286 



INDEX 



Dew, 1 8 



Diffusion of gases, 44 



of light, 223 

 Digestion, 9 

 Doldrum, 186 

 Drainage, 83 



Earth, as planet, 170 



axes and poles, 172 



crust, 52 



depth, 47 



inclination of axes, 172 



inside, 47 



movements of, 169-177 



orbit, 171 



revolution around sun, 170, 171 

 Electrolysis, 158 



Energy, 117, 164 



combustion, 214 



conservation of, 137, 138 



forms, 117 



heat, a form of, 216 



kinetic, 118, 119, 142 



light, a form of, 216 



potential, 118, 119, 142 

 Entomology, 277 

 Environment, 266 

 Equator, 185 

 Equinoxes, 173 



storms, 1 74 

 Erosion, 25, 28 

 Ether, 217 

 Evaporation, 5, 9, 10, 16, 143 



from leaves (transpiration), 35 

 Evolution, 265 



environment, 266 



heredity, 266 



Expansion, 12, 89, 129, 141, 143, 144 



Fahrenheit (1686-1736) thermom- 

 eter, 130 

 Fats, 234 

 Feldspar, 94 

 Fertilization, 251 

 Fertilizers, 107 

 Filters, 68 

 Fishes, 270 

 Fog, 18 

 Food, 5, 232-240 



carbohydrates, 234 



fats, 234 



inorganic, 233 



Food, nitrogenous, 234 



non-nitrogenous, 235 



nutritive cycle, 236 



organic, 233 



oxidation of, 238 



proteins, 235 

 Freezing, 136 

 Frost, 1 8 



Fulcrum, 112, 114 

 Fungi, 105, 106, 258 



mushrooms, 106 



puffballs, 106 



toadstools, 106 

 Fusion, heat of, 143 



Galileo (1564-1642), 124 

 Gas, 3, 53 

 Glaciers, 35, 36 



glacial till, 38 



Gravel, 33, 52 



Gravitation, 119, 120, 149 



Gravity, 16, 21, 74, 75 (law of gravi- 

 tation, 22) 



Great Basin, 191 

 Ground-water, 31 



Hail, 19 



Heat, i, 4, 9, 13, 49, 137-140, 145 



and atmosphere, 1 50 



calorimeter, 128 



conduction, 137, 166 



convection, 145, 167, 180 



day and night, 169 



form of energy, 216 



measurement, 128 



radiation, 165 



solar, 172 



thermometer, 124, 128, 130, 131 



variation, 141, 142, 180 



vibration, 217 

 Heating, 200-208 



fireplace, 200 



furnace, 202 



stove, 202 

 Heredity, 266 

 Houses, 190-200 

 Humidity, 17, 143 

 Hurricane, 185 

 Hydration, 91, 92, 160 

 Hydraulic press, 65 

 Hydrogen, 155, 157, 158, 159 



