xviii Illustrations 



FACING 



e\i;r. 



A PHOTOGRAPH OF AN OSCILLATORY ELECTRIC SPARK FROM A LEYDEN 



JAR TAKEN ON A REVOLVING PHOTOGRAPHIC PLATE . . 828 



From Fifty Years of Electricity (The Wireless Press, Ltd.). 



DAMPED WAVES .828 



UNDAMPED WAVES .... .... 828 



LINES OF ELECTRIC FORCE AND OF MAGNETIC FORCE ROUND A PLAIN 



AERIAL WIRE ..... 828 



From Fifty Years of Electricity (The Wireless Press, Ltd.). 



CARNARVON MARCONI WIRELESS STATION AERIAL SYSTEM . . . 829 

 By permission of Marconi's Wireless Telegraph Co., Ltd. 



DOT AND DASH IN WAVES .... . 829 



THE TOWERS AT THE NEW BERNE STATION OF THE MARCONI RADIO- 

 BERNE. THESE TOWERS ARE 300 FEET HIGH AND SELF-SUPPORTING; 

 THEY CARRY THE MAIN AERIAL SYSTEM (Coloured Illustration} . 832 

 Reproduced by permission of Marconi's Wireless Telegraph Co., Ltd. 



THERMIONIC VALVE ... . 836 



By permission of Marconi's Wireless Telegraph Co., Ltd. 



A DIAGRAM ILLUSTRATING THE NATURE OF THE APPARATUS FOR CON- 

 DUCTING WIRELESS TELEPHONY ..... . 836 



From Fifty Years of Electricity (The Wireless Press, Ltd.). 



CARNARVON MARCONI WIRELESS STATION THE LARGEST VA'LVE PANEL 



IN THE WORLD ........... 837 



By permission of Marconi's Wireless Telegraph Co., Ltd. 



AMPLITUDE OF BEAT CURRENT . 



From Usrfitt Notes on Wireless Telegraphy, Book V (The Wireless 

 Press, Ltd.). 



THE AERIAL MOTOR-CYCLE .... . . 844 



THE FIRST MACHINE TO FLY .... . 844 



THE D.H. 29 MONOPLANE ... 844 



MAP OF THE WORLD'S GREATEST FLIGHTS . . 845 



THE ARRANGEMENT OF WIRELESS TELEPHONE AND WIRELESS TELEGRAPH 



APPARATUS IN AN AEROPLANE . 



By permission of Marconi's Wireless Telegraph Co., Ltd. 



LONDON FROM THE AIR . ...... 



PART OF THE "BRISTOL" FAMILY ..... ... 849 



