Chapter XVII: Science in the Twentieth Century (9)

Optimal Temperature, xi, 51

Optophone, v, 332-5, 384

Orange (color), complementary color of, iv, 367;
heat color, 361;
soothing effects, vi, 274, 275

Orange Juice, for babies, ix, 347

Oranges, food values, x, 266, 268;
origin, xiii, 226;
spread, 354;
true berries, 54

Orang-utan, xii, 381, 383;
compared with man, xv, 59;
of Bronx Garden, v, 9

Orators, advantages over writers, xv, 145;
limited speeches of ancient, v, 62;
pitch of voice of, iv, 232

Orchards, frost protection, i, 259, 332;
warm and cold spots, 258-9

Orchestras, sounds of, iv, 199

Orchid Family, xiii, 184-7

Orchids, aerial roots, xiii, 20-1;
butterfly, 145;
epiphytic, 362;
fertilization, 144-5;
flowers, 50;
highest of monocotyledons, 181;
illustrations, 145-7;
leaves of saprophytic, 100;
Madagascar, 48;
seeds, 154, 344;
vanilla, 259-60;
in tropical forests, xiv, 368

Ordeals, xv, 373

Ordovician Period, iii, 20, 185-91, 381;
plants and animals, 251, 261, 266, 267, 268, 270, 273, 274, 277, 281;
sea extensions in, 183 (fig.)

Ore Deposits, iii, 355-70, viii, 197-200

Oregon, block mountains, iii, 139;
earthquakes in, xiv, 331;
forests of, 374;
lava formations, 102, 104, 318;
storm waves on coast, 300

Ores, defined, iii, 381, viii, 197;
electrolytic refining, vii, 319-21;
extraction of metals from, viii, 131, 269-72;
in metamorphic rocks, xiv, 234, 237;
veins, how formed, iii, 126

Oresme, Nicole, xvi, 101

Organic, defined, viii, 380

Organic Acids, viii, 52, 219-21, 336

Organic Chemical Industries, viii, 241-66

Organic Chemistry, viii, 52, 204-40;
beginnings, xvi, 162

Organic Compounds, viii, 51-2, 204, 205;
character of series, 207;
colors, 85-6, 258, 312;
explosion of, 63;
interchange of groups, 211;
physical state and molecular complexity, 298;
solubility in water, 37

Organic Life, beauty universal, xvi, 145-6;
climatic influences, 141-2;
distinction from inorganic realm, xii, 13-14;
origin, xiii, 300-1, xvi, 144-5, 149;
no traces in meteors, ii, 292;
studies of Mayer and Helmholtz, xvi, 142
(see also Life)

Organic Liquids, solubility, viii, 112

Organic Matter, chemical constituents, viii, 18, 29, 34, 42, 64;
food of animals, 349;
formed by plants, xiii, 14;
in atmospheric dust, i, 60-1;
in soils, viii, 339-40;
in waters, 40-1

Organicists, school of, x, 86

Organisms, binomial nomenclature, x, 84;
cell constitution, 119, xv, 16, xvi, 142;
chemical basis of, xii, 10-13;
chemistry of, viii, 204-5, 348-72;
chemosynthetic, xii, 15;
earliest, xiii, 299, 303;
frames and shells, xvi, 145;
growth and forms due to physical laws, xvi, 142, 144-5;
growth compared with crystallization, iii, 311;
metals congenial to, viii, 148;
microscopic (see Germs);
reproduction of, x, 228;
symmetry in, xvi, 155;
variations, meristic and substantive, xvi, 155;
vestiges in oldest rocks, iii, 249-50 (see Animals, Plants)

Organogens, viii, 18

Organs (physical), disordered functions of, x, 318-65;
vital function testing, 376-9, 382-3

Organs (musical), iv, 228-31;
flue and reed styles, 234-5;
intervals on, 208;
temperature effects on, 231-2;
pipes of, xv, 316

Oribasius, x, 31

Oriental Gobies, fins of, xii, 134

Orientation, in ancient temples, ii, 25-6

Orinoco Basin, arrau turtle of, xii, 193-4;
chocolate in, xiii, 234;
jaguars of, xii, 362

Orinoco River, caribes of, xii, 160;
connections with Amazon, xiv, 187

Orioles, xii, 269

Orion, great nebula in, ii, 357, 359, 363, 364;
moving clusters of, 343;
distortions from sun's motion, 306

Orion Stars, ii, 117;
moving clusters among, 343;
radial velocities, 308

Orkney Islands, wave action at Wick, xiv, 300

Ornaments, bodily, xv, 253-4

Ornithorhynchus, xii, 272

Orongo, Mongolian, xii, 327

Orpathology, x, 318

Orräus, of Russia, x, 164

Orris Root, source, xiii, 189

Orthoclase, iii, 328;
hardness of, 320

Orthodontia Appliances, xi, 373

Orthoptera, xii, 107-10

Osborn, Henry Fairfield, quoted, xii, 13

Osborn, Prof., on cave pictures, xv, 115-16;
on Neanderthal Man, 97

Osborne, J. W., i, 319

Oscillation Circuits, vii, 263, 265, 373-4;
theory of, 286-98

Oscillation Generators, vii, 273-8, 290-1

Oscillations, electric, iv, 313, 314, vii, 373-4;
damped and undamped (see Damped, Undamped Waves)

Oscillations, in planetary system, ii, 75

Osler, Sir William, x, 150-2;
on conceptions of disease and therapy, 380;
on Pasteur, 144;
on sleeping sickness, 169;
on yellow fever germ, 162-3;
on hardened arteries, x, 335

Osler's Disease, x, 152

Osler's Spots, x, 152

Osmium, viii, 172;
symbol and atomic weight, 383;
valence, 178, 180

Osmosis, xiii, 91-2, 93-4

Osmotic Pressure, viii, 113, xiii, 93-4;
bursting of fern spores by, 156;
discovery and law, xvi, 164;
in solutions, viii, 123, 311;
water supplied to plants by, xiii, 102

Ostracoderms, iii, 260, 281-2

Ostracods, xii, 18-19

Ostriches, xii, 249;
hunting of, by bushmen, xv, 134-5, 222

Ostrich Fern, xiii, 159

Ostrich Plumes, xii, 244

Ostwald, chemical work, xvi, 164, 165

Ostwald's Imperative, xi, 257

Oswego Tea Plant, xiii, 201, 205

Ottoman Turks, conquests of, xiv, 308-9

Otters, xii, 347

Ouachita Range, xiv, 227

Oughtred, William, xvi, 104

Ounce (leopard), xii, 357

Outcrop, defined, iii, 381

Outdoor Treatment, x, 240-1

Outgoing Reactions, xi, 54-6, 146

Outriggers, xv, 263-4

Outwash Plains, iii, 68-9

Ouzels, xii, 268

Ovaries, of plants, xiii, 46, 54-5, 118;
beginnings, 317-18;
grouping of plants by, 173-5;
superior and inferior, 202-3

Ovariotomy, x, 122, 147

Over-Compound Generators, vi, 189-90

Overeating, auto-intoxication by, xi, 370;
hardened arteries from, x, 335

Overhead Transmission, vii, 10-11, 14-24, 25
(see also Trolley System);
in telephony, 104, 105

Overheated Liquids, viii, 304

Overshot Wheels, v, 76

Overtones, iv, 213;
of organs, 230-1;
quality of sounds due to, 233

Overwork, fatigue from, xi, 269, 272, 371;
muscular soreness from, ix, 81

Ovules, plant, xiii, 118, 119;
action of fertilized, 153;
naked and enclosed, 173-5

Owen, morphology studies, xvi, 140-1

Owens Automobile, vi, 104

Owen's Valley, California, earthquake of, xiv, 334, 335

Owls, xii, 267

Oxalic Acid, viii, 222, 336

Oxbow Streams and Lakes, iii, 34, xiv, 162

Oxford University, foundation, xvi, 100

Oxidation, defined, viii, 380;
in water, 35;
of organic substances, 266;
of sewage, 326, 327;
of iron, v, 316 (see Rusting);
power extraction by, ix, 16, 24

Oxide of Manganese, ancient use of, xv, 113

Oxides, defined, viii, 380;
chemical formation, 11-13, 20, 36;
combinations with water, 38-9;
extraction of metals from, 47, 131, 271;
metallic and nonmetallic, 20;
ores, 47, 198

