Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1889-12-21
THE SOLAR ECLIPSE.
Why the American Scientists Go to
the Coast of Africa to
HAVE A PEEP AT OLD SOL.
What is Expected to be Accomplished by To-
MOrrow's Observation.
DELICATE INSTRUMENTS TO BE USED


men of common sense, wisdom and learning
should cease to run after shadows, anC
hence it may be trifle paradoxical to some
folks to learn that dozen or more wise me1
of science. armed with implements for OBJ
servation and literature for reference, should
60 clear across the sea, down into the wild'
of the African jungle, Drawing the dangers o.
the storm, of the savage and of the fever fol
the mere purpose of having a peep at the
sun when he cannot be seen. And there is
another paradox that the sun should never
be quite so interesting or so attractive to
his watchers as when his rays are blotted
from sight for few moments by the acci-
dental interference of the moon between his
solar majesty and this small sphere.
But it is nevertheless true that a party OF
American men of profound learning, en-
bracing several branches of scientific re-
search, have just landed on the west coast OF
Africa, at.the town of st. Paul de Loando,
having gone thither for the purpose of tax
ing some photographs and other observations
on the 22d of the present month (to-morrow),
when the sun will become invisible for a
few minutes.
TO PROBE NATURES MYSTERY.
It has only been by the most unremitting
efforts of the scientists, seizing every oppor-
tunity, risking every chance, encountering
every danger, that we have come at last to
know anything but what is here before us
on our own planet, to know anything about
the nature. the ways and means of our mys-
ferrous neighbors, anything about the causes
of our life, in fact. And this expedition,
sent to such great distance for such an ap-
pGrentlv small and unimportant object, is
simply the outcome OF generations of rest
less scientific energy.
To. some it might appear as though all
had been learned abont the sun that an
eclipse can teach. for ever since telescopes
were invented and men began to know how
to use them, astronomers have been peering
into space during the momentary darkness
of eclipses, measuring, counting, specu-
lating, theorizing, guessing as to just what
it is that gives us light and heat and life;
and it would seem as though the time had
come when all reasonable theories had been
advanced, discussed and disposed of. But
scientist generally goes upon the idea that q
man never knows so much that he cannot
new data on which to work new inspirations
or some additional proof of some old thought.
He takes the ground that there cannot be
too much proof and that it would not be q
waste OF time if he searched all his life for
one new item and never found it.
WHY THEY GO TO AFRICA.
1t is no wonder. then, that these men have
gone to Africa. The only question is: Why
did they select that dark, unknown, danger
GUS and forbidding land ior the basis of
their observations? The answer can easily
be given. By the operation of the law of
planetary motion the shadow of the moon,
as cast by the sun in his paSsageon the other
side, falls only upon limited portion of
the globe, varying in size according to the dis
tance of the moon from the earth at the time
of the eclipse. The nearer she is the wider the
shadow area. OF course in very large part
of this space the shadow is but partial one.
In fact, on the edge of the shadow field there
is no appreciable diminution in the suns
light, the only effect of the eclipse being the
darkening of one edge of the disk. As the
observer goes south or comes north this OBJ
scuration of the disk grows and the sunlight
becomes less and less until there is point
midway on which, the actual shadow of the
moon, as the word is generally used, falls.
This is called the cline of totality."
To an observer stationed at any point in
this line the eclipse appears to come over
the sun gradually, increasing momentarily,
until the entire surface is covered, when,
after very short period of what is known
as ''totality," lasting from one to seven
minutes in various eclipses, the black
screen begins to withdraw itself and finally
disappears. If one could start on the end
of the black line at the moment the period
of totalitY began there and run, fly or swim
eastward at a speed equal to that OF the
earth's surface in revolving, to the other
end of the line, distance of several thou
sand miles, he would be able to see the
eclipse throughout its existence. In other
words, he would be in darkness from the
time he started until he stopped.
To-MoRRow's ECLIPSE.
The line of totality of to-morrow's eclipse
runs over most of its course in the watery
spaces of the western hemisphere, touching
land but twice in this continent. These
points are Cape Orange, near Cayenne,
French Guiana, and an unnamed point of
land in the province of Piauhi, Brazil.
Thence it shoots out across the Atlantic,
hitting the western coast of Africa little
way from the port of st. Paul de Loando.
Il
server at either of the South American spots
where the line touches to obtain good view
of the eclipse, butit is probable that at those
places the horizon, where the sun will be
when the eclipse occurs, will be obscured
by the mists of morning. 1t is desirable to
note the eclipse when the sun is high in the
heavens, when he is free from interference,
and so the astronomers selected the western
coast of Africa as the objective point of their
expedition.
Had there been some chance island in the
ocean directly in the line OF totality it might
have been utilized. but unfortunately there
is nothing on the map that looks like solid
ground anywhere between the Brazilian
cape and ST. Paul de Loando, IN the imme-
diate vicinity of the black line, and after
they get there what do they do? That is
complex question to answer. They have a
ship load of instruments, telescopes, photo
graphic cameras and scores of other imple-
ments, with which they. will utilize every
one of the 1877 seconds when the sun is OBJ
scured. In order to obtain the most salts
factory results possible it is probable that
each observation will be duplicated by diff
ferent observers, as far as the number of in
struments will permit. 1t is this variety of
sources that gives the data obtained from an
eclipse its peculiar value. 1t may be stated
as an dAlOm lildL du dsIIOuOAulCstA tIu vi Can
not be said to be established until two per-
sous, working independently, have obtained
the same results.
WHY ECLIPsEs ARE OBSERVED.
The main object nowadays in viewing
eclipses is to obtain new light on the subject
of the nature and extent OF the corona, the
bright effulgence which is seen surrounding
the suns disk at the moment of totality. As
soon as the binding rays are shut off by the
medium OF the moon this halo appears. 1t
is an uncertain quantity in size as we'll as
character, for it varies tremendously in diff
ferent eclipses. There is first q very bright
rim of light lying close to the dark edge of
the moon, then the flames take definite
shape and shoot off into space to enormous
distances