the description, by the second correspondent of the newspapers,
where it is said, that during the appearance of the coruscations
in the zenith, “the wind blew gently from the south,” and the
spectator “frequently observed, that when it freshened a little,
the Aurora Borealis became more brilliant in its appearance;” to
which it may also seem the writer’s intention to add,—“sending
beautiful coruscations of light, in rapid succession toward the
zenith, and frequently passing that point, ten or fifteen degrees to
the southward.” Now the reality of any dependence of the light and
motion of the Aurora upon the freshening of the breeze, would seem
too strongly to affect the question of the nature and action of the
_auroral matter_, to be admitted without cautious examination. In
truth, what was it that constituted the luminous matter which we saw
in the zenith? The stars were visible through it. But for luminous
appearances that flew or skimmed along the heavens, we should have
said, that the latter were clear, and that there was nothing but the
purest atmosphere between the earth and the heavens. Was it, then,
the atmospherical matter which was thus illuminated, and which, being
ruffled by the breeze, can be supposed to have really exhibited
the appearances described by this writer, or, was it not, rather,
illuminated _auroral matter_, which was shot through the atmosphere;
and, if this last, how are we to understand that its brilliance, and
still less the frequency and vigour of its coruscations, could have
been affected by the freshening of the breeze?
* * * * *
X. But, taking, now, a final leave of the description of the Aurora
of the 25th of September, and of the observations specially suggested
by it, let us here examine the several particulars which are commonly
offered as part, at least, of its true history; an undertaking,
for the greater convenience of which the account given in a modern
work of much and [p405] deserved reputation, shall be quoted and
considered sentence by sentence, as follows:
1. “AURORA BOREALIS, _Northern Light_, or _Streamers_; a kind of
meteor, appearing in the Northern part of the heavens, mostly in the
winter time, and in frosty weather.
2. “It is in the Arctic regions that it appears in perfection,
particularly during the solstice.
3. “In the Shetland Islands, the Merry Dancers, as they are called,
are the constant attendants of clear evenings, and prove great
reliefs amidst the gloom of the long winter nights.
4. “They commonly appear at twilight, near the horizon, of a dun
colour, approaching to yellow; sometimes continuing in that state,
for several hours, without any sensible motion, after which they
break out into streams of stronger light, spreading into columns, and
altering slowly into ten thousand different shapes, varying their
colours from all the tints of yellow to the obscurest russet.
5. “They often cover the whole hemisphere, and then make the most
brilliant appearance.
6. “Their motions, at these times, are most amazingly quick, and they
astonish the spectators with the rapid change of their form.
7. “They break out in places where none were seen before, skimming
briskly along the heavens; are suddenly extinguished, and leave
behind a uniform dusky track.
8. “This again is brilliantly illuminated in the same manner, and as
suddenly left a dull blank.
9. “In certain nights, they assume the appearance of vast columns; on
one side of the deepest yellow, on the other, declining away till it
becomes undistinguished from the sky.
10. “They have generally a tremulous motion from end to end, which
continues till the whole vanishes.
11. “In a word, we, who only see the extremities of these northern
phenomena, have but a faint idea of their splendour and their motions.
12. “According to the state of the atmosphere, they differ in colour.
13. “They often put on the colour of blood, and then make a most
dreadful appearance[124].” [p406]
1. Now, with respect to the first and second of the sentences here
transcribed, there seems reason to doubt the accuracy of the account
which almost limits the appearances of the Aurora to the “winter
time,” to “frosty weather,” and especially to the winter “solstice.”
The frequency with which the season approaching to Christmas, or that
of the winter solstice, is distinguished by the occurrence of weather
peculiarly mild, insomuch that, almost every year, the period is
marked by observations upon what is annually called the extraordinary
and unseasonable genialness of the weather, cowslips blooming, leaves
budding, and birds building their nests; this frequency of a mild
temperature of the air about the period of the winter solstice, may
justify, even under a general view, a doubt of the accuracy with
which, as things of course, the winter solstice, and frosty weather,
are spoken of as arriving in conjunction. But, that the appearance
of the Aurora Borealis is not peculiar, either to the occurrence of
frosty weather, or to the period of the winter solstice, whether
the two latter phenomena are related or otherwise, seems probable,
as well from the mildness of the weather at the late appearance,
as from the various seasons of the year in which the few others
described in our books are recorded to have presented themselves.
