appeared at _half-past twelve_ o’clock, on Sept. 7, 1871. Below it is
the same prominence at _one_ o’clock (half an hour later), when it
has been shattered by some inconceivable explosion, blowing it into
fragments, and driving the hydrogen to a height of two hundred thousand
miles. The lowest figure on the right shows another case where inclined
jets (of hydrogen) were seen to rise to a height of fifty thousand
miles.
Professor Young says of these:--
“Their form and appearance change with great rapidity, so that
the motion can almost be seen with the eye. Sometimes they
consist of pointed rays, diverging in all directions, like
hedgehog-spines. Sometimes they look like flames; sometimes like
sheaves of grain; sometimes like whirling water-spouts, capped
with a great cloud; occasionally they present most exactly the
appearance of jets of liquid fire, rising and falling in graceful
parabolas; frequently they carry on their edges spirals like the
volutes of an Ionic column; and continually they detach filaments
which rise to a great elevation, gradually expanding and growing
fainter as they ascend, until the eye loses them. There is no end
to the number of curious and interesting appearances which they
exhibit under varying circumstances. The velocity of the motions
often exceeds a hundred miles a second, and sometimes, though
very rarely, reaches two hundred miles.”
In the case of the particular phenomenon recorded by Professor Young in
the last illustration, Mr. Proctor, however, has calculated that the
initial velocity probably exceeded five hundred miles a second, which,
except for the resistance experienced by the sun’s own atmosphere,
would have hurled the ejected matter into space entirely clear of the
sun’s power to recall it, so that it would never return.
It adds to our interest in these flames to know that they at least are
connected with that up-rush of heated matter from the sun’s interior,
forming a part of the circulation which maintains both the temperature
of its surface and that radiation on which all terrestrial life
depends. The flames, indeed, add of themselves little to the heat the
sun sends us, but they are in this way the outward and visible signs of
a constant process within, by which we live; and so far they seem to
have a more immediate interest to us, though invisible, than the corona
which surrounds them. But we must remember when we lift our eyes to the
sun that this latter wonder is really there, whether man sees it or
not, and that the cause of its existence is still unknown.
We ask for its “object” perhaps with an unconscious assumption that the
whole must have been in some way provided to subserve _our_ wants; but
there is not as yet the slightest evidence connecting its existence
with any human need or purpose, and as yet we have no knowledge that,
in this sense, it exists to any “end” at all. “As the thought of man is
widened with the process of the suns,” let us hope that we shall one
day know more.
III.
THE SUN’S ENERGY.
“It is indeed,” says good Bishop Berkeley, “an opinion strangely
prevailing amongst men that ... all sensible objects have an existence
... distinct from their being perceived by the understanding. But
... some truths there are, so near and obvious to the mind, that a
man need only open his eyes to see them. Such I take this important
one to be, namely, that all the choir of heaven and furniture of the
earth--in a word, all those bodies which compose the mighty frame of
the world--have not any subsistence without a mind.”
We are not going to take the reader along “the high priori road” of
metaphysics, but only to speak of certain accepted conclusions of
modern experimental physics, which do not themselves, indeed, justify
all of Berkeley’s language, but to which these words of the author of
“A New Theory of Vision” seem to be a not unfit prelude.
When we see a rose-leaf, we see with it what we call a color, and we
are apt to think it is in the rose. But the color is in _us_, for it is
a sensation which something coming from the sun excites in the eye; so
that if the rose-leaf were still there, there would be no color unless
there were an eye to receive and a brain to interpret the sensation.
Every color that is lovely in the rainbow or the flower, every hue
that is vivid in a ribbon or sombre in the grave harmonies of some
old Persian rug, the metallic lustre of the humming-bird or the sober
imperial yellow of precious china,--all these have no existence as
color apart from the seeing eye, and all have their fount and origin in
the sun itself.
