Evening star., 1934-12-02
GIANT TELESCOPE
EYE" TO Be CAST
Pouring Starts Today to
Replace Mirror DeveI-
opinq Flaw.
By the Associated Press.

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CORNING, N. Y, December L.
The second pouring of the 20O-inch
"eye" for the worlds largest telescope
which will open to mans vision a
universe 27 times larger than his
greatest telescope now see, is ready
to begin here at daybreak tomorrow
In the center of a huge building OF
the Corning Glass Works there is a
roar which has been growing for three
weeks, until today it equals an ex-
press train doing 20 miles an hour
The groundshaking noise comes from
the great oven where bowling gas jets
have heated the special glass for the
"eye" for three weeks.
Its temperature now is $500 de-
grees Fahrenheit, close to a third the
heat Of the surface of the sun. The
glass forms a small lake, its mass 65
tons, its intensity enough to burn a
large city if it could be sprayed with
out cooling.
Last Word in Eyes"
This roaring glass giant is the last
word in weeks of preparations be-
Ieved to assure high degree of per-
lection for the great mirror.
Tomorrow's eye will be a substitute
for the mirror poured here last March
before large crowd of spectators,
astronomers, educators and scientists
The first mirror was marred when
some of its ribs" part of the bot
tom of its mold, broke loose.
This time air-cooling, one of SCI
ence's newer tricks. will be used to
prevent a recurrence of this accident.
Nearly five weeks ago the condi-
tioning of the materials for tomor-
rows eye was begun in the oven,
which is approximately 80 feet long,
is wide and 10 high.
Heat Problem Met.
The first problem was the fact that
nothing is known which will stand a
sudden onset Of the terrific heat
needed to produce the purity and
toughness of the giant mirror.
To meet this the interior of the
empty oven was gradually heated for
10 days. This permitted the lining
bricks to make slow changes in crys-
taline structure. Then a material
which resembles almost white seashore
sand, little coarser than ordinary.
was fed into the oven twice an hour
for "a hours daily for three weeks.
This slow feeding gave time for gas,
principally carbon dioxide and air, to
escape from the melting silicate.
This gas formed about 10 per cent
Of the original weight of silicates and
boric acid fed into the oven. The final
result today is a purified mass of glass
too white-hot for the eye to look at
without glasses.
First Mirror Retained.
The mirror cast last March occupies
q large room near the furnace, its
proportions apparently perfect except
Tor the missing ribs on its under sur
face. These, the glass experts say,
can be drilled out without risk.
The first mirror, like the one to
be poured tomorrow, is the property
OF the California Institute of Tech
nology, which will erect the great
telescope at Palo-Mar Mountain, rear
Los Angeles, in cooperation with the
Mount Wilson Observatory of the
Carnegie Institution of Washington.
What the astronomers intend to
do with the first mirror they have
not announced. So far as the glass
makers now see. this first mirror can
be completed to make two Of the giant
eyes, if tomorrow's pouring is success
full. The new glass materials de-
veloped for it already have given as
tronomy squirt. Five other large
telescopes are the result. Four of
these mirrors already are made, a
76-inch for the Toronto Observatory,
81-inch for the Texas telescope of the
University of Texas and the Univer-
slty of Chicago, 6l-inch for Harvard
and 85-inch for Michigan.
The fifth is another 60-in:h for
Harvard, which will be poured prob
ably next week.