Omaha daily bee., 1902-05-04
WORLDS BIGGEST TELESCOPE
Wonderful Instrument Now Nearing Com
pletion at the Yerkes Observatory.
GREAT THINGS ARE EXPECTED OF IT
How Photographic and s~pectrOscOPic
Astronomy VIII Ne Developed
Far Beyond Present
Possibilities.

scope 1000 feet long, mounted on the sum-
init OF a lofty tableland In the clearest
obtainable atmosphere.
Conceive It not as a slender steel tube
mounted on an axis turned by a gigantic but
delicate astronomical clock In a dome cover
ing forty acres Of ground, but as a long, low
shed. without windows or doors In It's sides,
and with nothing about It to relate It to
the observatories Of today except a ten
foot plane mirror mounted on a coelostat
at one end, and back Of and about the
mirror laboratories filled with the largest
and best obtainable apparatus for the
analysis and study Of star images. And
with all this. what else7
Perhaps nothing at all, for the 1.000-foot
telescope is as yet only the Astronomers
dream, and in a large way its
future Is conditioned by the success
Of q smaller but still enormou telescope
under construction at the Yerkes observa-
tory Of the University of Chicago. at Will
liams bay, Wisconsin.
Perhaps, on the other hand, unimaginable
things about distant worlds. as yet undis-
covered; the details Of star clusters and
nebulae, OF which even the existence is as
yet unknown; more probably phenomena IN
connection with the moon and the planets,
which will make the fancies Of a sensa-
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fascinating literature.
And with all this, an emancipated as
tronomer, seated in the midst Of his appa-
ratus. directing. focusing, but no longer
following with weary eye and tired body
the slow progress Of the butt end Of the
telescope across the observing floor. For,
while the 1,000-foot instrument is still
. dream, the 165-foot instrument Is
nearing completion at the Yerkes OBJ
servatory. Should 1t be successful, It
will mark the Introduction of the methods
OF the physical laboratory into astronomy
on a large scale and will enable the
astronomer to apply TO the details OF his
work recording and measuring instruments
which can not be operated with any tele-
scope that must be balanced and moved
by an astronomical clock.
Photography in Astronomy.
We are accustomed to think OF a telescope
as a long steel tube equipped with lenses
for bringing close to the observer the image
of the star or nebula. We think Of the
astronomer as q man doomed to spend the
nights OF his life ip a cold dome, open to
the weather, while, with the eye glued to
the smaller end Of the big instrument, he
moves hour after hour across the floor of
the observatory, slowly noting down the
phShOhlohd NulSn NC NC6 lhtSS
phenomena the layman must take on the
astronomers word.
In the last twenty years, to be sure.
photography has come into vogue as a
method for recording these observations.
More recently 1t has been discovered that
astronomical photographs may show things
which cannot be seen with the naked eye,
even through the most powerful telescope.
The astronomer has learned that by at
taching a Photographic plate to his tele-
scope and keeping 1t at a given point In the
heavens tor several hours he will And on
developing the plate that he has a better
image of the stars in that part than his eye
gave him-since his eye was subject to
fatigue and the plate was not. Besides, he
will have a record that he may show wher-
'ever he will and which is as plain to any
one without a telescope as II Is to him.
Moreover. he may hnd-as has frequently
happened-that he has countless stars and
perhaps even nebulae recorded which he
has never seen. Though he may gaze for
hours he cannot see these with his eye.
Yet by the use of successive plates he can
study their phenomena from night to night
and preserve a record OF them that will
show whether any change in position or
shape is taking place.
Taking these stellar photographs Is a diff
fcult Job. In the first place. the lenses of
the telescopes are made for the use of the
eye. Glass will not refract all rays Of light
equally. Consequently. when we wish TO
focus rays with q lens we must use one
which will bring to a focus the particular
rays we need to use.
Our eyes see with the yellow and green
rays and these are the ones that are
focused In visual" lenses. such as are used
in Telescopes. Ordinarily the Photographic
plate is sensitive to blue and violet rays
and to those ultra violet rays which are
beyond the eye. When It was decided to
use the big Lick telescope for photograph
ing the heavens II was found necessary to
construct an additional lens, at a cost of
$12. 900, to put on over the visual lens, that
1t might focus the "actinic' rays needed.
That shortened the focus of the telescope
and made II awkward to handle. But IL en-
Abled the astronomers to get very wonder
tul pictures, especially OF the moon.
Improvement In Plates.
But Photographic plates need not be
sensitive to the blue and violet alone. 1t
is possible to 'orthrochromatiEe' the plate
that is. TO dye the solution with which
1t is sensitized SO that it will be affected
by other rays. And in this way a plate
can be made that will be affected
by the yellow and green. though It will
still be more sensitive to the blue and
violet. By introducing a yellow screen in
front Of the plate. 80 as to let no blue rays
through. this plate can be used with a
visual" lens and the picture that the eye
sees can be thus recorded, that is, the image
can be printed in by the same colored rays
that the eye sees with. This is the actual
process employed at several observatories
today. notably at the Yerkes observatory,
where II has made the forty-inch refractor,
the largest in existence. a Photographic in
strument
But when they came to take photographs
with this big telescope at the University OF
Chicago observatory the astronomers faced
the same experience others had, the big
telescope would not take such good photo
graphs OF the fainter stars as the smaller
instruments would. In fact, as the OBJ
servatory was equipped with a battery OF
three telescopes, IL was found that each OF
them-the l2-ineh refraetor. the 2-foot re-
Hector and the 40-inch refractor-was
best suited for some particular kind OF
Photographic work. The big fellow enor-
mously magnihed the images and showed
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