“Color” and “light,” then, are not, properly speaking, external things,
but names given to the sensations caused by an uncomprehended something
radiated from the sun, when this falls on our eyes. If this very same
something falls on our face, it produces another kind of sensation,
which we call “heat,” or if it falls on a thermometer it makes it rise;
while if it rests long on the face it will produce yet another effect,
“chemical action,” for it will _tan_ the cheek, producing a chemical
change there; or it will do the like work more promptly if it meet a
photographic plate. If we bear in mind that it is the identically same
thing (whatever that is) which produces all these diverse effects, we
see, some of us perhaps for the first time, that “color,” “light,”
“radiant heat,” “actinism,” etc., are only names given to the diverse
effects of some thing, not things themselves; so that, for instance,
all the splendor of color in the visible world _exists only in the
eye that sees it_. The reader must not suppose that he is here being
asked to entertain any metaphysical subtlety. We are considering a fact
almost universally accepted within the last few years by physicists,
who now generally admit the existence of a something coming from the
sun, which is not itself light, heat, or chemical action, but of which
these are effects. When we give this unknown thing a name, we call it
“radiant energy.”
How it crosses the void of space we cannot be properly said to know,
but all the phenomena lead us to think it is in the form of motion
in some medium,--somewhat (to use an imperfect analogy) like the
transmission through the air of the vibrations which will cause sound
when they reach an ear. This, at any rate, is certain, that there is an
action of some sort incessantly going on between us and the sun, which
enables us to experience the effects of light and heat. We assume
it to be a particular mode of vibration; but whatever it is, it is
repeated with incomprehensible rapidity. Experiments recently made by
the writer show that the _slower_ heat vibrations which reach us from
the sun succeed each other nearly 100,000,000,000,000 times in a single
second, while those which make us see, have long been known to be more
rapid still. These pass outward from the sun in every direction, in
ever-widening spheres; and in them, so far as we know, lies the potency
of life for the planet upon whose surface they fall.
Did the reader ever consider that next to the mystery of gravitation,
which draws all things on the earth’s surface down, comes that
mystery--not seen to be one because so familiar--of the occult force
in the sunbeams which lifts things _up_? The incomprehensible energy
of the sunbeam brought the carbon out of the air, put it together in
the weed or the plant, and lifted each tree-trunk above the soil. The
soil did not lift it, any more than the soil in Broadway lifted the
spire of Trinity. Men brought stones there in wagons to build the
church, and the sun brought the materials in its own way, and built up
alike the slender shaft that sustains the grass blade and the column
of the pine. If the tree or the spire fell, it would require a certain
amount of work of men or horses or engines to set it up again. So much
actual work, at least, the sun did in the original building; and if we
consider the number of trees in the forest, we see that this alone is
something great. But besides this, the sun locked up in each tree a
store of energy thousands of times greater than that which was spent in
merely lifting the trunk from the ground, as we may see by unlocking
it again, when we burn the tree under the boiler of an engine; for it
will develop a power equal to the lifting of thousands of its kind,
if we choose to employ it in this way. This is so true, that the tree
may fall, and turn to coal in the soil, and still keep this energy
imprisoned in it,--keep it for millions of years, till the black lump
under the furnace gives out, in the whirling spindles of the factory or
the turning wheel of the steamboat, the energy gathered in the sunshine
of the primeval world.
The most active rays in building up plant-life are said to be the
yellow and orange, though Nature’s fondness for green everywhere is
probably justified by some special utility. At any rate, the action
of these solar rays is to decompose the products of combustion, to
set free the oxygen, and to fix the carbon in the plant. Perhaps
these words do not convey a definite meaning to the reader, but it
is to be hoped they will, for the statement they imply is wonderful
enough. Swift’s philosopher at Laputa, who had a project for extracting
sunbeams out of cucumbers, was wiser than his author knew; for
cucumbers, like other vegetables, are now found to be really in large
part put together by sunbeams, and sunbeams, or what is scarcely
distinguishable from such, could with our present scientific knowledge
be extracted from cucumbers again, only the process would be too
expensive to pay. The sunbeam, however, does what our wisest chemistry
cannot do: it takes the burned out ashes and makes them anew into green
wood; it takes the close and breathed out air, and makes it sweet and
fit to breathe by means of the plant, whose food is the same as our
poison. With the aid of sunlight a lily would thrive on the deadly
atmosphere of the “black hole of Calcutta;” for this bane to us, we
repeat, is vital air to the plant, which breathes it in through all its
pores, bringing it into contact with the chlorophyl, its green blood,
which is to it what the red blood is to us; doing almost everything,
however, by means of the sun ray, for if this be lacking, the oxygen is
no longer set free or the carbon retained, and the plant dies. This too
brief statement must answer instead of a fuller description of how the
sun’s energy builds up the vegetable world.
