ECLIPSES OF THE SUN DURING THE NINETEENTH CENTURY.
Observations of total solar eclipses during the 19th century have been,
for the most part, carried on under circumstances so essentially
different from everything that has gone before, that not only does a new
chapter seem desirable but also new form of treatment. Up to the
beginning of the 18th century the observations (even the best of them)
may be said to have been made and recorded with but few exceptions by
unskilled observers with no clear ideas as to what they should look for
and what they might expect to see. Things improved a little during the
18th century and the observations by Halley, Maclaurin, Bradley, Don
Antonio Ulloa, Sir W. Herschel, and others in particular rose to a much
higher standard than any which had preceded them. However, it has only
been during the 19th century, and especially during the latter half of
it, that total eclipses of the Sun have been observed under
circumstances calculated to extract from them large and solid extensions
of scientific knowledge. Inasmuch as it has been deemed convenient to
sort out and classify our knowledge under particular heads in previous
chapters, I shall in this chapter speak only of the leading facts of
each eclipse in such an outline form as will avoid as far as possible
unnecessary repetition.
In 1806 a total eclipse of the Sun occurred, visible in N. America.
Observations made in the United States have been handed down to us. Don
Joachin Ferrer, a Spanish astronomer, observed the eclipse at Kinderhook
in the State of New York. The totality lasted more than 4½ m.--a somewhat
unusual length of time. One or two planets and a few 1st magnitude stars
were seen. During the totality there was a slight fall of dew.
On Nov. 19, 1816, there occurred the first total eclipse of the Sun in
the 19th century, the central line of which passed over Europe. There is
only one known observation of the total phase, and this was by Hagen at
Culm in Bohemia, but he appears to have seen only the beginning of the
totality and not the whole of it.
A partial eclipse of the Sun visible as such in England but which was
annular in the Shetland Isles took place on Sept. 7, 1820. The only
reason why this is worth mention is for its political associations. The
trial of Queen Caroline was going on in the House of Lords, and the
House suspended its sitting for a short time for the sake of the
eclipse.
On May 15, 1836, there occurred an annular eclipse of the Sun, which
though it was nowhere total, may be looked upon as the first of the
modern eclipses the observations of which have taken such a great
development during recent years. The annularity of this eclipse was
observed in the N. of England and in the S. of Scotland; and it was at
Jedburgh in Roxburghshire that Mr. Francis Baily[108] observed that
feature of eclipses of the Sun now universally known as "Baily's Beads."
Some indications of the Red Flames were also obtained at places where
the eclipse was annular.
Probably it was the recognition of Baily's Beads as a regular
concomitant of eclipses of the Sun, which helped to pave the way for the
extensive preparations made in France, Italy, Austria, and Russia for
observing the total eclipse of July 8, 1842. Many of the most eminent
astronomers of Europe repaired to different stations on the central line
in order to see the phenomenon. Amongst these may be named Arago, Valz,
Airy, Carlini, Santini, and O. Struve. The eclipse was witnessed under
favourable circumstances at all the various stations on the central line
across Europe, from Perpignan in France in the West to Lipesk in Russia
in the East.
Arago wrote[109] such an exceedingly graphic account of this eclipse
from what may be termed the standpoint of the general public, that I
will quote it at some length, because, with an alteration of date, it
might be re-written and applied to every total eclipse visible in much
populated tracts of country.
"At Perpignan persons who were seriously unwell alone remained within
doors. As soon as day began to break the population covered the terraces
and battlements of the town, as well as all the little eminences in the
neighbourhood, in hopes of obtaining a view of the Sun as he ascended
above the horizon. At the citadel we had under our eyes, besides
numerous groups of citizens established on the slopes, a body of
soldiers about to be reviewed.
"The hour of the commencement of the eclipse drew nigh. More than twenty
thousand persons, with smoked glasses in their hands, were examining the
radiant globe projected upon an azure sky. Although armed with our
powerful telescopes, we had hardly begun to discern the small notch on
the western limb of the Sun, when an immense exclamation, formed by the
blending together of twenty thousand different voices, announced to us
that we had anticipated by only a few seconds the observation made with
the unaided eye by twenty thousand astronomers equipped for the
occasion, whose first essay this was. A lively curiosity, a spirit of
emulation, the desire of not being outdone, had the privilege of giving
to the natural vision an unusual power of penetration. During the
interval that elapsed between this moment and the almost total
disappearance of the Sun we remarked nothing worthy of relation in the
countenances of so many spectators. But when the Sun, reduced to a very
narrow filament, began to throw upon the horizon only a very feeble
light, a sort of uneasiness seized upon all; every person felt a desire
to communicate his impressions to those around him. Hence arose a deep
murmur, resembling that sent forth by the distant ocean after a tempest.
