Chapter II: Preface (2)

Owls, why does their screeching denote change of weather, 1111

Owls, why does their moping foretell death, 1112

Oxen, sheep, deer, &c., why do they ruminate, 1088

Oxen, and other quadrupeds, why have they a tough elastic ligament in
their necks, 1138

Oxygen, why is it necessary to life, 5

Oxygen, what is its union with carbon called, 7

LESSON LIII.

Oxygen, what is it, 25

Oxygen of the air, why does it not take fire, 28

Oxygen, why do we know that it will not burn of itself, 29

Oxygen, why do we know that it is necessary to our existence, 30

Oxygen, where is it found, 31

Oxygen, why is it mixed with nitrogen in the air, 32

Oxygen of water, why does it not support fire, 307

Oxygen, in what way does man use it, 757

Ozone, what is it, 630

Ozone, why do we know that electricity produces it, 631

Ozone, what are the properties of, 632

Paleness, what is the cause of, 914

Palms, what are their characteristics, 1221

Paper held over a candle-flame, why does it become scorched, 244

Paper held below a candle-flame, why does it scarcely become warm, 245

Paper, why does it more readily ignite than wood, 294

Paper, why, if it is laid flat upon the fire, will it "char" before it
ignites, 304

LESSON LIV.

Paper on a fire, why will it ignite when you send a puff of air to it,
305

Parachutes, why do they fall gradually to the ground, 834

Parrots, &c., why have they crooked bills, 1047

Parrots, why can they move their upper as well as their lower beak, 1048

Particles of matter, why do they draw near each other, 776

Particles of matter, why will they attach themselves to sealing-wax
excited by friction, 779

Pea and pin, why do they rotate upon a jet of air blown through a
tobacco-pipe, 845

Peg-top, why does it make less noise than a humming-top, 811

Peg-top, why does it sometimes hum, and at other times not, 812

Pelican, why has it a large pouch under its bill, 1093

Pepper, where is it produced, 1229

Perspiration, why does it cool the body, 173

Perspire, why do we, 1009

Perspiration, how is it formed, 1010

Perspiration, what is insensible, 1011

Perspiration, what is sensible, 1012

LESSON LV.

Phosphorous, why does it look luminous, 94

Phosphorous, does it ignite spontaneously when placed upon a hot
surface, 314

Phosphorous, why does it ignite when sprinkled with powdered charcoal,
315

Photographic pictures, how does light produce them, 556

Photographic rooms, why are they glazed with blue glass, 557

Pith-tumblers, why do they always pitch on one end, 868

Planets, how can man weigh them, 785

Planets, how can man measure their distances, 786

Plants, do they absorb heat, 225

Plants, how do we know that they absorb heat, 226

Plants, why do screens prevent frost from killing them, 400

Plants, why, if we cut across their stems, do we see tubes arranged in
parallel lines, 1159

Plants, why do some droop and turn to the earth after sunset, 1167

Plants, why are the seeds of many enclosed in rich juice or pulp, 1172

Plants, why have some tough curly tendrils, 1173

LESSON LVI.

Plants, why have peas tendrils, and beans none, 1174

Plants, why have grasses, &c., joints or knots in their stalks, 1176

Plants, what is the circulation of sap in, 1179

Plants, why does their sap ascend and descend, 1180

Plants, why do they suffer from the smoke of cities, 1188

Plants, why is it understood that some of them feel, 1141

Plants, why is it understood that some of them move, 1142

Plants, of what elementary substances are they composed, 1143

Plants, whence do they derive their elementary substances, 1144

Plants, how do they obtain carbon, 1145

Plants, how do they obtain oxygen, 1146

Plants, their decomposition of gases by day and by night, 1147

Plants, how do they obtain hydrogen, 1147

Plants, how do they obtain nitrogen, 1148

Plants, how do they apply their elements to the formation of their
structures, 1149

Plants, how is their nutritive sap applied to their growth and
nourishment, 1150

LESSON LVII.

