Evening star., 1936-09-29
STARS. MEN AND ATOMS
Notebook of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY,

Debris of outer space flaming into the
upper reaches Of earth's atmosphere at
velocities approaching 40 miles second
is yielding astronomers new data on the
mysterious border line between the outer
most borders of the planet and the vast
emptiness.
A report on heights Of more than 5000
meteors observed by the Arizona expe-
dition from October, 1881, to July, 1898,
has Just been issued in the journal of
the National Academy Of Sciences here.
From the attitudes at which they ap-
peared a good deal can be deduced about
the nature Of the medium through
which they are moving.
The meteor, q chunk of rock or iron
from somewhere in outer space, strikes
the outer atmosphere at a terrific speed
Usually 1t is quickly consumed, its ashes
adding to atmospheric dust and gradually
drifting to earth. Only the largest of
meteors occasionally collide with the
surface Of the planet.
A notable observation in the report to
the National Academy was that. of the
seasonal variation in height of the CEN
ters Of meteor trails. This varied nearly
three miles between March and Novem-
Der, suggesting an actual fluctuation in
the height Of the atmosphere itself more
or less corresponding with the annual
temperature curve. The warmer atmos-
phere Of Summer naturally would rise
slightly higher than that of Winter.
The small difference between the sea-
sons, however, indicates that the varia-
tion is only about so per cent of the
annual amplitude of the mean tempera-
ture at the earth's surface.
The meteor observations also show
that the structure of the upper atmos-
phere must be quite different from that
at the surface and disprove some hy-
potheses concerning 1t. If the molecular
weight of the gas constituting the outer
most layers of air were the same as that
Of the atmosphere at sea level a tenn
perature Of approximately 100 centigrade
would be necessary to account for the
meteor phenomena. Obviously there can
be no such temperatures at 80 miles
above the earth's surface. Mathematical
calculations indicate that the tempera-
ture Is closer to 80 centigrade, calling
for somewhat smaller molecular weight
due probably to ionization or dissocia-
ton of the atmospheric gases by the
intense solar radiation. Assuming the
correctness Of this figure, the molecular
weight should be little more than half
the sea level value.
This affords little clue as to the actual
composition Of the upper atmosphere,
but yields considerable information as to
what it is not. It cannot, the report
points out, be hydrogen atmosphere,
as has been postulated by several
physicists.
BY studying the life histories Of single
transforms, Department of Agriculture
scientists have opened an entirely new
approach to the problems of upstream
reduction and control of flood waters.
The measurements, made comparatively
by Weather Bureau and Soil Conserva-
ton workers in Western Oklahoma,
show that the intensity Of rainfall dur
ing single storm varies markedly from
locality to locality within the storm area.
Previous rainfall records, based on less
frequent observations of widely spaced
gauges, thus provide an inaccurate
record Of the amount of water falling
upon the land. Thus it has been i'm
possible to gauge flood peaks with any
degree of accuracy.
In addition to the data on intensity
distribution, the measurements have pro-
vided valuable information relative to
the extent and migration tendencies Of