Evening star., 1939-05-09
Of Stors, Men
And Atoms
Notebook of Science Progress
In Field, Laboratory
And Study
BIZ Thomas r. Henri.

FORT DAVIS, Tex, May 9-The uni
verse is place Of orderly progression.
Even the great galaxies like the Milky
Way itself seem to show the laws of
evolution at work, according to Dr. Ed
win Hubble, astronomer of the Mount
Wilson Observatory Of the Carnegie
Institution Of Washington, speaking at
the dedication Of the new Mcdonald
Observatory telescope here this week.
1t was DR.. Hubble's discovery of vari-
able stars and measurement of their
distances that was responsible for the
present recognition Of great extra
galactic star systems, comparable in size
to the 100000, 900 000-star Milky Way.
DR.. Hubble said:
1.-THE portion of the universe that can
be explored with telescopes is populated
very sparsely by the extragalactic nebu-
lac. These nebulae are stellar systems
comparable with our own system of the
Milky Way. They are all the same order
of luminosity, averaging about 100 900 900
times as bright as the sun, but they
exhibit a wide variety of structural
forms.
"The different forms fall naturally
into progressive sequence. At one end
OF the sequence are structureless, globu-
lar nebulae, while at the other end are
the familiar spiral nebulae, consisting of
two arms winding outward from the
central nucleus along spiral paths.
Transitions along the sequence presum-
ably represent the evolutional develop-
ment of stellar systems, although a sat-
isfactory Interpretation of the data has
not yet been formulated.
Most Of the current interpretations
are in form of theories concerning the
formation of spiral arms. The theories,
for the most part, have been inspired
and guided by the study Of fully deve.-
oped spirals near the end of the sequence
OF forms Information concerning the
first appearance and the early develop
ment of spiral structure has been gen.
orally lacking, and the present contribu-
ton is an attempt to partially fill the
gap.
THE investigation is based on photo
graphs made with 100-inch and the
60-lnch reflectors of the 300 nebulae
brighter than the 18th magnitude and
north of declination 80 degrees, and
in addition of about 1000 of the fainter
catalogued nebulae. The extensive mate
rial permits the rare and accidental
features of nebulae to be readily distin-
guished from those which are character
istic and are normally present.
"A study Of the latter features leads to
the following conclusions:
Il. Progression along the sequence is
smooth and continuous There is no
evidence of sudden cataclysmic transi-
ton.
"2 The sequence begins with series OF
nebulae without internal structure (other
than the smooth fading of luminosity
from the centers outward, ranging from
globular masses, through fattening
ellipsoids to lens-shaped bodies whose
ratios Of axis are about 3 to l. The
lenticular form represents critical stage
in the sequence because all flatter
nebulae show internal structure.
%. In order Of appearance, the struc-
ture consists of (a) bright central lens
differentiated from the fainter surround
ing nebulosity, (b) circular patterns
Cares or rings) formed by dark, finely
divided material silhouetted against the
luminous backgrounds of the nebulae,
and (c) spiral patterns, generally, but
not always formed by dark material.
In normal spirals, the spiral land
CIRCULAR patterns first appear within
central lens or the surrounding envelopes.
but never at rims of either. The photo
graphs suggest segregation of material
already present rather than election of
material from nucleus, lens or envelope
into regions previously unoccupied. After
the spiral structure appears, the further
development can be followed, step by
step, to the patterns of conspicuous, late
type spirals that are we'll shown in pub
IShed illustrations.
These generalizations indicate the
kind of information that may be derived
from collection of photographs. A more
or less complete tabulation of data is
contemplated Meanwhile. 1t is hoped
that discussion between theoretical in
vestigators and observers may help to
clarity the problem and to distinguish
between significant data and unimpor-
tant details"
UnsOund Fiscal Policy