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