MAPS AND ILLUSTRATIONS xvii 



PAGE 



Sewage Disposal Bed, Solids 449 



Sewage Disposal, Liquids 450 



A Primitive Washing Scene in Mexico 451 



A Disease-bearing Mosquito ........ 452 



Amoeba Dividing 453 



A " Malarial " Swamp . ... 453 



House Fly . . . 454 



Bacteria Colonies . . . . 455 



Man's First War Machine 459 



Hand Grenade Throwing 460 



Battle "Tank" . . ........ . . .460 



Spinning Wheel 461 



Indian Weaving . . '_ 462 



Familiar Applications of the Lever . 463 



Grinding Corn, Scotch Highlands . . 464 



The Lever, as Used by the Romans for Weighing . . . . 465 



Combination of Pulleys Used to Lift Heavy Burden . . . 467 



Inclined Railv/ay, Switzerland 468 



Use of the Wedge 'v ,. , . . ..... 469 



An Ancient Sail Boat ,. 470 



A Simple Water Wheel Used for Grinding Corn .... 471 



Electric Power Plant at Niagara 473 



A Flash of Lightning 482 



A Tree Completely Shattered by a Stroke of Lightning . . . 483 



Electric Iron Showing Heating Element . . . . . . 486 



Tungsten Lamp . . . . 487 



Simple Apparatus for Electroplating . 488 



An Electrotype 489 



Electromagnetic Crane . . . 491 



Wireless Telegraph Station, Los Angeles 494 



Telephone Station in the Trenches during the World War . . 496 



Dynamo . . . . 497 



Power Plant and Dam of the Montana Power Company . . . 498 



Electric Locomotive \ t . . . . . ' 499 



San Miguel Harbor in the Azpres 502 



An Hawaiian Crater ; ..'.... . . 503 



Vesuvius and Naples . . * . - .... 505 



Mount Pelee and the Ruins of St. Pierre 507 



Lava Flow in the Hawaiian Islands 508 



Mount Lassen in Eruption . . . . . ... . . 509 



The City of St. Helena .. .' . . . . . 510 



Giant Geyser in Eruption ...... 511 



Fault Line of an Earthquake . . . . .... 513 