The hum of voices increased in intensity as the solar crescent grew more
slender; at length the crescent disappeared, darkness suddenly succeeded
light, and an absolute silence marked this phase of the eclipse with as
great precision as did the pendulum of our astronomical clock. The
phenomenon in its magnificence had triumphed over the petulance of
youth, over the levity which certain persons assume as a sign of
superiority, over the noisy indifference of which soldiers usually make
profession. A profound stillness also reigned in the air; the birds had
ceased to sing. After an interval of solemn expectation, which lasted
about two minutes, transports of joy, shouts of enthusiastic applause,
saluted with the same accord, the same spontaneous feeling, the first
reappearance of the rays of the Sun. To a condition of melancholy
produced by sentiments of an indefinable nature there succeeded a lively
and intelligible feeling of satisfaction which no one sought to escape
from or moderate the impulses of. To the majority of the public the
phenomenon had arrived at its term. The other phases of the eclipse had
few attentive spectators beyond the persons devoted especially to
astronomical pursuits."
The total eclipse of July 28, 1851, may be said to have been the first
which was the subject of an "Eclipse Expedition," a phrase which of late
years has become exceedingly familiar. The total phase was visible in
Norway and Sweden, and great numbers of astronomers from all parts of
Europe flocked to those countries. Amongst those who went from England
were Sir G. B. Airy, the Astronomer Royal (then Mr. Airy), Mr. J. R.
Hind and Mr. Lassell. The Red Flames were very much in evidence, and the
fact that they belonged to the Sun and not to the Moon was clearly
established. Hind mentions that "the aspect of Nature during the total
eclipse was grand beyond description." This feature is dwelt upon with
more than usual emphasis in many of the published accounts. I have never
seen it suggested that the mountainous character of the country may have
had something to do with it, but that idea would seem not improbable.
In the year 1858, two central eclipses of the Sun occurred, both
presenting some features of interest. That of March 15 was annular, the
central line passing across England from Lyme Regis in Dorsetshire to
the Wash, traversing portions of Somersetshire, Wiltshire, Berkshire,
Oxfordshire, Northamptonshire, Lincolnshire, and Norfolk. The weather
generally was unfavourable and the annular phase was only observed at a
few places, but important meteorological observations were made and
yielded results, as regards the diminution of temperature, which were
very definite. All over the country rooks and pigeons were seen
returning home during the greatest obscuration; starlings in many places
took flight; at Oxford a thrush commenced its evening song; at Ventnor a
fish in an aquarium, ordinarily visible in the evening only, was in full
activity about the time of greatest gloom; and generally, it was noted
that the birds stopped singing and flew low from bush to bush. The
darkness, though nowhere intense, was everywhere very appreciable and
decided. The second central eclipse of 1858 took place on September 7
and was observed in Peru by Lieutenant Gilliss of the U.S. Navy. The
totality only lasted one minute, and the general features of a total
eclipse do not appear to have been very conspicuously visible. Gilliss
remarks[110]:--"Two citizens of Olmos stood within a few feet of me,
watching in silence, and with anxious countenances, the rapid and
fearful decrease of light. They were wholly ignorant that any sudden
effect would follow the total obscuration of the Sun. At that instant
one exclaimed in terror "_La Gloria_," and both, I believe, fell to
their knees, filled with awe. They appreciated the resemblance of the
Corona to the halos with which the old masters have encircled their
ideals of the heads of our Saviour and the Madonna, and devoutly
regarded this as a manifestation of the Divine Presence."
The year 1860 saw the departure from England of the first great Ship
Expedition to see an eclipse. One was due to happen on July 18, and a
large party went out from England to Spain in H.M.S. _Himalaya_. Mr. De
La Rue took a very well-equipped photographic detachment, and his
photographs were eminently successful. This eclipse settled for ever the
doubt as to whether the Red Flames belonged to the Sun or the Moon, and
in favour of the former view.
