Professor C. S. Hastings, of the Johns Hopkins University, also includes
many interesting details in his account of the trip:
The voyage from New York to Panama was pleasant with the exception of a
few hot days near Aspinwall. Somewhat further south the wind changed,
obliging them to call their overcoats from the bottom of their trunks to
keep out the cold when crossing the equator. During a short stop in
Lima the party had an opportunity of studying South American life. The
products of this country are fruits and photographs of the young women.
The party enjoyed both eating the former and bringing the latter home
for the admiration of their friends. The expedition really began at
Callao, where the party embarked on the United States man-of-war
Hartford. Few circumstances contributed more to the enjoyment of the
trip than the lucky chance which threw this vessel in their way. The
Hartford was fitted out last August as flag ship of the South Pacific
squadron. The admiral had not yet removed his flag to the vessel, but
the extra accommodations provided for him and his train condoned the
dignity lost by his absence. On March 22 they weighed anchor for a sail
of more than four thousand miles over the blue ocean which stretches
between Callao and their destination, Caroline Island. The southeast
trade winds favored them, and from the first day there was actually no
necessity for altering the position of a sail....
The inhabitants--five men, one woman and two children, according to
the eclipse census--are natives of Tahiti. The houses are one story
structures with clapboard sides, probably cut out in California and
brought out in ships, to be erected on this island. The island on which
they are built is about three-fourths of a mile in diameter and nearly
circular in outline. The edge, which rises from five to twenty inches
from the water, according to the tide's phase, goes down under the water
to an even table of coral running out many feet into the sea; and is
impossible to step on it with bare feet. At the end of this table the
reef goes down perpendicularly, a sheer precipice, into the unfathomable
sea. No vessel can anchor here, and to make a landing was an exciting
matter. The island was approached in small boats on the side sheltered
from the wind, and here, with the luck which characterized the trip, was
found the only opening in this barrier of coral. A long cleft, perhaps
eight feet wide, at the outer edge of the reef, ran in, narrowing to a
mere crack near the shore. Watching a favorable chance, the boats were
guided through the surf into a cleft as far as shoal water, when the
men jumped on to the reef and carried baggage and instruments ashore as
quickly as possible. The boats, which were new when they entered the
surf, came out much the worse for wear, and the boat in which Dr.
Hastings landed was stove in. Once on shore, life became a succession of
wonders, rivaling the tales of Gulliver, and needing the conscientious
descriptions of exact scientists to make them credible.
The members of the observing party took up their abode in the larger of
the three houses, sleeping in swinging cots slung from the verandas,
which afforded shade on three sides of the building. The second house
was occupied by the sailors, while the third was left to the natives.
These latter were sufficiently conversant with English to serve as
excellent guides. Each day the party bathed in a lagoon in the center of
the island. This lagoon was bordered by a beach of dazzling white coral
sand, and all through its water extended reefs of living coral of
the more delicate and elaborate kinds. These corals gave the lake a
wonderful variety of colors, forming a picture impossible to paint or
describe, and with the least ripple from a passing breeze the whole
scene changed to new groups of color. The water was very clear, and
in some places deep; in others so filled with coral that a boat could
barely skim over the surface without scraping the keel. After crossing a
long reef, one day, they entered on a sheet of water so deep that their
longest line would not reach the bottom, plainly visible beneath. Fish
swarmed here, and it was characteristic of them that every species, if
not brilliantly colored, was marked in the most peculiar manner. One
variety which frequented the shallow water, where it was heated to the
degree uncomfortable to the touch, was a pure milky white, with black
eyes, fins, and tail.
The French party arrived two days after the Americans. They had steamed
directly from Panama with the hope of anticipating the Americans.
It rained on the morning of the eclipse, but cleared off in good time,
and the definition was particularly good. Photographs occupied the time
of the English and French observers. Professor Holden and Dr. Dickson
searched for intra-mercurial planets; Mr. Preston took the times of
contact; Dr. Hastings and Mr. Rockwell devoted their attention to
spectroscopic observations of the corona. Dr. Hastings' observations
have led to the production of a new theory of the corona. Briefly
stated, the theory is that the light seen around the sun during a total
eclipse is not due to a material substance enveloping the sun, but is a
phenomenon of diffraction.
From his observation during the eclipse of 1878, made at Central City,
Dr. Hastings conceived the first idea of this explanation of the solar
corona. Further study served to convince him of the truth of this
theory, but he had no means of proving it. Before the present eclipse,
however, he devised a crucial test of his theory. This test is based on
the following already known phenomena: When the moon covers the face of
the sun, an envelope of light is seen all round it; the envelope is
not visible when the sun is shining, on account of the sun's greater
brightness; this light is called the corona; it is extremely irregular
in outline. According to the drawing of Mr. J. E. Keeler at the eclipse
of 1878, it enveloped the sun as a hazy glow, extending for a distance
of several minutes of arc from the sun's limb and at two nearly opposite
points is extended out in two long streamers feathering off into space.
The opinion has been that this light was due to an atmosphere extending
millions of miles from the sun. According to Dr. Hastings' view, it must
be light from the sun which has undergone refraction, i.e., which has
been bent from its regular course by the interposition of an opaque body
like the moon.
