiral
one, frost or fair.

NORTH WINDS consist, first, of air flowing slowly from the north, so
that they acquire the velocity of the earth's surface as they approach,
are fair or frosty, seldom occur. 2. They consist of retrograde south
winds; these continue but a day or two, are preceded by south-west
winds; and are generally succeeded by north-east winds, cloudy or rainy,
barometer rising.

SOUTH WINDS consist, first, of air flowing slowly from the south,
loosing their previous western velocity by the friction of the earth's
surface as they approach, moist, seldom occur, 2. They consist of
retrograde north winds; these continue but a day or two, are preceded by
north-east winds, and generally succeeded by south-west winds, colder,
barometer sinking.

EAST WINDS consist of air brought hastily from the north, and not
impelled farther southward, owing to a sudden beginning absorption of
air in the northern regions, very cold, barometer high, generally
succeeded by south-west wind.

WEST WINDS consist of air brought hastily from the south, and checked
from proceeding further to the north by a beginning production of air in
the northern regions, warm and moist, generally succeeded by north-east
wind. 2. They consist of air bent down from the higher regions of the
atmosphere, if this air be from the south, and brought hastily it
becomes a wind of great velocity, moving perhaps 60 miles an hour, is
warm and rainy; if it consists of northern air bent down it is of less
velocity and colder.


_Application of the preceding Theory to Some Extracts
from a Journal of the Weather._

_Dec. 1, 1790._ The barometer sunk suddenly, and the wind, which had
been some days north-east with frost, changed to south-east with an
incessant though moderate fall of snow. A part of the northern air,
which had passed by us I suppose, now became retrograde before it had
acquired the velocity of the earth's surface to the south of us, and
being attended by some of the southern air in its journey, the moisture
of the latter became condensed and frozen by its mixture mith the
former.

_Dec. 2, 3._ The wind changed to north-west and thawed the snow. A part
of the southern air, which had passed by us or over us, with the
retrograde northern air above described, was now in its turn driven
back, before it had lost the velocity of the surface of the earth to the
south of us, and consequently became a north-west wind; and not having
lost the warmth it brought from the south produced a thaw.

_Dec. 4, 5._ Wind changed to north-east with frost and a rising
barometer. The air from the north continuing to blow, after it had
driven back the southern air as above described, became a north-east
wind, having less velocity than the surface of the earth in this
climate, and produced frost from its coldness.

_Dec. 6, 7._ Wind now changed to the south-west with incessant rain and
a sinking barometer. From unknown causes I suppose the quantity of air
to be diminished in the polar regions, and the southern air cooled by
the earth's surface, which was previously frozen, deposits its moisture
for a day or two; afterwards the wind continued south-west without rain,
as the surface of the earth became warmer.

_March 18, 1785._ There has been a long frost; a few days ago the
barometer sunk to 291/2, and the frost became more severe. Because the air
being expanded by a part of the pressure being taken off became colder.
This day the mercury rose to 30, and the frost ceased, the wind
continuing as before between north and east. _March 19._ Mercury above
30, weather still milder, no frost, wind north-east. _March 20._ The
same, for the mercury rising shews that the air becomes more compressed
by the weight above, and in consequence gives out warmth.

_April 4, 5._ Frost, wind north-east, the wind changed in the middle of
the day to the north-west without rain, and has done so for three or
four days, becoming again north-east at night. For the sun now giving
greater degrees of heat, the air ascends as the sun passes the zenith,
and is supplied below by the air on the western side as well as on the
eastern side of the zenith during the hot part of the day; whence for a
few hours, on the approach of the hot part of the day, the air acquires
a westerly direction in this longitude. If the north-west wind had been
caused by a retrograde motion of some southern air, which had passed
over us, it would have been attended with rain or clouds.

_April 10._ It rained all day yesterday, the wind north-west, this
morning there was a sharp frost. The evaporation of the moisture, (which
fell yesterday) occasioned by the continuance of the wind, produced so
much cold as to freeze the dew.

_May 12._ Frequent showers with a current of colder wind preceding every
shower. The sinking of the rain or cloud pressed away the air from
beneath it in its descent, which having been for a time shaded from the
sun by the floating cloud, became cooled in some degree.