The years 1868, 1869, and 1870 were each marked by total eclipses,
which were observed to a greater or less extent. In the first-named year
the eclipse occurred on August 18, the central line passing across
India. The weather was not everywhere favourable, but several
expeditions were dispatched to the East Indies. The spectroscope was
largely brought into play with the immediate result of showing that the
Corona was to be deemed a sort of atmosphere of the Sun, not
self-luminous, but shining by reflected light. The eclipse of 1869 was
observed by several well-equipped parties in the United States, and a
very complete series of excellent photographs was obtained.
To view the eclipse of December 22, 1870, several expeditions were
dispatched, the central line passing over some very accessible places in
Spain, Sicily, and North Africa. The English observers went chiefly in
H.M.S. _Urgent_, though some of them travelled overland to Sicily. The
expenses, both of the sea and land parties, were to a large extent
defrayed by Her Majesty's Government. It deserves to be noted that so
great was the anxiety of the French astronomer Janssen to see this
eclipse, that he determined to try and escape in a balloon from Paris
(then besieged by the Germans) and succeeded, carrying his instruments
with him. The weather seriously interfered with the work of all the
observers who went out to see this eclipse, which was the more to be
regretted because the preparations had been on a very extensive and
costly scale. The chief result was that it was ascertained that the Red
Flames (hence forward generally called "Prominences") are composed of
hydrogen gas in an incandescent state.
The year 1871 saw, on December 12, another Indian eclipse, noteworthy
for the numerous and excellent photographs which were obtained of the
Corona, of the rifts in it, and of the general details, which were well
recorded on the plates.
There was an eclipse visible in South Africa on April 16, 1874. Some
useful naked eye views were obtained and recorded, but as no
photographic work was done, this eclipse cannot be said to come into
line with those which preceded or followed it.
In the following year, that is to say on April 6, 1875, there was a
total eclipse of the Sun, visible in the far East, especially Siam; but
the distance from England, coupled with the very generally unfavourable
weather, prevented this from being anything more than a second-class
total eclipse, so to speak, although extensive preparations had been
made, and the sum of £1000 had been granted by the British Government
towards the expenses. A certain number of photographs were obtained, but
none of any very great value.
Perhaps of the next eclipse which we have to consider, it may be said
that the circumstances were more varied than those of any other during
the second half of the 19th century. The eclipse in question occurred on
July 29, 1878.
Several favourable circumstances concurred to make it a notable event.
In the first place, the central line passed entirely across the United
States; in other words, across a long stretch of inhabited and civilised
territory, accessible from both sides to a nation well provided with the
requisite scientific skill and material resources of every kind. But
there was another special and rare facility available: the central line
crossed the chain of the Rocky Mountains, an elevated locality, which an
American writer speaks of as overhung by "skies of such limpid
clearness, that on several evenings Jupiter's satellites were seen with
the naked eye." On the summit of a certain peak, known as Pike's Peak, a
party of skilled observers, headed by Professor Langley, observed the
wonderful developments of the Corona, mentioned on a previous page. The
fact that such a display came under the eyes of man was no doubt mainly
due to the superbly clear atmosphere through which the observations were
made. That this is not a mere supposition may be inferred from the fact
that at the lower elevation of only 8000 feet, instead of 14,000 feet,
the Coronal streamers were seen by Professor Newcomb's party, far less
extended than Langley saw them. Perhaps the best proof of the importance
of a diaphanous sky is to be found in the fact that on the summit of
Pike's Peak, the Corona remained visible for fully 4 minutes after the
total phase had come to an end. A comparison of the descriptions shows
that even at the elevation of 10,200 ft. the observers placed there,
whilst they were better off than those at 8000 ft., assuredly did not
see so much or so well as those at 14,000 ft.
There occurred a total eclipse on July 11, 1880, visible in California,
but as the totality lasted only 32 secs. and the Sun's elevation was
only 11°, not much was got out of this eclipse notwithstanding that it
was observed in a cloudless sky at a station 6000 ft. above the sea.
The eclipse of May 17, 1882, yielded several interesting and important
features although the totality was short--only about 1¼ minutes. Here
again favourable local circumstances helped astronomers in more ways
than one. It was in Egypt that the eclipse was visible, and Egypt is a
country which it is exceedingly easy for travellers to reach, and it is
also noted for its clear skies. These were doubtless two of the reasons
which combined to inspire the elaborate preparations which were made for
photographic and spectroscopic observations. The former resulted in a
very unprecedented success. One of Dr. Schuster's photographs of the
totality showed not only the expected Corona, but an unexpected comet.
