Study of cosmic rays between New York and Chile

A Compton Model‐C cosmic‐ray meter aboard the S.S. Santa Ana measured cosmic‐ray intensities between New York and Valparaiso from September, 1940, to February, 1942. The hourly deflections of the electrometer‐needle, recorded photographically, were measured and the computed cosmic‐ray intensities corrected for barometric pressure with a coefficient K = −1.74 per cent per cm mercury. After reduction to 30 inches of mercury, they were grouped into 2°.5 intervals of geomagnetic latitude with the corresponding mean temperatures and temperature‐coefficients for the various latitudes determined. The variation of intensity of ionization with geomagnetic latitude was then plotted, showing a latitude‐effect of 8.3 per cent. A longitude‐effect of 1.5 per cent between geographic longitudes 75° west and 145° west was also found. The curve of temperature‐coefficients was found to be symmetrical about 23° north geomagnetic latitude in contrast to a similar curve of P. S. Gill for the Pacific, which is symmetrical about the geomagnetic equator. Variations of cosmic radiation during the magnetic storm of March 1, 1942, are plotted and show the same characteristics and order of magnitude as those reported by other observers.