The earliest mentioned was seen in London in the year 1560, on the
30th day of January. The next was in 1564, on the 7th of October.
The next, in 1574, on the 14th and 15th of November. The two next,
observed in Brabant, in 1575, on the 25th of February, and 28th of
September. The next, at Wurtemburg, as we are assured by Meestlin,
seven times, in the year 1580. The next, in an extraordinary manner,
in the months of April and September, 1581; and in a less degree,
at some other places, in the same year. The next, observed all over
France, in 1621, on the 2nd of September. The next in 1707,and 1708,
during which two years the Aurora was witnessed five times. The
next, in the month of March, in 1715–16. The next, in 1737, on the
16th of December; that seen in London in 1791, of the month of which
the writer is uninformed; another in 1803, or 1804, at the latter
of September, or the beginning of October; and this, of 1827, on
the 25th of September. But, from these statements, it is now seen,
that, [p407] exclusive of appearances of the Aurora in respect of
which the month is not particularised, eight of the different months
of the year occur by name; that is to say, the months of September,
October, November, and December, January, February, March, and
April; leaving only four months (May, June, July, and August, the
identical summer-months of the Polar regions, or months during which
the sun visits the Polar horizon!) hitherto undistinguished by the
phenomenon of the Aurora, and almost establishing, as the season of
its occurrence, not the middle point of the winter solstice, but the
whole period extending, in general terms, from the autumnal equinox
to the vernal, beginning at or before the first, and ending at or
after the last; or, what may be called the entire winter of the
northern hemisphere, or the period during which the sun’s course is
to the southward of the tropic of Cancer; a deduction from the scanty
data offered by such archives of the phenomenon as we possess, not,
perhaps, of trifling importance toward the establishment of the true
theory of the cause, as well as of the purpose of its being.
2. The third sentence, where it describes the Aurora Borealis as the
_constant_ attendant of clear evenings in the Shetland Islands, and
thereby a great relief to the gloom of the long winter-nights, is
probably tainted with errors in regard to the phenomenon, such as
affect its whole history and philosophy. The suggestion has just been
hazarded above, that at least considerable displays of the Aurora are
probably almost as rare, even in the Arctic regions, as in climates
further south; and the truth of this persuasion, as the writer
anticipates, will fully appear below. In the sentence now referred
to, the word “constant” should, at least, give way to “frequent,”
if not to “often;” and a distinction should be allowed for, between
those feeble appearances which alone, it may be suspected, are even
_often_ beheld in the Shetland Islands, and those extraordinary
displays which make themselves visible to their southward.
3. The fourth of the above sentences, in which the Aurora is said
to appear commonly at twilight, will have been seen to agree with
the time assigned for the commencement of the Aurora in the late
example; and this, when coupled with the [p408] observation in the
third, that, in the Shetland Islands, it is the constant attendant of
_clear_ evenings, will seem to suggest, what, indeed, will probably
be easily agreed to, that the Aurora, in itself, is peculiar neither
to clear evenings nor to evenings at all; but is in activity during
the twenty-four hours, or without intermission; though, to be visible
to human eyes, first, the atmosphere must be dark, and, secondly, it
must be more or less clear. It may also be thought apparent, from
the terms of the twelfth and thirteenth sentences, that too much
has not been said by the present writer, of the degree in which the
peculiar spectacle, upon each separate occasion, depends, not alone
of the proper and really uniform features of the Aurora itself, but
also of the atmosphere through which it is seen, with the appearance
of which its own appearance is combined; and of the consequent
value of a careful separation of the real phenomena of the Aurora,
from the adventitious phenomena of the intervening and surrounding
atmosphere. That the colours which, whether visibly connected with
the atmosphere or otherwise, are displayed during the appearance of
the Aurora Borealis, are wholly derived from the atmospherical medium
through which we behold it, and that the Aurora itself exhibits
only a pure white light, is what the writer greatly inclines to
suspect, and what may seem to be rendered still more credible by
that which is reported by those who have obtained a partial glimpse
of the Aurora _Australis_, or corresponding phenomenon of the south.
