CONTENTS. XIX 



SECTION VI. 



AIR AND WATER. 



PAGE 



Light and heat not known as substances 155 



Nature of air 156 



Air, a state of matter 157 



Use of the aerial state 158 



Liquidity 161 



Natural chemistry 162 



Mobility of air 1 65 



Air the vehicle of sensation 166 



Fineness of air 168 



Fringes 169 



Sensibility of air 170 



Effects of heat on air the weather 171 



Ascent of smoke. . 173 



Signs of rain 174 



Winds 17S 



The spring 176 



Progress of the year 180 



Rivers , 1 82 



Value of water 184 



Evaporation 185 



Cold Hoar frost 188 



Catching cold 190 



London fog 192 



Dew 196 



Morning dew 198 



Breathing combustion 199 



Vapour in the air 204 



Descent of vapour 208 



Meteors and meteoric stones 215 



Mountain air and mountain mists 216 



