Measurements of cosmic-ray intensities in the equatorial and temperate regions are reported, and the instrument described. The apparatus consists of a single Geiger counter, the impulses of which are transmitted by radio to a ground station. The results are compared with high altitude electroscope measurements and are found to agree satisfactorily. Flights up to 70,000 feet were obtained in Peru. The results indicate that the intensity of cosmic radiation in the upper atmosphere in Peru is about half that at Washington. The component which produces about one-half the maximum total intensity of ionization at high altitudes over Washington is cut out by the earth's magnetic field and does not reach the top of the atmosphere in Peru. The energy of this component lies between 3 and 12×${10}^9$ ev. Analysis of the data shows agreement with the Carlson-Oppenheimer curves. The ionization at high altitudes is shown to be in large part due to secondaries.

• Received 2 November 1937

DOI:https://doi.org/10.1103/PhysRev.53.14