Oxyacetylene Blowpipe, i, 33

Oxy-acids, viii, 98, 380

Oxyhemoglobin, ix, 259-60

Oxygen, viii, 17, 34-6;
affinities, i, 12, viii, 33, 36, 47, 77, 85, 87, 134, 155;
amount inspired in sleep, xi, 283, 285;
atmospheric, i, 10, 11, 24, 25;
atmospheric, viii, 67;
atomic weight, 33, 39, 383;
atomic weight base, 92;
body needs and supply, ix, 198-9, 253-62, 267-8, x, 338-9;
boiling and freezing points, iv, 173;
carriers of, viii, 71;
carrying of, in blood, ix, 182-3, 258-61, x, 338-9;
combustion and, i, 10, iv, 138, viii, 12-13, 53, 54, 55-6, 61;
consumption by gas lighting, vi, 264;
consumption of, in exercise, ix, 261-2;
corrosion of metals by, viii, 13;
critical temperature, i, 29, iv, 174;
deficiency effects, i, 322, 328, ix, 268, x, 238, xi, 371;
density of, iv, 110;
diffusibility, viii, 108;
discovery, 34, 170, xiv, 65, xvi, 120;
energy source, viii, 268;
elimination from body, 353;
explosion with hydrogen, viii, 62;
hydrocarbon derivatives, 52, 212, 216-20;
importance, i, 24, 25;
in chlorophyll, xiii, 80;
in coal series, iii, 345;
in earth's crust, 308, viii, 19, 129, 192;
in organic compounds, 64, 204;
in proteins, 351;
in steel making, vii, 321;
in water, viii, 39-40, x, 26;
industrial uses, i, 32-3, viii, 274;
liquefied, i, 29, iv, 171, viii, 68;
melting point, iv, 162;
molecular structure, viii, 26-7, 36;
molecular velocity in, iv, 133, viii, 24;
most active form, 36, 41;
negativeness of, 31;
necessity of, to life, ix, 16, 18, 22, 267-8;
plant uses of, viii, 336-7, 340-1, xiii, 14, 80, 81, 109, xiv, 64-5;
potential energy in, iv, 82;
preparation, viii, 34-5;
production by plants, 49, 335, xiii, 81, 82, 109, xiv, 65;
production from liquid air, i, 30, 32-3, viii, 68, 274;
production from nitric acid and nitrates, 72;
production from water, 30, 31, 274;
rock decomposition by, 194, iii, 24, 25;
rusting produced by, 25;
solubility in water, viii, 35, 40, 111;
supply of, in air, ix, 254, 267-8;
symbol, viii, 383;
valences to, 178, 179-80

Oxygen Compounds, viii, 20, 34, 36-41, 70-4

Oxygen Cycle, viii, 334, 350

Oysters, iii, 260, 272, xii, 58-63;
enemies and destroyers, 50, 70, 72, 73;
food procuring by, ix, 19, 74;
raw, digestion of, 233

Oyster-Shells, deposits of, iii, 272

Ozone, i, 15-16, 378, vii, 353-5;
activity of, viii, 36;
allotropic form of oxygen, 43;
electrical production, vii, 238-9, 301;
molecular structure, viii, 26, 36;
production by lightning, i, 153

Pacas, xii, 289

Pacific Coast, geological changes, iii, 213, 222, 214 (maps);
ports and commerce of, xiv, 269;
potash from seaweeds, viii, 279;
seaweed of, xiii, 27, xiv, 67, 68;
shellfish of, xii, 62, 65, 68, 74;
thunderstorms rare, vii, 218;
width of continental shelf, xiv, 285

Pacific Coastal Plain, xiv, 215

Pacific Coast Forest, xiv, 374

Pacific Drainage System, xiv, 189-90

Pacific Islands, xiv, 277;
coco palm of, xv, 125;
weapons of, xv, 216, 219

Pacific Ocean, climate on opposite coasts, xiv, 345;
coral reefs in, 264;
currents of, 304, 305;
depths, iii, 51, xiv, 23;
extent, 22;
herring of, xii, 156;
salmon of, 157;
seals of, 333-4;
sharks of, 145, 146;
shoal-water belt, xiv, 25;
temperatures, 297;
trade winds, i, 127;
unchanged for ages, iii, 55;
volcanic dust in, 55;
whales of, xii, 298

Pacific Type of Coasts, xiv, 247-9, 250

Pack Rats, acquisitiveness of, xii, 292-3

Packing, Maudsley's cup leather, v, 99, 376

Paddle-fish, xii, 151

Paget, Sir James, xvi, 184

Pain, xi, 116-21;
"arrival platform" for, ix, 146;
contact sense of, 91;
expression of, by dogs and monkeys, xv, 64-5;
no space perception by, xi, 164;
organs and nerves in skin, ix, 314;
purpose as warning, 87;
sense of, in infants, 349;
use of morphine in, x, 381

Painter Fogs, i, 96-7, 378

Painting, art of, beginnings and development, xv, 108-9, 110-16, 120-1,
297-303, 325;
by compressed air, i, 29, iv, 130, v, 136;
of body, xv, 255-6

Paintings, depth impressions in, ix, 120;
skies in, i, 105

Paints, ancient, xv, 113-14;
chemistry of, viii, 264-6;
colors of, iv, 369-70;
drying oils in, viii, 245, 247;
lead in, 162;
linseed oil in, 231

Pajero, xii, 364

Paleolithic Man, iii, 303-5;
horses of, xii, 307;
implements of, xv, 103, 105-9;
state of, xiii, 209-10

Paleontology, defined, iii, 381;
history, xvi, 169, 170, 172

Paleophytology, xvi, 167

Paleozoic Era, iii, 20, 381;
animals, 263, 266-75, 276-8, 284, 285, xii, 49, 75, 104, 142, 151, 165;
climatic zones in, iii, 173;
divisions and species of, xv, 71;
plants, iii, 251-5;
rocks and history, 179-207;
vertebrates absent, 261

Paleozoic Rocks, iii, 179-207;
recognizable by fossils, 174, 179;
why rich in fossils, 264

Palestine, ancient rain measurements, i, 68, 213;
climate changes in, xiv, 361-2, 379;
maritime plain of, xv, 138

Palisades of the Hudson, iii, 111, 212, xiv, 108-9, 122;
blocks at foot of, 76;
jointing at Bergen Cut, 133

Palladium, viii, 173;
as catalyzer, 103;
symbol and atomic weight, 383

Pallas, meteor found by, ii, 284

Pallas (asteroid), discovery, ii, 255;
orbit, 258

Pallor, causes of, x, 337;
temporary, ix, 161, 162, 163, 165, 166

Palm Beach, millionaires at, xi, 52

Palmer, Dr. G. T., i, 323

Palm Family, xiii, 188

Palmitic Acid, viii, 220, 221, 350

Palm Kloof, xiv, 369-70

Palm Oil, African development and, xiii, 11;
source, xiv, 383;
vegetable fat, viii, 246

Palm-Oil Tree, xiii, 188

Palms, cocoanut, xiii, 219-20;
first appearance, xiii, 319;
in tropics, distribution of, xiv, 368;
leaves of, xiii, 176;
monocotyledons, 178;
trunks of, 26

Paloverde, leaves of, xiii, 379

Pamias, rock disintegration on, xiv, 73-4

Pamlico Sound, bar of, xiv, 264

Pampas, absence of trees in, xiv, 381;
armadillo burrows on, xii, 284;
cattle-raising and agriculture on, xiv, 384;
dust whirls, i, 60;
flatness of, xiv, 158, 216;
grass and other plants of, xiii, 375-6;
grasses, drying of, xiv, 381;
horses of, xii, 307;
true plains, xiv, 218

Pampas-Cat, xii, 364

Panacea, x, 16

Panaceas, medicinal, x, 41

Panama Canal, Caribbean traffic, i, 282;
Chagres River and, xiv, 195;
dredges used, v, 255-6;
material excavated, 258

Panama Canal Zone, health conditions, i, 327, x, 162;
sanitary control, costs, xiv, 344, 356;
temperatures, i, 209

Panama, Isthmus of, anteaters of, xii, 283;
earthquakes on, xiv, 331;
pearl fisheries of, xii, 62;
sea devils of, 150;
temperature, i, 208-9;
yellow fever extermination, x, 162, xiv, 356, 357

Pancreas, functions of, ix, 237, x, 330, 347;
secretin effects on, 325

Pancreatic Juice, viii, 358, ix, 237-8, 242, x, 325-6, 330;
of infants, ix, 346

Pangolins, xii, 281

Pangong Lake, Tibet, xiv, 211

Panpipes, xv, 315 (fig.), 316

Panspermia, xii, 9

Panthers, xii, 363;
stalking of game, xi, 224

Pantograph, in trolley systems, vii, 197

Papaw, origin, xiii, 226

Paper, electrical conductivity, iv, 259;
electrification by tearing of, 260;
heat conductivity, 179;
making of, v, 289-99, 380;
making of, in ancient Egypt, xvi, 72;
made from corn fiber, xiii, 213;
made from mulberry, v, 290, xiii, 244;
made from spruce wood, 10, 236;
Manila, 240;
origin of name, xv, 157

Paper Machines, v, 295-9, 377

Paper, Mulberry, xiii, 244;
bark as cloth, xv, 256-7

Paper Pulp, making of, viii, 153

"Paper Sailor," xii, 78

Paper Showers, i, 359

Papier-Maché, ancient, xvi, 73

Papillæ, xi, 70-1

Papin's Digester, iv, 170-1

Papuans, hair of, xv, 38;
prayer, 346

Pappus, Greek author, xvi, 94-5

Papyrus, v, 289;
Egyptian, xvi, 72

Paracelsus, x, 46-50;
classifying tendency of, 83;
compared with Vesalius, 53;
followed by Van Helmont, 68;
Locke on, 75

Parachutes, v, 234

"Paradise Lost", quotations, ii, 36, 210-11, 350

Paraffin, viii, 51, 208;
combustion of, 52;
meaning of name, 206, 380;
melting requirements, iv, 162

Paraffin Candles, viii, 247

Paraffins, Paraffin Hydrocarbons, viii, 206-210, 241;
contrasted with benzenes, 232-4;
defined, 380;
derivatives, 210-32;
molecule configuration, 233;
residues in benzenes, 235-6, 238-40;
unsaturated, 230-2

