Ferdinand Braun was certainly one of the great scientists of his time. He discovered the rectifier effect on which all of modern solid-state electronics is based; he made significant contributions to thermodynamics and to the development of magnetic compounds; he invented the cathode-ray oscilloscope, the precursor of the television picture tube; and he advanced radiotelegraphy sufficiently to warrant the joint award of the 1909 Nobel Prize for physics to himself and to Marconi. He was a modest, private man who died an alien in a hostile country in the midst of a world war and has since been unreasonably forgotten by his peers and by historians alike.

Where did Braun come from? One reads that when he was born there was no gas, railroad, water main, or sewer in Fulda, his birthplace in Germany. There was no electricity, and streets were lit by kerosene, homes by oil or candles. The prime mover for Fulda's main industry was a waterwheel. It was not until Braun's graduation from the local Gymnasium in 1868 that the railroad was extended to Fulda. He boarded it to reach Marburg, where he attended the university and matriculated in mathematics. In 1869 he moved to the University of Berlin, then the dominant school of science in Germany. His teachers Quincke and Helmholtz sharpened his sense of the essential and of the interplay between theory and experiment.

Braun made his first important discovery while at Leipzig in 1874. He had devised a method of electrical contact with minerals in order to investigate electrolysis. In the course of this work he found that the junctions of some metals and semiconductors did not conform to Ohm's law but were influenced by the magnitude and direction of the current flow. This observation led eventually to the use of semiconductor "rectifiers" in radio crystals, transistors, and solid-state electronic devices. The four papers Braun published in the Annalen der Physik on the rectifier effect established the basis for future development.

It is typical of Braun that he made an early decision not to obtain patents for discoveries that resulted from his experimental work. This was an attitude shared by inventors as diverse as Franklin, Faraday, Joseph Henry, Roentgen, and Galileo Ferraris. Franklin's position was that "as we enjoy great advantage from the invention of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously." In July 1898, however, Braun joined two others in a wireless telegraphy patent application so that they would not be limited in further experimentation. Many patents followed.

Braun's career spanned the period of great expansion in Central Europe when Prussia, under Bismarck, seized the initiative to unite the German states into an empire. He was in Berlin in 1871 when Wilhelm I was crowned Emperor of Germany, and his career included appointments at Leipzig, Marburg, and Berlin before he moved to the politically sensitive university at Strasbourg in 1880. His contemporaries and associates included the creators of modern physics-such giants as William Thomson, John Tyndall, Gustav Wiedemann, Hermann Helmholtz, and Conrad Roentgen.

Braun played an important part in the establishment of applied science as an accepted discipline at the universities. At age 33, he undertook a professorship of electrical engineering at the technical university at Karlsruhe in Baden. Studies in the theory of electricity formed part of his work in physics in those early years; it required a broad exposure in the basics of the new science, a knowledge of engineering applications, an ability to pick up new directions, and the confidence to weave these strands into a meaningful academic discipline. At Karlsruhe Braun's contributions included an electrical pyrometer with a reading galvanometer that could be placed at a distance from the furnace, an early example of electrical telemetry. The Braun electrometer, a greatly improved version of the gold-leaf electroscope calibrated in volts, was described in the Annalen in 1887. (Heinrich Hertz, who succeeded Braun in the physics chair at Karlsruhe, was to perform there one of the most significant experiments in electrical history-the demonstration of the existence of electromagnetic waves.)

Braun was one of the early supporters of high-voltage transmission of alternating current. Strasbourg, where Braun taught, was among the first cities in Europe to adopt alternating current at its power station. The power lines were extended to the physics department of the university, and the controversial current became the focus of much investigating and much lecturing. The 5o-cycle frequency of the generating station became the standard for most of the world.

The discovery of x rays by Roentgen in 1895 opened a new era in electrical science, as it did in medicine, metallurgy, and communications. The air-exhausted tube, as an instrument for further study, rose in importance and led to "glow tubes" holding gases under pressure, cathode-ray tubes, and later neon tubes and fluorescent lighting. Braun undertook a series of experiments to influence the cathode-ray beam by placing magnets in strategic configurations, causing a spot of moving light on a fluorescent screen at the tube's flared end. This was the origin of the cathode ray oscilloscope, the television tube, and the computer terminal. The Braun tube was adapted for use in many fields even in Braun's lifetime, especially after a series of improvements and refinements had produced a sharper image. Further work led to radar, the scanning electron microscope, satellite communication, radio astronomy, and broadcasts to and from space.

As credit for the invention of the electric light goes to Edison not only by virtue of priority but also because of his perseverance in making the device practical and backing it up with a supply system, so credit for the introduction of wireless telegraphy (radio) is given to Marconi in spite of the work of others with Hertzian waves. Marconi was neither a trained physicist nor an electrical engineer, and he therefore faced unresolvable technical problems early in his designs. Braun faced similar problems but drew on his store of physical analogies to build his transmitter for radio telegraphy. He produced four improvements in circuitry that were recognized by the committee awarding the Nobel Prize. It was also noted that Braun's replacement for the Marconi spark-gap circuit was not simply an improvement but an important new advance. Whereas Marconi's earliest transmitter emitted damped waves with resulting uncertainty of reception, the Braun apparatus generated less damped and therefore more powerful emissions. Braun introduced a sparkless antenna circuit by inserting a magnetic coupler that provided a transformer effect instead of having the antenna directly in the power circuit. He later experimented with methods of improving directional transmission quality; this work was a boon for military applications.