Though on more than one previous occasion in history the darkness which
is a special accompaniment of a total eclipse had caused a comet to be
seen, yet the 1882 eclipse was the first at which a comet had thrust
itself upon the notice of astronomers by means of a photographic plate.
It will be remembered that the political circumstances of Egypt in 1882
were of a somewhat strained character and probably this contributed to
the development of an unusual amount of astronomical competition in
connection with this eclipse. Not only did the Egyptian Government grant
special facilities, but strong parties went out representing England,
France, and Italy, although not perhaps in set terms at the direct
instigation of their respective Governments.
The next eclipse, that of May 6, 1883, had some dramatic features about
it. To begin with its duration was unusually long--nearly 5½ minutes, and
Mrs. Todd in her genial American style remarks:--"After the frequent
manner of its kind, the path lay where it would be least useful--across
the wind-swept wastes of the Pacific. But fortunately one of a small
group of coral islands lay quite in its line, and, nothing daunted, the
brave scientific men set their faces toward this friendly cluster, in
cheerful faith that they could locate there. Directed to take up their
abode somewhere on a diminutive island about which nothing could be
ascertained beforehand, save the bare fact of its existence at a known
spot in mid-ocean, the American observers were absent from the United
States more than three months, most of which time was spent in
travelling, 15,000 miles in all, with ten full weeks at sea. Their tiny
foothold in the Pacific was Caroline Island, a coral atoll on the
outskirts of the Marquesas group."
In spite of the unattractive, not to say forbidding, character of the
place to which they would have to go, parties of astronomers went out
from England, France, Austria, and Italy, and although rain fell on the
morning of the day the sky became quite clear by the time of totality
and the observations were completely successful. One of the pictures of
the Corona obtained by Trouvelot, an observer of French descent, but
belonging to the American party, has been often reproduced in books and
exhibited the Corona in a striking form. How few were the attractions of
Caroline Island as an eclipse station may be judged from the fact that
the inhabitants consisted of only four native men, one woman, and two
children who lived in three houses and two sheds.
On September 8, 1885, there occurred a total eclipse, which was seen as
such in New Zealand, but the observations were few, and with one
exception, unimportant and uninteresting. A certain Mr. Graydon,
however, made a sketch which showed at one point a complete break in the
Corona so that from the very edge of the Moon outwards into space, there
was a long and narrow black space showing nothing but a vacuity. If this
was really the condition of things, such a break in the Corona is
apparently quite unprecedented.
In 1886, on August 29, there occurred a total eclipse, visible in the
West Indies, which yielded various important results. It was unfortunate
that for the greater part of its length, the zone of totality covered
ocean and not land, the only land being the Island of Grenada and some
adjacent parts of South America. The resulting restriction as regards
choice of observing stations was the more to be regretted because the
duration of the totality was so unusually long, and therefore
favourable, being more than 6½ minutes in the middle of the Atlantic
Ocean. Parties of English, American, and Italian astronomers assembled,
however, at Grenada, and though the weather was not the best possible,
some interesting photographs were obtained which exhibited an unusual
development of hydrogen protuberances. The central line in this eclipse
not only stretched right across the Atlantic, but entered Africa on the
West Coast where a missionary saw the eclipse as a mere spectator, and
afterwards expressed his regret that no astronomers were within reach
with instruments to record the remarkable Corona which was displayed to
his gaze.
Though the unusual opportunities which, so far as the Sun and the Moon
were concerned, were afforded by the eclipse of 1886 were lost,
astronomers looked out hopefully for August 19, 1887, when another
eclipse was due to happen which, weather permitting, would be observable
over a very long stretch of land, from Berlin through Russia and Siberia
to Japan. Unusually extensive preparations were made in Russia at one
end and in Japan at the other, but clouds prevailed very generally, and
the pictures of the Corona which were obtained fell far short in number
and quality from what had been hoped for, having regard to the number
and importance of the stations chosen, and of the astronomers who made
their preparations thereat. An enthusiastic Russian, in the hopes of
emancipating himself from the risks of terrestrial weather at the
Earth's surface, went up in a balloon to an elevation of more than two
miles. His enthusiasm was so far rewarded that he had a very clear view
of a magnificent Corona; but as, owing to some mischance, the balloon
rose, conveying only the astronomer and leaving behind his assistant who
was to have managed the balloon, all his time was engrossed by the
management of the balloon, and he could do very little in the way of
purely astronomical work.
