The Reason Why. Robert Kemp Philp

       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