ILLUSTRATIONS 



WILDE'S SEPARATELY EXCITED DYNAMO .... Facing p. 178 



THE EVOLUTION OF THE DYNAMO " 180 



VIEW IN ONE OF THE POWER HOUSES AT NIAGARA . " 186 



ELECTRICAL TRANSFORMERS " 198 



THOMAS A. EDISON AND THE DYNAMO THAT GENERATED 



THE FIRST COMMERCIAL INCANDESCENT LIGHT . " 228 



A FLINT-AND-STEEL OUTFIT, AND A MINER'S STEEL MILL " 248 

 THE LOCOMOTIVE " PUFFING BILLY" AND A MODERN 



COLLIERY TROLLEY " 258 



[viii] 



