Part 138

=Lightning bugs=, why they produce light, 231

=Lignite=, found in coal mines, 262

=Liner=, of a gun, 54

=Linseed oil=, extraction of, 228 what it is, 227 where it comes from, 227

=Liquid=, definition, 348

=Living=, why do some people live longer, 199 reproduction necessary why, 174 reproduction of, in birds, 179 reproduction of, in fishes, 177

=Loading= machines in powder factory, 50

=Lobsters=, red, what makes them, 245

=Lock=, cylinder (illus.), 492 how a key turns a (illus.), 491 how key changes are provided (illus.), 491 how a spring lock works (illus.), 492 master-keyed cylinder (illus.), 492 what happens when the key is turned? (illus.), 491 what happens when the knob is turned? (illus.), 491

=Locomotives=, boiler of articulate type (illus.), 440 boiler of (illus.), 442 cab of (illus.), 442 cylinders description of, 441 low pressure cylinders of (illus.), 441 electric, newest (illus.), 443 one of the largest (illus.), 440 signal tower, latest (illus.), 444 stoker, automatic (illus.), 443 water tank (illus.), 444

=Lodestone=, what it is, 327

“=Long Bow=,” in Sherwood Forest (illus.), 42

=Loom=, cloth making machine, 86

=Magnet=, breaking iron (illus.), 330 electro (illus.), 326, 328, 335 electric lift (illus.), 326 experiments with, 327 great lifting by (illus.), 330 how made, 335 what makes it lift things? 326 wonders performed by, 326 work it can do (illus.), 328

=Man=, writing, how man learned, 11 counting himself, 19 is he an animal? 180

=Matches=, are they poisonous? 294 first, 292 how made, 293 lucifer (illus.), 292 making by machinery, 293 modern safety (illus.), 292 oxymuriate (illus.), 292 promethean (illus.), 292 what we would do without, 292 when first used (illus.), 292

=Match-lock=, of early firearms, 45

=Melting= of iron, 35

=Men= who made the telephone, 70

=Mercury=, fulminate of, 49

=Merrimac and Monitor=, fight of, 32

=Merry=, why eyes sparkle when, 92

=Messages=, how men learned to send, 412 Indian smoke signals, 412 marathon runner by (illus.), 413 pony telegraph (illus.), 413

=Messenger boy=, how to call a (illus.), 414 the first (illus.), 413

=Metal=, what is a, 265 what is the most valuable? 265 why we use for coining, 456

=Meter=, description of gas, 304 how it measures gas, 304

=Milk=, does thunder sour? 196

=Milky way=, why is it called, 255 what is, 255