Belmont chronicle. [volume] (St. Clairsville, Ohio) 1855-1973, 1874-12-10
Transit of Venus.

A large portion OF tno astronomical
world has for two years been busy
| with preparations to observe one of the
rarest of celestial phenomena. When
Venus last passed over the face of the
sun the infants Napoleon and Yelling
ton were sleeping in The arms of their
nurses, all unconscious of the parts
they were to play in the worlds histo-
ry; Washington, loyal subject of King
George, lived quietly on his Virginian
plantations; and American indepen-
dence was dream of few enthuiasts.
Now, after the lapse of more than q
century, the present generation is to
witness two occurrences of the phe-
nomenon, the one during the present
year, and the other eight years later.
Then the rest ofthe nineteenth centu-
tury and the whole of the twentieth
are to pass away without its being
again Seen.s Finally, on June Sth,
2004, our posterity will have an oppor-
tuniiy of again observing it.
We know from our astronomical ta-
bles that this phenomena hasrecurred
in its regular cycle four times every
23i years for many centuries past. But
it has been only in times Imperative
ly recent that it could be predicted and
observed. In the years l519 and 1926
the idea of looking for such a thing
does not seem to have occurred to any
one. The following century gave birth
to Kepier, who 80 far improved the
planetary tables as TO predict that
transit would occur on December 9th,
1881. But it did not commence until
after sunset in Europe, ami was over
before sunrise next Inerning, so that it
passed entirely unobserved. Unfortu-
nately the tables were so far from accu-
rate that they failed to indicate the
transit that occurred eight years later,
and led Kepler to announce that the
would not occur till 1851.
The transit of 1859 would, therefore,
like all former ones have passed entire
ly unObServed had it not been for the
talent and enthusiasm of Il young En-
glishman. Jeremiah HorrOX WAS then
a young curate of eighteen, residing in
the north of England, but who, even
at that early age, was master of the
of his times. Comparing
different tables with his own observa- |
tiOns of Venus, he found that a transit
might be expected to occur on Decem-
Der 4, and prepared to observe it after |
the fashion then in vogue, by letting |
the image of the sun passing through |
his telescope fall Oh screen behind il.
Unfortunately the day was Sunday,
and his clerical duties prevented his |
seeing the ingreSs of the planet upon |
the solar disk-a circumstance which |
science has mOurneG for century past,
md will have reason to mourn for q
to come. When he returned
In hA 70
,he planet upon the face of the sun, but
sfter following it half an hour the ap-
Droach of fsunset compelled him to sus-
pend observing. -, e.. --
During the interval between this and
he next transit, which occurred in
761, exact astronomy made enormous
tribes, through the discovery of the
aW OF gravitation and the application
" the telescope to celestial measure
nents. A great additional interest was
ent to the Phenomenon by Hafley's
discovery that observations of it made
n distant portions of the earth could
,e used to determine the distance of
he sun-an element of which scarcely
was then certainly known.
from some ancient observations of
clipses it has been concluded by Ptol-
my that the distance of ithe sun was
bout HOO semi-diameters, and this
'alue was adopted with few modifi-
ations for more thsn thousand years.
When the telescope enabled more ac-
urate observations to be made, it was
Ound that this estimate must be far too
mall; and from observations on Mars
q 1872 Cassini concluded that the So
ar parallax was between nine and ten
econds, and consequently that the sun
nust be distant more than 10000 semi
iameters of the earth. But this result
Vas necessarily very uncertain, and
With the means then known, the only
easible way of attaining certainty
eemed to be to adopt Halley's plan of I
bserving transits of Venus.-Prof. ST.
ION NEwCoMB, In Harper's Magazine
,r December.