But the ox, the sheep, and the lamb feed on the vegetable, and we in
turn on them (and on vegetables too); so that, though we might eat
our own meals in darkness and still live, the meals themselves are
provided literally at the sun’s expense, virtue having gone out of him
to furnish each morsel we put in our mouths. But while he thus prepares
the material for our own bodies, and while it is plain that without him
we could not exist any more than the plant, the processes by which he
acts grow more intricate and more obscure in our own higher organism,
so that science as yet only half guesses how the sun makes us. But the
making is done in some way by the sun, and so almost exclusively is
every process of life.
It is not generally understood, I think, how literally true this is
of every object in the organic world. In a subsequent illustration
we shall see a newspaper being printed by power directly and visibly
derived from the sunbeam. But all the power derived from coal, and all
the power derived from human muscles, comes originally from the sun,
in just as literal a sense; for the paper on which the reader’s eye
rests was not only made primarily from material grown by the sun, but
was stitched together by derived sun-power, and by this, also, each
page was printed, so that the amount of this solar radiation expended
for printing each chapter of this book could be stated with approximate
accuracy in figures. To make even the reader’s hand which holds this
page, or the eye which sees it, energy again went out from the sun; and
in saying this I am to be understood in the plain and common meaning of
the words.
Did the reader ever happen to be in a great cotton-mill, where many
hundreds of operatives watched many thousands of spindles? Nothing is
visible to cause the multiplied movement, the engine being perhaps away
in altogether another building. Wandering from room to room, where
everything is in motion derived from some unseen source, he may be
arrested in his walk by a sudden cessation of the hum and bustle,--at
once on the floor below, and on that above, and all around him. The
simultaneousness of this stoppage at points far apart when the steam
is turned off, strikes one with a sense of the intimate dependence of
every complex process going on upon some remote invisible motor. The
cessation is not, however, absolutely instantaneous; for the great
fly-wheel, in which a trifling part of the motor power is stored, makes
one or two turns more, till the energy in this also is exhausted,
and all is still. The coal-beds and the forests are to the sun what
the fly-wheel is to the engine: all their power comes from him; they
retain a little of it in store, but very little by comparison with the
original; and were the change we have already spoken of to come over
the sun’s circulation,--were the solar engine disconnected from us,--we
could go on perhaps a short time at the cost of this store, but when
this was over it would be over with us, and all would be still here too.
Is there not a special interest for us in that New Astronomy which
considers these things, and studies the sun, not only in the heavens as
a star, but in its workings here, and so largely in its relations to
man?
* * * * *
Since, then, we are the children of the sun, and our bodies a product
of its rays, as much as the ephemeral insects that its heat hatches
from the soil, it is a worthy problem to learn how things earthly
depend upon this material ruler of our days. But although we know it
does nearly all things done on the earth, and have learned a little of
the way it builds up the plant, we know so little of the way it does
many other things here that we are still often only able to connect the
terrestrial effect with the solar cause by noting what events happen
together. We are in this respect in the position of our forefathers,
who had not yet learned the science of electricity, but who noted
that when a flash of lightning came a clap of thunder followed, and
concluded as justly as Franklin or Faraday could have done that there
was a physical relation between them. Quite in this way, we who are in
a like position with regard to the New Astronomy, which we hope will
one day explain to us what is at present mysterious in our connection
with the sun, can as yet often only infer that when certain phenomena
there are followed or accompanied by others here, all are really
connected as products of one cause, however dissimilar they may look,
and however little we know what the real connection may be.
