The penetrating radiation in the atmosphere at Hobart

McAulay, Alexander Leicester and Hutchison, NL 1924 , 'The penetrating radiation in the atmosphere at Hobart' , Papers and Proceedings of the Royal Society of Tasmania , pp. 123-135 .

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If a gas be enclosed in a thick-walled vessel and protected
from all external disurbances a few of its atoms are
still found to be ionised during every second. It can be
shown that this residual ionisation cannot be due to the
heat energy of the gas itself (1), the atoms must therefore
be broken up by a radiation coming from without. This
external radiation must. arise in the walls of the vessel
itself, or penetrate them. If the former is the case we may
say with fair certainty that it is due to radio-active matter
in_ the walls, and if the latter it must be a radiation of
extremely great penetrating P!JWer, as shielding the vessel
-with several feet of water has little effect on the ionisation.
The residual ionisation is now known to be due to both
these causes, and they may 1be distinguished from one
another experimentally. The origin of at any rate a part
of the radiation is still in doubt, and measurements made
at different parts of the earth's surface may be expected
to provide evidence indicating what factors are concerned.
Recenti experiments by ~various workers have given
-curiously contradictory indications as to the nature of the
penetrating radiation, leaving the matter in a condition most
stimulating for further research.
Millikan (2) and others (3, 4, 5) have shown that the
radiation increases in intensity with the height above sea
level at which the measurement is made, and, further, that
it varies with meteorological conditions (6). This would
seem to show decisively that it is an external radiation, and
that it probably arises in the upper atmosphere.

Item Type: Article
Authors/Creators:McAulay, Alexander Leicester and Hutchison, NL
Keywords: Royal Society of Tasmania, RST, Van Diemens Land, natural history, science, ecology, taxonomy, botany, zoology, geology, geography, papers & proceedings, Australia, UTAS Library
Journal or Publication Title: Papers and Proceedings of the Royal Society of Tasmania
ISSN: 0080-4703
Collections: Royal Society Collection > Papers & Proceedings of the Royal Society of Tasmania
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