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WIRELESS TRANSMISSION OF PHOTOGRAPHS
[Illustration: FIG. 10.]
* * * * *
WIRELESS TRANSMISSION OF PHOTOGRAPHS
by
MARCUS J. MARTIN
SECOND EDITION
REVISED AND ENLARGED 1919
The Wireless Press, Ltd.
12-13 Henrietta Street, Strand
London, W.C. 2
{v}
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.
{vii}
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.
* * * * *
{ix}
CONTENTS
PAGE
PREFACE TO SECOND EDITION v
PREFACE vii
CHAPTER I
INTRODUCTORY 1
Foreword--Early experiments--Advantages of
Radio-Photography--Difficulties in Cable working--Bernochi's
System--Knudsen's System.