THE
REASON WHY:
A CAREFUL
COLLECTION OF MANY HUNDREDS OF REASONS FOR THINGS WHICH, THOUGH
GENERALLY BELIEVED, ARE IMPERFECTLY UNDERSTOOD.
A BOOK OF CONDENSED SCIENTIFIC KNOWLEDGE FOR THE MILLION.
By THE AUTHOR OF "INQUIRE WITHIN."
This collection of useful information on "Common Things" is put in
the interesting form of "Why and Because," and comprehends a familiar
explanation of many subjects which occupy a large space in the
philosophy of Nature, relating to air, animals, atmosphere, caloric,
chemistry, ventilation, materia medica, meteorology, acoustics,
electricity, light, zoölogy, etc.
NEW YORK:
DICK & FITZGERALD, PUBLISHERS,
No. 18 ANN STREET.
PREFACE.
We are all children of one Father, whose Works it should be our delight
to study. As the intelligent child, standing by his parent's knee,
asks explanations alike of the most simple phenomena, and of the most
profound problems; so should man, turning to his Creator, continually
ask for knowledge. Not because the profession of letters has, in these
days, become a fashion, and that the man of general proficiency can
best work out his success in worldly pursuits; but because knowledge is
a treasure which gladdens the heart, dignifies the mind, and ennobles
the soul.
The occupation of the mind, by the pursuit of knowledge, is of itself
a good, since it diverts from evil, and by elevating and refining the
mind, and strengthening the judgment, it fortifies us for the hour of
temptation, and surrounds us with barriers which the powers of sin
cannot successfully assail.
It is not contended that the mere acquisition of knowledge will either
ensure a good moral nature, or convey religious truth. But both
religion and morals will find in the diffusion of knowledge a ground
work upon which their loftier temples may discover an acceptable
foundation.
The man who comprehends the order of Nature, and the immutability
of Divine law, must of necessity bring himself in some degree into
accordance with that order, and under submission to the law: hence the
_tendency_ of knowledge will always be found to harmonise the fragment
with the mass, and to subvert the evil to the good.
The troubles of the world have arisen from the want of knowledge,
not from the possession of it. And in proportion as man becomes an
intelligent and reflective being, he will be a better creature in all
the relations of life. If these benefits, vast and incalculable as they
are, be the real tendency and result of knowledge, why is ignorance
allowed to remain, and why is the world still distracted by error?
It is because the moral and intellectual qualities of man are, like all
creations and gifts of God, the subjects of development, whose law is
progression.
We can aid human improvement, but we cannot unduly hasten it. Whenever
man has sprung too rapidly to a conclusion, he has alighted upon error,
and has had to retrace his steps.
The greatest philosophers have been those who have clung to the
demonstrative sciences, and have held that a simple truth well
ascertained, is greater than the grandest theory founded upon
questionable premises. Newton made more scientific revelations to
mankind than any other philosopher; and his discoveries have borne the
searching test of time, because he snatched at nothing, leaped over
no chasm to establish a favourite dogma; but, by the slowest steps,
and by regarding the merest trifles, as well as the highest phenomena,
he learnt to read Nature correctly. He discovered that her atoms were
letters, her blades of grass were words, her phenomena were sentences,
and her complete volume a grand poem, teaching on every page the wisdom
and the power of an Almighty Creator.
When he observed an apple fall to the ground, he asked the "Reason
Why;" and in answer to that enquiry, there came one of the grandest
discoveries that has ever been recorded upon the book of science. With
that discovery a flood of light burst upon the human mind, illustrating
in a far higher degree than had ever previously been conceived, the
vastness of Almighty Power.
Why should not each of us enquire the "Reason Why" regarding everything
that we observe? Why should we mentally _grope_ about, when we may
_see_ our way? When addressed in a foreign tongue, we hear a number
of articulated sounds, to which we can attach no meaning; they convey
nothing to the mind, make no impression upon the in-dwelling soul.
When those sounds are interpreted to us, in a language that we can
understand, they impart impressions of joy, hope, surprise, or sorrow,
because the words convey to us _a meaning_. In like manner, if we fail
to understand Nature, its beauties, its teachings are lost. Everything
speaks to us, but we do not understand the voices. They come murmuring
from the brook, trilling from the bird, or pealing from the thunder;
but though they reach the ear of the body, they do not impress the
listening spirit.
Every flower, every ray of light, every drop of dew, each flake of
snow, the curling smoke, the lowering cloud, the bright sun, the pale
moon, the twinkling stars, speak to us in eloquent language of the
great Hand that made them. But millions lose the grand lesson which
Nature teaches, because they can attach no meaning to what they see or
hear.
"THE REASON WHY" is offered as an interpreter of many of Nature's
utterances. Great care has been taken that these interpretations may
be consistent with the latest knowledge, obtained from the highest
sources. If the author finds that his work if accepted for the good of
those who seek not only to know, but to _understand_, he will make it
his constant care to read the Book of Nature, and to add to the pages
of this volume whatever interpretations the progress of enquiry and
discovery may demand and supply.
INDEX, AND INDEX LESSONS.
[Pointing hand symbol] _The numbers refer to the Questions. The Index
Lessons do not correspond with the Chapters, but are designed to bring
together in their alphabetical connection, all the Questions and
Answers upon each particular subject included in the work._
LESSON I.
Acids, vegetable, whence are they obtained, 1256
Actinism, what is it, 552
Actinism, what effect has it upon vegetation, 559
Actinism, at what season of the year is it most abundant, 560
ærial spectra, what is the cause of, 527
Affinity, what is the attraction of, 777
Air, why do we breathe it, 4
Air, what is the composition of it, 12
Air, what is its state after it has been breathed, 13
Air, is that sent from the lungs light or heavy, 14
Air, is it a good or bad conductor of heat, 150
Air, why is a still summer said to be sultry, 171
Air, why does it feel cooler when in motion, than when still, 175
LESSON II.
Air, when is it hot enough to destroy life, 179
Air, why is it often excessively hot in chalk districts, 219
Air, is it heated directly by the sun's rays, 221
Air, why does it ascend the chimney, 240
Air, why does it fly through the doors and windows towards the
fire-place, 241
Air, what does the motion of it in our rooms illustrate, 242
Air, why does it become charged with watery vapour, 346
Air, when is it said to be saturated with vapour, 430
Air, what proportion of water is air capable of holding in the form of
vapour, 431
Air, what is its weight relative to that of water, 647
LESSON III.
