1. Detailed reviews of cosmic ray research, with comprehensive bibliographies, have recently been published by A. Corlin (Annals of the University of Lund, No. 4; 1934) and E. Steinke (Ergeb. exakt. Naturwiss., 13, 89; 1934). I shall here give references only to some of the very recent work not discussed by these authors.
2. A. H. Compton and R. J. Stephenson, Phys. Rev., 45, 441; 1934.
3. A. H. Compton, Proc. Phys. Soc. London, April 1935.
4. Compare especially T. H. Johnson, Phys. Rev., in press.
5. A. H. Compton and I. A. Getting, Phys. Rev., in press.