Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-10-20
GIANT TELESCOPE
P|ERCES BARRIERS
Scientist Tells of Great
Field Awaiting Astronomers
Through Mammoth Lens.
RY HH. SHELDON.

BY II. II. SHELDON.
Professor of Physics. New York University.
We have heard of late about the 200
inch telescope proposed for the Mount
Wilson Observatory What do they
want with such an instrument? Is it
that they have exhausted all the posi-
bilities of their present instruments?
Do they merely wish to boast Of the
largest instrument In the world? They
already possess one of the best.
Is it not true that there is much
work of great value that can be done
by the amateur with a homemade in
strument? Even with the unaided eye,
we are told, We can be of service to
astronomy in such observations as those
on meteorS. Then why the enormous
instrument? The astronomers certainly
have not run out of work.
The fact is that astronomy Is def
nitely entering new era, which de-
mands the use of such an instrument.
Without it we are more or less con-
fined to cleaning up some of the old
problems. Much valuable astronomical
work was done ages before the inven-
ton of the telescope. The Chaldeans
in 1000 BIC. were sufficiently CONVEX
SAINT with the behavior of the heavens
to be able TO predict eclipses. Hip
parchus in $50 BIC. prepared his fa-
NOUS catalogue of more than 1000 stars
and divided them into six classes, &C
cording to their brightness.
Copernicus Lacked Telescope.
We must not forget that the famous
astronomers Copernicus and Tycho
Brache did their work without the aid
Of a telescope, whose extensive study OF
the solar system led to his famous three
laws, had no telescope to assist him.
It remained for Calico to invent the
telescope and to recognize the value of
the pendulum for making exact meas
urements of time-both indispensable
to the work of the astronomers.
The brilliant work of Newton led to
his laws of motion and, together with
the work which he inspired, led to an
understanding of the solar system. This
marked the end of great achievement
which might be expected from obser-
vations with the unaided eye and with
simple telescopes.
Since the close of this period astron-
omers have been working with larger
and larger instruments. They have been
studying what they thought to be the
universe They have stored up enor-
nous quantities of information on the
stars. their motions. their sizes, their
contents, distances from the earth, etc.
AS the size of their instruments has
~
farther and farther out. Perhaps not
more than 5000 stars can be seen with
out telescope. With good telescope
this can be increased by million to
one and with our best telescopes the
ratio can be raised to ten million to one.
Use Of Instruments Neared Limit.
But with telescopes of this size we
appeared to have reached a limit.
Glass telescopes larger than those now
In use seem to be prohibited by many
physical factors. The glass becomes so
heavy that it flows and says under its
own weight. It changes its shape to
such an extent with even small tenn
perature changes that 1t would be use
less.
And this limit was reached just as
things were getting really interesting.
We we're discovering that what we
thought was the universe was merely
our own galaxy of stars extending out
not more than 100000 light years. Be-
yond this were other galaxies even
larger than ours. The nearest of these
is 900, 900 light years away. There ap-
pears to be, to use the expression Of
DR. Harlow Shapley, galaxy Of gall
axies. That is our universe.
But to study other galaxies with our
present instruments with any precision
Is practically impossible. It requires ex-
QOSuI6S Ol pIlOOOSTdpIllC pIdJeS 10 dS
much as 100 hours. This is both diff
cult and tedious. Not every night is
clear night and it requires good sky
even to detect the presence of such dis
tant galaxies.
New Material Sought.
1t appeared then that we should be
denied forever the privilege of carrying
astronomy to its third stage. There was
no material available with which to
make satisfactory mirrors. Quartz
seemed the only possibility, but this
appeared unobtainable in sufficient
quantity to make large telescope mir
rors.
Much quartz could, of course, be OBJ
tanned Ia fused state, but 1t was
full Of air bubbles and unsuitable for
telescope use. Fortunately, scientists
In different fields have habit of dis
covering things useful to each other
at opportune times.
It happened in this case. Edward r.
Berry of the General Electric Co., dis
covered method of making clear fused
quartz. 1t is this discovery which will
enable the astronomers to go ahead
with their observations. The instrument
and the uses to which it can be put
cannot be described briefly in more
suitable words than those of DR.. Walter
S. Adams of Mount Wilson Observatory,
to whom the author is indebted for the
following:
'The design of this huge instrument
Is being studied from the outset with a
view to providing the greatest possible
light gathering power and efficiency to
aid In the discovery and investigation
of rebulae and faint stars, the analy-
sis of their light by the spectroscope
and the extension of the limits of space
beyond those which can be attained
with existing telescopes