Air, which is heavier, dry or vaporised, 697
Air-pistol (or pop-gun), why does pressure applied to the handle propel
the cork, 854
Air-pistol, why must the handle be drawn out before the cork is placed
in, 855
Air, why does fresh impart a healthy appearance, 915
Albumen, what is it, 899
Alkalies, what are they, 36
Amber, or electrum, what is it, 564
Animals, how is their greater warmth in winter provided for, 168
Animal forms, why are there so many, 1029
Animal furs, why do they become thicker in the winter, 1035
Animals, why have carnivorous, long pointed teeth, 1038
LESSON IV.
Animals with long necks, why have they large throats, 1049
Animals, why cannot flesh-eaters live upon vegetables, 1071
Animals, why can ruminating recover the food from their paunches, 1089
Animals, why can ruminating keep the chewed from the unchewed food in
their stomachs, 1090
Animals, why do the smaller animals breed more abundantly than the
larger ones, 1094
Animals, domestic, why may change of weather be expected when they are
restless, 1107
Animals, plants, and minerals, what are the differences between them,
1140
Animals that graze, why do they crop the tender blades, but leave the
tall grass, 1287
LESSON V.
Animals, distribution of, 1326
Arms and hands, why do we see blue marks upon them, 896
Arms and legs, why does it require the influence of the will to set
them in motion, 917
Arms and legs, why are they made subject to the will, 919
Ascending, what is the cause of bodies, 775
Atmosphere, how is it heated, 232
Atmospheric humidity, why does it sometimes form clouds, at others form
dews, fogs, mists, &c., 409
Atmospheric pressure, how high will it raise water, 652
Atmosphere, what is the, 639
Atmosphere, to what height does it extend, 639
Atmosphere, what is the amount of its pressure, 641
Atmosphere, what is the proportion of watery vapour in the, 642
Atmosphere, why are its upper regions intensely cold, 444
Atmosphere, what is the greatest height ever reached in the, 648
LESSON VI.
Atmospheric pressure, what is the total amount on the earth's surface,
644
Atmosphere, what is the amount of its pressure upon the human body, 645
Atmosphere, why do we not feel its pressure, 646
Atmosphere, to what extent may its pressure vary, 702
Attractive agent, what is an, 76
Attraction, what is it, 772
Attraction, how many kinds are there, 773
Aurora Borealis, what is the cause of, 590
Bananas or plantains, where are they cultivated, 1220
Bark Peruvian, where is it produced, 1228
Barometer, what is a, 691
Barometer, why does it indicate the pressure of the atmosphere, 692
Barometer, why is it also called a "weather-glass", 693
Barometers, why are they constructed with circular dials, 694
Barometer, why does the hand change its position when the mercury rises
or falls, 695
Barometer, why does tapping its face cause the hand to move, 696
Barometer, why does its fall denote the approach of rain, 699
LESSON VII.
Barometer, why does its rise denote the approach of fine weather, 700
Barometer, how does it enable us to calculate the height of the
mountains, 701
Barometer, when does it stand highest, 704
Barometer, when does it stand lowest, 705
Barometer, what effect has heat upon the, 707
Barometer, what effect has cold upon the, 708
Balloons, why do they ascend in air, 830
Balloons, why do air balloons become inflated, 831
Balloons, why do they sometimes burst when they reach a high altitude,
832
Bat and ball, what principles of natural philosophy are illustrated in
the play, 867
Bats, why have they hooked claws in their wings, 1079
Bats, why do they fly by night, 1080
LESSON VIII.
Bats, why do they sleep during winter, 1081
Beds, why should they be raised two feet from the ground, 15
Bed-room windows, why are they sometimes covered with ice crystals, 344
Beer, why will it not run out of a cask until a hole is made at the
top, 660
Beer, why does it get flat, 805
Bees, why have they stings, 1101
Bees, why may we expect fine weather when bees wander far from their
hives, 1114
Beetles, why are they called "coleoptera", 1319
Beetles, why have they hard horny wing-cases, 1320
Beetles, why have many of them hard horns, 1321
Bile, why does it separate nutritious from innutritious matter, 884
Birds, why have water-fowls feathers of a close and smooth
texture, 1033
Birds, why are they covered with feathers, 1030
Birds, why does black down grow under their feathers on the approach of
winter, 1036
Birds, why have they hard beaks, 1040
Birds, why are their beaks generally long and sharp, 1041
Birds, why are their bones hollow, 1050
Birds, why do they lay eggs, 1051
LESSON IX.
Birds, why have those with long legs short tails, 1052
Birds, why have aquatic web-feet, 1059
Birds, why have those that swim and dive short legs, 1060
Birds, why have some deep rough notches on the under surfaces of their
feet, 1061
Birds, why have they gizzards, 1072
Birds of prey, why have they no gizzards, 1084
Birds, why may wet and thunder be expected when they cease to sing, 1121
Birds of passage, why, if they arrive early, may severe weather be
expected, 1121
Birds, geological distribution of, 1326
Birds, tameness of in unfrequented countries, 1327
Birds, why are birds of song not also remarkable as birds of plumage,
1328
Birds, what are the velocities of their flights, 1329
Birds, what is the cause of their migrations, 1330
Black, why should parts of kettles and saucepans be allowed to remain,
204
Blood, in what proportions are the gases found in it, 39
LESSON X.
Blood, what is venous, 41
Blood, what is arterial, 42
Blood, what is the constitution of the, 899
Blood, what quantity does the human body contain, 920
Blood, how frequently does the whole quantity pass through the system,
922
Blowing upon tea, why does it cool it, 174
Bow, why does it propel the arrow, 847
Bow and arrow, what line does the arrow describe, 848
Bow and arrow, what forces tend to arrest the arrow, 849
Bow and arrow, why are there feathers at the ends of arrows, 850
Bones, how many are there in the human body, 923
Bones, of what substances are they composed, 924
Bones, what are the uses of the, 925
Bones, why are those of the back hollowed out, 927
Bones, why are those of the skull arched, 930
Bones, why are those of the skull divided by small sutures, 931
Bones, why are they hollow, 934
LESSON XII.
Bones, why are those of the arms and legs formed into long shafts, 935
Bones, why are those of the feet and hands numerous and small, 936
Botanical geography, 1208
Brain, why is it placed within the skull, 926
Bread-fruit trees, where are they natives of, 1223
Breathing, is it a kind of combustion, 17
Breaths, have people ever been poisoned by their own, 24
Breezes, why are summer said to be cool, 170
Breezes, what is the cause of sea and land, 235
Bubbles, why do they ascend in the air, 236
Bubbles, why do they fall, after having ascended, 237
Bubbles, why do they display rainbow colours, 499
Bubbles, why are they round, 825
Bubbles, why are they elongated when being blown, 826
Bubbles, why do they close, and become perfect spheres when shaken from
the pipe, 827
Bubbles, why do they change their colours in the sunshine, 828
Bubbles, why do they burst, 829
LESSON XI.