Paragreles, i, 341, 378

Parallactic Motion, ii, 317

Parallax, ii, 311-18;
Galileo's method, 55;
Hipparchus on, 32;
in distance perception, xi, 182;
photographic study, ii, 137, 314

Parallel Forces, resultant of, iv, 99

Parallel-veined Leaves, xiii, 32, 37 (fig.), 176, 177, 178

Parallelogram of Forces, v, 184-6

Paralysis, electric treatment, vi, 17, vii, 238

Paranthelion, i, 378

Parantiselenæ, i, 378

Para Rubber, xiii, 246-7

Paraselanæ, i, 180, 183, 378

Parasitic Clouds, i, 104, 378

Parasitic Plants, xiii, 15, 21, 100, 364

Parasitology, xvi, 181

Parchment Paper, strength, viii, 255

Paré, Ambroise, x, 46, 54-6, 97, 129, xvi, 108

Pareira, "Materia Medica", xvi, 186

Parental Instinct, xi, 56

Parental Solicitude, xi, 149

Parents, care of children, ix, 352;
children's resemblance to (see Heredity);
pleasure of, in children, 153

Parhelia, Parhelic Circles, i, 179-80, 181, 183, 378

Parian Chronicle, meteor recorded in, ii, 284

Paris, balloons in siege of 1871, v, 225;
bombardment in World War, 369-70, iv, 201-2;
Salpêtrière Hospital, xvi, 184;
sewage disposal, viii, 327

Paris Green, viii, 169

Paris-London Air Service, i, 44-5, 95, 285-6

Paris Observatory, ii, 58

Paris, University of, founded, xvi, 100;
medical school, x, 38

Park, Mungo, xvi, 123

Park Cattle, xii, 331

Parker, morphology studies, xvi, 140-1

Park Forests, xiv, 374

Parkinson, James, x, 112

Parklike Landscapes, xiii, 374-5, 376

Parliament, British, gold mace of, xv, 208

Parmenides, Greek philosopher, xvi, 84

Paros, fossils in rocks of, iii, 14

Parrakeet, Carolina, xii, 266

Parrots, xii, 265, 266-7;
dyeing of, 179;
monogamous, xv, 276

Parsec, astronomical unit, ii, 315

Parsley, xiii, 200-1, 223

Parsnips family, xiii, 200-1;
origin, 223;
swelled roots, 19

Parsons Steam Turbine, v, 150-1, 382

Particles, technical meaning, iv, 382

Partridge Berry, crossbreeding devices, xiii, 122;
in madder family, 205;
illustration, 96

Partridges, xii, 261

Pascal, Blaise, atmospheric pressure studies, iv, 114-16;
mathematical work, xvi, 105, 114, 119;
vacuum studies, 110

Passenger Aircraft, i, 41-3, 44-5, 50

Passerine Birds, xii, 268-9

Passiflora, origin, xiii, 226

Passion Flower, tendrils, xiii, 112

Passions (see Emotions)

Past comparisons with present, vii, 76

Pasteboard, making of, v, 299

Pasteur, Louis, x, 136-44, 208;
bacteria studies, xvi, 143, 182, 184, 185;
chemical work, 163-4;
courage of, x, 101;
Lister and, 144, 145, 146;
references to work of, 107, 132, 133

Pasteurization, x, 139-40

Pasteurized Milk, xiii, 71, x, 132, 140;
scurvy from, 266;
vitamines in, 263, ix, 347

Pastries, as food, x, 273, 315

Patagonia, bushlands of, xiv, 381;
huanacos of, xii, 313;
plains of, xiv, 218;
rhea of, xii, 249;
tides of, xiv, 298

Patagonians, height of, xv, 39

Patches of Peyer, x, 287-8

Patella, ix, 69, 70 (fig.)

Patent Medicines, remarks on, vii, 241

Pater Noster, in Aztec, xv, 169

Pathfinders, of flowers, xiii, 134, 140

Pathogenic Germs, x, 194-5 (see Disease Germs)

Pathological Anatomy, Morgani's work in, x, 98

Pathology, Cellular, founded by Virchow, x, 119, 128

Patriotism, sentiment of, xi, 145, 151

Pavloff, Ivan, x, 131, 319

Pavlov's Law, xi, 198, 201

Pay-as-you-enter Cars, vii, 184

Peach Trees, xiii, 197, 226

Pea Family, xiii, 198-9;
antiquity, 324-5;
fertilization, 137-9;
food devices, 97-8;
nitrogen-fixing parasites, i, 35, xiv, 66;
seed dispersal by, xiii, 339, 347

Peake Deep, xiv, 289

Peanuts, oil of, ix, 28

Pearl Islands, xii, 62

Pearls, finding by X-rays, vii, 256;
origin, xii, 62-3, 66

Pearly Nautilus, xii, 75-6;
evolution of, iii, 273-5

Pear Psylla, honeydew of, i, 351-2

Pearson, eugenic studies, xvi, 157;
on artificial selection, 154;
statistical methods, 153

Pear Trees, development of fruit, xiii, 54;
in rose family, 197;
origin, 224, 226

Peary, Arctic soundings of, xiv, 22;
mirage of Crocker Land, i, 173

Peas, as food, viii, 365, ix, 34, x, 262;
crossing experiments, 231-2;
flowers, xii, 44 (fig.);
food-obtaining devices, 97;
leaf-tendrils, 38;
leaves, 36-7, 113;
origin, 223;
petals, 47, 190;
pods, dry fruit, 54;
seeds, 56;
sleeping of leaves, 88-9
(see also Pea Family)

Peat, elements, iii, 345;
formation, xiii, 68, 313;
in relation to coal, iii, 344;
in sheep plant, xiii, 380;
per cent of carbon in, viii, 44;
wood fiber seen in, 45

Peat Bogs, dust from burning, i, 56, 57;
extent of present, v, 173;
of Denmark, xv, 87

Pebrine, Pasteur's study of, x, 140

Peccaries, xii, 310-11;
jaguars and, 362

Pekans, xii, 350, 351

Peking, Temple of Sun, ii, 26

Pelagic Fauna, xii, 16

Pelee, Mount, eruption, iii, 102-3, xiv, 28, 325;
dust from eruption, i, 58, 59;
earthquakes preceding eruption, xiv, 338

Pelée's Hair, iii, 105

Pelicans, xii, 254

Pellagra, x, 265, 268;
cause of, viii, 351;
eruptions on uncovered surfaces, x, 254

Pelterie, R. Esnault, v, 175-6

Pelton Wheels, v, 77-9, 80, 81, 170, vi, 368

Pelvis, ix, 63, 66-7 (fig.);
in man and apes, xv, 58;
vestiges of, in snakes, xii, 213

Pelycpoda, xii, 58-63

Pemba, clove production, xiii, 263

Penang, clove trees, xiii, 262

Penck, Prof., climate studies, xiv, 361;
land and water curves, 26

Pendulum, discovery, v, 63-5;
Galileo's observations, ii, 53;
gravity action on, iv, 97-8;
oscillations and regulation of, 147, 225, 226;
types in clocks, v, 73, 74

Pendulum Clocks, invention, ii, 58;
escapement, v, 73-4;
regulation to temperature, iv, 147

Peneplains, iii, 30, 34-5, 381;
cretaceous, 232

Penetrating Radiation, i, 143-4, 146, 379

Pennsylvania, coal beds, iii, 199, 347-8;
former volcanoes, xiv, 318;
glacial soil of, 70, 170;
natural gas, iii, 355

Pennsylvanian Period, iii, 198-202;
coal deposits, 198-201, 345;
insects, 279;
plants, 252-4

Pennyroyal, source, xiii, 205

Penguins, xii, 251

Penstocks, vi, 363

Pentane, derivatives, viii, 210

Pentose, viii, 229

Pentstemon, corolla, xiii, 201

Penumbra, of shadows, iv, 332-3

Peony, pollen of, xiii, 124

Pepin, Lake, xiv, 202

Pepo, xiii, 54

Pepper, black, xiii, 265;
red, 223

Peppermint, viii, 251, 252

Pepsin, in gastric juice, ix, 235, x, 320, 326

Peptones, x, 277

Pepys, Samuel, "Diary" quoted, iv, 53

Per, defined, viii, 380

Perceptions, defined, xi, 160-2;
differences in power of, 152;
Greek theories, xvi, 87;
misinterpreted, x, 358;
of color, ix, 114-17;
of light and shade, 105;
of objects, 105-11;
of space, xi, 162-91;
of time, 192-6;
relativity of, xvi, 85

Percussion, in diagnosis, x, 99, 110, 371

Percussion Cap, viii, 145

Percussion Drills, v, 129, 261-2, 263

Percussion Shells, v, 372

Percussive System, of oil boring, v, 265-7

Perennials, buds, xiii, 53;
roots, 16;
planting tables, 289-96

Perfection, Man's struggle for, xv, 38-9

Perfumes, chemistry of, viii, 251-2

Pericles, reference to, x, 20

Peridot, iii, 334

Perier, Pascal and, iv, 114-15

Perigee, defined, ii, 197

Perigord District, human relics, iii, 304-5

Perihelion, defined, ii, 50, 275

Period, technical meaning, iv, 383

Periodic Breathing, x, 340

Periodic Classification, viii, 177-83, 307, 309

Periods, Geological, iii, 19-21, 381

Peripatus, xii, 81

Perique Tobacco, xiii, 258

Periscopes, v, 200-1

Peristalsis, x, 327

Peritonitis, asepsis in, x, 147;
causes of, 195, 288

Periwinkles, xii, 71

Perkins Ice Machine, v, 358, 379

Perlite, viii, 160, 274

Permanent Magnets, iv, 243, vi, 30, 37, 117, vii, 372;
care of, vi, 34, 38;
lifting force of, iv, 289

