Caroline Islands was supposed to be more desirable than Flint Island.
Admiral Wilkes's expedition had lain off the latter several days
without being able to land on account of the tremendous surf, so that
it was eminently desirable to "beat the Frenchman," as the sailors put
it. With this end in view our party had secured (through a member of
the National Academy in Washington) the verbal promise of the proper
official of the Navy Department that the Hartford's orders should read
"to burn coal as necessary." The last obstacle to success was thus
removed. We were all prepared, and now the ship would take us speedily
to our station.
Imagine our feelings the next day after leaving Callao, when the
commanding officer of the Hartford opened his sealed orders. They read
(dated Washington, in February), "To arrive at Caroline Islands (in
April) with full coal-bunkers!"
Officialism could go no further. Here was an expedition sent on a
slow-sailing ship directly through the regions of calms for four
thousand miles. It was of no possible use to send the expedition at
all unless it arrived in time. And here were our orders "to arrive
with full coal-bunkers."
Fortunately we had unheard-of good-luck. The trade-wind blew for us as
it did for the Ancient Mariner, and we sped along the parallel of 12°
south at the rate of one hundred and fifty miles a day under sail,
while the _Eclaireur_ was steaming for thirty days a little nearer the
equator in a dead calm. We arrived off the island just in time, with
not a day to spare. It was a narrow escape, and a warning to all of us
never to sail again under sealed orders unless we knew what was under
the seal.
Here we were, then, lying off the island and scanning its sparse crown
of cocoanut palms, looking for a French flag among their wavy tufts.
There was none in sight. We were the winners in the long race.
Directly a whale-boat was lowered, and rowed around the white fringe
of tremendous surf that broke ceaselessly against the vertical wall of
coral rock. There was just one narrow place where the waves rolled
into a sort of cleft and did not break. Here was the "landing," then.
Landing was an acrobatic feat. In you went on the crest of a wave,
pointing for the place where the blue seas did not break into white.
An instant after, you were in the quiet water inside of the surf. Jump
out everybody and hold the boat! Then it was pick up the various
instruments, and carry them for a quarter of a mile to high-water mark
and beyond, over the sharp points of the reef.
In one night we were fairly settled; in another the Hartford had
sailed away, leaving us in our fairy paradise, where the corals and
the fish were of all the brilliant hues of the rainbow, and where the
whiteness of the sand, the emerald of the lagoon, and the turquoise of
the ocean made a picture of color and form never to be forgotten.
But where are the Frenchmen? The next morning there is the _Eclaireur_
lying a mile or so out, and there is a boat with the bo'sun--_maître
d'équipage_--pulling towards the surf. I wade out to the brink. He
halloes:
"Where is the landing, then?"
"_Mais ici_"--Right here,--I say.
"Yes, that's all very well for _persons_, but where do you land _les
bagages_?"
"_Mais ici_" I say again, and he says, "_Diable!_"
But all the same he lands both persons and baggage in a neat,
sailor-like way. In a couple of days our two parties of fifty persons
had taken possession of this fairy isle. Observatories go up,
telescopes, spectroscopes, photographic cameras are pointed and
adjusted. The eventful day arrives. Everything is successful. Then
comes the Hartford and takes us away, and a few days later comes the
_Eclaireur_, and the Frenchmen are gone. The little island is left
there, abandoned to the five natives who tend the sickly plantation of
cocoa-palms, and live from year to year with no incident but the
annual visit of "the blig" (Kanaka for brig), which brings their store
of ship biscuit and molasses.
[Illustration: "OBSERVATORIES GO UP."]
Think of their stupendous experience! For years and years they have
lived like that in the marvellous, continuous charm of the silent
island. The "blig" had come and gone away this year, and there will
be no more disturbance and discord for a twelve-month longer.
"Surely, surely, slumber is more sweet than toil, the shore
Than labor in the deep mid-ocean, wind, and wave, and oar,
Then rest ye, brother mariners, we will not wander more!"
Not so! for here comes a great warship out of the East under a press
of canvas. What event is this? See! she clews up her light sails and
fires an eleven-inch gun! One of those guns of Mobile Bay. Then swarms
out the starboard watch, one hundred and sixty strong, and a fleet of
boats brings ashore these pale astronomers with those useless tubes
that they point at the sky every night. But there are useful things
too; cooking-stoves, and lumber, and bricks.