Burning or supporting combustion, what is the difference, 45
Burning-glasses, why do they appear to set fire to substances, 80
Butterflies, why do they lay their eggs upon cabbage-leaves, 1099
Butterflies' eggs, why do they lie dormant in the winter, 1288
Butterflies, why do they fly by day, 1296
Calms, why do they prevail at the equator, 671
Caloric, what is it, 72
Caloric, what is the source of it, 73
Caloric, what are the effects of it, 74
Caloric, why is it called a repulsive agent, 75
Caloric, how may it be excited to develope heat, 79
Caloric, is there any in ice, snow, water, marble, &c., 89
Caloric, how do we measure the quantity of in any substance, 329
Caloric, how does it travel, 332
Caloric, how do we know that it is caloric which fuses metals, 334
Calves and lambs, why have they no horns, 1069
Camel, why has its stomach a number of distinct bags, 1065
Candles, why do tallow require snuffing, 264
LESSON XIII.
Candles, why do composite and wax not require snuffing, 265
Candle, what becomes of it after it is burnt, 269
Capillary blood-vessels, why are they found in every part of the
system, 919
Capillary attraction, what is it, 780
Carbonic acid gas, how is it formed, 9
Carbonic acid gas, what becomes of it, 10
Carbonic acid gas, is it heavier or lighter than air, 11
Carbonic acid gas, what are the chief sources of, 16
Carbonic acid gas, what is its effect upon the human system, 21
Carbonic acid gas, what becomes of that formed by combustion, 59
Carbonic acid gas, what proportion is dangerous to life, 60
Carbonic acid, what is it, 798
Carbonic acid, where does it chiefly exist, 799
Carbonic acid, what are its pure states, 800
Carbon, what is it, 18
Carbon, will it produce flame when burnt in oxygen, 106
Carbon and hydrogen, what differences characterise the combustion of,
268
LESSON XIV.
Carbon, what is the purest form of it, 277
Card, why do the images on each side blend while a card is revolving,
846
Caterpillars, why do they appear in the spring, 1289
Caterpillars, why do they eat voraciously, 1290
Caterpillars, why do they pass into the state of the chrysalis, 1291
Caterpillars, why do they become torpid in the chrysalis, 1292
Caterpillars, why do they attach themselves to the leaves of plants
when in the chrysalis, 1294
Cats, &c., why do they see in the dark, 981
Cats' eyes, why are the pupils of nearly closed by day, 982
Cats, &c., why have they whiskers, 1096
Cattle, why if they run round in meadows may thunder be expected, 1122
Ceiling, how did Mr. Sands walk on the, 664
Champagne, why does it effervesce, 806
Champagne, why do bubbles rise from it in two or three columns, 807
Charcoal, why is it dangerous to burn it in rooms, 20
LESSON XV.
Charcoal fires, why do they not give flames, 107
Charcoal, what is it, 275
Charcoal, why does it act as a disinfectant, 809
Chicory, what is it, 1196
Chimney, why does it cease smoking after the fire has been lighted a
little while, 680
Chimney, why does a long one create a better draught than a short one,
681
Chimneys, why do some smoke when windows and doors are closed, 683
Chimneys that stand under elevated objects, why do they smoke, 685
Chimneys, why do sooty smoke, 687
Chimneys, why do they smoke in damp and gusty weather, 688
Chimney, why does it smoke when first lighted, 679
Chocolate, what is it, 1194
Circulation, why are the venous blood and chyle sent to the lungs, 887
Circulation, what is the course of the arterial blood, 888
Circulation, why does the blood impart vitality, 891
LESSON XVI.
Circulation, how do we know the blood is alive, 892
Circulation, why does the blood circulate, 893
Circulation, how is the body renewed by the blood, 894
Circulation, how does the blood return to the lungs after it has
reached the extremities, 895
Circulation, why are the veins more perceptible than the arteries, 897
Circulation, why when we prick the flesh does it bleed, 893
Circulation, what occurs during the, 899
Circulation, what becomes of the matter collected by the blood, 901
Circulation, how is the blood propelled through the arteries, 916
Circulation, why are the capillary vessels capable of receiving the
quantity of blood sent through larger vessels, 917
Cinnamon, where is it produced, 1239
Cleanliness, why does it promote health, 1015
Clothes on fire, why should persons throw themselves down, 252
Clothing, why do some articles feel cold, and others warm, 120
LESSON XVII.
Clothing, are conductors or non-conductors the warmer, 121
Clothing, why are white and light-coloured articles cool, 218
Clothing, why are dark-coloured dresses worn in winter, and light in
summer, 230
Clouds, what are they, 373
Clouds, why do we not see them ascend, 375
Clouds, why are they invisible when they rise, but become visible when
they have ascended, 376
Clouds, why do they not descend to the earth, 377
Clouds, at what altitudes do they fly, 378
Clouds, how many descriptions are there, 379
Clouds, what produces their various shapes, 380
Clouds, what are their dimensions, 381
Clouds, how are they affected by winds, 382
Clouds, what do Cirrus foretell, 389
Clouds, what do Cumulus foretell, 390
Clouds, what do Stratus foretell, 391
Clouds, what do Nimbus foretell, 392
Clouds, what do Cirro-cumulus foretell, 393
Clouds, what do Cirro-stratus foretell, 394
Clouds, what do Cumulo-stratus foretell, 395
LESSON XVIII.
Clouds, why are cloudy days colder than sunny days, 396
Clouds, why are cloudy nights warmer than clear nights, 397
Cloudy days and nights, why are they not always wet, 432
Clouds, why are they white, 531
Clouds, why are they sometimes yellow, 533
Clouds, what develops the electricity in the, 581
Clouds, why do they sometimes move towards each other from opposite
directions, 778
Clouds, why do they gather around mountain tops, 781
Cloves, where are they produced, 1231
Coal, what is it, 271
Coal, why do we know that it is of vegetable origin, 273
Coal, what are the chemical components of, 274
Coals, why do they produce yellow flame, 279
Cockles, why have they stiff muscular tongues, 1087
Cocoa, what is it, 1195
Cocoa, what tree produces it, 1221
Coffee-pot, why has it a wooden handle, 125
LESSON XIX.