Plants, why do they grow, 1154

Plants, why if we break the stem of a hyacinth do we see a glutinous
fluid exude, 1155

Plants, why if we split the petal of a tulip do we see cells containing
different colouring matters, 1156

Plants, why if we break a pea-shell across do we find a transparent
membrane, 1157

Plants, why if we cut through a cabbage-stump do we find a tough
coating enveloping a cellular substance, 1158

Plants, why are their seeds formed within the corollas of flowers, 1168

Plants, why does the flower of the poppy turn down during the early
formation of seed, 1169

Plants, why have those of the pea-tribe a folding blossom, 1170

Plants, why are leaf-buds enclosed in scales which fall off as the
leaves open, 1171

Plants, what is meant by "species" of, 1209

Plants, what is meant by "genus" of, 1210

Plants, progressive discovery of new species, 1211

Plants, what are the three great classes of, 1212

LESSON LVIII.

Plants, what are the characteristics of exogenous, 1213

Plants, what are the characteristics of cryptogamus, 1216

Plants, what are the effects of diverse climates upon, 1242

Plants, what are the effects of altitude upon mountains, 1243

Plants, what agencies influence their geographical distribution, 1250

Plants, what are the chief facts connected with the distribution of by
man, 1251

Plants, why are herbaceous less solid than woody, 1265

Plants, why are the stalks of herbaceous generally cylindrical, 1266

Plants, what are the stomata of, 1267

Plants, why are their stomata generally on the underside of their
leaves, 1268

Plants, why have they pith in their centres, 1269

Porter, why does bottled produce large volumes of froth, 801

Pulse, why do we feel it beat, 900

Quadrupeds, geographical distribution of, 1331

Quicksilver, why does it reflect light from mirrors, 513

LESSON LIX.

Radiation, why does scratching a bright metal surface increase its
powers of, 199

Radiation of heat, what benefits arise from it, 415

Radiation of light, what is it, 503

Radiation, do all bodies radiate light, 504

Rain, what is it, 416

Rain, does it ever occur without clouds, 417

Rain-drops, why are they sometimes large, and at other times small, 418

Rains, at what seasons are they most prevalent, 419

Rainy days, in what months of the year are they most frequent, 420

Rainy days, why are there more from September to March, 421

Rain, in what part of the world does the greatest quantity fall, 422

Rain, in what part of the world do the heaviest rains fall, 423

Rain, in what part of the world does the least rain fall, 424

Rainy days, how many are there in a year, 425

Rain, in what part of England does the greatest quantity fall, 426

Rains, why do the heaviest occur in hot countries, 427

LESSON LX.

Rain, why does the greatest quantity fall at the equator, 428

Rain, why are some parts of the earth without it, 429

Rain, why does it purify the air, 433

Rainy localities, why are mountainous countries more rainy than flat
ones, 434

Rain, why does more fall by night than by day, 435

Rain, why do bunches of dried sea-weed indicate its coming, 436

Rain, why do weather-toys foretell its coming, 437

Rain, the Capuchin toy; mysterious walk of a wooden horse, 438

Rain, why does ladies' hair drop out of curl as rain approaches, 438

Rain, why is it said to be coming, when the mountains are "putting on
their night-caps", 439

Rainbow, what causes a, 486

Rainbow, why does it exhibit colours, 487

Rainbows, why are there sometimes two, 488

Rainbows, why are the columns of the secondary bow, arranged in the
reverse order of those of the primary, 489

LESSON LXI.

Rainbow colours, why do glass lustres and chandeliers exhibit them, 498

Rainbows, why are the colours of the secondary bow fainter than those
of the primary, 491

Rainbow, what is a lunar, 492

Rainbow, why is a lunar bow fainter than the solar, 493

Rainbow, why is one in the morning the shepherd's warning, 538

Rainbow, why is one at night the shepherd's delight, 539

Refraction of light, what is it, 472

Refraction and reflection of light, what is the difference, 502

Reflections, why are they reversed, 490

Reflection, why do black bodies reflect any light, 505

Reflection, why does a window-pane appear to reflect better by night
than by day, 516

Reflection, what is the line of, 520

Reflection, what is the angle of, 522

Repulsion, what is it, 792

Respiration, why does the chest expand when we breathe, 889

Respiration, how does blood communicate with the air in the lungs, 890

Rest, why does it invigorate us, 1018

Rice, where is it cultivated, 1219

Rosewood, what is it, 1191

LESSON LXII.

