iminals 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.

CHAPTER II

TRANSMITTING APPARATUS 13

Wireless Apparatus--Preparing the Photographs--Transmitting
Machines--Transmitting Apparatus--Effects of
Arcing--Spark-Gaps--Contact Breakers--Complete Station--Professor
Korn's Apparatus--Poulsen Company's Photographic Recorder--Comparison
of various systems--Practical applications.

CHAPTER III

RECEIVING APPARATUS 37

Methods of Receiving--Author's Photographic Receiver--Decohering
Apparatus--Description of Einthoven Galvanometer--Use of Galvanometer
in Receiving--Belin's Application of Blondel's
Oscillograph--Description of Charbonelle's Receiver--Use of Telephone
Relay--Description of Telephone Relay--Telephotographic
Receiver--Polarisation Receiver--Kathode-Ray Receiver--Electrolytic