Illustrations 



FACING 

 PAGE 



DETECTIM. \ SM.M.I. QIANTITY OK MATTER 254 



Prom Scientific Itli* of To-day. 



THIS X-lUv PHOTOGRAPH 18 THAT OF A HAND OF A SOLDIER WOUNDED 



IN THE GREAT WAR 254 



Reproduced by permission of X-Rays Ltd. 



As X-RAY PHOTOGRAPH OF A GOLF BALL, REVEALING AN IMPERFECT 



CORE 254 



Photo: National Physical Laboratory. 



A WONDERFUL X-RAY PHOTOGRAPH 255 



Reproduced by permission of X-Rays Ltd. 



ELECTRIC DISCHARGE IN A VACUUM TUBE ...... 258 



THE RELATIVE SIZES OF ATOMS AND ELECTRONS .... 258 



ELECTRONS STREAMING FROM THE SUN TO THE EARTH .... 259 



PROFESSOR SIR J. J. THOMSON 262 



ELECTRONS PRODUCED BY PASSAGE OF X-RAYS THROUGH AIR . . 262 

 From the Smithsonian Report, 1915. 



MAGNETIC DEFLECTION OF RADIUM RAYS 263 



PROFESSOR R. A. MILLIKAN'S APPARATUS FOR COUNTING ELECTRONS . 263 

 Reproduced by permission of Scientific American. 



MARINO THK INVISIBLE VISIBLE ........ 266 



THE THEORY OF ELECTRONS 267 



ARRANGEMENTS OF ATOMS IN A DIAMOND 267 



DISINTEGRATION OF ATOMS ......... 270 



SILK TASSEL ELECTRIFIED 270 



Id-produced by permission from The Interpretation of Radium (John 

 Murray). 



SILK TASSEL DISCHARGED BY THE RAYS FROM RADIUM .... 270 

 A HUOK ELECTRIC SPARK 271 



ELECTRICAL ATTRACTION BETWEEN COMMON OBJECTS .... 271 

 From Scientific Idiot of To-day. 



Aw ELECTRIC SPARK 274 



Photo i Leadbeater. 



Aw ETHER DISTURBANCE AROUND AN ELECTRON CURRENT . . . 275 

 From Scientific Idtat of To-day. 



