My boy had learned to read when very young by having stories read to him while he watched the printed pages. The construction of sentences out of words and words out of letters had come to him very incidentally but all in due time, and when he first went to school rather late in life for a beginner he found himself more proficient than the other boys of his own age both in reading and in understanding the printed pages. I could see no good reason why he should not pursue the same method in studying electricity. We live in a modern apartment house in a great city. My boy likes to visit engine rooms and talk with the engineers about their machinery. His mother and I always encourage him to talk with us about the things in which he is most interested. If the family is alone at dinner, he is quite likely to lead the conversation into the field of electricity. When particularly burdened with my work I have learned to find relief by giving an afternoon to Harold, who generally takes me to some electrical store or power station or to ride by electric train out into the country. CONTENTS CHAPTER PAGE I. The Dynamo and The Power Station 3 II. Dynamo continued--The Magnet 11 III. The Ammeter 25 IV. The Wattmeter 35 V. The Electric Motor 43 VI. Applications of the Electro-magnet 57 VII. Electric Heating 97 VIII. Applications of Electric Heating 107 IX. Lighting a Summer Camp by Electricity 160 X. How Electricity Feels 168 XI. The Electric Sparking Equipment for a Gasolene Engine 178 XII. Electricity From Central Stations 204 XIII. Electricity From an Old Mill 218 XIV. Doing Chores by Electricity 240 XV. Electric currents from Chemical Action and Chemical Action from Electric Currents 248 XVI. Electrocution at Millville 271 XVII. The Telephone 274 XVIII. Electric Bell Outfit for the Cottage 296 XIX. Using Electricity to Aid the Memory 300 XX. The Electric Brick Oven 305 XXI. Electric Waves 309 XXII. Ringing Bells and Lighting Lamps by Electric Waves 324 XXIII. Telegraphing by Electric Waves 329 XXIV. Halley's Comet and Electric Waves 333 XXV. How the Idea of a Universal Ether Developed 339