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THE THE PRINCIPLES OF WIRELESS TELEGRAPHY
THE THE PRINCIPLES OF WIRELESS TELEGRAPHY
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"THE THE PRINCIPLES OF WIRELESS TELEGRAPHY" by Frederick K. Vreeland, discusses the principles and methods of practical wireless telegraphy. Mechanical analogies, frequently quite ingenious and novel, are freely employed in the explanation. Analytical discussions are entirely absent yet it is written as a remarkably simple and lucid explanation of the practice of wireless telegraphy discussing principles rather than details.
No attempt is made to develop the subject in all the multiplicity of detail which the present state of the art would admit. As the author says:—
"This is not intended as a treatise on wireless telegraphy—no attempt is made to describe the myriad forms of apparatus nor to settle questions of priority and history. Such material is readily accessible to those who may desire it. The object is rather to deal with principles and to trace the development of the art in its essential features. Where specific cases are cited they are chosen with reference to their fitness to illustrate an idea or to serve as milestones on the path of progress, and they are treated with a view to emphasize that which is essential and minimize superficial or unimportant details."
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AUTHOR'S PREFACE
It has been my purpose to take up the thread where M. Poincare dropped it, carrying the line of thought into the practical field of wireless telegraphy, and applying the principles laid down in Part One to the various problems involved; to describe certain typical systems, to show why some have failed while others succeeded; and to explain their mode of operation in the light of Maxwell's ideas.
This is not intended as a treatise on wireless telegraphy — no attempt is made to describe the myriad forms of apparatus nor to settle questions of priority and history. Such material is readily accessible to those who may desire it. The object is rather to deal with principles and to trace the development of the art in its essential features. Where specific cases are cited they are chosen with reference to their fitness to illustrate an idea or to serve as milestones on the path of progress, and they are treated with a view to emphasize that which is essential and minimize superficial or unimportant details.
In Chapter IV is discussed the question of wave-propogation over a conducting surface, and various hypotheses are reviewed and tested in the light of the preceding chapters. In approaching a conclusion it has seemed advisable to depart a little from the purely Maxwellian idea of displacement currents, which does not readily appeal to the imagination in this connection, and to substitute Faraday's conception of moving tubes of induction, which embodies the same principles in more tangible form. It is hoped that this figure, so successfully used by J. J. Thomson in explaining other electrical phenomena, may give the reader a clear understanding of what takes place when an electromagnetic wave glides over the surface of the earth.
The other chapters are self-explanatory and need not be considered here.
I desire to acknowledge my indebtedness to M. Poincare for his most courteous permission to translate and publish the work that appears as Part One, and to the many writers on whom I have drawn for references and historical data. My thanks are due also to the Macmillan Company for permission to copy some of the figures illustrating the wrork of Hertz, and to the. publishers for their hearty cooperation in seeing the work through the press.
Frederick K. Vreeland
No attempt is made to develop the subject in all the multiplicity of detail which the present state of the art would admit. As the author says:—
"This is not intended as a treatise on wireless telegraphy—no attempt is made to describe the myriad forms of apparatus nor to settle questions of priority and history. Such material is readily accessible to those who may desire it. The object is rather to deal with principles and to trace the development of the art in its essential features. Where specific cases are cited they are chosen with reference to their fitness to illustrate an idea or to serve as milestones on the path of progress, and they are treated with a view to emphasize that which is essential and minimize superficial or unimportant details."
***
AUTHOR'S PREFACE
It has been my purpose to take up the thread where M. Poincare dropped it, carrying the line of thought into the practical field of wireless telegraphy, and applying the principles laid down in Part One to the various problems involved; to describe certain typical systems, to show why some have failed while others succeeded; and to explain their mode of operation in the light of Maxwell's ideas.
This is not intended as a treatise on wireless telegraphy — no attempt is made to describe the myriad forms of apparatus nor to settle questions of priority and history. Such material is readily accessible to those who may desire it. The object is rather to deal with principles and to trace the development of the art in its essential features. Where specific cases are cited they are chosen with reference to their fitness to illustrate an idea or to serve as milestones on the path of progress, and they are treated with a view to emphasize that which is essential and minimize superficial or unimportant details.
In Chapter IV is discussed the question of wave-propogation over a conducting surface, and various hypotheses are reviewed and tested in the light of the preceding chapters. In approaching a conclusion it has seemed advisable to depart a little from the purely Maxwellian idea of displacement currents, which does not readily appeal to the imagination in this connection, and to substitute Faraday's conception of moving tubes of induction, which embodies the same principles in more tangible form. It is hoped that this figure, so successfully used by J. J. Thomson in explaining other electrical phenomena, may give the reader a clear understanding of what takes place when an electromagnetic wave glides over the surface of the earth.
The other chapters are self-explanatory and need not be considered here.
I desire to acknowledge my indebtedness to M. Poincare for his most courteous permission to translate and publish the work that appears as Part One, and to the many writers on whom I have drawn for references and historical data. My thanks are due also to the Macmillan Company for permission to copy some of the figures illustrating the wrork of Hertz, and to the. publishers for their hearty cooperation in seeing the work through the press.
Frederick K. Vreeland
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