Saliva, why does saliva enter the mouth while we are eating, 872

Sea, why is it salt, 764

Sea, what is the estimated amount of salt in the, 765

Sea, what is the depth of the, 766

Sea-gulls, why are they numerous in fine weather, 1119

Sea-gulls, why do they fly over the land on the approach of stormy
weather, 1120

Sea-crow, why is its lower bill longer than the upper, 1135

Sealing-wax, why does rubbing it attract to it small particles of
matter, 565

See, why do we, 963

Seeds, why are they generally enveloped in hard cases, 1152

Seeds, why do they throw out roots before they form leaves, 1153

Seeds, why does the leaf-germ come up to the light and the root-germ
penetrate the earth, 1285

Seeds, why are they indigestible, 1286

See-saw, why may a little boy balance a larger boy, 863

See-saw, why does the little boy sink to the earth, when the larger boy
kicks the ground, 861

LESSON LXIII.

See-saw, why may the little boy keep the larger one up, when once he is
up, 864

Shadows, what is the cause of, 508

Shadows, why is there some light where shadows fall, 510

Shadows, why do they lengthen as the sun goes down, 526

Shuttle-cock, why does it travel slowly through the air, 836

Shuttle-cock, why do we hear a noise when we strike it with the
battledore, 837

Sight, why are two persons able to see each other, 551

Sight, why can we see so many upon the small retina, 966

Sight, why are we able to see at long or short distances, 974

Sigh, why do we, 1025

Silica, what is it, 1260

Silk, what is it, 1200

Skin, why does a chill of the produce inflammatory action in the lungs,
1014

Sky, what is it, 530

Sky, why is it red at sunset, 532

Sleet, what is it, 447

Sleep, what is it, 1019

Smell, why do we, 992

Smoke, what is it, 102

Smoke, why is there so little when the fire is red, 105

Smoke, what is it, 289

LESSON LXIV.

Smoke, why do fresh coals increase the quantity of, 291

Smoke, why does it issue in folds and curls, 632

Smoke, why does it ascend in mild and fine weather, 689

Snails, why can they move in an inverted position, 666

Snails, where do they obtain their shells, 1306

Snails, why do their shells grow, 1307

Snails, why are their shells spiral, 1308

Snails, why have they four tentacula attached to their heads, 1309

Snails, why are they able to move without feet, 1310

Snails, why do we see none in the winter time, 1311

Snails, why can they live in sealed shells, 1312

Sneeze, why do we, 1024

Snipes and woodcocks, why have they long, tapering bills, 1042

Snore, why do we, 1028

Snow, why does it keep the earth warm, 160

Snow, why is it a good non-conductor of heat, 162

Snow, what is it, 440

Snow, why is it white, 441

LESSON LXV.

Snow, why is it warm, though white garments are cool, 442

Snow, why is it always on the tops of high mountains, 443

Snow-line, what is meant by the, 445

Snow, what is red, 446

Soda-water, why does it effervesce, 802

Soils, why are clayey unfavourable to vegetation, 1160

Soils, why are sandy unfavourable to vegetation, 1162

Soils, why are chalk unfavourable to vegetation, 1162

Soils, why are mixed favourable to vegetation, 1163

Soils, why do farmers manure their land, 1165

Soot, why should it be prevented from accumulating at the bottom and
sides of saucepans, 205

Soot, what is it, 290

Sound, what is it, 716

Sounds, what causes the air to produce, 717

Sounds, how do we know that they are produced by vibrations, 718

Sounds, how do we know that without air there would be none, 719

Sounds, how are the vibrations of sonorous bodies imparted to the air,
720

LESSON LXVI.

