Evening star., 1939-09-14
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
Bv Thomas r. Henri.

By Thomas r. Henry.
4 definite seasonal effect at high al
titudes in the intensity of cosmic radia-
tion-the incredibly powerful showers of
particles constantly bombarding the
earth from outer space-was reported to
the cosmic ray symposium at the Uni
versity of Chicago by DR.. William P.
Jesse of the Chicago faculty. 1t was dis
covered from series of flights with
unnamed balloons carrying cosmic ray
apparatus which have been carried out
since last October.
The symposium was attended by the
worlds foremost physicists interested in
the cosmic ray problem in an effort to
coordinate the many new and in some
cases paradoxical findings being reported
from all over the world. Both the origin
and the actual nature of this highly
penetrating radiation are subjects OF
much dispute.
DR.. Jesses measurements were taken
with specially devised apparatus which
made constant measurements both OF
the radiation itself and the pressure,
from which the altitude could be CAL
culated In each flight the apparatus
attained height sufficient to be con-
sidered the cosmic ray ceiling.
From November to April but little
change was observed from the maxi
mum intensity of cosmic rays. A flight
on April 10, however, showed a very small
diminution of the peak value. Flights
on May 80 and June 10 showed a peak
value about 10 per cent lower than the
highest attained during the winter. This
change is about 10 times the estimated
error of the experiment.
This agrees, DR.. Jesse said, with results
recently reported by Dr. Robert A. Milli-
kan of the California Institute Of Tech
nology at Omaha He found diminu-
ton in cosmic ray intensity in summer
flights over that in winter flights.
For some Of the winter flights, DR.. Jesse
said, it appeared that the pressure at
which the maximum value of cosmic ray
intensity occurred shifted slightly in the
direction of higher pressures as COM
pared with the spring and autumn
flights.
The results, it was stressed, are con-
trary to expectation in showing larger
variations in the upper atmosphere than
are found at sea level. According to
the widely accepted theory of DR.. P. M.
S. Blackett of Manchester University,
England, this could not exist since the
sea level variation is due to mesotrons,
newly discovered exploding elementary
particles of matter, which are themselves
produced in the upper atmosphere. The
levels at which they are formed are
closer to the earth in cold weather than
in hot, when the air is expanded by
heat.
The mesotron is supposed to disin-
tegrate near the top Of the atmosphere
by emitting alpha rays like radium, so
that relatively few of the particles them
selves reach the earth. More of them
would come through in cold weather be-
cause they do not have so far to travel.
A new yardstick for measuring cosmic
ray intensity was reported by DR.. j.
Clay of the University of Amsterdam.
Using ionization, the electrical conduc-
tivity of the air as his basic measure, he
has determined the average ionization
per cubic centimeter at sea level. This
is about hundredth- -millionth of that
caused by an x-ray beam, and is one of
the smallest electric current magnitudes
with which physicists have had to deal.
Due to its minuteness it has escaped
attention up to the present.
The determination is of practical value
to physicists because 1t makes possible a
common value for measurements made
anywhere in the world. This has con-
stituted difficult problem for physicists,
similar to that which once confronted
them in determining the dosage OF
X-rays for patients.
Failure to find significant differences
in cosmic ray intensity in the northern
and southern hemispheres was reported
by Drs. A. H. Compton and P. S. Gill Of
the University of Chicago.
Theoretically, If the radiation is COM
ing from outside the Milky Way galaxy
the intensity in the northern hemisphere
should be approximately half of one per
cent greater than in the southern hemi-
sphere. The fact that there is no differ
ence beyond the limits of experimental
error may indicate that the radiation
originates in the galaxy itself snd shares
its rotation.
RaIiovoc prof3foorirr