The Iola register. [volume] (Iola, Allen County, Kansas) 1875-1902, 1883-01-19
The Problem to be Solved.

Prof. Robinson, Of Rochester, in the
New York Examiner. gives q rough
outline of the problem sough to DE solved
in the recent observations upon the tran
sit of Venus. He says: 1.-The apparent
motion of Venus across the sun in a
transit is from east to west. 1t was
essential to the plan of the observers
that some of the stations should be in
the Northern and some in the Southern
Hemisphere. Let us look at the ques-
ton by means of an Illustration. From
my study window see gilt ball on
distant cupola. Let that represent the
sun. Suppose sparrow to fly between
the ball and my window from east to
west. The position of the path traced
across the ball will depend upon the
position of the Observers eyes. If l
look through the upper sash Of the win
dow, the passage of the sparrow will be
projected upon the lower half OF the
bali; if friend looks through the lower
sash, to him it will be projected on the
upper half of the ball. If now l knew
that the bird passed at just one-third the
distance from my window to the ball,
and that my friends eyes were five
inches lower than mine at the time, it
would follow that the parallel paths
traced on the ball were ten inches apart,
Now by well-known laws the relative
distances of Venus and the sun from the
earth can be found with great precision.
Thus we know that all the time of the
transit of 1874 the sun was 1888 times
as far as Venus. The distance of one
station north from another can also be
found. From these data it is an easy
matter to find the distance in miles be-
tween the two apparent paths of Venus
across the sun as seen from the two
stations. If for instance the sun were
Just three times as far from us as Venus,
and one observing station $500 miles
north of the other, the parallel paths
on the sun would be 13, 600 miles apart.
Having found the distance between
the two paths, if we could in some way
locate them permanently on the disk OF
the sun, so that we could see how far
apart they would appear to be to a single
observer, the problem of the SUMS dis
lance would be solved. What we want
to know is the rate of divergence of two
straight lines drawn from the same point
on the earth to these two paths. This
could be easily measured with an instru-
ment if the positions of the paths were
known. A single case, in which the
suggestions do not differ much from the
actual facts. will make the matter plain.
If, on measuring the angle, we should
find that the lines are nine inches apart
at the distance of one mile from the
point of observation, it would be easy to
tell how far we must 60 from the point
to find them $4,000 miles apart. This
would give the suns distance 81, 1900
miles.
The limits of this paper do not allow
statement even of the different modes Of
determining the position of the paths
traced by Venus across the sun as seen
at different stations. 1t has already
been stated that the Americans rely
mainly on photography. ....'-..
1.-The difficulties of the problem do not
appear in the outline as indicated above.
The actual angle which the astronomers
are seeking to determine, known as the
paralIax of the sun, would be repre-
scented by inverting the lines which we
have supposed, and letting them diverge
from point on the sun, so that the dis
lance between them here should be
equal to the radius of the earth.
This angle is so small that the
rate of divergence is only about two
and one-half inches to the mile. The
distance to be found from this angle is
so great that an error in the divergence OF
one-hundredth of an inch at the distance
of a mile would make an error in the
suns distance of over $4,000 miles.
The distance between the stations has to
be reckoned in a straight line. and not
on the surface of the earth. The earth
on which the observers stand is itself
revolving around the sun in a path
slightly inclined to that of Venus: and it
is also rotating on its axis. At every
station allowance must be made for this
double motion. All these difficulties
could be overcome. however, by our
magnificent instruments, and our mathe-
mates, if it were not for others which as
yet seem insurmountable. The great
trouble is with the light, which, pro-
ceeding from the sun, grazing the sur
face of Venus in its course. and suffering
refraction in our atmosphere, is so dis
torted and so unsteady as it enters our
instruments that the exact position of
the planet on the SUMS disk at any time
cannot be determined with absolute GER
tainty.
The effort made, notwithstanding the
difficulties, to solve this great and inter-
esting problem by means of this pair of
transitS is not unworthy of the scientific
spirit of the age. Whether the distance
to be hereafter adopted shall be found
by this means or some other remains to
be seen. Certain it is that neither we
nor our children will know anything Of
the modes of observing the next transit.
1t is probable that before its occurrence,
in June of 1904, the distance to the sun
will be so well known that expensive
expeditions for observation will not be
needed