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ABSTRACT THIS month (August 1949) a party of American men of Science, sponsored by the National Geographic Society and by the Bartol Research Foundation, will visit the Canadian settlement
Churchill on Hudson Bay, to investigate the cosmic-ray intensity at a height of twenty miles. A fourfold coincidence arrangement of Geiger counters carried aloft on free balloons will be
used, and the observations, together with data for the atmospheric pressure, and the temperature within the apparatus, will be transmitted by radio and recorded on moving tape on the ground.
Previous height measurements of cosmic rays up to 30,000 ft. were made with specially equipped B-29 aircraft. Churchill is chosen as the venue of the expedition because of its high
geomagnetic latitude (69°). It is hoped to determine whether at 100,000 ft. height the cosmic-ray intensity continues to increase with geomagnetic latitude ; if not, one interpretation would
be that the cut-off is caused by the action of a solar magnetic field. Canadian meteorologists stationed at Churchill will take part in the work. It may be hoped that it has been possible
to arrange to use these flights for the determination of the winds at 100,000 ft., on which our information is still very scanty. Access through your institution Buy or subscribe This is a
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ARTICLE CITE THIS ARTICLE Cosmic Ray Expedition. _Nature_ 164, 214–215 (1949). https://doi.org/10.1038/164214f0 Download citation * Issue Date: 06 August 1949 * DOI:
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