Permian Period, iii, 20, 202-5, 381

Perpetual Motion, v, 97, vi, 214, xvi, 135

Perpetual Snow Line, iii, 59

Perpetuation of the Race, ix, 324-44;
marriage and the family, xv, 273

Perret, Prof. F. A., i, 194

Perrine, astronomer, ii, 136, 146, 262, 362

Perseids, ii, 288

Perseus, star clusters in, ii, 336, 343

Persia, ancient, Mediterranean aims, xiv, 306;
astronomy of ancient, ii, 26;
cheeta of, xii, 365;
climate changes, xiv, 361-2;
lions of, xii, 359;
magi of, xvi, 59;
plateau of, xiv, 222;
sun-worship, ii, 20;
use of opium, xiii, 253;
wild asses of, xii, 308

Persian Cats, xii, 356

Persian Gulf, first civilization around, xvi, 47;
pearl fisheries of, xii, 62

Persian Language, xv, 162;
words from, in English, 161

Persimmons, xiii, 226, 352-3

Persistence of Vision, iv, 346-7, v, 329, vi, 155

Persistency and will, xi, 264

Personal Equation, xi, 156

Personal Hygiene, disease prevention through, x, 302-17;
teaching of, 283-5

Personality, changed in emotion, xi, 134;
dreams as revelation of, 302;
loss of, in crowds, 324, 325-6, 329-30;
source, 33;
splitting of, in hysteria, x, 360-1, 362

Perspective, xi, 181-2;
in distance perception, ix, 119-20

Perspiration, absorption by various materials, x, 307, 308, 309;
amount of "insensible," 70-1;
caused by fear, xi, 131,132, 133;
constitution of, x, 310;
humidity and, i, 77;
temperature regulation by, 317, v, 348-9, ix, 169, x, 251, 274 (see
also Sweat, Cold Sweat)

Peru, ancient use of cocaine, xiii, 254;
ancient corn-growing, 212;
ancient stone structures of, xv, 271;
conquest of, xiv, 250;
foot plow of Indians, xv, 236 (fig.);
harbors and commerce, xiv, 265, 266;
Incas (See Incas);
rainfall and fog, i, 95, 96-7;
rain-tree, 352;
source of quinine, xiii, 251;
words derived from, xv, 161

Peruvian Art, ancient, xv, 297 (fig.), 311 (fig.)

Peruvian Bark, xiii, 250-1

Peruvian Earthquake, xiv;
tidal waves of, xiv, 337

Peruvian Paint, i, 96-7, 378

Pessimism, physical causes, xi, 339, 369-70, 372

Pestles, xv, 238-9

Petals, of flowers, xiii, 45, 47;
importance in classification, 47;
first appearance, 318;
lacking in some flowers, 46

Peter Pan, story of, xv, 330

Peters, Dr., of Hamilton, ii, 256

Petiole, of leaves, xiii, 34, 35

Petit, Jean-Louis, x, 90-1, xvi, 161

Petrels, xii, 251, 252

Petrified Animals and Plants, iii, 15-16, 126-7

Petroleum, composition, products, and supply, viii, 208-10;
fluorescence of, iv, 323, 379-80;
origin and occurrence, iii, 348-54;
production and supply (U. S.), v, 172-3;
supply and approaching exhaustion, vii, 309

Petrology, iii, 381, xvi, 170

Pfeiffer, immunity theory of, x, 211;
influenza germ discovery, 295

Phaestos Disk, xv, 176 (fig.)

Phagocytosis, x, 209-10

Phaleropes, xii, 262

Phanerogams, xiii, 62-3;
reproduction, 117-54 (see Flowering Plants)

Phantasies, in psychoanalysis, x, 365

Phantom Circuits, vii, 105-6, 119

"Pharaoh's Chicken," xii, 260

Pharmacognosy, xiii, 249

Pharmacology, x, 381, xvi, 186;
chemical, founded by Paracelsus, x, 50

Pharmacy, history, xvi, 186-7

Pharnyx, condition in thirst, xi, 66

Phase (electricity), defined, vi, 204-5;
"in," 168;
"out of," 167, 204
(see also Single-Phase, Two-phase, Three-phase)

Phase Law (chemistry), xvi, 136, 164

Phase Relations, vi, 167-9, 171-4

Phases, of Mars, ii, 227;
of moon, 190, 193-5, 196

Phasing-in, defined, vi, 263, 342

Pheasants, xii, 261;
hearing of, i, 188

Phenology, i, 254-6, 379

Phenolphthalein, viii, 294, x, 378

Phenols, viii, 236, 237-8, 380;
as disinfectants, 333

Philadelphia, summer of 1816, i, 360;
water supply of, xiv, 140;
yellow fever epidemic, x, 159

"Philadelphia Ledger," first Hoe press, v, 301

Philippine Islands, aerial exploration work, i, 47;
baguios, 136;
beriberi in, ix, 35, x, 257;
carabao of, xii, 329;
civilization in mountain valleys, xv, 131;
continental islands, xiv, 274;
copra production, xiii, 220;
dipterocarp forests, 350;
fiber-wear, 236;
fire obtained by friction, viii, 89;
fire by air-compression, v, 128;
Manila hemp, xiii, 239-40;
new volcano in Camiguin, xiv, 320;
ocean depths near, iii, 51;
octopod fishing, xii, 78;
rainfall at Baguio, i, 110;
rice growing, xiii, 213, 214;
Weather Bureau, i, 223

Philo of Byzantium, thermoscope, i, 69

Philosophers, Faraday on, x, 376

Philosopher's Stone, xvi, 14

Philosophy, Greek, xvi, 76-80, 83-8, 99;
18th century, 117;
mediæval, x, 35;
recent, xvi, 195-8;
Roman and Mediæval, 99-100;
science and, 112, 115;
social spirit and, 195

Philostratus, on death of Domitian, ii, 221;
on sun, 165

Phlegmatic Temperament, xi, 153

Phlegraean Fields, xiv, 225, 316, 320

Phlogopite, iii, 334

Phœnician Language, xv, 162

Phœnicians, Africa circumnavigated by, xiv, 196;
commerce of, 307;
in Iberian group, xvi, 49;
introduction of cats by, xii, 355;
invention of Alphabet, xv, 175;
navigation of, v, 182;
ships of, xiv, 265

Phonisms, xi, 222

Phonograph v, 328-9, 381;
combined with motion pictures, 331;
making of records of, iv, 240;
motor-driven, vii, 87;
vibration rates in, ix, 101

Phosgene, viii, 263, x, 187

Phosphate Baking Powders, viii, 136

Phosphate Group, viii, 93

Phosphate of Lime, plant needs of, xiv, 67

Phosphate Rock, as fertilizer, viii, 89, 344, 345;
occurrence and supply, xiv, 67

Phosphates, derivation and uses, viii, 89;
fertilizers, 153, 279-80;
in blood, x, 280;
in urine, x, 343;
test, viii, 290
(see also Calcium Phosphate, Sodium Phosphate)

Phosphine, viii, 89

Phospholipins, viii, 351

Phosphorescence, iv, 380;
of decaying wood, i, 346;
of marine animals, xii, 18-20, 24, 84

Phosphoric Acid, composition, viii, 89, 115;
in body, x, 280;
plant needs and sources, xiv, 67, 68, 69;
salts from, viii, 116;
solubility, 112;
stability, 115

Phosphorus, viii, 18-19, 87-9;
burning under water, 54-5;
ignition point, 53;
in body, functions, 354-5;
in fertilizers, 343, 344-5;
in iron ores, iii, 356;
melting requirements, iv, 162;
plant needs of, viii, 337, 341, 342, 344-5, ix, 29;
sources, viii, 345;
symbol and atomic weight, 383

Phosphorous (plant), ancient name of Venus, ii, 191

Phosphorus Pentoxide, viii, 87, 89

Photisms, xi, 222

Photochemical Climate, i, 325, 379

Photo-engraving, xvi, 129

Photographic Action, of different colors, iv, 365-6

Photographic Films, composition, viii, 255;
invention, v, 330-1

Photographic Map-Making, i, 45-8

Photographs, savage ideas of, xv, 331;
X-ray, vii, 250, 253-4

Photography, chemistry of, viii, 171-3;
color, iv, 368-9;
history, xvi, 192;
in astronomy (see Astronomical Photography);
in aurora studies, i, 162;
in lightning study, 146-8;
lenses used in, iv, 373;
underwater, i, 47-8
(see also Camera)

