The existence of an effect upon cosmic-ray intensity at the boundaries separating different types of air masses is clearly established by the results of these observations, and has lately received additional confirmation from the work of Nishina, Sekido, Simamura, and Arakawa. This effect is evidently of the type postulated by Blackett to explain the seasonal variation in cosmic-ray intensity, although in this case both temperatures and pressures in the upper air contribute to the change. Work is now in progress to compare cosmic-ray intensities with the daily meteorological sounding balloon records which have recently become available.

• Received 29 July 1940

DOI:https://doi.org/10.1103/PhysRev.58.583