A fat and fascinating plum-pudding of a book, crammed with a variety of facts about the mysterious forces of light, heat, radio, X-rays and other rays, and some of their uses by man. Much of this is fairly complex, but the author, an experienced science-writer, is so obviously familiar with, and devoted to, his subject that he conveys his sense of excitement and of the ""magic"" quality of the material to the reader. The book is arranged by sections- the earlier chapters dealing with the basic facts of the spectrum... visible light, ultraviolet, infra-red,- while later chapters deal with radio waves, TV, radioactivity, and the enormously intricate machines invented to utilize these forces. The book is full of arresting examples of the natural and practical uses and effects of rays, and some powerful, almost poetic descriptions of phenomena such as luminescence and Northern lights. There are brief biographies of inventors and their inventions. There are fascinating bits about ""witches' meat"", ""black-out brooches"", and the use of foil strips literally to ""foil"" German radar. There is, in fact, little in, or related to, this field that the author does not include in his restless range. Most is clearly, concisely and excitingly explained, and, though some of the complex machines may be beyond the average reader, the book's character and variety give a generally vivid, readable view of what is indeed a ""magic"" subject.