The Significance of Recent Cosmic-Ray Experiments

The particular recent cosmic-ray experiments, the significance of which we wish to discuss, are (1) as yet unpublished results of work by Millikan and Cameron on absorption coefficients of cosmic rays on high mountains and at great depths in mountain lakes, (2) recent experiments by Millikan and Bowen on the absorption of gamma rays in mountain lakes, (3) new experiments in the Norman Bridge Laboratory by Chao on gamma-ray absorption, and (4) experiments by Bothe and Kolhorster and by Curtis on coincidences obtained with the use of cosmic rays in Geiger-Muller ionization counters.