Sounds, how rapidly do the vibrations of travel, 721

Sounds, do all sounds travel at the same rate, 722

Sounds, why are bells and glasses stopped from ringing by touching them
with the finger, 723

Sounds, why does a cracked bell give discordant, 724

Sounds, why do we see the flash of a gun before we hear the report, 725

Sound, why does the marching of long ranks of soldiers appear to be
irregular, 726

Sounds, what are the numbers of vibrations that produce various, 727

Sounds, why does the length of a wire or string influence the sounds it
produces, 728

Sound, why does the tension of a wire or string affect its vibrations,
729

Sound, why are some notes low and solemn, and others high and quick, 730

Sound, why can our voices be heard at a greater distance when we speak
through tubes, 731

Sound, is air a good conductor, 732

Sounds, why can we hear them at a greater distance on water than on
land, 733

LESSON LXVII.

Sound, why do sea-shells give a murmuring noise when held to the ear,
734

Sound, why can people in the arctic regions converse when more than a
mile apart, 735

Sounds, why do savages lay their heads upon the earth to catch sounds,
736

Sounds, why can church clocks be heard striking more plainly at some
times than at others, 737

Sound, why may the scratching of a pin at one end of a long pole be
heard at the opposite extremity, 738

Sound, why is the hearing of deaf persons assisted by ear-trumpets, 739

Sounding-boards, why are they used to improve the hearing of
congregations, 740

Sounds, why, when we are walking under arches or tunnels, do our voices
appear louder, 747

Spark, what causes it when a horse's shoe strikes against a stone, 340

Specific gravity, what is it, 789

Spiders, why have they the power of spinning webs, 1082

Spiders, why may fine weather be expected when they build their webs,
1108

LESSON LXVIII.

Spiders, why may wet weather be expected when they hide, 1109

Spiders, why may wet weather be expected when they break off their webs
and remove them, 1113

Spider, why, if the webs of the gossamer fly about in autumn, may east
winds be expected, 1124

Spiders, gossamer, why can they float through the air, 1125

Spinal cord, what is the, 952

Spinal cord, why is it placed in the back-bone, 953

Spinal-cord, how do the branches pass out from it, 954

Spontaneous combustion, what substances are liable to it, 317

Spontaneous combustion, has it ever occurred in living bodies, 319

Spontaneous combustion, why does it occur in the case of the drunkard,
320

Spoon-bill, why has it a long expanded bill, lined with sharp, muscular
points, 1045

Spoon-bill, why has it long legs, 1046

Squint, why do some people, 967

Starch, what is it, 1202

Star-lit nights, why are they usually colder than cloudy nights, 350

Stars, why do they twinkle, 484

LESSON LXIX.

Stars, why does their twinkling foretell bad weather, 485

Steam, why does it issue from the spout of a kettle, 750

Storms, what is the cause of, 676

Storms, why do the most violent occur in and near the tropics, 677

Straw, why is it frequently used for manure, 1264

"Sucker," why does it raise a stone, 860

Sugar, what is it, 1197

Sugar-cane, where is it cultivated, 1226

Sun, what is its distance from the earth, 452

Sun, what is the, 455

Sun, from what does its luminosity arise, 456

Sun and moon, why do they appear smaller when near the meridian, than
when near the horizon, 525

Sun, why do we see it before sunrise, and after sunset, 482

Sun, what is the magnitude of the, 787

Suppers, why do they cause dreams, 1021

Swallows, why may wet weather be expected when they fly low, 1104

Syringe, why does pressing in the handle force out a jet of water, 856

Syringe, why will not the water run out, unless the handle is pressed
in, 857

LESSON LXX.