This is described, by Mr. Forster, who sailed round the world with
Captain Cook, as consisting in “long columns of clear white light;”
but the whiteness, in the eyes of the narrator, seemed to establish
a difference, instead of a similitude, between the Auroræ Australis
and Borealis, Mr. F. wholly overlooking the explanation which his own
account supplies! “These columns,” says he, “though in most respects
similar to the Northern Lights (Aurora Borealis) of our hemisphere,
yet differed from them in being always of a whitish colour, whereas
ours assume various tints, especially those of a fiery or purple hue.
The sky was generally clear when they appeared, and the air sharp
and cold, the thermometer standing at the freezing point.” Now this
text is its own commentary. The [p409] Aurora could not have been
seen if the sky had not been more or less _clear_. But the sky was
_very clear_; and this because the weather was _severely frosty_.
The thermometer “was standing at the freezing point.” The weather
was settled frosty, and therefore settled clear; for the Aurora
appeared for “several following nights.” The atmosphere, therefore,
was clear; there was neither cloud nor fog, and thence the whiteness
of the Aurora. But these views of the Aurora _Australis_ were
partial occurrences, and were characterised, as we must conclude,
by the state of the atmosphere at a particular conjuncture, or at
a particular season of the year. In point of fact, the Aurora was
seen on the 16th of February, 1773, in latitude 58° S. This was the
beginning of the Australian winter, and it might be a very cold, and
therefore a very clear beginning. But the atmosphere of the southern
half of the globe is not always thus translucent; and when it is
otherwise, we may depend upon it that the columns of its Aurora
“assume various colours; especially those of a fiery and purple
hue,” more or less like our own. A friend of the present writer
was in the same latitude (58° 12′ S.) in the month of March, a few
years since; and, upon asking that gentleman whether he had ever
beheld an Aurora in the Southern Hemisphere, his answer was in the
negative. The season of his visit, however, was a month later in
the southern winter than the visit of Messrs. Cook and Forster; the
weather was thick and sleety; it was unfavourable to any view of an
Aurora at all; but, had the phenomenon happened to present itself,
its appearance, we may believe, would not have presented that of a
uniform, clear, white light.
4. In the fourth and sixth sentences, what is said of “change of
shape,” and “change of form,” is of a nature exceedingly to mislead
such as, never having themselves witnessed the phenomenon, may
desire either to figure it to their imagination, or to reason upon
its appearances. In reality, there is no such change of shape or
form as the words naturally suggest to our ideas; the forms, under
all changes, are still linear; and the actual changes, as to form,
are limited to such changes only as can be produced with the single
material of lines, lengthened, shortened, varied in their direction,
and now fixed, now shaken, now darting; and now joined in rapid and
intermingling motion. [p410] Add, that these lines are luminous,
and varied in colour from white to yellow, red, and crimson, and,
sometimes, perhaps, to purple and to violet; that they play, in the
lower heavens in a field of light, and in the upper over a sky of
blue; and the picture of the Aurora Borealis is well nigh complete.
The observation in the ninth sentence, that the vast columns, of
which, upon some occasions, the Aurora displays the forms, are of a
deep yellow upon one side, which, upon the other, fades gradually
into that of the sky, is to be understood, as expressing, that, as in
the late example, the outer edges of the columns, or those next the
dark or unillumined portion of the horizon, are sharp and strongly
defined; while the inner ones are less distinguished from the general
field of light in which they stand; and which distinction, after
all, is but a delusion of the eye, which more readily distinguishes
the variation of colour in the outer edge, which is so strongly
relieved by the dark and colder-coloured part of the sky, than the
colour of the inner part and edge of the column, which, more or less,
approaches that of the ground behind it.
