GeneralPOSITIVE RAY ANALYSIS, MASS SPECTROGRAPHS, STABLE ISOTOPES, ATOMIC SPECTRA AND THE PERIODIC CLASSIFICATION OF THE ELEMENTS, X-RAYS AND X-RAYS SPECTRA, THE PRINCIPLE OF WAVE MECHANICS, MAGNETIC PHENOMENA, NATURAL RADIOACTIVITTY, THE ACCELERATION OF PARTICLES TO HIGH ENERGIEIS, BETA-PARTICLES AND GAMMA RADIATION, COSMIC RAYS, FISSION OF THE NUCLEUS AND NUCLEAR ENERRGY, THE INTERACTION OF NEUTRONS WITH NUCLEI