Therese de Dillmont - "Encyclopedia of Needlework"

John Mavrogordato - "The World in Chains"

Isabella Lucy Bird - "The Englishwoman in America"

Aristotle - "Ethics"

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 Outline of Science, Vol. 1 (of 4)

J >> J. Arthur Thomson >> The Outline of Science, Vol. 1 (of 4)





Light without Heat

There are substances--"phosphorescent" things we call them--which give
out a mysterious cold light of their own. It is one of the problems
of science, and one of profound practical interest. If we could produce
light without heat our "gas bill" would shrink amazingly. So much energy
is wasted in the production of heat-waves and ultra-violet waves which
we do not want, that 90 per cent. or more of the power used in
illumination is wasted. Would that the glow-worm, or even the dead
herring, would yield us its secret! Phosphorus is the one thing we know
as yet that suits the purpose, and--it smells! Indeed, our artificial
light is not only extravagant in cost, but often poor in colour. The
unwary person often buys a garment by artificial light, and is disgusted
next morning to find in it a colour which is not wanted. The colour
disclosed by the sun was not in the waves of the artificial light.

[Illustration: ROTATING DISC OF SIR ISAAC NEWTON FOR MIXING COLOURS

The Spectroscope sorts out the above seven colours from sunlight (which
is compounded of these seven colours). If painted in proper proportions
on a wheel, as shown in the coloured illustration, and the wheel be
turned rapidly on a pivot through its centre, only a dull white will be
perceived. If one colour be omitted, the result will be one colour--the
result of the union of the remaining six.]

Beyond the waves of violet light are the still shorter and more rapid
waves--the "ultra-violet" waves--which are precious to the photographer.
As every amateur knows, his plate may safely be exposed to light that
comes through a red or an orange screen. Such a screen means "no
thoroughfare" for the blue and "beyond-blue" waves, and it is these
which arrange the little grains of silver on the plate. It is the same
waves which supply the energy to the little green grains of matter
(chlorophyll) in the plant, preparing our food and timber for us, as
will be seen later. The tree struggles upward and spreads out its leaves
fanwise to the blue sky to receive them. In our coal-measures, the
mighty dead forests of long ago, are vast stores of sunlight which we
are prodigally using up.

The X-rays are the extreme end, the highest octave, of the series of
waves. Their power of penetration implies that they are excessively
minute, but even these have not held their secret from the modern
physicist. From a series of beautiful experiments, in which they were
made to pass amongst the atoms of a crystal, we learned their length. It
is about the ten-millionth of a millimetre, and a millimetre is about
the 1/25 of an inch!

One of the most recent discoveries, made during a recent eclipse of the
sun, is that light is subject to gravitation. A ray of light from a star
is bent out of its straight path when it passes near the mass of the
sun. Professor Eddington tells us that we have as much right to speak of
a pound of light as of a pound of sugar. Professor Eddington even
calculates that the earth receives 160 tons of light from the sun every
year!


ENERGY: HOW ALL LIFE DEPENDS ON IT

As we have seen in an earlier chapter, one of the fundamental entities
of the universe is matter. A second, not less important, is called
energy. Energy is indispensable if the world is to continue to exist,
since all phenomena, including life, depend on it. Just as it is humanly
impossible to create or to destroy a particle of matter, so is it
impossible to create or to destroy energy. This statement will be more
readily understood when we have considered what energy is.

Energy, like matter, is indestructible, and just as matter exists in
various forms so does energy. And we may add, just as we are ignorant of
what the negative and positive particles of electricity which constitute
matter really are, so we are ignorant of the true nature of energy. At
the same time, energy is not so completely mysterious as it once was. It
is another of nature's mysteries which the advance of modern science has
in some measure unveiled. It was only during the nineteenth century that
energy came to be known as something as distinct and permanent as matter
itself.


Forms of Energy

The existence of various forms of energy had been known, of course, for
ages; there was the energy of a falling stone, the energy produced by
burning wood or coal or any other substance, but the essential
_identity_ of all these forms of energy had not been suspected. The
conception of energy as something which, like matter, was constant in
amount, which could not be created nor destroyed, was one of the great
scientific acquisitions of the past century.

[Illustration: WAVE SHAPES

Wave-motions are often complex. The above illustration shows some fairly
complicated wave shapes. All such wave-motions can be produced by
superposing a number of simple wave forms.]

