INDEX 



Radiation, 164, 165, 205 

 Rain, 4, 14 



thunder-storms, 195 



uses of, 189 

 Rainbow, 220, 225 

 Rainfall, 189, 100 



effect of mountains, 191 



in Mississippi Valley, 194 



in United States, 31 

 Reclamation Service, 82 

 Reflection of light, 222 

 Refraction, 222 

 Refrigeration, 179 

 Revolution of earth, 172 

 Rivers, 24, 46 



deposition, 24 



erosion, 24 

 Rock, 50, 88 



disintegration, 92 



formation, 49, 51 



granite, 51 



layers, 32, 50, 51 



limestone, 49, 51, 52 



sandstone, 51, 52 



sedimentary, 51 



shale, 51 

 Roots, 243 



Rotation of earth, 172, 185 

 Rust, 210 



Sand, 52, 84, 94 



porous, 33 

 Sap, 41 

 Saturation, 13 

 Seasons, 169-177 



causes, 160-177 



changes of, 169 

 Sediment, 41 

 Seeds, 247-256 



algae, 249 



fertilization, 251 



reproduction, 248, 249 

 Siphon, 58 



Smoke, 213, 214 

 Snow, 189, 190 



* auuVii, 96 



eolian, 97, 98 



fertility, 101, 107 



food-supply, 107 



formation, 87 



grains, 84 



Soil, layers, 32 



nature of, 09 

 Solar system, 169-177 

 Solid, 3 



Solution, 40-45 



Soot, 213 



Sound, 216-224 



Spectrum, 220, 225 



Spores, 252 



Springs, 32, 33, 46, 52 



Stalactites, 47, 48, 52 



Stamens, 254 



Stand-pipe, 68 



Stars, 1 20, 149 



Steam, 9, 10 



Steam-power, 70-78 



Strata, 33, 50, 52 



Subsoil, 52 



Substances, inorganic, 233, 242 



organic, 233, 242 

 Sun, 147 



centre of solar system, 170 



effect on atmosphere, 162 



revolution of earth around, 1 70, 



171 



rising and setting, 171 



Telescope, 227 



Temperature, 128 (see "Heat and 

 Cold," 135-Uo) 



of day and night, 169 



of land and water, 139 

 Thermometer, 128, 129, 130 



centigrade, 130 



Fahrenheit, 130 

 Thermostat, 208 

 Thunder-storms, 195 

 Topography, 35 

 Tornadoes, 197 

 Torricelli's experiment, 60, 61 

 Trade-winds, 182 

 Transpiration, 35 

 Turbine, 72, 73 



Vacuum, 163, 164 



Vapor, 10 



Ventilation, 199, 200, 206, 207 



Vertebrates, 270-272 



Volcanoes, 48, 49 



Water, 8, 16, 46, 67, 89 



air enters, 42 



