RADIOACTIVITY— RUTHERFORD I75 



bodies, and our views of the nuclear structure of all atoms to observa- 

 tions on the scattering of a-particles. 



It is clear that the study of radioactivity, both old and new, has 

 been extraordinarily fruitful in extending our knowledge of the 

 nature and varieties of atoms and of the way in which one atom can 

 be changed into another. Although much progress has been made in 

 the last few years, much still remains to be done before we can hope 

 to understand how the atoms have been built up from elementary 

 particles or to grasp the significance of the relative abundance of 

 the varieties of atoms in our earth. 