[Illustration: THE POWER OF A MAGNET

The illustration is that of a "Phoenix" electric magnet lifting scrap
from railway trucks. The magnet is 52 inches in diameter and lifts a
weight of 26 tons. The same type of magnet, 62 inches in diameter, lifts
a weight of 40 tons.]

[Illustration: _Photo: The Locomotive Publishing Co., Ltd._

THE SPEED OF LIGHT

A train travelling at the rate of sixty miles per hour would take rather
more than seventeen and a quarter days to go round the earth at the
equator, i.e. a distance of 25,000 miles. Light, which travels at the
rate of 186,000 miles per second, would take between one-seventh and
one-eighth of a second to go the same distance.]

[Illustration: ROTATING DISC OF SIR ISAAC NEWTON FOR MIXING COLOURS

The Spectroscope sorts out the above seven colours from sunlight (which
is compounded of these seven colours). If painted in proper proportions
on a wheel, as shown in the coloured illustration, and the wheel turned
rapidly on a pivot through its centre, only a dull white will be
perceived. If one colour be omitted, the result will be one colour--the
result of the union of the remaining six.]

It is not possible to enter deeply into this subject here. It is
sufficient if we briefly outline its salient aspects. Energy is
recognised in two forms, kinetic and potential. The form of energy which
is most apparent to us is the _energy of motion_; for example, a rolling
stone, running water, a falling body, and so on. We call the energy of
motion _kinetic energy_. Potential energy is the energy a body has in
virtue of its position--it is its capacity, in other words, to acquire
kinetic energy, as in the case of a stone resting on the edge of a
cliff.

Energy may assume different forms; one kind of energy may be converted
directly or indirectly into some other form. The energy of burning coal,
for example, is converted into heat, and from heat energy we have
mechanical energy, such as that manifested by the steam-engine. In this
way we can transfer energy from one body to another. There is the energy
of the great waterfalls of Niagara, for instance, which are used to
supply the energy of huge electric power stations.


What Heat is

An important fact about energy is, that all energy _tends to take the
form of heat energy_. The impact of a falling stone generates heat; a
waterfall is hotter at the bottom than at the top--the falling particles
of water, on striking the ground, generate heat; and most chemical
changes are attended by heat changes. Energy may remain latent
indefinitely in a lump of wood, but in combustion it is liberated, and
we have heat as a result. The atom of radium or of any other
radio-active substance, as it disintegrates, generates heat. "Every hour
radium generates sufficient heat to raise the temperature of its own
weight of water, from the freezing point to the boiling point." And what
is heat? _Heat is molecular motion._ The molecules of every substance,
as we have seen on a previous page, are in a state of continual motion,
and the more vigorous the motion the hotter the body. As wood or coal
burns, the invisible molecules of these substances are violently
agitated, and give rise to ether waves which our senses interpret as
light and heat. In this constant movement of the molecules, then, we
have a manifestation of the energy of motion and of heat.

That energy which disappears in one form reappears in another has been
found to be universally true. It was Joule who, by churning water, first
showed that a measurable quantity of mechanical energy could be
transformed into a measurable quantity of heat energy. By causing an
apparatus to stir water vigorously, that apparatus being driven by
falling weights or a rotating flywheel or by any other mechanical means,
the water became heated. A certain amount of mechanical energy had been
used up and a certain amount of heat had appeared. The relation between
these two things was found to be invariable. Every physical change in
nature involves a transformation of energy, but the total quantity of
energy in the universe remains unaltered. This is the great doctrine of
the Conservation of Energy.


Sec. 13

Substitutes for Coal

Consider the source of nearly all the energy which is used in modern
civilisation--coal. The great forests of the Carboniferous epoch now
exists as beds of coal. By the burning of coal--a chemical
transformation--the heat energy is produced on which at present our
whole civilisation depends. Whence is the energy locked up in the coal
derived? From the sun. For millions of years the energy of the sun's
rays had gone to form the vast vegetation of the Carboniferous era and
had been transformed, by various subtle processes, into the potential
energy that slumbers in those immense fossilized forests.

