BOOK REVIEW (by R. J. HYND): Current progress in the study of solar-terrestrial relations consistently emphasises the interdependence of the various disciplines involved. Thus a concise discussion of cosmic ray physics can be of particular interest to workers in related fields. Dr. Cranshaw’s book is indeed concise, yet it succeeds in covering all the main topics of interest. These include: the cosmic ray primary radiation and its possible origins; very high energy nuclear interactions and the so-called “extensive air showers”; electron-photon cascades of considerable lateral dimensions, produced in the atmosphere as the end product of the impact of very high energy cosmic rays on the top of the atmosphere; a brief survey of geomagnetic effects and the study of the time variations of the cosmic radiation. At a time when books on cosmic ray physics tend to show a steadily increasing length, and price, an attempt to reduce both is certainly welcome. However, the book seems to have one weakness. I think one may reasonably require two things of a publication of this sort: that the reader may subsequently study the relevant literature intelligently, and that he may have a clear picture of future trends in the field. Dr. Cranshaw succeeds in the former but not the latter. He is perhaps unfortunate in writing at a time of considerable progress in cosmic ray studies, but I feel that a book published in 1963 might have sacrificed some detail to indicate the considerable effect of the IGY, and the earlier satellite studies, on present theories. The editing and diagrams are good and there appear to be few misprints, the most important being the interchange of the captions to the diagrams on page 101.