Photometers, vii, 374

Photosphere, defined, ii, 173

Photosynthesis, xiii, 81, 105, 109;
in cactus plants, 378

Phrenic Nerve, xi, 37

Phrenology, ix, 145

Phrygian Stone, ii, 284

Phylum, Phyla, xii, 29

Physas, xii, 69, 71

Physical Changes, contrasted with chemical, viii, 14-15

Physical Characters, classification of man by, xv, 36-47

Physical Chemistry, viii, 296-316

Physical Examinations, x, 370-1

Physical States of Matter, viii, 22, 382;
changed by heat, iv, 139, 151-3;
chemical interpretation, viii, 296-316;
in relation to pressure and temperature, 303-5;
suspended changes, 113, 304, 305

Physical Training Exercises, x, 305

Physicians, Babylonian laws controlling, x, 14-15;
capacity and preparation of, 367, 369;
earliest distinction from surgeons, 16-17;
essential duties of, 21, 75-6;
Oath of Hippocrates, 18-19;
Paracelsus on province of, 49

PHYSICS, Volume iv

Physics, branches of, iv, 50;
concrete science, xvi, 42;
daily applications of, iv, 10, 187, xvi, 17, 19, 30;
defined, 36;
energy the subject of, iv, 12, 13-14, 50;
exact, positive science, x, 368;
history of development of, iv, 11, 18-20, 24-30, xvi, 54, 82, 89,
91-2, 101, 103, 105, 109-10, 129-38;
interrelation of phenomena of, iv, 39, 40;
measurements in, iv, 45, xvi, 129-30;
medicine and, x, 81, 369;
realm of, iv, 13-20;
technical terms, glossary, 381-4

Physik, Philip, x, 121

PHYSIOGRAPHY, Volume xiv

Physiography, defined, iii, 381, xvi, 36

Physiological Meteorology, i, 316-31

PHYSIOLOGY, Volume ix

Physiology, daily applications, xvi, 15, 16-17;
history of development, x, 29, 30-1, 81, 125-8, xvi, 82-3, 180;
medicine based on (Boerhaave), x, 76-7;
science of body, xvi, 37;
teaching of, remarks on, x, 284-5

Piano, automatic, vi, 97;
evolution of, xv, 318;
intervals on, iv, 208;
sympathetic vibration, vii, 261-2;
vibration rate of notes, ix, 99

Picard, astronomer, ii, 58, 59, 64

Piche, A., deperditometer, i, 319

Pickerel Frogs, xii, 180

Pickerels, xii, 163

Pickering, Prof. Edward C., astronomical work, ii, 17, 116, 118, 122,
127, 130, 132-3, 133, 145, 146, 233, 237-8, 297, 307, 359

Pickering, W. H., ii, 271

Picric Acid, viii, 63, 238, 262

Pictou, Nova Scotia, pollen shower, i, 359

Picture Writing, xv, 167-9
(see also Hieroglyphics)

Pictures, depth impressions in, ix, 120

Piddington, Henry, i, 135

Piddocks, xii, 59

Pie Crust, "taste" of, xi, 127

Piedmont Glaciers, iii, 60

Piedmont Plateau, xiv, 27-8, 213;
building stones of, iii, 371, 372;
forests of, xiv, 378;
geology, iii, 28, 112, 172, 188, 231-2

Pig Iron, v, 318, viii, 157, 158, 159;
electric furnace production, vii, 312

Pigeons, xii, 265;
equilibrium disturbances in, x, 126, xi, 31

Pigments, viii, 162, 264, 265-6;
ancient, xv, 113-14;
colors of, iv, 369-70

Pigs (swine), xii, 310-11;
evolution of hoof, iii, 300

Pikas, xii, 287-8

Pikes (fish), xii, 163

Pike's Peak, shadow in sky, i, 170

Pile-driving, by water jets, v, 88-9

Pileus, of mushrooms, xiii, 163

Pilgrim Shell, xii, 65

Pili Erectores, xi, 113

Pillows, and sleep, xi, 290

Pillsbury, Prof., quoted, xi, 168-9

Pilot Balloons, i, 21-2, 312, 379

Pilot Charts, i, 273-5

Piloting, wireless system, vii, 285

Pilot Lights, vi, 276

Pilot Snakes, xii, 219-20, 233

Piltdown Man, xv, 92-5;
brain of, 96;
implements of, 107;
period of, 102

Pimento, origin, xiii, 265

Pimpernel, xiii, 203

Pimples, ix, 186, 187;
germs of, x, 201

Pineapple, American origin, xiii, 221, 226, xiv, 382;
fiber of leaves, xiii, 236;
introduction, 10;
water-holding leaves, 106

Pineapple Family, in tropical forests, xiii, 362-3;
restricted to America, 320

Pine Forests, conditions favorable to, xiii, 371;
pollen showers, i, 359

Pinel, Philippe, x, 110-11

Pine Needles, measuring heat in, vi, 62-3

Pine Trees, in American forests, xiv, 372, 374;
lightning dangers, i, 155;
planting conditions, xiii, 270;
pollen of, 118, 149;
polycotyledons, 60;
seeds of, 345;
seed-dispersal, 343;
wind-fertilization, 148
(see also Conifers)

Pinhole Camera, ix, 107-8, 109

Pinion Gears, v, 29, 30 (fig.)

Pink Family, petals and sepals, xiii, 194, 195

Pink Lady's Slipper, xiii, 145 (fig.)

Pinks, meadow, xiii, 133-5;
sea or marsh, 204

Pinuela, origin, xiii, 226

Pipal Tree of India, xiii, 108

Pipefishes, xii, 163

Pipe Organ, of Ctesibius, v, 110-11 (see Organs)

Pipes, lead, viii, 162
(see also Water Pipes)

"Pipes", in ingots, v, 323

Pipes of Pan, xv, 316, 315 (fig.)

Pipette, viii, 294, 295 (fig.)

Pipe Vine, fertilization, xiii, 131-3

Piracy, Stream, iii, 38-9, xiv, 177-83

Piranha, xii, 159

Pirogoff, Nikolai, x, 131

Pisa Cathedral, lamp in, ii, 53, v, 63-4

Pisa, Leaning Tower (see Leaning Tower)

Pistillate Flowers, xiii, 46-7

Pistils, xiii, 45, 46;
in reproduction, 117-22;
of highly cultivated plants, 51

Pistons, measurement of work of, vi, 81-2;
reciprocating and rotating, v, 148;
service in internal combustion engines, i, 57-9

Pita, origin and product, xiii, 244

Pitch of Sounds, iv, 205-6, ix, 99-100, xi, 104, 105;
extremes of audibility, iv, 204;
hearing of, xi, 103;
modulations of, in voice and music, iv, 209;
motion effects on, iv, 209-10;
of bells, 222;
of organ pipes, 230-1, 231-2;
of vibrating strings and rods, 223-4;
resonators for special, iv, 232, 233;
temperature effects on, 231-2

Pitchblende, radium from, xvi, 193

Pitcher Plant, xiii, 39-40

Pith Balls, electrification of, iv, 257-8, vi, 286-7

Pithecanthropus Erectus, iii, 302-3, xv, 88-92;
brain of, 96;
period of, 102

Pittsburg, dryness of, i, 337;
growth as river city, xiv, 219;
smoke nuisance, i, 64, 65;
"Smoky City", vii, 343;
water supplies of, viii, 318;
water supply and typhoid rate, 322

Pittsburg Bituminous Coal Bed, iii, 200-1, 347

Pituitary Gland, x, 347

Plaaters Kill, xiv, 179

"Place in the Sun", struggle of plants for, xiii, 27-8, 38-9, 76-7, 361-3

Placental Animals, iii, 297, 298;
evolution of, xii, 271, 332

Placer Deposits, defined, iii, 381;
gold, 331, 365-6, 366-7;
platinum, 335;
tin, 369

Plagioclase, iii, 328-9

Plague, Greek ideas of, x, 285;
immunity to, 207;
inoculation against, 208;
racial susceptibility to, xv, 50, 51

Plagues, great, x, 153-70;
uncleanliness and, xv, 49

Plains, xiv, 212-19;
civilization in relation to, xv, 128;
define and distinguished, xiv, 27, 213, 220;
Great (see Great Plains);
outwash, iii, 68-9;
perfect, seldom attained, 35;
populations mostly on, xiv, 218-19;
sea-cut, 46-7, 216;
surfaces of high and low, 28

Planarians, xii, 44

Plane of Ecliptic, ii, 70, 163

Planers, invention, v, 47

Plane Tree, in landscaping, xiii, 271-2;
leaf buds, 34
(see also Sycamores)

Planet Deep, iii, 51

Planetary Motions, ii, 163, iii, 158, 159;
compared with whirling of pail, iv, 71;
Copernicus on, ii, 43-4;
gravitation and, iv, 95, 98;
Huygen's studies, ii, 58;
irregularities, 66, 67, 71, 73, 79, 87;
Kepler's laws, 49-52;
Ptolemaic theory, 35-6;
spectroscopic investigation, 120-1;
theory of relativity and, 80-1;
tidal friction theory, 376-7

Planetary Nebulæ, ii, 360;
distribution and motion, 364;
star streaming by, 347;
stars and, 308-9

Planetary Orbits, ii, 162-3;
deviations, 66, 67, 79;
elliptical form, 39, 50-1, xvi, 102;
first thought to be circular, ii, 34, 49;
variations in elements, 74-5

Planetesimal Hypothesis, ii, 372-4, iii, 160-3;
not sustained by Mt. Wilson studies, ii, 157;
origin of moon by, 376;
rings of Saturn by, 266

