MAKING A ROTARY GLASS-CUTTER -- TO SMOOTH GLASS EDGES -- CUTTING HOLES IN GLASS -- ANTI-HUM DEVICE FOR METALLIC LINES -- A REEL-CAR FOR WIRE -- INSULATORS -- JOINTS AND SPLICES -- “GROUNDS” -- THE EDISON ROACH-KILLER -- AN ELECTRIC MOUSE-KILLER CHAPTER XIII.--FRICTIONAL ELECTRICITY 312 ITS NATURE -- LIMITED USES -- SIMPLICITY OF APPARATUS -- A “WIMSHURST INFLUENCE MACHINE” -- MATERIALS REQUIRED -- GLASS, TIN-FOIL, SPINDLES, UPRIGHTS, WHEELS, ETC. -- A LARGE LEYDEN-JAR -- APPARATUS FOR INTERESTING EXPERIMENTS -- NECESSITY OF CAUTION CHAPTER XIV.--FORMULÆ 327 ACID-PROOF CEMENTS -- HARD CEMENT -- SOFT CEMENT -- VERY HARD CEMENT -- CLARK’S COMPOUND -- BATTERY FLUID -- GLASS RUBBING -- ACETIC GLUE -- INSULATORS -- NON-CONDUCTORS -- INSULATING VARNISH -- BATTERY WAX CHAPTER XV.--ELECTRIC LIGHT, HEAT AND POWER 334 (By Joseph B. Baker) THE WORK OF THE DYNAMO -- THE ELECTRIC LIGHT -- USES OF THE ARC-LIGHT -- INCANDESCENT AND OTHER LAMPS -- ELECTRIC HEAT -- ELECTRIC FURNACES -- WELDING METALS -- ELECTRIC CAR-HEATERS -- HOUSEHOLD USES -- ELECTRIC POWER -- POWER FROM WATER-WHEELS -- TRANSFORMERS -- ROTARY CONVERTERS -- OIL-SWITCHES -- ELECTRIC TRACTION -- THE TROLLEY-CAR -- THE CONTINUOUS-CURRENT MOTOR -- THE CONTROLLER -- ELECTRIC LOCOMOTIVES -- OTHER FORMS OF ELECTRIC TRACTION A DICTIONARY OF ELECTRICAL TERMS 359 INTRODUCTION If a handy-book of electricity like this had fallen into the hands of Thomas A. Edison when he was a newsboy on the Grand Trunk Railway, or when he was a telegraph operator, he would have devoured it with the utmost eagerness. To be sure, at that time, in the early sixties, all that we knew of electricity and its applications could have been told in a very brief compass. It was an almost unknown field, and the crude form of the telegraph then in use represented its most important application. There were no electric lights; there was no telephone or phonograph; there were no electric motors. Telegraphing, itself, was a slow and difficult process. All the conditions were as far removed as possible from the broad field of applied electricity indicated in this book.