Coffee, what is it, 1193
Coffee, where is it cultivated, 1224
Cohesion, what is the attraction of, 776
Coke-fires, why do they not give flames, 107
Coke, what is it, 278
Cold, when is a body said to be, 78
Cold, what is the cause of the sensation, 133
Cold, does it radiate, 207
Colour, why is a substance white, 466
Colour, why is a substance black, 467
Colour, why is a rose red, 468
Colour, why is a lily white, 469
Colour, why is a primrose yellow, 470
Colour, why are there so many varieties of colour and tint in nature,
471
Colours, remarks upon, 501
Combustion, what takes place during, 48
Combustion, how many kinds are there, 93
Conductors of heat, what substances are good, 110
Conductors of heat, why do bad conductors readily ignite, 295
Combustion, what is spontaneous, 311
Combustibles used for lighting, which vitiates the air most, 62
Conduction of heat, what is the, 113
Convection, what is the chief effect of the law of, 243
LESSON XX.
Cork, what is it, 1271
Cork-tree, why does it shed its own bark, 1272
Corns, why when they ache may rain be expected, 1115
Corn, why does the young ear come up enfolded in two leaves, 1167
Cotton, what is it, 1199
Cough, why do we, 1023
Crickets, why do they make a chirping noise, 1123
Cross-bills, why do their mandibles overlap each other, 1136
Cup in a pie, why does it become filled with juice, 631
Cup in a pie, does it prevent the juice from boiling over, 662
Dates, what are they produced by, 1221
Death-watch, why does it make a ticking noise, 1301
Dew, what is it, 345
Dew, what causes the decline of temperature which produces it, 347
Dew, why is there little or none, when the nights are cloudy, 348
Dew, why does it form most abundantly on cloudless nights, 349
Dew, why is there little under the branches of thick foliage, 351
LESSON XXI.
Dew, why is there none formed on windy nights, 352
Dew, why are valleys and low places chiefly subject to it, 353
Dew, what bodies receive little of it, 355
Dew, what bodies receive most of it, 354
Dew, at what period of the night is it chiefly formed, 356
Dew, why is it chiefly formed at that period, 357
Dew, in what parts of the world is the greatest quantity formed, 358
Dew, in what parts of the world is the least quantity formed, 359
Dew, why is it seldom formed at sea, 360
Dew, why is it, when heavy, regarded as a precursor of rain, 361
Dew, what is honey-dew, 364
Dew, why does it lie on the exposed sides of screens of plants, 401
Dew, why does it rest upon the upper surfaces of leaves, 402
Dews, why are cultivated lands more subject to them than those that are
uncultivated, 403
LESSON XXII.
Dew, why does the gravel-walk receive less dew than the grass, 404
Dew, why does little of it form at the base of hedges, walls, and
trees, 406
Dews, why do morning dews and mists usually come together, 407
Dew, what effect have winds upon its formation, 408
Dew, why does it form in round drops upon leaves, 794
Diamond, what causes the brilliant colours of the, 501
Digestion, why does food flow more freely to the stomach during, 879
Digestion, why does excess in eating impair, 880
Digestion, what changes occur to food in the stomach, 881
Digestion, what causes bilious attacks, 882
Digestion, how is the nutritious matter taken from that which is
innutritious, 885
Digestion, what becomes of the nutrition when it enters into the
circulation, 886
Dish-covers, why should they be plain in form, and have bright
surfaces, 203
Dogs, geographical distribution of, 1333
Dream, why do we, 1020
Drowsiness, why is it felt in crowded rooms, 22
LESSON XXIII.
Ducks and geese, why do they dash water over their backs on the
approach of rain, 1105
Ducks and geese, why have they square-pointed bills, 1044
Dyes, vegetable, what are they, 1259
Ear, why is it spread out externally, 984
Ears, why do hairs grow across them, 986
Ear-wig, why is it so called, 986
Ears, why is wax secreted in the, 987
Ears, why do singing noises occur in the, 988
Ears, why do people become deaf, 989
Ears, why do people accustomed to loud noises feel no inconvenience
from them, 990
Ears of animals of prey, why do they bend forward, 1063
Ears of animals of flight, why do they bend backward, 1064
Earth, why is it warmer than air during sunshine, 398
Earth, why is it colder than air after sunset, 399
LESSON XXIV.
Earth, how can man weigh the, 784
Earth, what is the weight of the, 788
Earth-worms, why have they no feet, 1085
Echoes, why do some occur immediately after the sounds, 742
Echoes, why do some occur at a considerable interval after the sound,
743
Echoes, why do some change the tone and quantity of sounds, 744
Echoes, why are there sometimes several to one sound, 745
Echoes, are they caused only by distant objects, 746
Echoes, what are they, 741
Electricity, what is it, 561
Electricity, why is it so called, 562
Electric fluid, why is it so called, 566
Electrics, what substances are, 567
Electricity, what is positive, 568
Electricity, what is negative, 569
Electricity, what is vitreous, 570
Electricity, what is resinous, 570
Electrical phenomena, what produces them, 571
Electricity, how does its equilibrium become disturbed, 572
Electricity, how does it seek to regain its equilibrium, 573
Electricity, what substances are conductors, 574
Electricity, what substances are non-conductors, 575
Electricity, what substances are insulators, 576
LESSON XXV.
Electricity, what is the effect when a current of electricity meets
with an insulator, 577
Electric sparks, what is the cause of, 578
Electricity, why does lightning attend it, 584
Electricity, why does it affect the shape of clouds, 613
Electric storms, why are they more frequent in hot than in cold
weather, 624
Electric storms, why do they frequently occur after dry weather, 625
Electric storms, why do they purify the air, 629
Electricity, what is Voltaic, 636
Electrical attraction, what is it, 778
Elementary body, what is meant by, 19
Element, what is the most abundant in nature, 756
Elephant, why has it a short unbending neck, 1076
Elephant, why has it a trunk, 1077
Elephants' hind legs, why do they bend forward, 1078
Etna, what are the botanical regions of Mount, 1240
Endogenous stems, what are they, 1280
LESSON XXVI.