Planetesimals, ii, 374, iii, 161, 162

Planets, atmospheres of, i, 10, ii, 231-2, 245;
conjunction recorded by Hindus, 21;
days and seasons in, 228;
distances and periods, 51-2;
erratic amplitudes, 25;
farthest, 267-9;
hypotheses of origin, ii, 369-74, 379, iii, 160, 162;
inner, ii, 189-92;
law of sun's attraction, 65;
life on, 245-50;
lucid, 264;
minor, 16, 254-9 (see Asteroids);
motions (see Planetary Motions);
orbits (see Planetary Orbits);
photography in study, 130-4;
sizes and motions, 162-3;
of stars, 252-3;
trans-Neptunian, 270-2;
weighing of, 75-7

Plankton, Sea, xii, 17-21, xvi, 147-8;
copepods in, xii, 84;
one-celled animals of, 25

Planning, of work, xi, 377-8

Planosphere, xvi, 91

Plantain Eaters, xii, 265

Plantains, xiii, 217, 226

Plant Breeding, ix, 327, 337

Plant Classification, xiii, 168-81;
by cotyledons, 60-1;
by factor expressions, 330;
by morphological characters, xvi, 165-6;
by reproductive processes, 166-7;
former method, xiii, 175;
Linnæan System, x, 84;
outline, iii, 251

Plant Distribution, xiii, 337-84;
determined by climate, xiv, 364-79, 380-1;
facilitated by land arrangement, xiv, 21;
Ice Age and, xiii, 321, xiv, 375-7;
importance of study of, xiii, 12;
land changes and, xiii, 320

Plant Ecology, xiii, 354-7

Plant Families, xiii, 179-207;
restricted areas of some, 320

Plant Formations, xiv, 371-2, (see Plant Societies)

Plante, ball lightning studies, vii, 215

Planting, index plants, i, 255-6;
rules and tables, xiii, 267-97

Planting Machines, v, 244

Plant Kingdom, distinguished from animal, xii, 14-15, xiii, 13-14;
history of, xiii, 298-336

Plant Names, xiii, 168-71

Plants, active principle, xiii, 250;
adaptations in (see Adaptation to Environment);
aerial, xiii, 21;
ancient study, 249;
animals and, interdependence, viii, 334-5, 347, 349, 350, xiii, 82;
autophytic, 96-7;
behavior, 76-115;
blended characters in, ix, 337;
borrowing and robbing, xiii, 97-101;
breathing of, 109;
Brownian movements, xvi, 166;
carbon dioxide used by, i, 13-14, viii, 49;
cell constituents of, ix, 26;
cellulose of, 30;
chemical composition and processes, iii, 344, viii, 335-8, 341, 348,
349, 354-5, xiv, 64-5;
chlorophyll (see Chlorophyll);
chromosomes in different species, ix, 46;
classification (see Plant Classification);
climate and, xiv, 363;
colorless, xii, 14-15;
cultivated (see Cultivated P.);
defined, xiii, 13-14;
distribution (see Plant Distribution);
distinguished, xii, from animals, vii, 14-15;
evolution, iii, 249-58;
flowering and flowerless (see Flowering, Flowerless Plants);
fog drip, i, 351;
food and feeding, viii, 339-46, 347, 349, 350, xiii, 13-14, 17-18, 19,
23, 24, 25-6, 39-41, 42, 90-101, xiv, 64-8;
food of green and other, xiii, 70;
food-making and storage by, viii, 334, ix, 25-30, xiii, 77-84, 95, 96;
food varieties for man and animals, ix, 24-5, 30;
frost protection, i, 259;
frost susceptibilities, 258;
galls on, xii, 125;
garden (see Garden Plants);
geotropism, xiii, 85;
growth electrically stimulated, vii, 351-3;
growth, upward and downward, xiii, 84-5;
guttation, i, 350-1;
highly cultivated, xiii, 51;
hybrid, 147;
immobility, 14, 109-10;
index, i, 255;
inheritance laws, x, 231, 232;
injured, hasty flowering of, xiii, 167;
insect-capturing, 39-41;
instinct in, xi, 49;
land (see Land Plants);
light effects on, x, 253;
marine, xii, 16-17;
microscopic (see Bacteria);
modern, origin and development, xiii, 316-25;
movements, 109-15;
motion pictures of growth, iv, 348;
mutation (see Mutants);
new species, how developed, xiii, 325-36;
nitrogen needs, i, 34, viii, 280, 345-6, xiv, 66;
nitrogen supply in soil, x, 193-4;
northward movement, xiii, 321;
number of species, 323;
of oceanic islands, xiv, 277, 278;
oils of, ix, 28;
parasitic, xiii, 100 (see Parasitic Plants);
parts of, 15;
petrified, iii, 15-16;
phenology, i, 254, 256, 379;
protective methods (see Protective Methods);
proteins of, ix, 278-9, 280, 287;
protoplasm of, xiii, 74;
rate of increase in, xv, 19, 21;
reasoning in, xiii, 3, 97;
reproduction, 116-67 (see Reproduction of Plants);
restless and irritable, 109-15;
rock disintegration by, viii, 194, 338;
rootless, xiii, 15, 21;
salt and fresh water, ix, 174, 175;
saprophytic, xiii, 99-101;
seat of life in, ix, 17;
seed-dispersed (see Seed);
struggle for dominance (see Struggle for Dominance, Struggle for
Existence);
sunlight and, ix, 27, xi, 52, xiii, 76-7, 84-90, 361-3, xiv, 365-6,
367;
unicellular and multicellular, xiii, 166;
uses to man, 9-12, 208-66;
variation in, xv, 22-3 (see Variation);
vascular and nonvascular, xiii, 65-6;
water sources and uses, 90-6, 101-9;
water storage, 28, 41-2, 106-7, 378, 379, 380
(see also Vegetation)

Plant Societies, xiii, 356-83, xiv, 371-2

Plaskett, reflector of, ii, 106-7

Plaster of Paris, iii, 332, viii, 153;
made from gypsum, xiv, 209;
manufacture of, iii, 376

Plastic Surgery, x, 57, 189, 384

Plateaus, xiv, 220-4;
dissection and destruction, 224;
distinguished from plains and mountains, 27-8, 213;
formed by warping, 38;
mountains from dissected, iii, 139-40, xiv, 225, 226;
oceanic, 286;
re-elevated, 96-8;
topography developed from stratified, 80-1

Plate Condensers, vi, 293-4

Platelets, of blood, ix, 188-9;
held by capillary walls, 194

Plates, photographic, viii, 172-3

Platiarius, Joannes, x, 37

Plating of Metals (see Electroplating)

Platinum, iii, 335, viii, 126-7, 173-4;
affinity intensity, 128;
atomic weight and symbol, 383;
catalyzer, 82, 103;
coefficient of expansion, vi, 265;
density of, iv, 113;
electrical conductivity, 283;
extraction from ores, viii, 131;
melting point, iv, 162, viii, 384;
occurrence, 131, 198;
positiveness of, vi, 59;
specific gravity, viii, 384

Platinum Metals, viii, 173

Plato, classifying fault of, x, 83;
greatness of, 20;
on forms and knowledge, xvi, 87, 88;
on passions, xi, 130

Platte River, overloading results, xiv, 161;
sediment deposited, iii, 32-3

Platyhelminthes, xii, 44

Plauen Laces, v, 288

Play, of animals and men, ix, 21, xvi, 143

Playfair, xvi, 170

Pleasure, artistic forms of, xv, 296-325;
emotions of, ix, 153, 165;
significance of, xi, 121-2;
stimulation requisite, 195

Pleiades, star cluster, ii, 122, 336;
in moving cluster, 343;
nebulosity, 110, 359-60

Pleistocene Animals, xii, 279, 306, 313, 327

Plesiosaurs, iii, 288, xii, 182, 202

Pleurisy, friction sounds in, x, 109

Pliny, harvesting machines mentioned by, v, 240;
natural history of, xvi, 98;
on Roman physicians, x, 25

Pliocene Epoch, species surviving from, xv, 71

Plovers, xii, 262

Plowing, deep, xiv, 69;
modern, v, 218, 243

Plows, evolution and kinds, v, 239-40, 241-3, xv, 235-6

Plucker, experiments of, xvi, 193

Plucking of Rock, iii, 29, 64, 65

Plumbago, viii, 43

Plumbing, of houses, how worked, v, 84-6

Plumb Lines, iv, 99

Plumed Seed and Fruits, xiii, 343-4, 345
(see also Winged Seed)

Plum Trees, xiii, 197, 271-2

Plums, drupes, xiii, 54;
origin, 226;
splitting, 94

Plutarch, on rain and battles, i, 336;
on sun, ii, 165, 220-1

Plutarch's Lives, Copernicus' study, xvi, 102

Plutonic Rocks, defined, iii, 381, xiv, 105;
exposure by denudation, 100, 105;
forms, iii, 102 (fig.), 110-12, 170, xiv, 105-11;
topography due to, iv, 105-13;
weathering of, 105-6, 107, 110, 112-13

Pneuma, x, 27, 29, 63, 85

Pneumatic Breakwaters, v, 125

Pneumatic Caissons, v, 116-21 (see Caissons)

Pneumatic Cars, v, 133

Pneumatic Cement Gun, v, 136

Pneumatic Cushions, v, 133-5

Pneumatic Dispatch, i, 29

Pneumatic Drills, i, 27, iv, 129, v, 129, 261-2, 263, 380, 381

Pneumatic Engineering origin, v, 109

Pneumatic Hammer, i, 28, v, 129

Pneumatic Motors, v, 129-30

Pneumatic Musical Toys, of Hero, xvi, 92

Pneumatic Power Transmission, i, 26, 27-8

Pneumatic Riveters, v, 129

Pneumatic School, of medicine, x, 26-7, 29

Pneumatic Shovels, v, 262

Pneumatic Tampers, v, 135

Pneumatic Tires, v, 133-4, 206, 382;
bursting by heat, iv, 151

Pneumatic Tools, i, 27-8, iv, 129

Pneumatic Trough, viii, 32 (fig.)