What is all this? No sooner are these established than comes another
ship and fires its gun! and another set of hardy sailormen pours out,
and here is another party of madmen with tubes,--yes, and with
cooking-stoves and lumber, too. Then comes the crowning, stupendous,
and unspeakable event. The whole sun is hidden and the heavens are
lighted up with pearly streamers! In the name of all the Polynesian
gods, what is the meaning of all this?
And then in a few days all these are gone. All the madmen. They have
taken away the useless tubes, but they have left their houses
standing. Their splendid, priceless, precious cook-stoves are here.
See! here is a frying-pan! here are empty tin cans! and a keg of
nails! They must have forgotten all this, madmen as they are!
And the little island sinks back to its quiet and its calm. The lagoon
lies placid like a mirror. The slow sea breaks eternally on the outer
reef. The white clouds sail over day by day. The seabirds come back to
their haunts,--the fierce man-of-war birds, the gentle, soft-eyed
tern. But we, whose island home was thus invaded--are we the same? Was
this a dream? Will it happen again next year? every year? What indeed
was it that happened,--or in fact, did it happen at all? Is it not a
dream, indeed?
If we left those peaceful Kanakas to their dream, we Americans have
brought ours away with us. Who will forget it? Which of us does not
wish to be in that peaceful fairyland once more? That is the personal
longing. But we have all come back, each one with his note-books full;
and in a few weeks the stimulus of accustomed habit has taken
possession of us again. Right and wrong are again determined by
"municipal sanctions." We have become useful citizens once more.
Perhaps it is just as well. We should have been poor poets, and we do
not forget. So ends the astronomer's voyage to fairyland.
[Illustration]
HALOS--PARHELIA--THE SPECTRE OF THE BROCKEN, ETC
(FROM THE ATMOSPHERE.)
BY CAMILLE FLAMMARION.
[Illustration]
Treatises on meteorology have not, up to the present day, classified
with sufficient regularity the divers optical phenomena of the air.
Some of these phenomena have, however, been seen but rarely, and have
not been sufficiently studied to admit of their classification. We
have examined the common phenomenon of the rainbow and we have seen
that it is due to the refraction and reflection of light on drops of
water, and that it is seen upon the opposite side of the sky to the
sun in day-time, or the moon at night. We are now about to consider an
order of phenomena which are of rarer occurrence, but which have this
property in common with the rainbow, viz., that they take place also
upon the side of the sky opposite to the sun. These different optical
effects are classed together under the name of _anthelia_ (from
Greek, opposite to, and Greek, the sun). The optical phenomena which
occur on the same side as, or around the sun, such as halos, parhelia,
etc., will be dealt with later on.
Before coming to the anthelia, properly so called, or to the colored
rings which appear around a shadow, it is as well first to note the
effects produced on the clouds and mists that are facing the sun when
it rises or sets.
Upon high mountains, the shadow of the mountain is often seen thrown
either upon the surface of the lower mists or upon the neighboring
mountains, and projected opposite to the sun almost horizontally. I
once saw the shadow of the Righi very distinctly traced upon Mount
Pilate, which is situated to the west of the Righi, on the other side
of the Lake of Lucerne. This phenomenon occurs a few minutes after
sunrise, and the triangular form of Righi is delineated in a shape
very easy to recognize.
The shadow of Mont Blanc is discerned more easily at sunset. MM.
Bravais and Martins, in one of their scientific ascents, noticed it
under specially favorable circumstances, the shadow being thrown upon
the snow-covered mountains, and gradually rising in the atmosphere
until it reached a height of 1°, still remaining quite visible. The
air above the cone of the shadow was tinted with that rosy purple
which is seen, in a fine sunset, coloring the lofty peaks. "Imagine,"
says Bravais, "the other mountains also projecting, at the same
moment, their shadows into the atmosphere, the lower parts dark and
slightly greenish, and above each of these shadows the rosy surface,
with the deeper rose of the belt which separates it from them; add to
this the regular contour of the cones of the shadow, principally at
the upper edge, and lastly, the laws of perspective causing all these
lines to converge the one to the other toward the very summit of the
shadow of Mont Blanc; that is to say, to the point of the sky where
the shadows of our own selves were; and even then one will have but a
faint idea of the richness of the meteorological phenomenon displayed
before our eyes for a few instants. It seemed as though an invisible
being was seated upon a throne surrounded by fire, and that angels
with glittering wings were kneeling before him in adoration."
