Discussion on Ultra-Penetrating Rays Geiger, H. ; Rutherford, Lord ; Regener, E. ; Lindemann, F. A. ; Wilson, C. T. R. ; Chadwick, J. ; Gray, L. H. ; Tarrant, G. T. P. ; Dobson, G. M. B. ; Bragg, William ; Richardson, O. W. ; Eddington, Arthur ; Soddy, F. ; Chapman, S. Abstract Publication: Proceedings of the Royal Society of London Series A Pub Date: July 1931 DOI: 10.1098/rspa.1931.0104 Bibcode: 1931RSPSA.132..331G