Endogenous stems, why do they abound in tropical climates, 1281
Endogenous stems, why have they no bark, 1282
Endogenous stems, why do they grow to a great height, 1283
Exogenous stems, what are they, 1279
Exercise, why does it promote health, 1016
Exercise, why does it make us feel warm, 839
Explosions of gas, what is the best method of preventing, 65
Eye-balls, why are they white, 911
Eye-balls, why do they sometimes become blood-shot, 912
Eyes, why are they placed in the sockets of the skull, 929
Eyes, why are we able to move them, 965
Eye, why does the pupil look black, 968
Eye, why is the pupil larger sometimes than at others, 969
Eyes, why have we two, 970
Eyes, why having two, do we see singly, 971
Eyes, why are they provided with eyelids, 972
Eyelids, why are they fringed with eyelashes, 973
Eyes, whence are their humours derived, 976
LESSON XXVII.
Eyes, why do we feel inconvenienced by sudden light, 978
Eyes, why if we look upon a bright object and turn away, are we unable
to see, 979
Eyes, why are we able to see better after a little while, 980
Eyes, why do cats, bats, owls, &c., see in the dark, 981
Eels, why are their eyes covered with a transparent horny coat, 1130
Falling, what is the cause of bodies, 774
Fanning the face, why does it make us feel cooler, 172
Fata morgana, what is the cause of, 527
Fatigue, why do we feel, 1017
Feather, why does it fall to the earth more gradually than a shilling,
791
Features, why do we preserve the same through life, 903
Feel, why do we, 1004
Feeling, why is it impaired when the hands are cold, 1006
Feeling, why do the fingers prick and sting when they again become
warm, 1007
LESSON XXVIII.
Feeling, why do persons whose legs or arms have been amputated, for
some time continue to feel the part that has been removed, 1008
Fibrin, what is it, 899
Fingers, why can we raise them, 943
Fingers, why can we draw them back after they have been raised, 944
Fire, why does it burn more brightly when blown by a bellows, 27
Fire, what is it, 82
Fire, what are its properties, 83
Fire, what elements take part in its maintenance, 84
Fire, how does its combustion begin, 85
Fire-screens, how do they contribute to keep rooms cool, 217
Fire, why is it sometimes put out by blowing it when it is low, 262
Fire, why does poking it cause it to burn more brightly, 287
Fires, why do "blowers" improve the draft of air, 288
Fire, why does it sometimes appear red, and without flame, 283
Fire, what effect has it upon air, 284
Fires, why do charcoal and coke burn without flame, 292
Fires, why are charcoal and coke difficult to light, 293
Fires, a new plan of kindling, 293
LESSON XXIX.
Fires, why in lighting them do we first lay in paper, wood, and coal,
298
Fire, why does a poker laid across the top revive it when dull, 302
Fire-places, why should they be near the ground, 303
Fire, why does the blacksmith sprinkle water upon the coals of his
forge, 308
Fires, what is the best method of conveying air to, 684
Fish, why does putrifying look luminous, 95
Fishes, why have they fins, 1053
Fishes, why are their fins proportionately so much smaller than the
wings of birds, 1054
Fishes, why have they scales, 1055
Fishes, why do they float in streams, with their heads towards the
current, 1056
Fishes, why have they air-bladders, 1057
Fishes, why do not their eyes contract, 1129
Fishes, why have they no eyelids, 1132
Fishes, why have they the power of giving their eye-balls a sudden
motion, 1133
Fishes, why are their tails so much larger than their fins, 1137
Flame, what is it, 96
LESSON XXX.
Flame, what temperature is required to produce it, 101
Flame of a candle, why does the lower part of the flame appear blue, 246
Flame of a candle, why does the middle of the flame look dark, 217
Flame of a candle, why does the upper part produce a bright yellow
light, 248
Flame of a candle, why is there a fringe of pale light around the
flame, 249
Flame of a candle, why does it terminate in a point, 250
Flame of a candle, why does it lengthen when anything is held over it,
251
Flame or spark, why does pressing it put it out, 253
Flame of a candle, why does holding a candle upside down put it out, 257
Flame of a candle, why is it more difficult to blow out the flame of a
candle with a cotton wick than one with a rush wick, 258
Flame of a candle, why does blowing sharply on it put it out, 259
Flame of a candle, why will a gentle puff of air sometimes relight it,
260
LESSON XXXI.
Flame of a candle, why will not a similar puff rekindle a rushlight, 261
Flame of a candle, why will a piece of paper twisted to form an
extinguisher put it out, 263
Flame of a candle, why does it become dim when the wick is loaded with
carbon, 267
Flames of a fire, why do some appear much whiter than others, 280
Flames of a fire, why do some of them appear blue, 282
Flesh, why does it heal when we cut it, 902
Flesh-eaters, why do they satisfy themselves with a rapid meal, 1092
Flesh, why do the marks of deep cuts remain, 905
Flesh, why does that under the nails look red, 907
Flies, how can they walk on the ceiling, 663
Flies, why have they fine hairs growing on the extremities of their
legs, 1102
Flowers, what is the chief cause of the differences of their
temperatures, 227
Flowers, why may wet weather be expected when their perfume is strong,
1103
LESSON XXXII.
Flowers, why, if certain close, may rain be expected, 1116
Flying-top, why does it rise on the air, 843
Flying-top, why does it return to the earth, when its rotations are
expended, 844
Focus, what is a, 81
Fogs, what are they, 365
Fogs, why are certain coasts very liable to them, 366
Fogs, what are dry, 367
Fogs, why do they frequently rise in the morning and fall in the
evening, 371
Fogs, why do they sometimes rest upon a locality for days together, and
then disappear, 372
Food, why do we eat it, 869
Food, why do we eat animal and vegetable, 172
Food, why do we masticate it, 871
Food, how does it descend into the stomach, 875
Food, why do we not feel it being transmitted through the throat, 876
Food, why do we feel uneasy after eating to excess, 877
Food, why do we feel drowsy after eating heartily, 878
Food, why do some portions nourish us, while other portions are
useless, 883
LESSON XXXIII.
Fossil, vegetable, what is it, 272
Friction, why does it produce heat, 321
Friction, why does rubbing two surfaces together attract latent heat,
322
Frost, why is the air warmer during, 163
Frost, what is white, 412
Frost, what is black, 413
Frost, why are black frosts said to last, 414
Fruit, why do gooseberries, plums, &c., taste acid, 1184
Fruit, why do ripe taste sweet, and unripe sour, 1185
Fruits, why are succulent most abundant in tropical climates, 1207
Fruits and vegetables, why do they ripen in succession, 1284
Furs, why are they worn in winter, 166
Galvanism, what is it, 635
Gas, what kind lights our streets, 56
Gas, why does it expand in thin air, 833
Geology, what has been its influence upon botanical geography, 1249
Giraffes, why have they small heads, 1322
Giraffes, why have they long necks, 1323
Giraffes, why have they long and flexible tongues, 1324
LESSON XXXIV.