5. Sentences seven and eight appear to the present writer to convey
the most accurate description possible, of the appearance of the
Aurora in the _zenith_. The “dusky track,” which remains after
the lights which have enlivened it are extinguished, and in which
they are so often seen again, may seem to attest the justice of
his opinion, that these appearances in the zenith are no other
than the far-projected tops of the columns which have their bases
in, or rather below, the horizon; tops which, while they fill the
southern half of the zenith, to the view of spectators under our
parallel, must gradually descend toward the horizon, in the eyes of
such as behold them further and still further to the south; till,
like the topmast of a receding ship, they first scarcely remain
discoverable above the convexity of the surface intervening, and
finally dip and sink beneath it. But, upon this assumption, the
appearance, and therefore office, of the Aurora Borealis, must
be conceived as extending far to the southward of even our own
island; and the statement, as in the eleventh sentence, becomes
more or less inaccurate, that “only the extremities of these
northern phenomena” are witnessed by ourselves. In reality we are
[p411] ourselves inhabitants of the Northern hemisphere; and the
relationship of the Aurora to the wants of the whole hemisphere is
more extended, perhaps, than we have commonly imagined. It is even
a contradiction to say, as in the eleventh sentence, that we see
only the extremities, that is, the Southern extremities of these
Northern phenomena, after having said, in the fifth sentence, that
“they often cover the whole heavens, and then make the most brilliant
appearance;” unless, indeed, in both of these remarks reference
is made to the spectacle beheld under more Northerly parallels, a
reference which is further suggested, together with their apparent
origin, in the terms of a description by Gmelin, to be cited below,
of the Aurora as beheld upon the coasts of the Icy Sea; If the
Aurora, there, or upon the banks of the Lena or Yenesei, is seen
to rise in the north, but yet to stretch itself over the whole
hemisphere, it must follow, that its “extremities,” that is, its
southern extremities, so far from being all that is seen in these
situations, are really projected, on those occasions, so far to the
southward, as to escape the ken of our northern optics; a fact of
which the explanation must be familiar, inasmuch as, owing to the
convexity of the surface of the globe, the horizon of every part is
narrowly bounded, whether upon the South or upon the North; whence
it results, that any celestial, or even atmospherical appearance,
stretching only a little way beyond us to the Southward, or toward
the East, or toward the West, must soon reach the horizon upon
either of those sides, and thus cover all that, to the eye of any
individual, is visible of the “whole hemisphere.”
6. But the description, by Gmelin, of the Aurora, as seen upon the
shores of the Icy Sea, and more than all, the simplicity with which
the naturalist is disposed to fix its birth-place in that precise
interval of the earth’s surface which divides the mouth of the river
Yenesei from that of the river Lena, in the North-east of Asia, (a
spot so far to the _North-eastward_, too, of our own!) while it may
possibly explain the origin or bearing of remarks, that it “sometimes
covers the whole hemisphere, and then makes the most brilliant
appearance,” will also afford something of an answer to such as, with
the writer quoted above, seeking to connect the Aurora Borealis with
the [p412] Magnetic Pole, would discover its same birth-place, or
focus, in the _North-west_, or nearer to the North-west of America,
than to the North-east of Asia! It may furnish a reply, also, to
Gmelin himself, who, though he tells us that, even upon the banks of
the Lena and Yenesei, the Aurora is still seen to rise to the North
or North-east of those situations, yet imagines those very banks to
be its “real birth-place;” for is it not plain, in the meantime,
and this from the very statement of the author, that, travel as far
northward, or north-eastward, as we will, the birth-place of the
Aurora still retires from our feet; that, even upon the shores of the
Icy Sea, the joyous phantom is still to our Northward, or North-east,
and that we may reasonably conclude, that even a voyage upon that
sea would not carry us to the cradle in pursuit; that, in short, at
the North Pole, we should still behold it rise in the North, or the
North-east, or the North-west; that we might sail down the Western
Hemisphere, and yet only discover, that the Aurora was now in the
North behind our backs, as it had been before in the North before our
faces; and that, in short, so long as we do but admit its existence
in the North, the particular soil or sea is best described in the
most general terms:—
“In Nova Zembla, or the Lord knows where!”