The exhaustion of our coal deposits would mean, so far as our knowledge
extends at present, the end of the world's civilisation. There are other
known sources of energy, it is true. There is the energy of falling
water; the great falls of Niagara are used to supply the energy of huge
electric power stations. Perhaps, also, something could be done to
utilise the energy of the tides--another instance of the energy of
moving water. And attempts have been made to utilise directly the energy
of the sun's rays. But all these sources of energy are small compared
with the energy of coal. A suggestion was made at a recent British
Association meeting that deep borings might be sunk in order to utilise
the internal heat of the earth, but this is not, perhaps, a very
practical proposal. By far the most effective substitutes for coal would
be found in the interior energy of the atom, a source of energy which,
as we have seen, is practically illimitable. If the immense electrical
energy in the interior of the atom can ever be liberated and controlled,
then our steadily decreasing coal supply will no longer be the bugbear
it now is to all thoughtful men.

The stored-up energy of the great coal-fields can be used up, but we
cannot replace it or create fresh supplies. As we have seen, energy
cannot be destroyed, but it can become _unavailable_. Let us consider
what this important fact means.


Sec. 14

Dissipation of Energy

Energy may become dissipated. Where does it go? since if it is
indestructible it must still exist. It is easier to ask the question
than to give a final answer, and it is not possible in this OUTLINE,
where an advanced knowledge of physics is not assumed on the part of the
reader, to go fully into the somewhat difficult theories put forward by
physicists and chemists. We may raise the temperature, say, of iron,
until it is white-hot. If we stop the process the temperature of the
iron will gradually settle down to the temperature of surrounding
bodies. As it does so, where does its previous energy go? In some
measure it may pass to other bodies in contact with the piece of iron,
but ultimately the heat becomes radiated away in space where we cannot
follow it. It has been added to the vast reservoir of _unavailable_ heat
energy of uniform temperature. It is sufficient here to say that if all
bodies had a uniform temperature we should experience no such thing as
heat, because heat only travels from one body to another, having the
effect of cooling the one and warming the other. In time the two bodies
acquire the same temperature. The sum-total of the heat in any body is
measured in terms of the kinetic energy of its moving molecules.

There must come a time, so far as we can see at present, when, even if
all the heat energy of the universe is not radiated away into empty
infinite space, yet a uniform temperature will prevail. If one body is
hotter than another it radiates heat to that body until both are at the
same temperature. Each body may still possess a considerable quantity of
heat energy, which it has absorbed, but that energy, so far as reactions
between those two bodies are concerned, _is now unavailable_. The same
principle applies whatever number of bodies we consider. Before heat
energy can be utilised we must have bodies with different temperature.
If the whole universe were at some uniform temperature, then, although
it might possess an enormous amount of heat energy, this energy would be
unavailable.


What a Uniform Temperature would mean

And what does this imply? It implies a great deal: for if all the energy
in the world became unavailable, the universe, as it now is, would cease
to be. It is possible that, by the constant interchange of heat
radiations, the whole universe is tending to some uniform temperature,
in which case, although all molecular motion would not have ceased, it
would have become unavailable. In this sense it may be said that the
universe is running down.

[Illustration: NIAGARA FALLS

The energy of this falling water is prodigious. It is used to generate
thousands of horse-power in great electrical installations. The power is
used to drive electric trams in cities 150 to 250 miles away.]

[Illustration: _Photo: Stephen Cribb._

TRANSFORMATION OF ENERGY

An illustration of Energy. The chemical energy brought into existence by
firing the explosive manifesting itself as mechanical energy, sufficient
to impart violent motion to tons of water.]

[Illustration: _Photo: Underwood & Underwood._

"BOILING" A KETTLE ON ICE

When a kettle containing liquid air is placed on ice it "boils" because
the ice is intensely hot _when compared with the very low temperature of
the liquid air_.]

If all the molecules of a substance were brought to a standstill, that
substance would be at the absolute zero of temperature. There could be
nothing colder. The temperature at which all molecular motions would
cease is known: it is -273 deg. C. No body could possibly attain a lower
temperature than this: a lower temperature could not exist. Unless there
exists in nature some process, of which we know nothing at present,
whereby energy is renewed, our solar system must one day sink to this
absolute zero of temperature. The sun, the earth, and every other body
in the universe is steadily radiating heat, and this radiation cannot go
on for ever, because heat continually tends to diffuse and to equalise
temperatures.

But we can see, theoretically, that there is a way of evading this law.
If the chaotic molecular motions which constitute heat could be
_regulated_, then the heat energy of a body could be utilised directly.
Some authorities think that some of the processes which go on in the
living body do not involve any waste energy, that the chemical energy of
food is transformed directly into work without any of it being
dissipated as useless heat energy. It may be, therefore, that man will
finally discover some way of escape from the natural law that, while
energy cannot be destroyed, it has a tendency to become unavailable.

