The Bolivar bulletin. [volume] (Bolivar, Hardeman County, Tenn.) 1865-1888, 1883-11-01
HOW FAR no THE SUM-

HOW FAR no THE SUIT
Latest scientifcT CALCULATIONS of the Solar
Dtstance-The Great Astron on1fcai Prob
lem Approaching Solution. 81
The Decentralization of the precise dis
lance which Separates the sun from the
earth would be Rrachievement which
nearly every one would admit to. be SURF
prising, but Which would scarcely I'M
press the mind of the average man
with an idea7of~emiuen6- laTaotical -util=,
ity. Those Of Our. readers, however,
who will felIo1p-ProE-Ba through The
discourse which he delivered before the
British Association yesterday wilL-net
only derive from it, in most cases, an
enlarged conception of The IaboriOus
and patient accuracy of Scientific work,
but they will also learn 4hat the desired
measurement, still only approximately
obtained, would furnish a standard to
which all other astronomical magni-
tudes could be referred. In every
branch Ofup1ysc cal science some stand
ard of this kind is necessary; and, Just
rs the weight of a given bulk of water
is taken as the standard of specific
gravity, or the length of a ten-milliOnth
part of quadrant of the earth's
meridian as q standard of terrestrial
measurement, so some larger but still
invariable unit is required as a stand
ard of those ma0nitudes, almost be-
yond the powers of the human magma
tion ktO conceive, which intervene be-
tween the fixed stars Of themebulas.a In
consequence of the motion of the earth
reund- -elliptical-o orbit, the distance
which separates us from the sun is
variable, being greatest When our planet
is on the major axis, smallest wien
cIlirOgo
This variation, however, merely. sue
peradded 10 a constant distance winch
has hitherto eluded accurate Ineasures
ment, and which has been estimated at
from 81 eco, GEO to 90, 600, 900 of miles.
These words convey at first no mean
ing, and DR. Ball assists his hearers to
attach one to them by qu6tinga useful
illustration. An express train, travel
ing night and day at q uniform speed.
which is not stated, but which we may
perhaps set rat fifty miles an hour,
would require about three hundred
wears in order to traverse the interval.
The difference of 5000, 900 of miles be-
tween dilieFgat calculations amounts, it
will be seen, to about one-nineteenth
of the whaIe, and tho ambition Of as
tronomers is to red ace this range of ef-
Tor to one thousandth of the whole, or,
roughly speaking, TO determine the dis
tance of the sun Within 100, 600 miles,
For many years the rsnppOsed' Fdetermi-
nation of 6,O0p066 as taesJlfstatiee was
generally accepted and Taught; next
the estimate was reduced by new 4neth-
DDS to 81, 0O0,000 and still more recent
ly something between g2,00U,00O and
$4,000, 900 has been believed to be very
near tbeStruFh: II isl be -fe'rrect-t that
the phfsicaFTE llieWtissg whidh strand in
Of
always prevent the attainment of. abSo7
lutte accuracy; but DIR. BARS descrip-
ton shows that the plpblemshas Sf late
years been attacked bySIh aIlysIn ct hOcts,
and these, even if none OF thenf should
furnish results which are { conclusive
when taken alone, will ut, least recipro-
cally eorreot- OneaanetlreH g = -
1t has long beene Familiarity known
that the astrononIiGal .phenomena most
relied upon for Gre discovery Of the
solar DISTANCE We're those called the
transits of Venus-thatis TO say, the oc-
casions, sometimes separated by long
intervals, When the planet Venus passes
directly between the suusandlthe earth,
and becomes visible as a-sdark1spot
crossing the SUMS disc If the moments
of apparent contact with the edge of
the sun, ofapparent complete interven-
ton, the planet being wholly on the
disc, and the corresponding moments
of first and of final cmergence could be
accurately determined by two or more
observers, situated at distant points of
the carth's surface, then the materials
for calculation would be obtained, and
the distance capable of producing the
difference in the times which the differ
ent observations would disclose would
become question of trigonometrv.
,N.,lv- H. IsAs
can not be perfectly fulfilled, partly on
account of an element of uncertainty in
trQduced by the atmosphere of Venus,
which produces apparent distortion of
the edge at the moment of contact. and
partly from other optical reasons, to
which DR.. Ball has referred. To some
extent, perhaps, the errors incidental to
imperfect seeing may be corrected by
photography; and-on the occasion OF
the last transit, the last, moreover,
which will occur until the year 2004, the
British and other Governments did all
that could be accomplished to obtain the
required information. In some places
the weather was unfavorable, and DIR,
Ball gave graphic description of his
own disappointment from this cause,
the clouds only allowing him to See the
planet aftersit had half entered upon the
disc, and again for brief period in thS
middle of the transit. AS in the anal
ogous case of solar ecipses-the tran
sit would be an eclipse if Venus were
nearer to us-the observation of each
will afford guidance in the use of future
opportunities; but eclipses are compare
lively frequent, and the experience de
rived from them comes often into play
Astronomers can not be expected tC
wait patiently for more than a hundred
wears, until the course of Venus in rela
ton to the sun and earth once more
brings her to their assistance; and Sc
various other methods have been sug
gested and applied. The chief of these
are sketched by DIR. Ball with admirabl,
Iueiditv, and he enables even non
scientific persons to arrive at clear no
tions of what they are intended to &C
complish. He explains how a deter
mination of the weight of the earth il
comparison with the sun, if it could b,
obtained, would lead 70 solution o