High altitude cosmic radiation measurements near the north geomagnetic pole

Abstract
During the summer of 1937, a scientific expedition to Baffin Bay, led by Mr J. M. Wordie (1937, 1938) in the specially chartered Norwegian sealer, Isbjørn, had as its principal object the measurement of cosmic radiation at great altitudes near the north geomagnetic pole in North-West Greenland. In this paper we describe the apparatus used in these measurements and discuss the results obtained. Detailed discussion of the balloon equipment and of the meteorological data obtained will be found in the adjoining paper (Carmichael and Dymond 1939). Thanks to the courtesy of Professor E. Regener, we were able to adopt a balloon technique (Regener 1935) which has been consistently successful. This was a great advantage, as during preparation, and on the expedition itself, there was little opportunity for experiment with balloons. Regener’s method involves the use of two balloons so that when one bursts from the reduction of atmospheric pressure, the other, itself insufficient to support the load, ensures a gradual descent. In our experiments this method had a further important advantage—when the earth was reached on descent, the intact balloon floated 15 m. up in the air, and assisted us in finding the apparatus.