XX CONTENTS. 



PAGE 



Clouds currents in the air 218 



Whirlwinds 220 



Thunder storms 222 



March of the thunder cloud 224 



Boiling springs 227 



SECTION VII. 



WATER AND EARTH. 



General effects of air and water upon the earth 229 



Softer strata of the earth 231 



Rocks and their productions r 232 



The " Scotch laird " and the pebbles 234 



Where to study rocks 237 



Action of water on the earth ....... ...... 238 



Pressure of water 240 



Characters of mountains 248 



Valleys and basins .............. 245 



Formation of rocks 246 



Action of rivers 248 



Gravel chalk flint 250 



Fertility of the sea 253 



Early state of the globe 254 



Volcanic islands 256 



Action in deep water 263 



Coal fields 264 



Limestone and marble 265 



SECTION VIII. 



ORGANIZED BEINGS. 



Light a sight, heat a sensation 267 



Elements of bodies.... ,. 269 