Syringe, why will the water leak out, but not run, 858

Syringe, why cannot the handle be pressed in, if a finger is kept on
the orifice, 859

Tannin, what is it, 1257

Taste, why do we, 996

Taste, why are some substances sweet, others sour, &c., 997

Taste, why is it most powerful after substances have been a little
while in the mouth, 998

Taste, why if we put out the tongue and touch it with a nub of sugar,
shall we perceive no taste, 999

Taste, why when we draw in the tongue do we then perceive the taste of
the sugar, 1000

Taste, through what nerves are we made sensible of the contact of sugar
with the tip of the tongue, 1001

Taste, why do connoisseurs of wines hold wine in their mouths a few
seconds when judging of it, 1002

Taste, why do they also pass the fumes of the wine through their
nostrils, 1003

Tea-pot, why does a bright metal one produce better tea than a black
earthenware, 200

LESSON LXXI.

Tea-pot, if the earthenware one were set by the fire, why would it then
make the best tea, 201

Tea, what is it, 1192

Tea, where is it cultivated, 1225

Tears, what is the cause of, 977

Temperature, why do some articles feel colder than others, 138

Temperature, why does it feel warmer after a frost has set in, 163

Tendons, what are they, 939

Tendons, why are they used to attach the muscles to the bones, 940

Teneriffe, what are the botanical regions of the Peak of, 1241

Thaumatrope, why do the figures on appear to dance, 869

Thaw, why is it colder when a thaw takes place, 164

Thermometer, what is the, 709

Thermometer, why does it indicate degrees of heat, 710

Thermometer, why are there Reaumur's and Fahrenheit's, 711

Thermometer and barometer, what is the difference, 712

Thermometer, in what season of the year does it vary most, 715

Thunder, what is it, 614

Thunder-peal, why is it sometimes loud and continuous, 616

LESSON LXXII.

Thunder-peal, why is it sometimes broken and unequal, 617

Thunder-peal, why is it sometimes a low, grumbling noise, 618

Thunder-peal, why does it sometimes follow immediately after the flash
of lightning, 620

Thunder, through what distance will the sound travel, 621

Thunderbolt, what is a, 628

Tinder-box, the history of a, 340

Toasting-fork, why has it a wooden handle, 124

Tops, why do they stand erect while they spin, but fall when they stop,
814

Tops, why do they "sleep", 816

Tops, why do they cease to spin, 817

Touch, in what part of the body is the sense of most perfect, 1005

Toxicologists, what are they, 61

Trap and ball, why is the ball propelled upward, when the trigger is
struck, 866

Trees, what are the estimated ages of, 1214

Trees, what are the northern limits of, 1237

Trees, why are they covered with bark, 1270

LESSON LXXIII.

Trees, why have those with large trunks a great number of leafy
branches, 1274

Trees, why have poplars comparatively few leaves, 1275

Trees, why had the mammoth comparatively few leaves, 1276

Trees, why have oaks an abundance of leaves, 1277

Trees, why are their trunks generally round, 1278

Twilight, what is the cause of, 482

Vacuum, what is a, 649

Vacuum, is it possible to obtain a perfect, 650

Vegetables, have they any heat, 90

Vegetable structures, of what do they consist, 1151

Vegetables, why do farmers sow different crops in rotation, 1164

Vegetables, why are the hearts of cabbages, &c., pale yellow, 1182

Vegetable productions, why are they so widely diffused, 1189

Vegetable eaters, why do they feed so continually, 1091

Vegetation, geographical distribution of, 1208

Vegetation, what are the characteristics of tropical, 1218

Vegetation, what are the changes in on quitting the tropics, 1232

LESSON LXXIV.

Vegetation, what are the characteristics of, upon approaching the polar
zones, 1234

Vegetation, what are the characteristics of mountain, 1238

Vines, where are their favourable climates, 1233

Walking, why does it make us warmer, 26

Water, what becomes of that formed by combustion, 58

Water, is it a good or bad conductor of heat, 151

Water, why does it extinguish fire, 306

Water, why, when a blacksmith thrusts a hot iron into a tank, do we
perceive a peculiar smell, 309

Water, why does it freeze, 324

Water, why does it become steam, 326

Water, how many degrees of latent heat are hidden in its several
states, 327

Water, why does it expand when freezing, while bodies generally
contract with cold and expand with heat, 341

Water, why does it never freeze to a great depth, 342

Water, how much deeper is it than it appears to be, 480

LESSON LXXV.