_June 20._ The barometer sunk, the wind became south-west, and the whole
heaven was instantly covered with clouds. A part of the incumbent
atmosphere having vanished, as appeared by the sinking of the barometer,
the remainder became expanded by its elasticity, and thence attracted
some of the matter of heat from the vapour intermixed with it, and thus
in a few minutes a total devaporation took place, as in exhausting the
receiver of an air-pump. See note XXV. At the place where the air is
destroyed, currents both from the north and south flow in to supply the
deficiency, (for it has been shewn that there are no other proper winds
but these two) and the mixture of these winds produces so sudden
condensation of the moisture, both by the coldness of the northern air
and the expansion of both of them, that lightning is given out, and an
incipient tornado takes place; whence thunder is said frequently to
approach against the wind.

_August 28, 1732._ Barometer was at 31, and _Dec. 30_, in the same year,
it was at 28 2-tenths. Medical Essays, Edinburgh, Vol. II. p. 7. It
appears from these journals that the mercury at Edinburgh varies
sometimes nearly three inches, or one tenth of the whole atmosphere.
From the journals kept by the Royal Society at London it appears seldom
to vary more than two inches, or one-fifteenth of the whole atmosphere.
The quantity of the variation is said still to decrease nearer the line,
and to increase in the more northern latitudes; which much confirms the
idea that there exists at certain times a great destruction or
production of air within the polar circle.

_July 2, 1732._ The westerly winds in the journal in the Medical Essays,
Vol. II. above referred to, are frequently marked with the number three
to shew their greater velocity, whereas the easterly winds seldom
approach to the number two. The greater velocity of the westerly winds
than the easterly ones is well known I believe in every climate of the
world; which may be thus explained from the theory above delivered. 1.
When the air is still, the higher parts of the atmosphere move quicker
than those parts which touch the earth, because they are at a greater
distance from the axis of motion. 2. The part of the atmosphere where
the north or south wind comes from is higher than the part of it where
it comes to, hence the more elevated parts of the atmosphere continue to
descend towards the earth as either of those winds approach. 3. When
southern air is brought to us it possesses a westerly direction also,
owing to the velocity it had previously acquired from the earth's
surface; and if it consists of air from the higher parts of the
atmosphere descending nearer the earth, this westerly velocity becomes
increased. But when northern air is brought to us, it possesses an
apparent easterly direction also, owing to the velocity which it had
previously acquired from the earth's surface being less than that of the
earth's surface in this latitude; now if the north-east wind consists of
air descending from higher parts of the atmosphere, this deficiency of
velocity will be less, in consequence of the same cause, viz. The higher
parts of the atmosphere descending, as the wind approaches, increases
the real velocity of the western winds, and decreases the apparent
velocity of the eastern ones.

_October 22._ Wind changed from south-east to south-west. There is a
popular prognostication that if the wind changes from the north towards
the south passing through the east, it is more likely to continue in the
south, than if it passes through the west, which may be thus accounted
for. If the north-east wind changes to a north-west wind, it shews
either that a part of the northern air descends upon us in a spiral
eddy, or that a superior current of southern air is driven back; but if
a north-east wind be changed into a south-east wind it shews that the
northern air is become retrograde, and that in a day or two, as soon as
that part of it has passed, which has not gained the velocity of the
earth's surface in this latitude, it will become a south wind for a few
hours, and then a south-west wind.

The writer of this imperfect sketch of anemology wishes it may incite
some person of greater leizure and ability to attend to this subject,
and by comparing the various meteorological journals and observations
already published, to construct a more accurate and methodical treatise
on this interesting branch of philosophy.




NOTE XXXIV.--VEGETABLE PERSPIRATION.


_And wed the enamoured Oxygene to Light._

CANTO IV. l. 34.


When points or hairs are put into spring-water, as in the experiments of
Sir B. Thompson, (Philos. Trans. Vol. LXXVII.) and exposed to the light
of the sun, much air, which loosely adhered to the water, rises in
bubbles, as explained in note on Fucus, Vol. II. A still greater
quantity of air, and of a purer kind, is emitted by Dr. Priestley's
green matter, and by vegetable leaves growing in water in the sun-shine,
according to Mr. Ingenhouze's experiments; both which I suspect to be
owing to a decomposition of the water perspired by the plant, for the
edge of a capillary tube of great tenuity may be considered as a circle
of points, and as the oxygene, or principle of vital air, may be
expanded into a gas by the sun's light; the hydrogene or inflammable air
may be detained in the pores of the vegetable.

