CONTENTS XI 



PAGE 



XIV. MAGNETISM AND ELECTRICITY . . 167 

 Electromagnets. Electricity and chemical changes. 



XV. PHENOMENA OF LIGHT . . .172 



Shadows and eclipses.* Images by reflection. Color phe- 

 nomena.* 



XVI. THE EARTH AS A PLANET . . .180 



Day and night and the earth's rotation. Rotation combined 

 with revolution and changes in seasons.* The moon and its 

 phenomena. Time and time-keeping, and standard time.* 



XVII. THE HEAVENS* .... 193 