Giraffes, why are their nostrils narrow and small, and studded with
hairs, 1325
Glass upon a lamp, why does it increase the brilliancy of the light, 266
Glass, why is it transparent, 506
Glass, does transparent reflect any light, 507
Glow-worms, why have they brushes attached to their tails, 1127
Glow-worms, why do they emit light, 1128
Gnats, why are their larvæ and pupæ found in water, 1314
Gnats, why may fine weather be expected if they fly in large numbers,
1110
Grasses, why are they so widely diffused throughout nature, 1166
Grasshoppers, why are they comparatively active in their pupa stages,
1293
Gravitation, what is the attraction of, 774
Guano, why is it a good manure, 1262
Gum resins, what are they, 1255
Gums, vegetable, what are they, 1254
Gunpowder, why does it explode, 808
Gutta-percha, whence is it obtained, 1254
LESSON XXXV.
Hail, what is it, 448
Hail, why is it supposed that the electrical state of the clouds
affects the formation of hail, 449
Hail-storms, why do they usually occur by day, 450
Hairs, why do they grow across the passages of the nostrils, 993
Halo, what is a, 494
Halo, what is the cause of a, 495
Haloes, why are they sometimes large, and at other times small, 496
Haloes, why do they foretell wet weather, 497
Hands, why when we hold them against the candle do we perceive a
crimson colour, 906
Hay-stacks, why do they sometimes take fire spontaneously, 316
Head, why is it set upon the neck, 928
Hearing, why do people engaged in battle frequently lose their, 991
Hearing, death of a dog through noise, 991
Heart, why does it beat without any effort of the will, 948
Heart, why is it placed in the chest of the body, 932
Heart and lungs, why are they enclosed by ribs, 933
Heart, why are its motions made independent of the will, 950
LESSON XXXVI.
Heat, what is it, 71
Heat, what are the properties of, 86
Heat, what is animal, 87
Heat, what is latent, 88
Heat, what is a conductor of, 108
Heat, what is a non-conductor of, 109
Heat, how is it transmitted from one body to another, 119
Heat, what is the radiation of, 114
Heat, what is the reflection of, 115
Heat, what is the absorption of,116
Heat, what is the convection of, 117
Heat, what is the cause of the sensation, 134
Heat, what becomes of that which the hearth-stone receives, 136
Heat, how long does a substance feel hot or cold to the touch, 139
Hearth-rug, and hearth-stone, their relative states of heat, 142
Heat, which are the better conductors, fluids or solids, 146
Heat, why are dense substances the best conductors, 147
Heat, why are fluids bad conductors, 148
Heat, why are woollen fabrics bad conductors, 149
Heat, is air a good or bad conductor, 150
LESSON XXXVII.
Heat, is water a good or a bad conductor, 151
Heat, how do we know that air is not a good conductor, 155
Heat, how do we know that water is not a good conductor, 156
Heat, why are bottles of hot water wrapped in flannel, 158
Heat, why are hot rolls wrapped in flannel, 159
Heat, what is the highest degree that man can bear, 176
Heat, why may man endure a high degree without injury, 178
Heat, why may we believe that the internal heat of the earth does not
arise from terrestrious combustion, 224
Heat, what is the radiation of, 181
Heat, what becomes of that which is radiated, 186
Heat, when does a body radiate it, 184
Heat, does the movement of the air affect the radiation of, 188
Heat, why will not the motion of air disturb the rays of, 190
Heat, what bodies are good radiators of, 192
Heat, what bodies are bad radiators of, 193
Heat, why does water keep hot longer in a bright metal jug, 195
LESSON XXXVIII.
Heat, may it be reflected, 210
Heat, are light or dark-coloured bodies the best reflectors, 211
Heat what bodies are the best reflectors of, 212
Heat, why is that which is reflected less intense than the primary, 214
Heat, can it be reflected in any great intensity, 215
Heat, are good reflectors also good absorbers, 216
Heat of the sun's rays, how is it diffused, 219
Heat, how do we know that it is absorbed by the earth, 222
Heat, do plants absorb it, 225
Heat, how is it diffused through the atmosphere, 232
Heat, how is it diffused through the ocean, 233
Heat, why is it developed during chemical changes, 312
Heat, what are the sources of, 323
Heat, what is the accepted theory of, 328
Heat, what is the point at which it becomes luminous, 545
Heat, what is the relative intensity of primary and reflected, 548
Heat to cold, why does a sudden change bring on illness, 1013
LESSON XXXIX.
Heat of the earth, Humboldt's opinion upon the internal, 1335
Heat of the earth, Hunt's opinion upon the internal, 1336
Hear, why do we, 983
Hiccough, why do we, 1027
Hoar-frost, what is it, 362
Hoar-frost, why does it foretell rain, 363
Hoar-frosts, why are they so frequent, and black-frost so unfrequent,
412
Hogs, why have Indian large tusks turning back towards their eyes, 1068
Hog, why is the under-jaw of the, shorter than the upper-jaw, 1039
Hoop, why does it roll without falling to the ground, 861
Hoop, why does it when falling make several side revolutions, 862
Horses, why have they smaller stomachs proportionately than other
animals, 1097
Horse, why has it no gall-bladder, 1098
Horses, why is the secretion of their eyes thick and glutinous, 1134
Horses and cattle, why do they stretch out their necks, and snuff the
air on the approach of rain, 1106
Horse-chestnut, why is it unfit for food, 1203
Hot, when is a body said to be, 77
LESSON XL.
Hot water, why does it feel hotter in a metal jug than in an
earthenware one, 126
Hot metal, why does it feel hotter than hot wool, 130
Hot metal and hot wool, which would become cold first, 131
Hot and cold bodies, why, when placed near each other, do their
temperatures approximate, 331
Humming-tops, why do we see the figures painted on them before they
spin, but not while they are spinning, 813
Humming-top, why does it make a noise, 810
Hydrogen, what is it, 49
Hydrogen, will it support animal life, 50
Hydrogen, will it support combustion, 51
Hydrogen, why will it explode, 52
Hydrogen, where does it chiefly exist, 54
Hydrogen, how is it obtained from coal, 57
Hydrogen-gas, is an escape of it dangerous to life, 63
Hydrogen-gas, what proportion mixed with air will explode, 64
Hydrogen-gas, does it rise or fall, 66
LESSON XLI.
