Ferdinand Braun was one of the great scientists of the late nineteenth and early twentieth centuries and one of the most productive. He discovered the rectifier effect, the basis of modern solid-state electronics--the seed from which grew today's semiconductors, transistors, silicon chips. He invented the cathode-ray oscilloscope, one of the most useful and versatile scientific instruments of the twentieth century--and the basis for our indispensable TV tubes. And he made pioneering and fundamental contributions to "wireless telegraphy"--The work for which he and the universally remembered Marconi were jointly awarded the Nobel Prize in physics in 1909 and which led to today's radio, radar, and television transmissions. Add to this Braun's further accomplishments in pure science--his thermodynamic studies, his development of magnetic compounds--and it becomes clear that Braun has been unjustly neglected in the modern era whose technological foundation owes so much to his work. This scientific biography, however, does considerably more than restore Braun to his proper reputation: it has a fascinating story to tell. Of particular interest is its account of the early days of radio transmission, and the competition of Braun and his associates with Marconi and company to extend the range and improve the reception of radio signals. The technical basis of Braun's contributions are clearly explained.