Oxygen, in atmosphere of earth, 8; and liquid air, 9; one of earth’s atmospheres, 29; nucleus of atom of, 31; stimulating effect of, 32; union of, with hydrogen to constitute water, 32; functions of, 33-35; proportion of, in free air, 34; in places with restricted ventilation, 34; necessary to life, 35; causes of decrease of, 37; ozone is highly electrified, 40; absence of, above thirty miles, 212 Ozone, 33; source of, 40; characteristics of, 40; effects of, 40, 41; variation of, due to seasons and locality, 41; effects of winds on, 41 Paris, France, Christmas Day in, 270 Permanent Highs and Lows in the Pacific, great Centers of Action, 158; interference with storms from Orient by, 158 Petrograd, Russia, Christmas Day in, 273 Philippine Islands, climate of the, 255, 256 Pittsburgh, Pa., climate of, 210 Planets, quicker cooling of the small, 2; lifeless, 2, 3 Plant life, necessity of oxygen to, 35; carbon dioxide and, 35 Poles, temperature and circulation of wind at the, 99; barometer low at, 103; not the coldest points in the world, 280 Population, storm tracks and, 214-223 Porto Rico, climate of, 253, 254 Precipitation, factors controlling, of a region, 230 Pressure, difference between, and weight of air, 77; belt of high, at latitudes 30° north and south, 99, 101; indicated on weather map by Highs and Lows, 115, 116 “Principles of Human Geography”, 196, 215; quoted, 219, 220, 236, 237 Putrefaction, bacteria of, diminish with elevation, 10 Races of Man, climate and the dominant, 213-224 Radiation, earth, 8; of heat, 54; and frost, 85-97; and circulation of wind, 98; earth and air cooled by, 171; and temperature of valleys, 203, 204 Radium, nucleus of atom of, 32 Raindrops, size and composition of, 282; falling or evaporation of, 283; where, are formed, 283; what causes, 284; cannot form at great altitudes, 284; velocity of falling, 284, 285; air retards falling, 285 Rainfall, cause of heavy, in tropics, 104, 105; monsoon winds and heavy, 106; in Himalaya Mountains, 206; average monthly, in North America and in the Old World, 207-210; forests as conservers of, 241; in Hawaiian Islands, 255; instantaneous precipitation of all water vapor and, 285; causes of heavy, 285 Rain making, artificial, 288, 289 Rain water, pure when condensed, 284; collects impurities in falling, 284 Redfield, 296 Red Sea, temperatures of waters of, 176 Reflection, water rejects heat by, 172 Refrigerator, an economical, 59 Relative humidity, tables of, 69-71 Rio de Janeiro, Brazil, Christmas Day in, 274 Rivers, influence of, on climate, 199, 200 Rocky Mountains, influence on cold waves by the, 131; effects of reduction in height of, 230-232; records inscribed by waters on, 234, 235