CHAPTER PAGE I. THE BIRTH OF THE SCIENCE OF ELECTRICITY 1 II. ELECTRICAL MACHINES AND THE LEYDEN JAR 9 III. ELECTRICITY IN THE ATMOSPHERE 18 IV. THE ELECTRIC CURRENT 27 V. THE ACCUMULATOR 38 VI. MAGNETS AND MAGNETISM 44 VII. THE PRODUCTION OF MAGNETISM BY ELECTRICITY 56 VIII. THE INDUCTION COIL 61 IX. THE DYNAMO AND THE ELECTRIC MOTOR 66 X. ELECTRIC POWER STATIONS 75 XI. ELECTRICITY IN LOCOMOTION 83 XII. ELECTRIC LIGHTING 93 XIII. ELECTRIC HEATING 109 XIV. ELECTRIC BELLS AND ALARMS 116 XV. ELECTRIC CLOCKS 124 XVI. THE TELEGRAPH 128 XVII. SUBMARINE TELEGRAPHY 144 XVIII. THE TELEPHONE 154 XIX. SOME TELEGRAPHIC AND TELEPHONIC INVENTIONS 171 XX. WIRELESS TELEGRAPHY AND TELEPHONY--PRINCIPLES AND APPARATUS 179 XXI. WIRELESS TELEGRAPHY--PRACTICAL APPLICATIONS 203 XXII. ELECTROPLATING AND ELECTROTYPING 213 XXIII. INDUSTRIAL ELECTROLYSIS 224 XXIV. THE RÖNTGEN RAYS 228 XXV. ELECTRICITY IN MEDICINE 241 XXVI. OZONE 247 XXVII. ELECTRIC IGNITION 253 XXVIII. ELECTRO-CULTURE 258 XXIX. SOME RECENT APPLICATIONS OF ELECTRICITY--AN ELECTRIC PIPE LOCATOR, ETC. 266 XXX. ELECTRICITY IN WAR 274 XXXI. WHAT IS ELECTRICITY? 287 INDEX 295 LIST OF PLATES PLATE IN COLOUR: THE MARCONI TRANSATLANTIC WIRELESS STATION AT GLACE BAY, NOVA SCOTIA _Frontispiece_ FACING PAGE HYDRO-ELECTRIC POWER STATION 30 (_a_) EXPERIMENT TO SHOW MAGNETIC INDUCTION 48