There is no more common inquiry than as to the influence of sun-spots
on the weather; but as we do not yet know the real nature of the
connection, if there be any, we can only try to find out by assembling
independent records of sun-spots and of the weather here, and noticing
if any changes in the one are accompanied by changes in the other; to
see, for instance, if when sun-spots are plenty the weather the world
over is rainy or not, or to see if when an unusual disturbance breaks
out in a sun-spot any terrestrial disturbance is simultaneously noted.
[Illustration: FIG. 48.--SUN-SPOTS AND PRICE OF GRAIN. (FROM
“OBSERVATIONS OF SOLAR SPOTS.”)]
When we remember how our lives depend on a certain circulation in
the sun, of which the spots appear to be special examples, it is of
interest not only to study the forms within them, as we have already
been doing here, but to ask whether the spots themselves are present
as much one year as another. The sun sometimes has numerous spots on
it, and sometimes none at all; but it does not seem to have occurred to
any one to see whether they had any regular period for coming or going,
till Schwabe, a magistrate in a little German town, who happened to
have a small telescope and a good deal of leisure, began for his own
amusement to note their number every day. He commenced in 1826, and
with German patience observed daily for forty years. He first found
that the spots grew more numerous in 1830, when there was no single
day without one; then the number declined very rapidly, till in 1833
they were about gone; then they increased in number again till 1838,
then again declined; and so on, till it became evident that sun-spots
do not come and go by chance, but run through a cycle of growth and
disappearance, on the average about once in every eleven years. While
amusing himself with his telescope, an important sequence in Nature had
thus been added to our knowledge by the obscure Hofrath Schwabe, who
indeed compares himself to Saul, going out to seek his father’s asses
and finding a kingdom. Old records made before Schwabe’s time have
since been hunted up, so that we have a fairly connected history of the
sun’s surface for nearly a hundred and fifty years; and the years when
spots will be plentiful or rare can now be often predicted from seeing
what has been in the past. Thus I may venture to say that the spots, so
frequent in 1885, will have probably nearly disappeared in 1888, and
will be probably very plentiful in 1894. I do not know at all why this
is likely to happen; I only know that it has repeatedly happened at
corresponding periods in the past.
“Now,” it may be asked, “have these things any connection with weather
changes, and is it of any practical advantage to know if they have?”
Would it be, it may be answered, of any practical interest to a
merchant in bread-stuffs to have private information of a reliable
character that crops the world over would be fine in 1888 and fail in
1894? The exclusive possession of such knowledge might plainly bring
“wealth beyond the dreams of avarice” to the user; or, to ascend
from the lower ground of personal interest to the higher aims of
philanthropy and science, could we predict the harvests, we should
be armed with a knowledge that might provide against coming years of
famine, and make life distinctly happier and easier to hundreds of
millions of toilers on the earth’s surface.
“But can we predict?” We certainly cannot till we have, at any rate,
first shown that there is a connection between sun-spots and the
weather. Since we know nothing of the ultimate causes involved, we can
only at present, as I say, collect records of the changes there, and
compare them with others of the changes here, to see if there is any
significant coincidence. To avoid columns of figures, and yet to enable
the reader to judge for himself in some degree of the evidence, I will
give the results of some of these records represented graphically by
curves, like those which he may perhaps remember to have seen used to
show the fluctuations in the value of gold and grain, or of stocks in
the stock-market. It is only fair to say that mathematicians used this
method long before it was ever heard of by business men, and that the
stockbrokers borrowed it from the astronomers, and not the astronomers
from them.