Hydrogen-gas, what proportion is dangerous if inhaled, 67
Hydrogen-gas, what proportion may be recognised by its smell, 68
Hydrogen-gas, may the use of it be considered dangerous, 70
Hydrogen-gas, what sources of it are there in our dwellings, 69
Hydrogen, why will it burst into flame when coals become heated, 100
Hydrogen, why does hi-carburetted burn with a whiter flame than common
coal-gas, 281
Ice, why are blocks of it wrapped in flannel in summer time, 154
Ice, why does it melt, 325
Ice, why does it occupy more space than water, 752
Ignis fatuus, what is it, 318
Incidence, what is the line of, 519
Incidence, what is the angle of, 521
India-rubber, where is it obtained, 1254
Infants, why have they no teeth, 1070
Insects, why have they a large number of eyes, 1083
Insects, why have they long projections from their heads, 1100
Insects, why do they attach their eggs to leaves, 1295
Insects, why do they multiply so numerously, 1300
LESSON XLII.
Insects, what is a larva, 1302
Insects, what is a pupa, 1303
Insects, what is a chrysalis, 1304
Insects, what is a nymph, 1305
Insects, why do they abound in decaying substances and in putrid
waters, 1313
Insects, why do we see them in tanks of rain-water, 1314
Iron articles, why are they intensely cold in winter, 132
Iron articles, why do they usually feel cool, even when near a fire, 132
Ironing-box, why does the iron sometimes become too large for the box
to receive it, 335
Ironing-box, why does the iron enter it, when partially cooled, 336
Iron, why does it rust when wetted, 768
Jew's-harps, why do they give musical sounds, 851
Jew's-harps, why will they not produce loud sounds unless they are
applied to the mouth, 852
Jew's-harps, why does the alteration of the form of the mouth alter the
sounds, 853
Kangaroos and opossums, why have they pouches in which they carry their
young, 1139
LESSON XLIII.
Kettle-holders, of what use are they, 128
Kettles and saucepans, why should the lids and fronts of be kept
bright, 206
Kettles, why do they become encrusted with stony deposits, 762
Kite, why does it rise in the air, 840
Kite-string, why does it feel hot when running through the hand, 841
Kite, why does running with it cause it to ascend, 812
Knowledge, why should we seek it, 1
Knowledge, why does the possession of it give us power, 2
Knowledge, what are the benefits of, 3
Latent heat, will the abstraction of it reduce the bulk of bodies, 337
Latent heat, how do we know that it exists in air, 339
Laugh, why do we, 1026
Ligaments, what are they, 937
Ligaments, why are they wrapped around the joints, 938
Light, what is it, 451
Leaves, why are they green, 1181
Leaves, why do some turn yellow, 1186
Leaves, why do they fall off in the autumn, 1187
Leaves, how to make skeleton, 1159
LESSON XLIV.
Leaves, why do they turn brown in autumn, 1183
Legs crossed, why do we see the elevated leg move at regular intervals,
918
Light, at what velocity does it travel, 453
Light, how long does it take to travel from the sun to the earth, 454
Light what are the minor sources of, 457
Light, what is a ray of, 458
Light, what is a medium of, 459
Light, what is a beam of, 460
Light, what is a pencil of, 461
Light, what is the radiant point, 462
Light, what is the focus of, 463
Light, what is the constitution of a ray of, 464
Light, why are its rays white, 465
Light, what are the estimated vibrations of, 465
Light, what is the refraction of, 472
Light, is it refracted when it falls upon a surface in a straight line,
473
Light, is the direction in which its rays are best dependent on the
densities of the media, 474
Light, why does a spoon look bent when placed in a basin of water, 477
Light, why do we see the rays of the sun burst through the clouds in
different directions, 478
LESSON XLV.
Light, why is the apparent depth of water always deceptive, 479
Light, why are some substances opaque to it, 511
Light, how do we know that bodies reflect it in every direction, 517
Light, meditation on, 517
Light and heat, what are the differences between, 540
Light and heat, are they combined in the sun's rays, 541
Light and heat, how do we know that they are separate elements, 542
Light and heat, in what respects are they similar, 543
Light and heat, in what respects are they dissimilar, 544
Light, what is polarized, 549
Light, what is the velocity of artificial, 546
Light, at what rate does the light of the stars travel, 547
Light, why does it tarnish silver, 553
Light, why does it affect colours, 554
Light, why can pictures be taken by the sun's rays, 555
Light, when does it scorch plants, 558
Lightning, what is the cause of, 580
Lightning, why does it sometimes become zigzag, 586
Lightning, why is it sometimes forked, 587
LESSON XLVI.
Lightning, why is it sometimes like a lurid sheet, 588
Lightning, when is the flash straight, 587
Lightning, when does the flash appear blue, 591
Lightning, why is it sometimes red, at others blue, yellow, or white,
592
Lightning, does it ever pass from the earth to the clouds, 593
Lightning, does it pass from the clouds to the earth, 594
Lightning, what is the force of, 595
Lightning, why is it dangerous to stand near a tree during a storm, 596
Lightning, why is it dangerous to sit near a fire during a storm, 598
Lightning, why is it dangerous to be near water during a storm, 599
Lightning, are iron houses dangerous, 600
Lightning, why does it seize upon bell wires, &c., 601
Lightning, are umbrellas with steel frames dangerous, 603
Lightning, are iron bedsteads dangerous, 604
Lightning, what is the safest situation during a storm, 606
Lightning-conductors, do they attract electricity, 608
LESSON XLVII.
Lightning-conductors, which is the best metal for, 610
Lightning-conductors, why have they sometimes been found ineffective,
609
Lightning-conductors, why should large buildings have several, 611
Lightning-conductors, why should they have several branches penetrating
the earth, 612
Lightning, through what distance will its light penetrate, 622
Lightning, how may we calculate the distance of a storm, 623
Lightning, why is the flash generally succeeded by heavy rain, 626
Lightning, why is a flash generally followed by a gust of wind, 627
Lime-kilns, why do persons viewed through the hot air of, appear
distorted and tremulous, 483
Limpets, why is it difficult to strike them from rocks, 665
Lips, why are they red, 913
Liver, what effect has it upon the circulation, 901
Looking-glass, why, if you hold one at an angle towards the sun, will
light be thrown in an opposite direction, 208
Loss, is there any such thing in the operations of nature, 270
LESSON XLVIII.