The search, too, for the paternal hearth of the Aurora Borealis in
any particular division of the Northern Hemisphere, and especially
the attempt to find it at the Magnetic or Electric Pole, is, perhaps,
so much the more hopeless, after ascertaining, as above, that each
hemisphere has its Aurora; and after concluding, as we may have
been led to conclude with reason, that each Aurora, other things
equal, resembles the other! What is remarkable, also, is that, in
the Southern Hemisphere, as well as, according to Gmelin, in the
Northern, it is to the Eastward, or to the East of North, that the
Aurora has its apparent focus. “A beautiful phenomenon,” says Mr.
Forster, (Feb. 17, 1773, lat. 58° S.) “had been observed during the
preceding night, which appeared again this and several following
nights. It consisted of long columns of white light, shooting up from
the horizon to the eastward, almost to the zenith, and gradually
spreading over the whole southern part of the sky. These columns
are gradually bent sideways [p413] at their upper extremities; and,
though in most respects similar to the Northern Lights (Aurora
Borealis) of our hemisphere, yet differed from them in being always
of a whitish colour; whereas ours assume various colours, especially
these of a fiery or purple-hue. The sky was generally clear when they
appeared, and the air sharp and cold; the thermometer standing at the
freezing point.” This occasional bending of the columns, “sideways
at their upper extremities,” instead of uniform convergence toward
the zenith, observed by Mr. Forster in the Aurora of the South, is
plainly the same peculiarity which was recently witnessed in London,
in the Aurora of the North, and a circumstance which, in whatever
way explained, assists in the identification of the natures of the
two phenomena; and, if we are still to hesitate, upon account of the
whiter light of that of the South, let us believe that particular to
originate in some peculiar constitution of the Southern atmosphere,
from which, in one way or another, not here to be discussed, the
cause of the difference may offer itself. But Gmelin’s account of
the Aurora of the North, to which the attention of the reader has
already been called, is that which is here required to follow. It is
to serve to illustrate, as will be remembered, much of the foregoing:
“This Northern Light,” says that author, “begins with the rising of
single light pillars in the North, and almost at the same time in the
North-east, which, gradually increasing, fill a large space in the
heavens, rush about, from place to place, with incredible velocity,
and finally almost cover the whole sky, up to the zenith: the streams
are then seen meeting together in the zenith, where they produce an
appearance as if a vast tent was expanded in the heavens, glittering
with gold, rubies, and sapphires. A more beautiful spectacle cannot
be described; but whoever should witness such a Northern Light for
the first time, could not behold it without terror; for, however
beautiful the illumination may be, it is attended, as I have learned
from the relation of many persons, with a hissing, crackling, and
rushing noise, throughout the air, as if the largest fireworks were
playing off. To describe what they then hear, they make use of
the expression, ‘Spolochi chodjat;’ that is, ‘The furious army is
passing!’ The hunters, who, upon the confines of the [p414] Icy Sea,
follow the chase of the blue and white foxes, are often overtaken in
their excursions by the Northern Light; and, upon this occurrence,
their dogs are so much frightened, that they will not move, but cower
obstinately upon the ground till the noise is over. The weather,
after the appearance of the Northern Light, is usually clear and
calm. I have heard these accounts, not from one person only, but from
many of those who have spent several years in these very Northerly
regions, and inhabited different countries from the Yenesei to the
Lena, so that no doubt of its truth can remain; for here seems to be
the real birth-place of the Aurora Borealis.”