Cosmic Ultra-radiation and Auroræ Boreales

RECORDS of the ionisation in a closed vessel, caused mainly by the cosmic ultra-radiation, have been obtained at Abisko in northern Sweden (lat. 68° 21′ N.) during two periods : October 1929–July 1930 and September 1932–July 19331. During the first period, a Kolhörster apparatus, placed within an iron shield 6–11 cm. in thickness (free opening upwards), was… CONTINUE READING