Gallant's brief, efficient historical survey begins refreshingly with a quotation from physicist Aflred Romer: ""Do not think for a moment that you know the real atom. The atom is an idea, a theory, a hypothesis. . . . An idea in science, remember, lasts only as long as it is useful."" Assuming the tentative nature of scientific investigation and progress he reviews the development of atomic theory from Democritus, especially the chain of discoveries beginning with J. J. Thompson's study of the electron's ""puzzling glow"" in a vacuum tube and the investigations of ""mysterious rays"" by Roentgen, Becquerel and Marie Curie, then on to Chadwick and Heisenberg and the ""weighing of atoms"" leading to the production of radioactive isotopes. Thus prepared, readers can better appreciate both Gallant's discussion of atomic energy from Fermi's early experiments to the promise of fusion reactors and his sober concluding chapter on the dangers of radioactive wastes -- none of which are ""clean"" or unconditionally ""safe."" Non-mathematical and undemanding but admirably free of hand-waving leaps and misleading simplification, this provides a valuable orientation and a timely warning.