Hence plants growing in the shade are white, and become green by being
exposed to the sun's light; for their natural colour being blue, the
addition of hydrogene adds yellow to this blue, and _tans_ them green. I
suppose a similar circumstance takes place in animal bodies; their
perspirable matter as it escapes in the sun-shine becomes decomposed by
the edges of their pores as in vegetables, though in less quantity, as
their perspiration is less, and by the hydrogene being retained the skin
becomes _tanned_ yellow. In proof of this it must be observed that both
vegetable and animal substances become bleached white by the sun-beams
when they are dead, as cabbage-stalks, bones, ivory, tallow, bees-wax,
linen and cotton cloth; and hence I suppose the copper-coloured natives
of sunny countries might become etiolated or blanched by being kept from
their infancy in the dark, or removed for a few generations to more
northerly climates.

It is probable that on a sunny morning much pure air becomes separated
from the dew by means of the points of vegetables on which it adheres,
and much inflammable air imbibed by the vegetable, or combined with it;
and by the sun's light thus decomposing water the effects of it in
bleaching linen seems to depend (as described in Note X.): the water is
decomposed by the light at the ends or points of the cotton or thread,
and the vital air unites with the phlogistic or colouring matters of the
cloth, and produces a new acid, which is either itself colourless or
washes out, at the same time the inflammable part of the water escapes.
Hence there seems a reason why cotton bleaches so much sooner than
linen, viz. because its fibres are three or four times shorter, and
therefore protrude so many more points, which seem to facilitate the
liberation of the vital air from the inflammable part of the water.

Bee's wax becomes bleached by exposure to the sun and dews in a similar
manner as metals become calcined or rusty, viz. by the water on their
surface being decomposed; and hence the inflammable material which
caused the colour becomes united with vital air forming a new acid, and
is washed away.

Oil close stopped in a phial not full, and exposed long to the sun's
light, becomes bleached, as I suppose, by the decomposition of the water
it contains; the inflammable air rising above the surface, and the vital
air uniting with the colouring matter of the oil. For it is remarkable,
that by shutting up a phial of bleached oil in a dark drawer, it in a
little time becomes coloured again.

The following experiment shews the power of light in separating vital
air from another basis, viz. from azote. Mr. Scheel inverted a glass
vessel filled with colourless nitrous acid into another glass containing
the same acid, and on exposing them to the sun's light, the inverted
glass became partly filled with pure air, and the acid at the same time
became coloured. Scheel in Crell's Annal. 1786. But if the vessel of
colourless nitrous acid be quite full and stopped, so that no space is
left for the air produced to expand itself into, no change of colour
takes place. Priestley's Exp. VI. p. 344. See Keir's very excellent
Chemical Dictionary, p. 99. new edition.

A sun-flower three feet and half high according to the experiment of Dr.
Hales, perspired two pints in one day (Vegetable Statics.) which is many
times as much in proportion to its surface, as is perspired from the
surface and lungs of animal bodies; it follows that the vital air
liberated from the surfaces of plants by the sunshine must much exceed
the quantity of it absorbed by their respiration, and that hence they
improve the air in which they live during the light part of the day, and
thus blanched vegetables will sooner become _tanned into green_ by the
sun's light, than etiolated animal bodies will become _tanned yellow_ by
the same means.

It is hence evident, that the curious discovery of Dr. Priestley, that
his green vegetable matter and other aquatic plants gave out vital air
when the sun shone upon them, and the leaves of other plants did the
same when immersed in water, as observed by Mr. Ingenhouze, refer to the
perspiration of vegetables not to their respiration. Because Dr.
Priestley observed the pure air to come from both sides of the leaves
and even from the stalks of a water-flag, whereas one side of the leaf
only serves the office of lungs, and certainly not the stalks. Exper. on
Air, Vol. III. And thus in respect to the circumstance in which plants
and animals seemed the furtherest removed from each other, I mean in
their supposed mode of respiration, by which one was believed to purify
the air which the other had injured, they seem to differ only in degree,
and the analogy between them remains unbroken.

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