INDEX 



17 



References are to pages 



Ocean Continued 



floor of 155-156, 168 



heat vs. distance from . . . 213 

 land interchanges with . 249-251 

 life in and of ... 531-535, 552 

 pressure in ... 154-155, 168 

 swell below surface of . . . 155 

 temperature of water of 156-157, 



168 



tides of ... 17, 19, 164-166, 169 

 value of, to man and other 



life 166-169 



volume of air in water of . . 155 



waves 157-161, 169 



" Oil on water " 158 



Ooze (of ocean-floor) .... 156 



Optic nerve 414 



Orbits (of planets) ... 12, 26-31 

 Organic matter (or substance) . 426 

 Osmosis (diffusion through 



membrane) 371 



Ovary (of flower) 387 



Oxbow lakes 182, 184 



Oxidation 429 



Oxygen (a gas) .... 97-100, 



132-133, 136, 141, 152, 167, 280, 



399-400, 410, 413, 425, 456 



a constituent of air . . . 97-100, 



132-133 



a constituent of water . . 136, 167 

 agent of combustion ... 98 

 agent of weathering . . . 280 

 constituent of food .... 456 

 necessary for life . . 98, 141, 

 152,410,413 



Pancreas 421 



Parallels ; see Meridians and 

 parallels 



Parasites 397-400 



Passes (in mountainous re- 

 gions) 176 



Pasteurization (of milk) . . . 447 



P.eat 309,517-518 



Peroxide of hydrogen (disin- 

 fectant) 444-445 



Perspiration 106 



Petrified trees 522-523 



Petroleum 519-520 



Phosphate rock (as fertilizer) . 317 

 Phosphorescence .... 533-534 

 light-emission by micro- 

 scopic animals .... 533 

 Phosphoric acid (as fertilizer) . 316 

 Phosphorus (as fertilizer) . 97,311. 

 316, 345 



ignition qualities of ... 97 

 necessary for soil . . . . 311 

 Photography (utilization of 

 principles of light-refraction 

 and magnifying) .... 356 

 Physical changes (in matter) 53, 58 

 Physical features (of earth) 541-552 

 effects upon life .... 541-552 



Piston (of engine) 471 



Pith rays 374 



Plains . . 181-182,185,257-259, 

 268-276, 285, 301-302, 544-548, 553 



coastal 257-259,274 



effects of life on . . 544-548, 553 



flood 181-182,185 



Great Plains of U.S. . 273-275, 



276 



prairies . . 274,285,301-302 

 plateaus .... 268-273, 276 

 Planetary movements . . 48-49 

 laws of gravitation and in- 

 ertia 48 



discovery of Neptune and 



Uranus by 49 



Planetary wind belts .... 222 

 Planetoids ; see Asteroids 

 Planets . . . 4-15,18-19,20-21 

 brilliancy of Jupiter, Mars, 



Venus 12 



day and night on . 12-14, 18, 19 

 development of science con- 

 cerning 8-9,20-21 



distances from one another 



and sun 11, 19 



distinguishing features of . . 4-5 



light of 4, 5, 13, 19 



reflected rays from . . 13-14 

 moons of .... 11,14,15,19 



orbits of 12,19 



positions 11-12 



revolutions ... 5, 12, 18, 19 

 rotations 12, 19 



