The New York herald., 1876-03-25
The Solar Eclipse.

The Solar Eclipse
One of those extremely interesting astro-
nomical events, an eclipse of the sun, VIII
take place this afternoon about four o'clock,
and will be visible in partial phase over the
United States northward of FLORIDA. The
eclipse will last about one hour and forty
minutes, and will present over the wide area
of visibility, embracing the North American
continent all the phases, from the annular
to the mere external contact, between the
disks of the sun and moon. Beginning at
the edges of shadow, the obscurity will
increase the nearer the observer is to the
central line, and at points in Washington
Territory in the United States fully eleven
twelfths of the solar disk will be obscured.
The eclipse is recognized by astronomers as
the fifteenth repetition of one that was OBJ
served at Naples in 1905, and it is expected
that 1t will present features very similar to
those recorded at that time by Kepler. The
causes which produce eclipses of the sun and
moon can be easily comprehended when we
consider that the former is the source of light
in our system and the latter body which is
certain intervals crossing the apparent path
of the sun, or the ecliptic. If the orbits of
the earth and moon were exactly on the same
plane solar eclipse would occur at every
new moon, when the latter would be in con-
junction with the sun, and lunar eclipse
would occur at every full moon, when our
satellite was in opposition to the sun. Owing
to the obliquity of the planes of their
orbits tho periods of opposition and con-
junction are irregular, and we therefore
have eclipses only when the moons nodes
correspond with the phases of full and new
moon. When the eclipse is total or annular
the observer stands in direct line with the
centres of the sun and moon and in the
umbra or shadow projected by the latter
body. When the eclipse is partial, as
will be the case in New York to-
day, the observer stands in the penumbra
or indirect shadow of the moon, produced
by the suns converging rays being inter-
cepted by relatively opposite limbs of the
moon, and by which portion of his light is
thus cut off from the earth. This peculiar
feature of eclipses leads to an explanation of
the difference between the total and annular
phases of a solar eclipse. In the first case
the apparent diameter of the moon is greater
than that of the sun, and therefore total
observation of solar light takes place. But
in the second the apparent lunar diameter
is less than the solar, and ring or annulus
of unobscured light remains visible, sur
rounding the dark disk of the moon. Re-
cent researches into the character of solar
combustion have been rewarded by many
interesting discoveries, and advantage is
taken of eclipses to make spectroscopic
analysis of the photosphere. An interesting
letter from Professor Parkhurst, published
in to-day's HERALD, on the subject of the
eclipse, makes reference to this particularly.
1t is to be regretted that opportunities for
scientific investigation will not present
themselves in satisfactory forms during
to-day's eclipse, the centre line of OBJ
scuration being too far to the northward
to permit astronomers to avail themselves
of them. If the weather permits, piece
of smoked glass will reveal to even the least
learned beautiful phenomenon, which will
illustrate the grandeur of the work of the
Creator, who has drawn everything out of
nothing