Lungs, why are they placed in the chest of the body, 932
Magnetism, what is it, 633
Magnetic bodies, what are they, 634
Magpie, why is a single one said to foretell bad weather, 1118
Mahogany, what is it, 1190
Mahogany and other woods, why are there curious markings in, 1273
Man, why is he born without a covering, 1034
Man, why has he no external appendage to his mouth, 1037
Marbles, why do they revolve when propelled along the ground, 818
Marbles, why do striped appear to have more stripes when they are
rolling than when at rest, 819
Marbles, why do they rebound when dropped upon the pavement, 820
Marbles, why do they roll furthest upon smooth surfaces, 821
Marbles, how many forces contribute to stop their rolling, 882
Marbles, why do the stripes upon them disappear when they are spinning
rapidly, 823
Marbles, why are the rings upon them most perceptible at the "poles,"
while they are spinning, 824
LESSON XLIX.
Matches, do they ignite spontaneously, 313
Meat, why is it sooner cooked when a tin screen is placed before the
fire, 213
Metal, why does it run like a fluid when melted, 333
Mirrors, why do we see our features therein, 209
Mirrors, why do we see our faces in them, 512
Mirrors, what has the glass of to do with the reflection, 514
Mirrors, why do compound mirrors reflect many images of one object, 515
Mirrors, why do reflections appear as far behind a mirror as the object
reflected stands before it, 518
Mirage, what is the cause of the, 527
Mists, what are they, 368
Mists and fogs, what is the difference between them, 369
Mists end fogs, why do they disappear at sunrise, 370
Mistletoe, why have its berries a thick viscid juice, 1177
Mistletoe, how are its seeds conveyed to the bark of trees, 1178
Moles, why have they hard flat feet, 1074
Mole's fur, why is it glossy and smooth, 1075
LESSON L.
Moles, why are they permanent, 904
Moles, why may rain be expected when they throw up their hills, 1117
Monsoons, what are they, 672
Monsoons, what is the cause of, 673
Mornings, why are they usually clear when frosty, 410
Mother-of-pearl, what causes the rich tints displayed by, 500
Moths, why do they fly by night, 1297
Moths, why are their bodies generally covered with thick down, 1228
Moths, why do they fly against the candle-flame, 1299
Muscles, how many are there in the human body, 941
Muscle, what is the constitution of a, 942
Muscles, what degree of strength do they possess, 945
Muscles, what is the stimulus which sets them in action, 946
Mussels, why have they tendinous cords proceeding from their shells,
1086
Natural phenomena, a world of miniature, 690
Nails, why have we got them at the fingers' ends, 908
Nails, why is there a circular line of whitish colour at the root of
the, 909
LESSON LI.
Nails, why do white spots occur upon the, 916
Needle, why will it float if laid carefully upon water, 795
Nerves, what are they, 951
Nervous system, of what does it consist, 955
Nerve, what is the constitution of a, 956
Nervous fluid, what is the, 957
Nerves, how many kinds are there, 958
Nerves of motion, what are they, 959
Nerves of sensation, what are they, 960
Nerves of special sense, what are, 961
Nerves of sympathy, what are the, 962
Nights, why are they usually cold when clear, 411
Nitrogen, what is it, 33
Nitrogen, where is it found, 34
Nitrogen, could animals live in it, 37
Nitrogen, is it taken into the blood from the air, 40
Nitrogen, will it burn, 44
Nitrogen, what becomes of that which is inhaled, 46
Nitrogen, where does it find a fresh supply of oxygen, 47
Nitrous oxide, why does it excite the system, 38
Non-conductors of heat, what substances are, 111
Nostrils, why are they directed downwards, 994
LESSON LII.
Nose, why is it placed over the mouth, 995
Nutmegs, where are they produced, 1232
Ocean, how is it heated, 233
Oils and fats, what are vegetable, 1204
Oils and fats, animal, why are they found most abundantly in cold
climates, 1205
Oils and fats, vegetable, why are they found most abundantly in hot
countries, 1206
Opium, what is it, 1258
Ostriches, why have they small wings, 1031
Ostriches, why are their feathers soft and downy, 1032
Otters, seals, &c., why have they web-feet, 1062
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.
CHAPTER I.
1. _Why should we seek knowledge?_
Because it assists us to comprehend the _goodness and power of God_.
And it gives us power over the circumstances and associations by which
we are surrounded: the proper exercise of this power will greatly
promote our happiness.
2. _Why does the possession of knowledge enable us to exercise power
over surrounding circumstances?_
Knowledge enables us to understand that, in order to live healthily, we
require to breathe fresh and pure air. It also tells us that animal and
vegetable substances, undergoing decay, poison the air, though we may
not be able to see, or to smell, or otherwise discover the existence
of such poison. Knowing this, we become careful to remove from our
presence all such matters as would tend to corrupt the atmosphere. This
is only one of the countless instances in which knowledge gives us
power over surrounding circumstances.
3. _Name some other instances in which knowledge gives us power._
Knowledge of _Geography_ and of _Navigation_ enables the mariner to
guide his ship across the trackless deep, and to reach the sought-for
port, though he had never before been on its shores.
Knowledge of _Chemistry_ enables us to separate or to combine the
various substances found in nature. Thus we obtain useful and precious
metals from what at first appeared to be useless stones; transparent
glass from pebbles, through which no light could pass; soap from oily
substances; and gas from solid bodies.
[Verse: "Give instruction to a wise man, and he will be yet wiser;
teach a just man, and he will increase in learning."--PROVERBS IX.]
Knowledge of _Medicine_ enables the physician to overcome the ravages
of disease, and to save suffering patients from sinking prematurely to
the grave.
Knowledge of _Anatomy_ and of _Surgery_ enables the surgeon to bind up
dangerous fractures and wounds, and to remove, even from the internal
parts of bodies, ulcers and diseased formations that would otherwise be
fatal to life.
Knowledge of _Mechanics_ enables man to increase his power by the
construction of machines. The steam-ship crossing the ocean in
opposition to wind and tide, the railway locomotive travelling at
60 miles an hour, and the steam-hammer beating blocks of iron into
useful shapes, are evidences of the power which man acquires through a
knowledge of mechanics.
Knowledge of _Electricity_ enables man to stand in comparative safety
amid the awful war of the elements. Lightning, the offspring of
electricity, has a tendency to strike upon lofty objects by which
it may be attracted. By its mighty powers churches or houses may be
instantly levelled with the dust. But man, knowing that electricity
is strongly attracted by particular substances, raises over lofty
buildings rods of steel communicating with bars that descend into the
ground. The lightning, rushing with indescribable force toward the
steeple, is attracted by the bar of steel, and conducted harmlessly to
the earth. Man may thus be said to take even lightning by the hand,
and to divert its destroying force by the aid of Knowledge. And in
countless other instances "Knowledge is Power."