Letters of a Radio-Engineer to His Son is a fascinating and accessible introduction to the principles of radio engineering, written by John Mills and first published in 1922. Presented in the form of a series of letters from a knowledgeable father to his curious son, the book demystifies the science and technology behind radio communication at a time when radio was revolutionizing the world. Through clear explanations, practical examples, and engaging analogies, the author covers a wide range of topics, including the nature of electricity and magnetism, the workings of circuits and oscillators, the function of vacuum tubes, the transmission and reception of radio waves, and the construction and operation of radio receivers and transmitters. The book is notable for its conversational tone and its ability to make complex technical concepts understandable to readers with little or no background in science. Each letter builds upon the previous ones, gradually guiding the reader from basic electrical theory to the more advanced aspects of radio engineering. Along the way, the author addresses common questions and misconceptions, provides historical context, and encourages hands-on experimentation and critical thinking. Letters of a Radio-Engineer to His Son not only serves as an educational resource but also captures the excitement and wonder of the early days of radio. It reflects the spirit of discovery and innovation that characterized the era, making it both a valuable historical document and a timeless introduction to the fundamentals of radio technology. Whether you are a student, a hobbyist, or simply curious about the origins of modern communication, this book offers a unique and engaging perspective on the science that changed the world.