Belmont chronicle. [volume] (St. Clairsville, Ohio) 1855-1973, 1874-12-17
THE TRANSIT OF VENUS.

The transit of Venus which occurre
Tuesday Of last week has attracted tn
attention of the whole civilized worl,
-Of the scientific portion of it-for
| great many years. This transit is tn
passing of the planet Venus between
US and the Sun, Just as the Moon doe
at an eclipse. This may be called al
eclipse tsthat's all in your eye.1, Th,
planet makes q shadow that falls OF
your eye, but the dark cone of shadow
does not reach the earth.
There were transits of Venus Dec. 6
1881, Dec. 4, 1889, June 5, 1851, June 8
1863, Dec. 8, 1874; and there will be ont
Dec. 6, 1882, and another June Z, 1904
Thus there are pairs of transits occur
ring something over a hundred year,
apart, those of each pair separated by
eight years. These are alternately q
summer pair and winter pair.
One of the laws discovered by Kepler
was: "The squares of the times of rev.
olution of the planets are to each other
as the cubes of the distances of the
planets of the Sum-" In the proper
Ttions made from this law, if we have
three terms we can fud the fourth.
We know the times of revolution of the
planets. And two of these will make
two terms of the proportion, and if we
had the distance of one of the planets it
would be the third term, from which
three terms the distance of any other
planet of the Sun can be obtained,
Now, astronomers propose to find from
this transit the distance of the earth
from the Sun, and by using it as third
term find all the other distances. The
distance has been measured before; but
owing to the iinpeffections in the in
it was only gotten within
about One-tenth of second of the
truth. They wish now to get it within
one-hundredth of a second.
There are two methods of calculating
from these transits, Halley's and Des-
lilies. The former is the easier and
most reliable, and is the one used this
time. 1t was thought for some time
that it could not be used at this transit,
but Proctor, an English astronomer,
showed, at the eleventh hour, that it
could. In 1882 Deslile's will have to be
used, unless artificial stations can be
In the ocean. BY HaIEey's
method observers are placed as farl
north as the transit can be seen, and as
lar south as it is possible eshat is for this
.rasit.) To the northern observer the
planet makes one track over the Sun,
md to the southern observer it makes
another track farther north on the
sun. The distance between these
racks being known in miles and it be-
ng found by the transit what part of /
he SUMS diameter this distance is, the
diameter of the Sun is found. Havingl
his the distance from us to the Sun is
,asily found. 1ir4 aGs (" 20
The transit began, by Washington,
c., time, about $40 P. NJ. of Dee. 8,
md ended about l:l8 A. NJ. of Dec. 8:
hus lasting over four and one-haIfI
lourS.
The. invention of the spectroscope
nd of photography has added i'm
nensely to the facilities for observing
he transit. To see the need of the
you need but try this ex.
eriment: Take two large coppers and
old them between your eyes and the
bring them together slowly G
D that the edges touch, and you will Il
nd that you cannot see exactly when d
1ey touch. They will appear to stretch
ut 10 meet each other. BY the spec I
'oscope The exact moment of the be- a
inning of he'transit is known. The e
lines vanish gradually as I
ie planet approaches and entirely dis
spears as the planet completes its s
issage through the corona and begins ii
pass across the Suns disk. C
This transit really occurred on the il
nth of December, although when it a
gan il was the ei1hth here. II an as