The Reason Why. Robert Kemp Philp

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,