As expositors of nuclear energy the authors, to begin with the negative, do not offer political panaceas, broader perspectives of man's new magic-energy world, descriptions of weapons or theories of scientific instruments little-known to the public. What, positively, do they do? They put in simple but meaningful terms the physical laws and phenomena of modern nuclear science. They proceed to emphasize the means by which radioactivity is destructive to living organisms, and the specific effects that it creates. They disclose just what risks and biological horrors radioactivity might entail in the event of atomic war or excessive fallout during fission tests. The statement is terse, grim, highly factual. It is designed to inform, not to warn or alarm; but it does warn and it does alarm- as it informs clearly and generously.