These improvements assured the success of "wireless" and broke the Marconi radiotelegraphy monopoly. Braun was confident that his device could extend the penetrated distance more than fivefold. He had separated the closed oscillating circuit from the coupled antenna circuit and thereby provided an effective and safe apparatus that could extend the transmission range from 15 to over 100 kilometers. In the many experiments aimed at improving and extending transmission range, he reverted to the use of the semiconductor characteristics of certain metal sulfide crystals, with encouraging results. This led to today's transistor. Similarly, Braun's efforts to increase spark-gap length led to the development of powered iron-core inserts into induction coils, coherer improvements, and to today's ferrite core for computer memories and other applications.

The year 1901 was one of triumph for Marconi, who succeeded in spanning the Atlantic from Cornwall to Newfoundland by signaling the letter S; to do this, though, he had to use transmitter and receiver circuits resembling Braun's design. A coalition of competing German radiotelegraph developers was tried but failed, leaving the Marconi firm dominant. The parallel efforts of Marconi and Braun continued for a dozen years, each claiming priority in one form of record or another, each aware of not only the technical features of his improvement but also the political implication of two states heading toward a catastrophic conflict. Parallel developments by the Marconi group and by Braun and other German researchers led inevitably to extended patent litigation to resolve the numerous claims and counterclaims. Under political pressure, the four German radio pioneers pooled their resources to form Telefunken (much as General Electric and Westinghouse were to form RCA).

Braun's election to the coveted position of Rektor at the University of Strasbourg reflected his professional abilities and also the importance of the work being done in the advanced laboratories. In his remarks of acceptance of the honor paid him, he spoke of the new atomic age the students faced; radioactivity had been discovered and the physics of the atom was beginning to be gauged; man's flight by airplane had just been realized, and a new dimension in space had been added for man to conquer.

This thrust by theoretical and experimental scientists into the intricacies of the physical world caught the imagination of the advanced nations. The trend encouraged Alfred Nobel to establish his awards, which further stimulated scientific research in the public interest. The first prize in physics went in 1901 to Roentgen. In 1909 it was awarded to Braun and Marconi. The two laureates had approached the solution of "wireless telegraphy" by different routes; both showed the dedication and ingenuity that solved each succeeding problem as the art of radio communication improved. Now, in the presence of Swedish King Gustaf V, each pioneer cordially acknowledged the other's contributions and talents in his prepared papers. It was an occasion for mutual congratulation. A few uncertain years passed and the scene darkened.

Braun was of the opinion that "modern" war was unthinkable among civilized states. He was wrong. When the war came, he withdrew at first from the uncertain border between France and Germany to the quiet of Tuebingen, but then returned to Strasbourg as the active front moved west.

Wireless became an important instrument of war. By triangulation ships were spotted and followed, torpedo boats were alerted, and information was relayed. The range of radiotelegraphy increased rapidly from a few hundred kilometers to over 18,000 kilometers, circling half the globe from Germany to New Zealand.

Braun embarked on a Norwegian steamer bound for New York in December 1914 to defend the legitimacy of his work in a patent suit brought against a German-owned radiotelegraph station on Long Island-allegedly an important intelligence link between Germany and America. Marconi himself was expected to appear in court for the prosecution, and therefore Braun was asked to make the trip to appear for the defense. Marconi's failure to appear avoided a court confrontation, but Braun now found himself with little hope of returning home before war's end. He occupied himself by lecturing before science and engineering groups and preparing outlines for future publications, including a projected Physics for Women. He lived in a small house in Brooklyn witnessing the uncertain progress of the war, learning of the death of his wife, old friends, and associates, his health deteriorating to the point of total confinement to bed. When the United States declared war on Germany, his new status as an enemy alien further affected his spirit. In this nadir of his fortunes-ill, aging, suspect, and forgotten-this gentle educator, inventor, and benefactor of mankind died in April 1918.

The present work had its origin in a local dispute in the Catholic town of Fulda. In 1955 a proposal was made to name a new school for Ferdinand Braun, the town's most distinguished, if least known, son. A description of Braun's achievements aroused local pride, and the decision seemed assured until it was revealed that Braun was not Catholic but Protestant, and that what lay in the town cemetery was not Braun's body but his ashes. The resulting dispute in this Catholic stronghold was eventually resolved in Braun's favor, but not before it had caught the attention of a journalist, Friedrich Kurylo, who was sufficiently interested to start researching Braun's life and who eventually produced a biography that was published in Germany in 1965.

The English edition of Kurylo's biography was produced under the guidance of Mrs. Konrad Ferdinand Braun, daughter-in-law of the scientist. It has benefited greatly from the insight of its translator and adaptor, Charles Susskind, who has drawn upon his unmatched knowledge of the history of the science and technology of electronics to produce a book that will be valuable to historians and that also manages to convey something of the spirit of this warm and humane scientist who deserves not to be forgotten.

Bern Dibner

Copyright © 1981 by The Massachusetts Institute of Technology

All rights reserved. No part of this book may be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher.

Revised edition of Ferdinand Braun: Leben und Wirken des Erfinders der Braunschen Röhre, Nobelpreis 1909 by Friedrich Kurylo. Originally Published in 1965 by Heinz Moos Verlagsgesellschaft Gmbh & Co. KG, Munich

This book was set in Penta/202 Bembo by Grafacon, Incorporated, and printed and bound by Halliday Litho in the United States of America.

Library of Congress Cataloging in Publication Data

Kurylo, Friedrich.

Ferdinand Braun, a life of the Nobel prizewinner and inventor of the cathode-ray oscilloscope.

"Revised edition of Ferdinand Braun, Leben und Wirken des Erfinders der Braunschen Röhre, Nobelpreis[traeger] 1909"-Verso t.p. Originally published: Munich: Moos, 1965.

Bibliography: p.

Includes index.

I. Braun, Ferdinand, 1850-1918. 2. Physicists-Germany-Biography. I. Susskind, Charles. II. Title.

QC16.B68K813 530'.092'4 [B] 181-5063

ISBN 0-262-11077-6 AACR2