Receiver--Atmospherics in Long-Distance working.

{x}

CHAPTER IV

SYNCHRONISING AND DRIVING 63

Driving Motors--Isochronising the Electrolytic System--Professor Korn's
method--Description of Hughes Governor--Author's Speed
Regulator--Problem of Synchronising--Methods of Synchronising--Advances
made in Radio-Photography.

CHAPTER V

THE "TELEPHOGRAPH" 74

Author's System of
Radio-Photography--Requirements--Advantages--Transmitting
machine--Description of Differential Relay--Wireless Receiving
Apparatus--Photo-Telegraphic Receiving Apparatus--Circuit
Breaker--Friction Brake--Magnetic Clutch--Description of
Isochroniser--Method of working--Types of Nernst Lamp--Action of Nernst
Lamp--Comparison of Actinic Value--Inertia of Photographic
Films--Choosing Films--Speed of Films--Standard of Speed--Comparative
Film Speeds--Effects of Minimum Exposure--Effects of Maximum
Exposure--Considerations in working and choosing Films.

APPENDIX A

SELENIUM CELLS 109

Nature of Selenium--Preparation of Selenium--Forms of Selenium
Cells--Action of Selenium Cells--Characteristics of Selenium
Cells--Effects of Inertia in Photo-Telegraphy--Methods of counteracting
Inertia--Sensitiveness of Selenium to Light--Effect of Heat on
Selenium.

APPENDIX B

PREPARING THE METAL PRINTS 115

Outline of Process--Line Screens--Choice of Camera--Fixing Line Screen
in Camera--Lenses and Stops--Taking the Photograph--Copying
Stands--Choice of Photographic Plates--Sources of Illumination--Metal
Prints--Coating the {xi} Metal Sheets--Sensitising Solution--Printing
Operations--Developing--Intensifying--Precautions to be observed in
working--Preparing Sketches on Metal--Apparatus for Reducing or
Enlarging--Improvements to Copying Board--Lenses for Copying--Formula
for Copying.

APPENDIX C

LENSES 126

Action of Light--Law of Refraction--Lenses--Prisms--Action of
Lenses--Focal Length of Lenses--Formation of Images--Apparent Magnitude
of Objects--Real and Virtual Images--Formation of Virtual Images--Power
of Magnification--Defects of Lenses--Aberration.