Among the natural phenomena which now attract our attention, but fail
to excite our surprise, there are some which possess the
characteristics of a supernatural intervention. The names which they
have received still bear witness to the terror which they once
inspired; and even to-day, when science has stripped them of their
marvellous origin, and explained the causes of their production, these
phenomena have retained a part of their primitive importance, and are
welcomed by the _savant_ with as much interest as when they were
attributed to divine agency. Out of a large and very diverse number, I
will first select the _Spectre of the Brocken_.
The Brocken is the highest mountain in the picturesque Hartz chain,
running through Hanover, being three hundred and thirty feet above the
level of the sea.
One of the best descriptions of this phenomenon is given by the
traveller Hane, who witnessed it on the 23d of May, 1797. After having
ascended no less than thirty miles to the summit, he had the good
fortune at last to contemplate the object of his curiosity. The sun
rose at about four o'clock, the weather being fine, and the wind
driving off to the west the transparent vapors which had not yet had
time to be condensed into clouds. About a quarter-past four, Hane saw
in this direction a human figure of enormous dimensions. A gust of
wind nearly blowing off his hat at that moment, he raised his hand to
secure it, and the colossal figure imitated his action. Hane, noticing
this, at once made a stooping movement, and this was also reproduced
by the spectre. He then called another person to him, and placing
themselves in the very spot where the apparition was first seen, the
pair kept their eyes fixed on the Achtermannshohe, but saw nothing.
After a short interval, however, two colossal figures appeared, which
repeated the gestures made by them, and then disappeared.
Some few years ago, in the summer of 1862, a French artist, M.
Stroobant, witnessed and carefully sketched this phenomenon, which is
drawn in full-page illustration, opposite p. 272. He had slept at the
inn of the Brocken, and rising at two in the morning, he repaired to
the plateau upon the summit in the company of a guide. They reached
the highest point just as the first glimmer of the rising sun enabled
them to distinguish clearly objects at a great distance. To use M.
Stroobant's own words, "My guide, who had for some time appeared to be
walking in search of something, suddenly led me to an elevation whence
I had the singular privilege of contemplating for a few instants the
magnificent effect of mirage, which is termed the Spectre of the
Brocken. The appearance is most striking. A thick mist, which seemed
to emerge from the clouds like an immense curtain, suddenly rose to
the west of the mountain, a rainbow was formed, then certain
indistinct shapes were delineated. First, the large tower of the inn
was reproduced upon a gigantic scale; after that we saw our two selves
in a more vague and less exact shape, and these shadows were in each
instance surrounded by the colors of the rainbow, which served as a
frame to this fairy picture. Some tourists who were staying at the inn
had seen the sun rise from their windows, but no one had witnessed the
magnificent spectacle which had taken place on the other side of the
mountain."
Sometimes these spectres are surrounded by colored concentric arcs.
Since the beginning of the present century, treatises on meteorology
designate, under the name of the _Ulloa circle_, the pale external
arch which surrounds the phenomenon, and this same circle has
sometimes been called the "white rainbow." But it is not formed at the
same angular distance as the rainbow, and, although pale, it often
envelops a series of interior colored arcs.