Water, why has the exceptional law, by which it expands when freezing,
been ordained, 343

Water, why can we seldom succeed in the first attempt to touch anything
lying at the bottom of, 481

Water, what causes it to flow from a pump, 651

Water, why does it run through a syphon, 655

Water, what is it, 748

Water, why does it become solid when it freezes, 751

Water, why does it boil, 753

Water, what proportion of the earth's surface is covered by it, 554

Water, why does it dissolve substances, 758

Water, why does hot dissolve more readily than cold, 759

Water, why is it sometimes hard, 760

Water, why is rain-water soft, 761

Water, why is it difficult to wash in hard, 763

Waters, why are some impregnated with mineral matters, 767

Water, why does stagnant become putrid, 769

Water, is there danger attending drinking it on account of animalculæ,
770

Water, what are the means by which it may be purified, 771

LESSON LXXVI.

Water, what is the pressure of, 775

Water, why will a drop upon the blade of a knife leave a dark spot, 777

Water, why does it roll in agitated globules when dropped upon hot
iron, 796

Water, why does oil float upon it, 797

Water, why is spring fresh and invigorating, 803

Water, why is boiled flat and insipid, 804

Weather, why does a yellow sunset foretell wet, 534

Weather, why does a red sunset foretell fine, 535

Weather, why does a red sunrise foretell wet, 536

Weather, why does a grey sunrise foretell dry, 537

Weather, barometrical indications of, 708

Whales, why have they a large development of oily matter about their
heads, 1068

Whale, why has it feathery bones extending from its jaws, 1095

Whales, why are, their eyes provided with very thick coats, 1131

Wheat, why do the ears stand up by day and turn down by night, 1175

Wheat, what is it, 1199

LESSON LXXVII.

Wheat, what is the northern limit of, 1235

Wheat, why is silica diffused over its stem, 1261

Wheat-crops, why do they greatly exhaust the soil, 1263

Whirlwinds, what are they, 678

Why do we see, 963

Why do we wink, 975

Why do we weep, 977

Why do we hear, 983

Why do we taste, 986

Why do we smell, 992

Why do we feel, 1004

Why do we sleep, 1019

Why do we dream, 1020

Why do suppers produce dreaming, 1021

Why do we yawn, 1022

Why do we cough, 1023

Why do we sneeze, 1024

Why do we sigh, 1025

Why do we laugh, 1026

Why do we hiccough, 1027

Why do we snore, 1028

Why do we feel hungry, 1337

Why do we feel thirsty, 1338

Wick of a candle, why does it turn black as it burns, 225

Wick of a candle, why is there a spark generally at the end of it, 256

Will-o'-the-wisp, what is it, 318

Winds, what is the cause of, 234

Winds, why are east usually dry, 384

Winds, why are west usually wet, 385

Winds, why are north usually cold and dry, 386

LESSON LXXVIII.

Winds, why are south warm and rainy, 387

Wind, what is it, 666

Winds, what are the velocities of, 667

Winds, what are trade, 668

Winds, what is the cause of trade, 669

Winds, why do trade winds blow from east to west, 670

Winds, what determines the character of, 674

Wind-mills, why do their wings turn round, 690

Windows, why do they reflect the sun's rays in the evening, 523

Windows, why do they not reflect the sun's rays at noon, 524

Wood, why does decayed look luminous, 95

Wood, burning at one end, why does it not feel hot at the other, 118

Wood, why is it a bad conductor of heat, 119

Wood that is green, why does it hiss and steam when burning, 285

Wood, why does it ignite less readily than paper, 297

Woodcocks and snipes, why have they nerves running down to the tip of
their bills, 1043

Woodpeckers, why do they "tap" at old trees, 1066

Woollens, why are they worn in winter, 166

Wool, what is it, 1201

Yawn, why do we, 1026

Zoological geography, 1326

[Verse: "God looked down from heaven upon the children of men, to see if there were any that did understand that did see God."--PSALM LIII.]

THE REASON WHY.