In order to make this perfectly plain, suppose the front of a surface
of waves of any sort to be striking an object which resists them. If
an organ of sense is placed in the resisting object, it will judge the
direction of the waves or the direction of the object producing them by
a line at right angles with the wave front. Now suppose a body is placed
between the body producing the waves and the sensitive organ. The waves
must go around this body and will produce an eddy behind it, so that the
wave front will have a different direction, and the organ of sense will
conceive the origin of the waves to lie in a direction different from
that before the body was interposed. Now consider the waves to be waves
of light, and their origin the sun. The organ of sense is the retina of
the eye. The moon is the opaque body interposed in the course of the
waves, and they, being bent, make the impression on the eye that the
light comes from beyond the edge of the sun. The moon covers the sun
during the eclipse and a little more, so that it can move for about five
minutes and still cover the sun entirely. This movement is very slight,
and if the corona consists of light from a solar atmosphere, it should
not change at all during this movement of the moon. But if diffraction
is the cause of the light, then the slightest change in the relative
positions of the sun and the moon should change the configuration of the
corona, i.e., the corona should not remain exactly the same during
a total eclipse. The character of the light as shown by a spectrum
analysis should change.
To determine this point Dr. Hastings invented the following instrument:
Two lozenge-shaped prisms of glass were fastened in the form of a letter
V, and so arranged that all the light falling within the aperture of
the V was lost, and that falling on the ends of the glass prisms was
transmitted by a series of reflections to the apex of the V, where the
prisms touched; here was placed a refracting prism, so that the light
could be analyzed. This instrument was attached to the eye piece of the
telescope, and the image of the eclipse reduced to such a size that the
moon just fitted into the aperture of the V, while opposite sides of the
corona were reflected through the prisms to the place where they came
together. In this way both sides of the corona were seen through the
eye-piece at the same time. On looking at the eclipse this is what Dr.
Hastings saw: The light of the corona was divided into its constituents.
Prominent among them was a bright green line, which is designated by the
number 1,474; to this line attention was directed. Its presence in the
spectrum has been an argument in favor of the view that the corona is
a solar atmosphere. If this is the case, the line should remain fixed
during the eclipse; but if the corona is due to diffraction, this line
should change. It should grow shorter in the light from one side of the
corona, and longer on the other. The observation was now reduced to
watching for a change in the relative length of two green lines.
At the beginning of totality the line from the west side was much the
longer, but as the eclipse progressed it shortened notably, while the
line from the east side, shorter by about one-third at the beginning of
the eclipse, grew longer. When the eclipse ended, the proportions of the
lines were exactly reversed. There had been a change equal to two-thirds
the length of the lines, while the sun and moon had only changed their
relative positions by an extremely small amount. The only way in which
this phenomenon can be accounted for is on the diffraction theory. The
material view of the corona will not answer for it. But there are other
discrepancies in the older view which have been known for some time.
The principal ones are: 1. It is known from study of the sun that the
gaseous pressure at the surface must be less than an inch of mercury,
and is probably less than one-tenth of an inch, but an atmosphere
extending to the supposed limits would cause an enormous pressure at the
sun's surface, especially since the force of gravity on the sun is very
much greater than on the earth. 2. The laws of gravitation would require
a solar atmosphere to be distributed symmetrically around the sun, while
the corona is enormously irregular in form. The sun is irregular in
outline, which would make its diffracted phenomena show the observed
irregularity, but it is symmetrical as regards density. 3. The most
interesting discrepancy of the theory of the solar atmosphere is the
fact that while it is supposed to extend for millions of miles from the
sun, the recent comet passed within two hundred thousand miles of the
sun, and yet its orbit was not affected in the least, as it would have
been if it had plowed its way through a material substance. In taking
photographs of the corona it is seen to be larger as the time of
exposure is longer. This shows that the corona extends indefinitely, and
it decreases in brilliancy in exact accordance with the mathematical
laws of diffraction. These laws involve very complicated mathematics,
but by them alone Dr. Hastings has proved that there must be diffraction
where the corona is, and that it must follow the same laws as those
observed. There is a small envelope around the sun, but in the opinion
of Dr. Hastings it does not extend beyond what is known as the
chromosphere.
* * * * *
The question seems to be settled, with considerable certainty, that
nothing exists inside of Mercury large enough to be dignified by
the name of planet. There may be, and there probably are, for the
perturbations of Mercury indicate it, multitudes of small masses
circulating around the sun like the planets, being fragments of comets
or condensations of primitive matter, whose combined luster is seen in
the zodiacal light.
The other results of the work of the Commission, so far as now known,
are connected with the structure of the corona, the solar appendage
which extends out for millions of miles from the sun's disk. In the
photographs of the Egyptian eclipse of last summer these streamers can
be traced back of each other where they cross; no better proof of their
extreme tenuity could be given.
The duration of an eclipse of the sun depends on three things, the
distance of the sun from the earth, the distance of the moon from the
earth, and the distance of the station from the equator. All of these
were favorable to a long eclipse in the case of the recent one, and the
six minutes of totality gave opportunities for deliberate work not often
enjoyed.
* * * * *