Omaha daily bee., 1902-05-04

They had come to apply analytical APP
paratus to the end Of the telescope and
record Herewith facts about the stArs that
could not be perceived with the eye. And
they had come to a point beyond which
they could not utilize this apparatus with
the revolving telescopes. Every pound OF
weight added to the chance of deranging the
telescope, and. besides, there was no room
to attach the big spectroscopes. twenty-five
feet or more in length, to the end Of the
tube.
And the possibilities OF the use Of this
apparatus we're as ~alluring as we're those
Of photography. Away out there millions
Of miles distant IS a star. To the eye It
remains year in. year out, a fixed point Of
light. Even through the telescope 1t does
not appear to move, so slight Is it's orbit
compared with the enormous distance that
separates Il from us. Yet 1t is whirling
through space as we are, about some sun
which it obeys, as we do ours. How do the
astronomers learn this? Through the
spectroscope.
Everyone is familiar with the fact that
when a whistling locomotive Is approach
ing. the pitch OF the whistle rises, and as
the engine recedes II falls. This Is because
the sound waves are crowded together"
by the onrushing engine and shortened as
II approaches, and are drawn out longer
as It goes the other way. The same thing
happens to the light of an onrushing star.
The eye can not detect II, but the spectre
scope does. The astronomer allows the
light Of the star to come through a slit
and be broken up by the instrument. He
selects a single line Of the spectrum Of the
star, chooses a guide line beside 1t and
watches It. II the star is approaching the
light waves will be shortened and the light
will become slightly nearer the violet. II
It is receding the waves will be longer
and the light will approach the red.
Red is low pitch" in light, and blue
Is high pitch" AS the star swings about
the curve at this end of its orbit the light
gradually returns to normal, because the
star, while moving Just as fast, is not APP
preaching us as much. As the star turns
back the line goes the other side the nor
NAL. BY continual observation the ~astrono-
mer finds how fast and how far the star
goes each way and how often 1t does so.
In the case of some stars he discovers
that what appears to be one is really two,
which is shown by the fact that a line will
divide into two and one part move up and
down the spectrum at the same time. Such
stars are known as spectroscopic doubles.
With another bit Of apparatus the
astronomer measures the heat the stars
send US. Some night in winter when you
are out of doors hold your hands up and
let Arcturus warm them. You may not
feel the heat. yet Arcturus sends us most
heat of all the stars. Astronomers say 1t
is the hottest" 1t gives us as much heat
as a tallow dip six miles away would do.
You can not feel that, with your thick skin,
but the r~adiometer detects 1t and even less
with ease. For instance, this instrument
has been known to detect and measure the
heat emanating from a mans face 1000
feet away And the man was an Oberlin
professor in an ordinary state Of placidity.
Need for Fixed Telescopes.
With such instruments as that to use the
astronomer does not want to be kept down
longer to watching the stars through a re-
volving telescope. He wants to be able to
mount his apparatus on brick or stone
piers, solidly, and to have the best and
biggest apparatus he can get so he can
make his measurements with the greatest
accuracy. He doesn't want this apparatus
to be moved and swung at the end of a
slx-ton tube mounted on a pivot. He wants
1t where he can encase 1t and keep It at
even temperature, as he cannot do In the
old way. And he wants to be able to switch
the star image from one instrument to an
other.
So he has come to the horizontal fixed
telescope. There have been many small,
experimental telescopes of this character
built. There was a large one at the Paris
exposition of 1900, but It was probably
never finished, for no astronomer got the
benefit OF 1t. In that same year the Uni
versity Of Chicago astronomers, having &C.
casion to observe an eclipse of the sun
in North Carolina, built one. The eclipse
was to be total. The astronomers wanted
photographs made with long focus and
showing details. 1t would have been mani
testify too expensive for consideration to
build massive foundations and erect an
enormous telescope and dome down there
for that occasion. The eclipse would not
be total at Lake Geneva, Wisconsin, 80 they
built in North Carolina a long wooden shed,
light tight, horizontal, with a dark room
at right angles at one end OF 1t. The shed
WAS 611k feet long-the exact focal length
Of the 6-inch lens they proposed TO use.
A coelostat, or clock motor, carrying a
plane mirror, was set up In front OF the
shed, and reflected the image Of the
eclipsed sun through the lens down the
shed to the plate.
Remarkable Eclipse Photography.
II was necessary-or desirable-to make
several exposures. The total phase lasted
eighty-sexen seconds. So a track was built
in the focal plane and a ball-bearing car
rage set on It and on this seven plates
were put. Then the workers. who stood In
the dark room behind this line OF plates,
had but to move them along one at a time,
with the greatest possible speed. exposing
one a quarter Of a second, the next a half,
the next two seconds. the next four, the
next eight and one fourteen and another
thirty seconds. When they were developed
each was found to contain a fine picture Of
the e~clipse-each good for some especial
feature, the shorter exposures for the
brightest parts of the corona and the
'prominences" or bursts OF fame, the
longer exposures for the margins and duller
portions OF the corona. They were the
sharpest in detail and the best pic
lures of such an object ever taken, and
when enlarged many times and thrown upon
a screen by e magic lantern gave thousands
of persons. thousands Of miles from the
scene, views of the eclipse better than they
could have obtained had they been there
to see II.
This long, horizontal telescope was a per-
feet success. When that was demonstrated
the astronomers set to work to build a