(1) The Millikan-Cameron cosmic-ray curve extending for 80 equivalent meters of water below the top of the atmosphere up to 7.5 m has here been extended by accurate measurements in the critical region from 7.5 m up to 3.34 m (29,200 ft.) of water beneath the top in latitude 34, and up to 4.5 m (22,000 ft.) in the equatorial belt. The comparison of the two curves permits of the separation of the magnetically deflectable particles from the primary non-deflectable cosmic rays. (2) The rays thus separated reveal with much definiteness a banded structure of not less than three rather widely separated components, and by virtue of the high altitudes reached fix with considerable certainty the absorption coefficient of the least penetrating band. This single band is responsible for 90 percent of the cosmic-ray ionization of the atmosphere. The absorption coefficients of the more penetrating bands of indefinite number (not less than two) cannot be sharply determined, but their general character is indicated herein, as well as the limitations of this method of their determination. (3) These measurements combined with Bowen and Millikan's stratosphere observations, which agree well with the present measurements in the region in which they overlap, make possible the plotting of a complete cosmic-ray intensity curve extending from the lowest depths to the top of the atmosphere. (4) The graphical integration of this curve shows that the total energy reaching the earth in the form of cosmic rays is about one-half that coming to the earth in the form of heat and light from the stars. This makes the cosmic-ray energy in the universe from 30 to 300 times that of all other radiant energies combined.

• Received 19 June 1933

DOI:https://doi.org/10.1103/PhysRev.44.246