Vilas County news. [volume] (Eagle River, Vilas County, Wis.) 1896-1927, 1905-12-11

course, at A. When the telescope Is
pointed to the sky this end may be 80
or 40 feet above the floor, but by
small motor the entire floor is Iitteo
up with the observer on it, until he is
as near the end Of the great tube as
may be desired.
The observer then finds that the
smaller end OF the telescope looks as
shown in Fig. 8. Applying his eye TO
the small hole at B he would see, ii the
telescope were pointed at high star
not only this bright star itself, but
number of very faint stars, also which
are far too faint to be seen with the
naked eye. Beside these, Re will no
tice two fine straight lines, the whole
looking, perhaps, as shown in Fig. 5.
The two fine lines are two little spid
er threads which are lit up at night by
the little lamp at l., Fig 4. One OF
these lines can be moved back ana
forth over the field of view by turning
the very fine screw OF which the emu
is at S, Fig. 4, the number of turns OF
the thread from star to star being
shown by the graduated head at H.
In Fig. 5 it is supposed that the dis
lance from the star Z to the star A is
being measured. The whole instru
ment is turned until the wires are per-
pendicular to the line joining G and A
and the number OF turns OF the screw
necessary to move one OF the threads
from A to G is then found. In this way
it is evident that the exact position OF
c in reference to all the little faint
stars in the vicinity can be measured.
1t may be that if these measures are
continued from month to month it viii
be found that G does not stay always
in the same position in reference to the
faint stars. 1t the various measured
positions of G are drawn on map
Gig. g. it may be found that g in
moving about in little illipHcal path,
starting at M, reaching n months
later, O, 6 months later, and then in
twelve months coming back to NJ
again We then know that G is really
not in motion at all; it is only dis
placed backward and forward on the
sky because we ourselves are moving
around the sun in a great circle, LIB
million miles in diameter. In exactly
the same way a passenger on a train
may see the nearby trees and houses
apparently rush past distant range
of hills or mountains, although be
knows that the trees and houses are
stationary. Or, if we imagine man
to look at night at tall flag pole on
the top Of which there is light, he
will see this light projected against the
sky and apparently lying among the
stars If he now walks around in
circle on the ground the light will ap-
pear to him to move around among the
stars in a similar circle, and this las
circle will be the smaller the farther
away the light is. So infinitely far
away are the great majority OF the
stars that they do not suffer the slight,
est displacement even while the earth
moves in it's great circle around the
sun.
To return now to our star, the math-
ematician knows that the little orbit,
M, N, o, Fig. 6, looks to us OF exactly
the same size in the telescope as the
earth's orbit would look to an observer
viewing it with the same telescope
from the star. From this it is simple
matter to find how far away the star is.
In the case of Castor the whole diane.
ter of this little orbit, M N O., is but
slightly greater than the thickness OF