The Reason Why. Robert Kemp Philp

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,