Shenandoah herald. [volume] (Woodstock, Va.) 1865-1974, 1874-04-23
from the Ufbana Citizen and Gazettee.l
THE COMING TRANSIT or VENUS.
Translated from the German of D,
Zech, BY Herbert Il. CoMeigh, 0,
Urbana Ua,irersity.

! U'bana University.
| On the 9th of December, 1874, the
planet Venus will pass before the suns
disc. The same phenomenon will
again occur in the year 1889 After
this latter transit, none. that are how
living, will again be permitted to See
the phenomenon, for it will not recul
before one hundred years. Hence,
many generations will pass without
having seen this phenomenon. The
transists occur in pairs, always two in
an interval of about eight years. The
pairs themselves occur at intervals OF
10 to $50 !e.Y
On account Of the long periods elaps-
/ ing between two pairs OF the pheno-
menon,we can understand the NECESSITY
OF taking advantage of the few hours
OF its duration, especially when we
comprehend that upon the exact oh
servation Of this phe11omenon depends
the accurate calculation of the distance
OF the earth and all the planets from
the sun; also that of the stars from the
sun. AS soon as we knov the distance
OF one plaiets we have measure which
we according to the laws of the As
tronomer) wish to use to make our
! selves familiar with the distances and
orbits Of all the remaining planets
Indeed, with all the relations of the
whole universe. This measure we
seek from observing Venus while pas,
sing before the sun. The distance of a
/ point which we cannot reach from our
place OF observation can be measured
with the help of a triangle. But the
greater the disproportion in the length
OF the sides of the triangle, by means
OF which the calculations are made, the
| more inaccurate the final result must
be. AS we have in the eclipses of the
sun means of correction regarding the
calculation of the moons distance from
the earth, in like manner, we have in
the transits Of Venus before the suns
disc, means of correcting the calcula-
ton Of the suns distance.
This important truth was for the
first time intimatel in the 18th century
by the great Astronomer HALEY. The
translts OF Venus are for this reason
more valuable than those of other plan-
| cts, because Venus is the nearest to the
| earth.
HALEY died in the year ZAP, conse-
quently he could not observe the two
transits of Venus in the 18th century,
which occurred in the years 1851 and
1869 The hints given by him, how
ever, have been carefully used.
The transit in the year 1851 was not
very favorable.
The observations, prepared with the
greatest care, of the transit of 1863
were more successful.
We may say that the complete re-
suit of all these observations has only
been known from twenty to thirty
years. The most exact account drawn
from these has been given by Enke,
German Astronomer.
Since the year 1880 the distance of
our earth from the sun has been fixed
at 20 100000 German miles or 81, 500,
900 English miles.
A few decennial periods afterwards
doubts were entertained, regarding the
accuracy of the observation, from which
Enke's calculations had been made.
Several statements seem to indicate that
the above distance of the sun from the
earth is too great. The object of the
observations in December next, will be
to find how much the now reported
| distances deyiates from the true dis
lance. Extensive preparations for the
purpose have been made by Russia, in
Siberia, and by England, in the East
Indies. Whether France will carry
out the project made before the year
1870, is not yet definitely known. The
German navy will for the first under
take an expedition in the service of AS
tronomy upon the islands of Mauritius,
on the Auckland islands, and Kerguelen
islands. In China and Persia there are
German observations. Stations for oh
selvations will also probably be erected
in Yokoham, Japan.
At the imperial observatory in Stras.
burg. young Astronomers are purposely
trained, in order to make the most az,
curate observations.
To the question, why all these obser
vations are necessary, because Venus
can indeed be seen with a good tele-
scope, the answer may be given, that
several phenomena observed at the oc
casion of the transit in 1869, are now
to be definitely stated and eventually
explained. It was observed that the
round form of Venus, on entering or
coming before the suns disc, changed
almost to shape of pear; at the same
instant there appeared a dark bridge be-
tween the suns disc and the edge of
Vanus