The primary reservoir of energy is the atom; it is the energy of the
atom, the atom of elements in the sun, the stars, the earth, from which
nature draws for all her supply of energy. Shall we ever discover how we
can replenish the dwindling resources of energy, or find out how we can
call into being the at present unavailable energy which is stored up in
uniform temperature?

It looks as if our successors would witness an interesting race,
between the progress of science on the one hand and the depletion of
natural resources upon the other. The natural rate of flow of energy
from its primary atomic reservoirs to the sea of waste heat energy
of uniform temperature, allows life to proceed at a complete pace
sternly regulated by the inexorable laws of supply and demand,
which the biologists have recognised in their field as the struggle
for existence.[5]

[5] _Matter and Energy_, by Professor Soddy.

It is certain that energy is an actual entity just as much as matter,
and that it cannot be created or destroyed. Matter and ether are
receptacles or vehicles of energy. As we have said, what these entities
really are in themselves we do not know. It may be that all forms of
energy are in some fundamental way aspects of the same primary entity
which constitutes matter: how all matter is constituted of particles of
electricity we have already seen. The question to which we await an
answer is: What is electricity?


Sec. 15

MATTER, ETHER, AND EINSTEIN

The supreme synthesis, the crown of all this progressive conquest of
nature, would be to discover that the particles of positive and negative
electricity, which make up the atoms of matter, are points or centres of
disturbances of some kind in a universal ether, and that all our
"energies" (light, magnetism, gravitation, etc.) are waves or strains of
some kind set up in the ether by these clusters of electrons.

It is a fascinating, tantalising dream. Larmor suggested in 1900 that
the electron is a tiny whirlpool, or "vortex," in ether; and, as such a
vortex may turn in either of two opposite ways, we seem to see a
possibility of explaining positive and negative electricity. But the
difficulties have proved very serious, and the nature of the electron is
unknown. A recent view is that it is "a ring of negative electricity
rotating about its axis at a high speed," though that does not carry us
very far. The unit of positive electricity is even less known. We must
be content to know the general lines on which thought is moving toward
the final unification.

We say "unification," but it would be a grave error to think that ether
is the only possible basis for such unity, or to make it an essential
part of one's philosophy of the universe. Ether was never more than an
imagined entity to which we ascribed the most extraordinary properties,
and which seemed then to promise considerable aid. It was conceived as
an elastic solid of very great density, stretching from end to end of
the universe, transmitting waves from star to star at the rate of
186,000 miles a second; yet it was believed that the most solid matter
passed through it as if it did not exist.

Some years ago a delicate experiment was tried for the purpose of
detecting the ether. Since the earth, in travelling round the sun, must
move through the ether if the ether exists, there ought to be a stream
of ether flowing through every laboratory; just as the motion of a ship
through a still atmosphere will make "a wind." In 1887 Michelson and
Morley tried to detect this. Theoretically, a ray of light in the
direction of the stream ought to travel at a different rate from a ray
of light against the stream or across it. They found no difference, and
scores of other experiments have failed. This does not prove that there
is no ether, as there is reason to suppose that our instruments would
appear to shrink in precisely the same proportion as the alteration of
the light; but the fact remains that we have no proof of the existence
of ether. J. H. Jeans says that "nature acts as if no such thing
existed." Even the phenomena of light and magnetism, he says, do not
imply ether; and he thinks that the hypothesis may be abandoned. The
primary reason, of course, for giving up the notion of the ether is
that, as Einstein has shown, there is no way of detecting its existence.
If there is an ether, then, since the earth is moving through it, there
should be some way of detecting this motion. The experiment has been
tried, as we have said, but, although the method used was very
sensitive, no motion was discovered. It is Einstein who, by
revolutionising our conceptions of space and time, showed that no such
motion ever could be discovered, whatever means were employed, and that
the usual notion of the ether must be abandoned. We shall explain this
theory more fully in a later section.


