Sudden Increase of Cosmic-Ray Intensity

A sudden 30% increase in cosmic-ray intensity lasting approximately 12 minutes was observed at an atmospheric depth equal to 80 g/${\mathrm{cm}}^2$ by a Neher integrating ionization chamber flown from Bismarck, North Dakota on October 16, 1958. A similar measurement made simultaneously at Invercargill, New Zealand observed no increase. These observations are not in accord with the simple solar impact zone theory.