TABLE OF CONTENTS 



EAGE 



LIST OF ILLUSTRATIONS xiii 



CHAPTER 



I. THE UNIVERSE IN WHICH WE LIVE i 



II. THE EARTH'S ROCK FOUNDATIONS . . 43 



III. THE CONQUEST OF THE AIR 77 



IV. ALR AND WATER AS SERVANTS OF MAN 104 



V. THE SLING, Bow, AND OTHER WEAPONS 130 



VI. FIRE AND ITS USES 146 



VII. THE NATURE OF MATTER 163 



VIII. STEAM AND GASOLINE ENGINES 178 



IX. DISCOVERIES IN MAGNETISM AND ELECTRICITY 199 



X. ELECTRICAL INVENTIONS 211 



XL RADIO COMMUNICATION 250 



XII. DEVICES FOR SEEING BETTER, FARTHER, AND LONGER . . 281 



XIII. CAMERAS AND PICTURE-MAKING 309 



XIV. THE HOMEMADE ORCHESTRA 3 2 5 



XV. SOME SIMPLE MACHINES 339 



BOOK LIST 3Si 



INDEX . 357 