Pneumatic Tubes, i, 28-9, iv, 130, v, 137-8;
obstructions in, how located, iv, 200

Pneumatic Tunnel Shield, v, 122-4, 260

Pneumogastric Nerve, xi, 30

Pneumonia, x, 288-9;
discovery of cocci, xvi, 185;
germ of, x, 194, 196, 216, 221, 289;
immunity to, 207;
inoculation against, 208;
negro susceptibility to, xv, 50, 51;
toxin of, x, 196

Po (River), levees of, xiv, 53;
longitudinal character, 154

Pockels, F., i, 152-3

Pocky Clouds, i, 104, 379

Pocono Plateau, xiv, 221

Podalic Version, x, 56

Podalirius, x, 16

Pods, seed-shooting, xiii, 339

Poetry, development of, xv, 319-22, 325;
historic value of, 322, 323-4

Poggendorff's Illusion, xi, 187

Pogonip, ice fog, i, 95-6, 379

Poincaré, astronomical work, ii, 356, 377;
on relativity, xvi, 197

Pointed Objects, electric discharges from, i, 157, iv, 265, 269, vi,
295-7

Poiseuille, Jean Leonard Marie, x, 126

Poison Ivy, xiii, 252;
aerial roots, 20;
family, 200

Poisonous Amphibians, xii, 169-70

Poisonous Gases, in World War, i, 308-9, 313-14, x, 186-7;
scars of, 189

Poisonous Snakes, xii, 224-38

Poisonous Spiders, xii, 93, 95

Poisons, arsenic, 169;
carbon monoxide, viii, 50-1;
diseases from, x, 255;
effect on mind, xi, 13;
in air, ix, 270;
in plants, 30, xiii, 250, 252;
mercuric, viii, 170;
vegetable acids, 222;
wood alcohol, 214;
use of, by savages and others, xv, 227-9

Poisson, Simeon Denis, xvi, 122

Pola, harbor of, xiv, 253

Poland and Danzig, xiv, 306

Polar Bands, i, 99

Polar Bears, xii, 336-7;
Eskimo method of catching, xv, 224-5

Polar Coordinates, iv, 16

Polarimeter, viii, 226

Polaris (Pole Star), ii, 232;
a binary, 123;
color, 297;
magnitude, 295;
standard of magnitude, 297

Polariscope, viii, 309-10, x, 137

Polarity, magnetic, vii, 374

Polarization, meaning, iv, 354, 383

Polarization, in electric cells, iv, 296, 298, 383, vi, 136-7

Polarization of Light, iii, 319, iv, 353-6, 383;
discovery, xvi, 119;
Pasteur & Le Bel's studies, 163-4;
sugar testing by, iv, 354-6, viii, 226

Polar Regions, aurora in, i, 159;
clouds and fogs, 93, 95;
frozen soil, xiv, 75;
halos, i, 179;
land areas uncertain, xiv, 11, 20;
living conditions in, 344;
mirages, i, 172, 173;
plant conditions of, xiv, 365;
rain and snow in, i, 109, 119, xiv, 42;
rime in, i, 121;
sky shadows in, 170;
tundra vegetation, xiii, 381;
winds, i, 127, 128, 129

Polar Relays (telegraphy) vii, 114-18

Polecats, xii, 349

Pole Lathes, v, 42-3

Pole-line Transmission System, vii, 14-24

Poles of Earth, altitude of stratosphere at, i, 20;
aurora in relation to, 159;
compass in relation to, iv, 246;
flattening at, ii, 69;
weight of bodies at, 69, iv, 101
(see also Polar Regions)

Pole Strength, unit of, iv, 249, 250

Policeman's Whistle, iv, 220

Pollen, xiii, 118, 119;
attraction to insects, 124, 125, 134, 143;
found in ancient remains, 310;
hay fever from, x, 212;
in air, i, 61;
in aquatic plants, xiii, 149-52;
mixtures of, 146-8;
protection, 126;
"showers," i, 359;
wind-blown, xiii, 123, 148-9, 144 (illus.)

Pollution Gauge, i, 65, 379

Pollux, angular diameter, ii, 151

Polonium, discovery, xvi, 193

Polyandry, xv, 285, 286-7, 294-5

Polycotyledons, xiii, 60

Polycythemia, x, 152

Polygamy, xv, 285, 287-9

Polymerization, viii, 219, 232, 335

Polynesia, xiv, 277;
ease of life in, xv, 124;
overpopulation of, xiv, 282

Polynesians, clothes of, xv, 256-7;
fire generation by, 231;
hair of, 37;
in brown race, 37;
seamanship of, xiv, 282, 305-6;
susceptibility to tuberculosis, xv, 51;
tattooing among, 258;
wind gods of, 342

Polypeptides, viii, 353

Polypetalae, xiii, 47, 190, 195-201

Polyps, xii, 33-43

Polysaccharides, viii, 224, 227-9

Polyuria, x, 343-4

Polyzoa, xii, 46-7

Pomegranates, origin, xiii, 226

Pompeii, burying of, iii, 100;
earthquake at, xiv, 326;
volcanic material over, 326

Pomes, xiii, 54

Pondering, delays in brain, xi, 21

Ponds, depth appearances of, iv, 327;
dew, i, 352-3

Pond Snails, xii, 69

Pond-weed, xiii, 340

Pons, comet discoveries, ii, 275, 289

Pontchartrain, Lake, xiv, 203

Pontias, i, 131-2, 379

Poor Whites, of southern mountains, xv, 130-1

Popcorn, eating of, ix, 251;
known to Indians, xiii, 212

Poplar Trees, antiquity, xiii, 324-5;
earliest appearance, 318;
family, 191;
fluttering of leaves, 113;
in landscaping, 271-2;
seed dispersal, 343

Popliteal Aneurism, x, 121

Popoff, wireless system, xvi, 191

Poppy, cultivation and uses, xiii, 253-4;
seed in confections, 250, 254

Population, artificial selection, xvi, 154-5;
civilization in relation to, xv, 128-9;
distribution of, 12;
increase of, 26-7;
mostly on plains, xiv, 218;
of mountains, 245

Porbeagles, xii, 145

Porcelain, viii, 283;
Egyptian, xvi, 74

Porcupines, xii, 288-9;
absence of fear in, xi, 136

Porifera, xii, 30

Pork, calories in, ix, 299;
proteins in, 279;
trichina caused by, xv, 49;
vitamines in, x, 262

Porous Rock, water in, iii, 113-15

Porpoises, xii, 297

Portals of Entry (infections), x, 198, 201-2

Portal Vein, ix, 198, 245

Port Hudson, capture of, xiv, 194

Port Jackson Shark, xii, 143

Portland Cement, iii, 373, 374, viii, 280

Porto Bello, heavy rain, i, 110

Porto Rico, hookworm in, x, 174;
ocean depths near, iii, 51;
overpopulation of, xiv, 282;
zoölogy of, 274

Porto Rico Trench, xiv, 289

Portugal, aphysia dyes of, xii, 68

Portuguese Empire, xiv, 310

Portuguese Language, xv, 162

Portuguese Man-of-War, xii, 18, 37

Portuguese Navigators, xiv, 196, 309

Port Valais, xiv, 53

Position, perception of, xi, 162-3, 164, 165, 167-71

Positive, electrical meaning, vi, 57, 124

Positive Electricity, iv, 258, 265, vi, 287, 288

Positive Ions, i, 142, 143, viii, 121-2

Post, C. W., rain experiments, i, 339

Post, Wright, x, 121

Postage Stamps, dextrin gumming, viii, 228;
printing of, vii, 314

Postal Telegraph Company, vii, 108, 112

Post-Mortem Findings, x, 98

Postures, importance to health, x, 241-2;
importance of, to right growth, ix, 57;
mental effects, xi, 294, 301, 337, 338-40, 371, 372;
muscular activity in, ix, 83-4;
standing and walking, x, 305

Potash, available supplies and uses, viii, 275, 278-9, 344, xiv, 67-8,
69, 209;
from smoke precipitation, vii, 347, 348;
in body fluids, ix, 174;
in ground water, xiv, 142;
locked-up forms, viii, 200-1;
salts of, in protoplasm, ix, 82

Potash Lakes, xiv, 206, 212

Potassium, viii, 143-5;
affinity strength, 127, 128;
alkali metal, 132-4;
atomic weight and symbol, 383;
fusibility, 384;
in body tissues, 354;
in earth's crust, iii, 308, viii, 19, 129, 148, 192, 195, 279;
light metal, 17, 127;
metallic character, 181;
plant needs and sources, 337, 341, 342, 343, 344;
specific gravity, 384;
spectrum, 301-2;
test for, 287, 289

