CONTENTS xy 



PAGE 



CHAPTEB XVIII. ATMOSPHERE... 120 



Introduction; Composition; Properties and uses; Moisture 

 in atmosphere ; Dew point ; Dew and frost ; Fog and clouds ; 

 Rain; Snow and hail. 



CHAPTER XIX. ATMOSPHERIC PRESSURE 129 



Introduction; Air presses in all directions; Column of 

 mercury held by air pressure; Variations in pressure due 

 to elevation ; Barometer ; Uses of the barometer. 



CHAPTER XX. WINDS AND STORMS 137 



Winds; Cause of winds; General effect of unequal heating; 

 Land and sea breezes; Cyclones; Thunderstorms; Torna- 

 does; Effect of winds on rainfall. 



CHAPTER XXI. WEATHER AND CLIMATE 149 



Weather; Climate; Effect of temperature on climate; Day 

 and night; Seasons; Weather maps; Explanation of a 

 weather map. 



CHAPTER XXII. THE SURFACE OF THE EARTH 160 



Continents and oceans; Mountains, plateaus, and plains; 

 Minor land forms; Effect of the atmosphere on the earth's 

 surface; Effect of change of temperature on rocks; Chemi- 

 cal; Work of rain in causing relief. 



CHAPTER XXIII. STREAMS AND THEIR WORK 172 



Introduction; Streams and stream erosion; Stream develop- 

 ment; Maturity; Old Age; Accidents to stream develop- 

 ment; Streams as factors in human activities. 



CHAPTER XXIV. SOIL 186 



Introduction; Origin; Kinds; Clay; Sand. 



CHAPTER XXV. INTRODUCTION TO PLANTS 193 



Importance of plants; Plants are composed of cells; Com- 

 position of protoplasm; Properties of protoplasm; Com- 

 parison of plants and animals. 



CHAPTER XXVI. LEAVES 200 



Structure of leaves; Chlorophyll; Food making; Food stor- 

 age; Other foods manufactured by plants; Uses of food; 

 Transpiration ; Disadvantages of transpiration ; Advantages 

 to plant; Habitat dependent on water supply; Protection 

 against loss of water; Respiration; Air storage. 



