Wireless Transmission of Photographs Second Edition, Revised and Enlarged 1919   By: Marcus J. Martin

by

MARCUS J. MARTIN

SECOND EDITION REVISED AND ENLARGED 1919

The Wireless Press, Ltd. 12 13 Henrietta Street, Strand London, W.C. 2

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PREFACE TO SECOND EDITION

Although during the last few years very little, in common with other wireless work, has been possible in connection with the practical side of the wireless transmission of photographs, yet, now that the prospect of experimental work is once again occupying the minds of all wireless workers, advantage has been taken of a reprint of this little volume to amplify a few points that were insufficiently dealt with in the first edition, and also to add some fresh matter.

To Chapter V. has been added a short description of the Nernst lamp, and also some useful information regarding photographic films, and a few notes relating to enlarging included in the Appendix B.

A fresh appendix dealing with the principles of optical lenses has also been added. This is a subject that plays an important part in any system of wireless photography, and to those experimenters whose knowledge of optics is limited this section should prove useful.

To serious workers engaged on the problem of the wireless transmission of photographs, attention {vi} is called to a series of articles which are being published from time to time in the Wireless World , on the design and construction of wireless photographic apparatus.

M. J. M.

MAIDSTONE, 1919.

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PREFACE

In these progressive times it is only reasonable to expect that some attempt would be made to utilise the ether waves for other purposes than that of telegraphic communication, and already many clever minds are at work trying to solve the problems of the wireless control of torpedoes and airships, wireless telephony, and, last but not least, the wireless transmission of photographs.

It may seem rather premature to talk about the wireless transmission of photographs at a time when the ordinary systems are not fully developed; but the prospects of wireless photography are of a very encouraging nature, especially for long over water distances, as there are great difficulties to be overcome in long distance transmission over ordinary land lines and cables which will be entirely eliminated by wireless methods.

From a perusal of Chapter I. the reader will be able to understand something of the difficulties that are to be encountered in working over long distances, and he will also be able to appreciate something of the advantages that would be derived {viii} from a reliable wireless system. Apart from the value of such a system for transmitting news pictures, it would also be of great advantage to transmit to ships at sea photographs of criminals for identification purposes. In such a small volume as this it would be impossible to deal with the working of wireless apparatus and the many systems that have been devised for the transmission of photographs over metallic circuits. The Author has taken it for granted that other works have been studied in connection with these subjects, and will therefore only describe such apparatus as is likely to be of use in wireless transmission. At present the transmission of photographs by wireless methods is in a purely experimental stage, and this book will have served its purpose if it helps to put future experimenters on the right track and prevent them from making expensive and fruitless experiments, by showing them the right direction in which investigations are being carried out. As there is no claim to originality in respect of a good many pieces of apparatus, etc., described, I have not thought it necessary to state the various sources from which the information has been obtained.

M. J. M.

ASHFORD, 1916.

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CONTENTS

PAGE PREFACE TO SECOND EDITION v

PREFACE vii

CHAPTER I

INTRODUCTORY 1