The year 1889 afforded two total eclipses of the Sun for which the usual
preparations were made. The first occurred on New Year's Day, and the
path of the shadow crossed the North American Continent from California
to Manitoba. The weather was nearly everywhere very favourable, and an
enormous number of observers and instruments were assembled along the
central line. The consequence was that a very large number of
photographs were obtained. It may be said generally of this eclipse,
that as it coincided with a Sun-spot minimum, it left us in a position
to learn very distinctly what are the characteristic features of a solar
Corona at a period which is one of rest and repose on the Sun, at least,
so far as regards visible Sun-spots.
The second eclipse of 1889 occurred on December 22, and should have been
visible off the northern coast of South America and on the West Coast of
Africa. Attempts were made to utilise the South American chances by
English and American parties, whilst a small expedition comprising
astronomers of both nations went to Cape Ledo in West Africa. The
African efforts failed entirely owing to clouds, but the South American
parties at Cayenne were successful. One very deplorable result, however,
arising out of the expedition to Cayenne was the illness and subsequent
death of the Rev. S. J. Perry, S.J., who was struck down by malaria and
died at sea on the return journey. None who knew Mr. Perry personally
could fail to realise what a loss he was both to astronomy generally and
to his own circle of friends particularly.
On April 16, 1893, there happened a total eclipse of the Sun, which was
successfully watched by a large number of skilled observers throughout
its entire length. Indeed it is believed that only one party was
unsuccessful. The line of totality started on the coast of Chili, passed
over the highlands of that country, across the borders of Argentina and
Paraguay, and over the vast plains and forests of Central Brazil,
emerging at about noon of local time at a short distance to the N.-W. of
Ceara on the North Atlantic seaboard. Crossing the Atlantic nearly at
its narrowest part, it struck the coast of Africa N. of the river
Gambia, and finally disappeared somewhere in the Sahara. The South
American observations were the most extensive and successful, the latter
fact being due to the circumstance that the sky at many of the principal
stations was pre-eminently favourable, owing to the clearness and
dryness of the atmosphere.
On Sept. 29, 1894, there was a total eclipse of the Sun, but as its
duration was brief and the zone of totality lay chiefly over the Indian
Ocean, practically nothing came of it.
Things seemed, however, much more promising for the total eclipse of
Aug. 9, 1896, and a very large number of observers went out to the North
of Norway hoping to catch the shadow at its European end, whilst a
yacht party went to Nova Zembla in the Arctic Ocean, and a few observers
travelled as far as Japan. So far as the very large number of would-be
observers who went from England to Norway were concerned, the eclipse
was a profound disappointment, for owing to bad weather practically
nothing was seen in Norway except on the West coast near Bodö, where the
weather was beautifully fine, but where no adequate preparations had
been made, because nobody believed that the coast would be free from
fog. Exceptionally fine weather prevailed at Nova Zembla, and the small
but select party who were kindly taken there by the late Sir G. B.
Powell, M.P., in his yacht, were very fortunate, and an excellent series
of photographs was secured. One important result obtained at Nova Zembla
was a full confirmation by Mr. Shackleton of Prof. Young's discovery in
1870 of the "Reversing Layer," a discovery which was long and vehemently
disputed by Sir Norman Lockyer. Fairly successful observations were made
of this eclipse in Siberia and Japan.
The last total eclipse of the Sun which has to be noticed as an
accomplished fact was the "Indian Eclipse" of Jan. 22, 1898, which was
very successfully seen by large numbers of people who went to India from
all parts of the world. As usual in all total eclipses of the Sun
nowadays, the photographers were very much to the front, and the
photographs of the inner Corona, taken by the Astronomer Royal, are
thought to have been probably the best that have yet been done. Amongst
the miscellaneous observations made, it may be mentioned that more stars
were seen during the second partial phases than during totality (a
circumstance which had been noticed by Don A. Ulloa as far back as
1778). It is stated also that a mysterious object was seen between Mars
and Venus by two officers of H.M.S. _Melpomene_, which was not put down
on the published chart as a star to be looked for. The identity of this
object has not been ascertained.
FOOTNOTES:
[Footnote 108: _Memoirs_, R.A.S., vol. x. p. 5.]
[Footnote 109: _L'Annuaire_, 1846, p. 303.]
[Footnote 110: _Month. Not._, R.A.S., vol. xx. p. 301; May 1860.]