INFLUENCE OF THE TIDES: ORIGIN OF THE MOON: THE EARTH SLOWING DOWN

Sec. 16

Until comparatively recent times, until, in fact, the full dawn of
modern science, the tides ranked amongst the greatest of nature's
mysteries. And, indeed, what agency could be invoked to explain this
mysteriously regular flux and reflux of the waters of the ocean? It is
not surprising that that steady, rhythmical rise and fall suggested to
some imaginative minds the breathing of a mighty animal. And even when
man first became aware of the fact that this regular movement was
somehow associated with the moon, was he much nearer an explanation?
What bond could exist between the movements of that distant world and
the diurnal variation of the waters of the earth? It is reported that an
ancient astronomer, despairing of ever resolving the mystery, drowned
himself in the sea.


The Earth Pulled by the Moon

But it was part of the merit of Newton's mighty theory of gravitation
that it furnished an explanation even of this age-old mystery. We can
see, in broad outlines at any rate, that the theory of universal
attraction can be applied to this case. For the moon, Newton taught us,
pulls every particle of matter throughout the earth. If we imagine that
part of the earth's surface which comprises the Pacific Ocean, for
instance, to be turned towards the moon, we see that the moon's pull,
_acting on the loose and mobile water_, would tend to heap it up into a
sort of mound. The whole earth is pulled by the moon, but the water
is more free to obey this pull than is the solid earth, although small
tides are also caused in the earth's solid crust. It can be shown also
that a corresponding hump would tend to be produced on the other side of
the earth, owing, in this case, to the tendency of the water, being more
loosely connected, to lag behind the solid earth. If the earth's surface
were entirely fluid the rotation of the earth would give the impression
that these two humps were continually travelling round the world, once
every day. At any given part of the earth's surface, therefore, there
would be two humps daily, i.e. two periods of high water. Such is the
simplest possible outline of the gravitational theory of the tides.

[Illustration: THE CAUSE OF TIDES

The tides of the sea are due to the pull of the moon, and, in lesser
degree, of the sun. The whole earth is pulled by the moon, but the loose
and mobile water is more free to obey this pull than is the solid earth,
although small tides are also caused in the earth's solid crust. The
effect which the tides have on slowing down the rotation of the earth is
explained in the text.]

[Illustration: _Photo: G. Brocklehurst._

THE AEGIR ON THE TRENT

An exceptionally smooth formation due to perfect weather conditions. The
wall-like formation of these tidal waves (see next page also) will be
noticed. The reason for this is that the downward current in the river
heads the sea-water back, and thus helps to exaggerate the advancing
slope of the wave. The exceptional spring tides are caused by the
combined operation of the moon and the sun, as is explained in the
text.]

[Illustration: _Photo: G. Brocklehurst._

A BIG SPRING TIDE, THE AEGIR ON THE TRENT]

The actually observed phenomena are vastly more complicated, and the
complete theory bears very little resemblance to the simple form we have
just outlined. Everyone who lives in the neighbourhood of a port knows,
for instance, that high water seldom coincides with the time when the
moon crosses the meridian. It may be several hours early or late. High
water at London Bridge, for instance, occurs about one and a half hours
after the moon has passed the meridian, while at Dublin high water
occurs about one and a half hours before the moon crosses the meridian.
The actually observed phenomena, then, are far from simple; they have,
nevertheless, been very completely worked out, and the times of high
water for every port in the world can now be prophesied for a
considerable time ahead.


The Action of Sun and Moon

It would be beyond our scope to attempt to explain the complete theory,
but we may mention one obvious factor which must be taken into account.
Since the moon, by its gravitational attraction, produces tides, we
should expect that the sun, whose gravitational attraction is so much
stronger, should also produce tides and, we would suppose at first
sight, more powerful tides than the moon. But while it is true that the
sun produces tides, it is not true that they are more powerful than
those produced by the moon. The sun's tide-producing power is, as a
matter of fact, less than half that of the moon. The reason of this is
that _distance_ plays an enormous role in the production of tides. The
mass of the sun is 26,000,000 times that of the moon; on the other hand
it is 386 times as far off as the moon. This greater distance more than
counterbalances its greater mass, and the result, as we have said, is
that the moon is more than twice as powerful. Sometimes the sun and moon
act together, and we have what are called spring tides; sometimes they
act against one another, and we have neap tides. These effects are
further complicated by a number of other factors, and the tides, at
various places, vary enormously. Thus at St. Helena the sea rises and
falls about three feet, whereas in the Bay of Fundy it rises and falls
more than fifty feet. But here, again, the reasons are complicated.

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