[Illustration: "THE SPECTRE OF THE BROCKEN"]
Ulloa, being in company with six fellow-travellers upon the Pambamarca
at daybreak one morning, observed that the summit of the mountain was
entirely covered with thick clouds, and that the sun, when it rose,
dissipated them, leaving only in their stead light vapors, which it
was almost impossible to distinguish. Suddenly, in the opposite
direction to where the sun was rising, "each of the travellers beheld,
at about seventy feet from where he was standing, his own image
reflected in the air as in a mirror. The image was in the centre of
three rainbows of different colors, and surrounded at a certain
distance by a fourth bow with only one color. The inside color of each
bow was carnation or red, the next shade was violet, the third yellow,
the fourth straw color, the last green. All these bows were
perpendicular to the horizon; they moved in the direction of, and
followed, the image of the person they enveloped as with a glory." The
most remarkable point was that, although the seven spectators were
standing in a group, each person only saw the phenomenon in regard to
his own person, and was disposed to disbelieve that it was repeated in
respect to his companions. The extent of the bows increased
continually and in proportion to the height of the sun; at the same
time their colors faded away, the spectre became paler and more
indistinct, and finally the phenomenon disappeared altogether. At the
first appearance the shape of the bows was oval, but toward the end
they became quite circular. The same apparition was observed in the
polar regions by Scoresby, and described by him. He states that the
phenomenon appears whenever there is mist and at the same time shining
sun. In the polar seas, whenever a rather thick mist rises over the
ocean, an observer, placed on the mast, sees one or several circles
upon the mist.
[Illustration: THE ULLOA CIRCLE.]
These circles are concentric, and their common centre is in the
straight line joining the eye of the observer to the sun, and extended
from the sun toward the mist. The number of circles varies from one to
five; they are particularly numerous and well colored when the sun is
very brilliant and the mist thick and low. On July 23, 1821, Scoresby
saw four concentric circles around his head. The colors of the first
and of the second were very well defined; those of the third, only
visible at intervals, were very faint, and the fourth only showed a
slight greenish tint.
The meteorologist Kaemtz has often observed the same fact in the Alps.
Whenever this shadow was projected upon a cloud, his head appeared
surrounded by a luminous aureola.
To what action of light is this phenomenon due? Bouguer is of opinion
that it must be attributed to the passage of light through icy
particles. Such, also, is the opinion of De Saussure, Scoresby, and
other meteorologists.
In regard to the mountains, as we cannot assure ourselves directly of
the fact by entering the clouds, we are reduced to conjecture. The
aerostat traversing the clouds completely, and passing by the very
point where the apparition is seen, affords one an opportunity of
ascertaining the state of the cloud. This observation I have been able
to make, and so to offer an explanation of the phenomenon.
As the balloon sails on, borne forward by the wind, its shadow travels
either on the ground or on the clouds. This shadow is, as a rule,
black, like all others; but it frequently happens that it appears
alone on the surface of the ground, and thus appears luminous.
Examining this shadow by the aid of a telescope, I have noticed that
it is often composed of a dark nucleus and a penumbra of the shape of
an aureola. This aureola, frequently very large in proportion to the
diameter of the central nucleus, eclipses it to the naked eye, so that
the whole shadow appears like a nebulous circle projected in yellow
upon the green ground of the woods and meadows. I have noticed, too,
that this luminous shadow is generally all the more strongly marked in
proportion to the greater humidity of the surface of the ground.
Seen upon the clouds, this shadow sometimes presents a curious aspect.
I have often, when the balloon emerged from the clouds into the clear
sky, suddenly perceived, at twenty or thirty yards' distance, a second
balloon distinctly delineated, and apparently of a grayish color,
against the white ground of the clouds. This phenomenon manifests
itself at the moment when the sun re-appears. The smallest details of
the car can be made out clearly, and our gestures are strikingly
reproduced by the shadow.
[Illustration: THE SHADOW OF THE BALLOON WAS SEEN BY US.]
On April 15, 1868, at about half-past three in the afternoon, we
emerged from a stratum of clouds, when the shadow of the balloon was
seen by us, surrounded by colored concentric circles, of which the car
formed the centre. It was very plainly visible upon a yellowish white
ground. A first circle of pale blue encompassed this ground and the
car in a kind of ring. Around this ring was a second of a deeper
yellow, then a grayish red zone, and lastly as the exterior
circumference, a fourth circle, violet in hue, and imperceptibly
toning down into the gray tint of the clouds. The slightest details
were clearly discernible--net, robes, and instruments. Every one of
our gestures was instantaneously reproduced by the aerial spectres.
