Cosmic Rays is a two-part book that first elucidates the discovery, nature, and particles produced by cosmic rays. This part also looks into the primary cosmic radiation; radio waves from the galaxy; extensive air showers; origin of cosmic rays; and other cosmic radiations. Part 2 consists of reprinted papers involving cosmic rays. Papers 1 to 10 treat the nature of the radiation, arranged chronologically; in Papers 11 to 16 the scene moves away from the Earth.