内容简介：
It is very appropriate at this moment when radio has taken the country by storm, and aroused an enthusiasm never before equaled, that the possibilities for boys in this art should be brought out in the interesting and readable manner shown in the first book of this series. Radio is still a young science, and some of the most remarkable advances in it have been contributed by amateurs - that is, by boy experimenters. It is never too late to start in the fascinating game, and the reward for the successful experimenter is rich both in honor and recompense. Just take the case of E. H. Armstrong, one of the most famous of all the amateurs in this ountry. He started in as a boy at home, in Yonkers, experimenting with home-made apparatus, and discovered the circuit that has revolutionized radio transmission and reception. His circuit has made it possible to broadcast music, and speech, and it has brought him world-wide fame.