On the Energy of the Groups of β Rays from Radium

The author entitled his paper as 'The Origin of the ß and γ Rays from Radioactive Substances' in the October number of this Journal. The energy E of the electron has been calculated from the formula E = 12 m0c2 ß21-ß2 where m₀ is the mass of the electron at slow speeds, c the velocity of light, and ß the ratio of the velocity of the electron to the velocity of light. This is equivalent to multiplying the 'transverse' mass of the electron by half the square of the velocity given by the Lorentz-Einstein formula. Calculating on the latter formula the energy of the electrons comprising the different groups of homogeneous rays given in the paper of Danysz. If the relation found by Whiddington between the velocity required to excite the characteristic radiations and the atomic weight depends on the energy of the electron rather than on its velocity.