The anthelion remained upon the clouds sufficiently distinct, and for
a sufficiently long time, to permit of my taking a sketch in my
journal and studying the physical condition of the clouds upon which
it was produced. I was able to determine directly the circumstances of
its production. Indeed, as this brilliant phenomenon occurred in the
midst of the very clouds which I was traversing, it was easy for me to
ascertain that these clouds were not formed of frozen particles. The
thermometer marked 2° above zero. The hygrometer marked a maximum of
humidity experienced, namely, seventy-seven at three thousand seven
hundred and seventy feet, and the balloon was then at four thousand
six hundred feet, where the humidity was only seventy-three. It is
therefore certain that this is a phenomenon of the diffraction of
light simply produced by the vesicles of the mist.
The name of diffraction is given to all the modifications which the
luminous rays undergo when they come in contact with the surface of
bodies. Light, under these circumstances, is subject to a sort of
deviation, at the same time becoming decomposed, whence result those
curious appearances in the shadows of objects which were observed for
the first time by Grimaldi and Newton.
The most interesting phenomena of diffraction are those presented by
_gratings_, as are technically denominated the systems of linear and
very narrow openings situated parallel to one another and at very
small intervals. A system of this kind may be realized by tracing with
a diamond, for instance, on a pane of glass equidistant lines very
close together. As the light would be able to pass in the interstices
between the strokes, whereas it would be stopped in the points
corresponding to those where the glass was not smooth, there is, in
reality, an effect produced as if there were a series of openings very
near to each other. A hundred strokes, about 1/25th of an inch in
length, may thus be drawn without difficulty. The light is then
decomposed in spectra, each overlapping the other. It is a phenomenon
of this kind which is seen when we look into the light with the eye
half closed; the eyelashes in this case, acting as a net-work or
grating. These net-works may also be produced by reflection, and it is
to this circumstance that are due the brilliant colors observed when a
pencil of luminous rays is reflected on a metallic surface regularly
striated.
To the phenomena of gratings must be attributed, too, the colors,
often so brilliant, to be seen in mother-of-pearl. This substance is
of a laminated structure; so much so, that in carving it the different
folds are often cut in such a way as to form a regular net-work upon
the surface. It is, again, to a phenomenon of this sort that are due
the rainbow hues seen in the feathers of certain birds, and sometimes
in spiders' webs. The latter, although very fine, are not simple, for
they are composed of a large number of pieces joined together by a
viscous substance, and thus constitute a kind of net-work.
If the sun is near the horizon, and the shadow of the observer falls
upon the grass, upon a field of corn, or other surface covered with
dew, there is visible an aureola, the light of which is especially
bright about the head, but which diminishes from below the middle of
the body. This light is due to the reflection of light by the moist
stubble and the drops of dew. It is brighter about the head, because
the blades that are near where the shadow of the head falls expose to
it all that part of them which is lighted up, whereas those farther
off expose not only the part which is lighted up, but other parts
which are not, and this diminishes the brightness in proportion as
their distance from the head increases. The phenomenon is seen
whenever there is simultaneously mist and sun. This fact is easily
verified upon a mountain. As soon as the shadow of a mountaineer is
projected upon a mist, his head gives rise to a shadow surrounded by a
luminous aureola.
[Illustration: FOG-BOW SEEN FROM THE MATTERHORN.]
_The Illustrated London News_ of July 8, 1871, illustrates one of
these apparitions, "The Fog-Bow, seen from the Matterhorn," observed
by E. Whymper in this celebrated region of the Alps. The observation
was taken just after the catastrophe of July 14, 1865; and by a
curious coincidence, two immense white aerial crosses projected into
the interior of the external arc. These two crosses were no doubt
formed by the intersection of circles, the remaining parts of which
were invisible. The apparition was of a grand and solemn character,
further increased by the silence of the fathomless abyss into which
the four ill-fated tourists had just been precipitated.
[Illustration]
Other optical appearances of an analogous kind are manifested under
different conditions. Thus, for instance, if any one, turning his back
to the sun, looks into water, he will perceive the shadow of his head,
but always very much deformed. At the same time he will see starting
from this very shadow what seem to be luminous bodies, which dart
their rays in all directions with inconceivable rapidity, and to a
great distance. These luminous appearances--these aureola rays--have,
in addition to the darting movement, a rapid rotary movement around
the head.
[Illustration]
THE PLANET VENUS
BY AGNES M. CLERKE.
I.
HESPERUS AND PHOSPHOR.
[Illustration]