Potassium Compounds, viii, 144;
chlorate uses, 34, 35, 87, 88, 89, 146;
chloride, 188;
cyanide, in gold extraction, 174;
feldspar, 90;
flame color, 301;
hydroxide, in soap making, viii, 142;
nitrate, 72, 138, 144-5, 146, 372;
occurrence in nature, 130, 138, 143-4, 195, 196, 279, 344;
permanganate, 294, 333;
uses, 130, 144, 146

Potatoes, calories in, ix, 299;
eyes of, xiii, 22;
food value, ix, 34, viii, 365, x, 261, 265, 266, 268;
history and kinds, xiii, 218-19;
keeping of, viii, 371;
origin, xiii, 221, 223, xiv, 382;
starch from, viii, 248, xiii, 83;
starch storage in, ix, 27-8;
stems, xiii, 22, 23;
tubers, 24 (fig.), 83

Potential, Electrical, iv, 262-3, 383, vi, 49, vii, 374;
maintenance of constant, vi, 329;
positive and negative, iv, 265;
spark table, vii, 383

Potential Differences, iv, 263, 383, vi, 50, 51, 57, 72, vii, 366;
between earth and clouds, i, 144, iv, 269;
electric energy from, 263, 264-5, 294-5;
in thunderstorms, i, 149-50, 151-2, vii, 206-7;
measured by voltmeters, 154;
production of, iv, 271-3;
unit of, 280

Potential Energy, iv, 79, vii, 368;
conversion to kinetic, iv, 81, 82, 87-8;
forms of, 82

Potential Gradient, i, 144, 145

Potential Transformers, vii, 44, 45

Potholes, iii, 39-40

Potomac River, course of, xiv, 154, 168-9;
gap, 51, 52, 167;
rapids, 159;
shad season in, xii, 155

Pott, Percival, x, 92

Pott's Disease, x, 92

Pott's Fracture, x, 92

Potter's Wheel, xv, 249-50, 251 (fig.)

Pottery, viii, 282-3;
ancient making of, viii, 280-1, xv, 248-51, xvi, 74;
decorations of, xv, 250-1, 252, 253, 297-8

Pouched Gophers, xii, 290

Pouched Mice, xii, 278

Poulsen Arc Generators, vii, 274, 275-6, 291

Poultry, originals of, xii, 261

Poultry Products, drain on farm, viii, 342-3

Pound, unit of force and mass, iv, 58, 64-5, 69-70;
value in grams, 70, viii, 28

Poundal, unit of force, iv, 64, 69;
value in grams and dynes, 70

"Poverty Year," i, 359

Powder (see Gunpowder, Smokeless Powder)

Power, defined, iv, 80, vi, 83, 84;
electric (see Electric Power);
from fuels, ix, 15-16;
gain in elementary machines, v, 22-3, 31-5, 38;
relation to velocity in machines, iv, 92;
sources of, ix, 25-6;
unit of, iv, 80, vi, 83, 84, vii, 369
(see also Energy, Force)

Power Boats, cylinders, v, 159

Power Factor, in alternating currents, vi, 169, 172;
in induction motors, 255-6;
regulation by, synchronous motors, 255, 260-2;
in rotary converters, 348

Power Plants, vi, 349-84;
distribution of power, vii, 25-31
(see also Power Transmission);
extra charges for peak hours, vii, 177-8;
for farms, 231-4;
high and low head, v, 79-83;
interest of machinery, vi, 175-6;
number and capacity in U. S., vii, 74-5;
remote control in, vi, 100-1, 102;
Shuman's sun-using, v, 177-8;
tidal, 174-7;
turbine use, advantages, 151, 153;
use of alternators, vi, 215;
using volcanic heat, v, 179-80
(see also Hydroelectric Plants)

Power Transmission (electrical), vii, 9-31;
alternating currents in, vi, 159-61, 169, 195-6;
direct currents in, 160, 195;
Niagara Plant system, 375-8;
overhead and underground (see Overhead, Underground Transmission);
present distances attained, 365;
problem, 367-8;
prominent names in history, 26;
synchronous condensers in, 262;
traction methods, vii, 186-93, 197-200;
voltages and currents used, vi, 159, 160-1, 163, 169, 331-2, vii,
10-11
(see also Long Distance Transmission)

Power Transmission (Hydraulic), v, 104-8

Power Transmission (pneumatic), i, 26, 27-9

Practice, effects of, xi, 253

Praepositus, Nicolaus, x, 37

Præsepe, star cluster, ii, 336

Pragmatic Philosophy, xvi, 196

Prairie Dogs, xii, 294

Prairie Fires, smoke from, i, 56

Prairies, dominance of grasses on, xiii, 350;
plant societies of, 373-6;
soils of, xiv, 383;
United States, 374, xiv, 373;
windbreaks, i, 333

Prase, iii, 337

Praseodymium, symbol and atomic weight, viii, 383

Prayer, primitive conceptions of, xv, 344-7

Pre-Babylonian Science, xvi, 56-63

Precession, of gyroscopes, v, 336, 337-9, 340, 341, 342

Precession of Equinoxes, ii, 70-1;
Arab work on, 38;
discovery, xvi, 90;
Hipparchus on, ii, 31, 300

Precipitate, defined, viii, 380

Precipitation (atmospheric), annual amount, xiv, 135;
climate determined by, 351-2, 355-6;
measurement, i, 79-82;
mountain effects, xiv, 354-5;
source of terrestrial waters, 134, 151;
various kinds, i, 106-22, 379

Precipitation (electrical), vi, 164, vii, 216, 346-51

Precipitation Treaters, vii, 348-51

Prehistoric Man (see Primitive Man)

Prehistoric Times, before writing, xv, 167, 322-3;
geographical and climate changes since, xiv, 29-30

Prejudice (see Bias)

Preoccupation, of mind, xi, 154-5

Prepotent Inheritance, x, 230

Preservatives, action of, viii, 333;
chemical, 372

Preserving of Foods, viii, 371;
effect on vitamines, x, 263, 266

Pressure, boiling point and, iv, 167-8, 169-70;
critical, 171-3;
melting point and, 153, 162, 163-6;
sense of, xi, 109, 110, 111, 113, 114
(see also Atmospheric Pressure, Gases, Liquids)

Pressure Areas, ordinary movement, i, 237;
physiological effects of alternations, 329-30;
wind and weather attendants, 125, 134-5, 218, 237-8, xiv, 349-50 (see
also Highs, Lows)

Pressure Belts, i, 127-9

Pressure Cookers, iv, 171

Pressure Gradients, i, 126, 373;
reversal, 130, 131

Pressure Waves, in alternating currents, vi, 198

Prevailing Westerlies, i, 128, 379, xiv, 345-6, 349

Preventive Medicine, x, 282-317;
history of development of, 15, 99, 133-4, 171-6, 217-18

Prickly Fruits, xiii, 58, 343

Priestley, chemical work, xvi, 120, 177;
oxygen discovery, viii, 34, x, 89, xiv, 65

Priests, of savages, xv, 349-53, 354, 359

Primary Cells, iv, 299, 383, vi, 130, 131-44, vii, 363;
chemical action of, viii, 167

Primary Coils, iv, 383, importance of knowledge of, 9

Primary Colors, iv, 366

Primary Concepts, iv, 14-16

Primary Rocks, viii, 191;
disintegration, 194-5

Primates, iii, 301, 302, xii, 373-4, 375, xvi, 126

Prime Movers, ix, 15, vii, 373;
of future, v, 171-81;
various kinds, vi, 181-2, 351-2

Primitive Man, æsthetic arts of, xv, 296-325;
conditions of life, x, 10, xv, 188-92;
dogs of, xii, 345-6;
language of, xv, 140;
love of decoration in, 252-3;
mind and beliefs, xvi, 42, 43-5, 51, 56;
religion of, xv, 327-59;
sex relations of, 277-8;
tools and weapons of, v, 11, 12-15, xv, 102-10;
types of, 77-102
(see also Cave Men, Savages)

Primrose, leaves, xiii, 88;
petals, 190

Primrose Family, xiii, 203-4

Prince Rupert Drops, viii, 281

Princeton College, founding, xvi, 127

Prince's Island, groundsel in, xiii, 345

Principle of Archimedes, iv, 30, 102-5;
applicable to gases, 107, 126

Pringle, John, x, 104, 155

Print, machines to read, v, 332-5, 384

Printing, v, 300-13;
color, iv, 370-1;
electrotyping, vii, 313-14;
invention of, xv, 179;
invention, results on science, ii, 13, 40, 42, x, 44;
photographic, viii, 173

Printing Presses, development, v, 300-5, 378, 379, 381

Prisms, effect on light, i, 165, ii, 99, 111, 112, iv, 357-9, 365, viii,
301

Prisoners, habit in, xi, 255;
labor of, 275

Privet, leaf arrangement, xiii, 38

Proboscis, of insects, xiii, 126

Proctor, astronomer, ii, 249, 343

Procyon, ii, 297, 319

Prodigality of Nature, in ferns, xiii, 155, 156;
to insure reproduction, 117, 118, 124, 152

Produce Exchanges, weather reports at, i, 252

Professional Men, food requirements, ix, 297

Proficiency, unconsciousness of, xi, 254