New-York tribune., 1876-03-24

that il may here be stated that an observer on
earth might be 10000 miles in straight line behind
the point of the cone and would then see an anni-
lar eclipse Of II minutes duration; or he might be
ID OOOmiles within the cone, and then see total
eclipse lasting eight minutes But calculations OF
all the solar ecliDses Of this century indicate that
there will be no one Of them giving an observation
at place which it is practical for astronomers to
occupy, where the total phase will last much over
six minutes.
We may, however, approach nearer to the moon
during the progress of an eclipse than at its begin
ming at daybreak When the moon rises. although
it looks larger account of an optical deluslon 1t
is really 900 miles further off from than when
il is in the zenith over heads; the earths daily
rotation in the latter having carried the OBJ
server on the round surface to position so much
nearer the moon. Applying this Wow Of the case to
the eclipse Of next Saturday we find that the moons
distance will az rSs DO 23l G20 miles, and The length
Of the shadow-couc from base 80 point only 23l $50
miles Now if the central path OF the eclipse could
travel along the equator, an observer might ut
midday bo lifted there 1000 miles nearer, and
thus be brought within The shadow and see total
eclipse. But the line veers off 10 the n0rthward.
and hence only 900 miles of The earths curvature
is Ihus utilized the observer is ut best 2iO miles
below the point Of the cone At midday. For while
after sunrise the line about parallel with the
equator and in this part of the path there is rapid
approach toward tne moon. Early on Saturday
morning the ring ot The annular eclipse, to an Oh
server on the central path, would appear of com
paratively great width and long duration at the
Sandwich Islands the ring IS narrower and lasts
shorter time. 1t Yancouycr's Island the approach
to the point Of the is near that the ring will
be mere thread OF light. scarce lasting during
fow beats Of the pendulum.
The chief object Of observing solar ec!ipses il for
the purpose OF ascertanng more fully the properties
and character of tho an atmosphcra hundreds
OF thousands of miles in depth, which surrounds the
sun There is also afforded an opportunity 20 search
for planets near the sun; close study ot the mo-
tons Of tho known planets having made it almost
certain according to Ioverrier and other astroEo-
mers that one or more such bodies must exist within
the orbit OF Mercury. Annular Cclipscs not as
useful as are total for these purposes partly be
| cause of their biicf continuance, bat chiefly on
account of the sky being kept bright by the rng of
| sunlight. Hence there is little solcitudc ahont
| observing tie coming eclipse, and no costly OK
| peditions are sent l'ut perhaps some good work
| will be done at Hawaii. The fact that annular
| eclipses can occur has only been asccrtaNcd
certainly within a century and half, and the
| first of them of which we possess detailed
account was observed III February, 1877. Previous
annuar eclpscs had been very impcrfccIy recorded.
| and indeed the illustrious Tycho Brahc, nslcd by
! an error in calculation had pronounced them I'M
! possible Preparations have been made at the
United States Naval Observatory at Washington for
phoocraphing the partial eclipse there next Satur-
dqy. and doubtless smoked glass viii be in demand
Throughout The Unicd states II the sky is favorable"