If there is any other book on signals for this age group that is as complete as this one is, we don't know about it and can't find it. Not just the how-to but the history of each method--smoke, drums, flags, mirrors, lights, telegraphs and telephones--are all written up and illustrated with precision. The author could have stopped there and still had a very complete little book, but he goes on to give baseball, football and basketball hand signals; hand signals used in industry; aviation landing semaphores; conventions for light houses and light ships; the rules of racing flags; and railroad lights and signs. Radar and sonar come in for introductory remarks. The various flag codes and the Morse code are given in full. A check of what is in print at the adult level indicates that this book would save a few steps in reference rooms.