In Fig. 48, from Carrington’s work, each horizontal space represents
ten years of time, and the figures in the upper part represent the
fluctuations of the sun-spot curve. In the middle curve, variations
in vertical distances correspond to differences in the distance from
the sun of the planet Jupiter, the possibility of whose influence
on sun-spot periods can thus be examined. In the third and lowest,
suggested by Sir William Herschel, the figures at the side are
proportional to the price of wheat in the English market, rising when
wheat ruled high, falling when it was cheap. In all three curves
one-tenth of a horizontal spacing along the top or bottom corresponds
to one year; and in this way we have at a glance the condensed result
of observations and statistics for sixty years, which otherwise stated
would fill volumes. The result is instructive in more ways than one.
The variations of Jupiter’s distance certainly do present a striking
coincidence with the changes in spot frequency, and this may indicate
a real connection between the phenomena; but before we decide that
it does so, we must remember that the number of cycles of change
presented by the possible combination of planetary periods is all but
infinite. Thus we might safely undertake, with study enough, to find a
curve, depending solely on certain planetary configurations, which yet
would represent with quite striking agreement for a time the rise and
fall in any given railroad stock, the relative numbers of Democratic
and Republican congressmen from year to year, or anything else with
which the heavenly bodies have in reality as little to do. The third
curve (meant by the price of wheat to test the possible influence of
sun-spots on years of good or bad harvests) is not open to the last
objection, but involves a fallacy of another kind. In fact the price
of wheat depends on many things quite apart from the operations of
Nature,--on wars and legislation, for instance; and here the great
rise in the first years of the century is as clearly connected with the
great continental wars of the first Napoleon, which shut up foreign
ports, as the sudden fall about 1815, the year of Waterloo, is with
the subsequent peace. Meanwhile an immense amount of labor has been
spent in making tables of the weather, and of almost every conceivable
earthly phenomenon which may be supposed to have a similar periodic
character, with very doubtful success, nearly every one having brought
out some result which might be plausible if it stood alone, but which
is apt to be contradicted by the others. For instance, Mr. Stone,
at the Cape of Good Hope, and Dr. Gould, in South America, consider
that the observations taken at those places show a little diminution
of the earth’s temperature (amounting to one or two degrees) at a
sun-spot maximum. Mr. Chambers concludes, from twenty-eight years’
observations, that the hottest are those of most sun-spots. So each of
these contradicts the other. Then we have Gelinck, who, from a study of
numerous observations, concludes that all are wrong together, and that
there is really no change in either way.
[Illustration: FIG. 49.--SUN-SPOT OF NOV. 16, 1882, AND EARTH.]
I might go on citing names with no better result. One observer
tabulates observations of terrestrial temperature, or rain-fall, or
barometer, or ozone; another, the visitations of Asiatic cholera; while
still another (the late Professor Jevons) tabulates commercial crises
with the serious attempt to find a connection between the sun-spots and
business panics. Of making such cycles there is no end, and much study
of them would be a weariness I will not inflict.
[Illustration: FIG. 50.--GREENWICH RECORD OF DISTURBANCE OF MAGNETIC
NEEDLE, NOV. 16 AND 17, 1882.]
Our own conclusion is, that from such investigations of terrestrial
changes nothing is yet certainly known with regard to the influence
of sun-spots on the weather. There is, however, quite another way;
that is, to measure their effect at the origin in the sun itself.
The sun-spot is cooler than the rest of the surface, and it might be
thought that when there are many the sun would give less heat. As far
as the spots themselves are concerned, this is so, but in a very small
degree. I have been able to ascertain how much this deprivation of heat
amounts to, and find it is a real but a most insignificant quantity,
rising to about two-thirds of one degree Fahrenheit every eleven
years. This, it will be remembered, is the direct effect of the spots
considered merely as so many cool patches on the surface, and it does
not imply that when there are most spots the sun will necessarily give
less heat. In fact there may be a compensating action accompanying them
which makes the radiation greater than when they are absent. I will not
enter on a detailed explanation, but only say that in the best judgment
I can form by a good deal of study and direct experiment, there is no
certain evidence that the sun is hotter at one time than at another.