Door bells, 319-321.

    Drainage, of land, 194, 195.
      sewage, 196, 198, 199, 201.

    Drilled well, 199.

    Drinking water, 75-77.
      in camping, 195-196.
      and rural supplies, 198, 201.

    Driven well, 196-197.

    Drought, 217.

    Drugs, 255, 260.

    Dry cell, 312.

    Dyeing, 244-249.
      color designs, 248.

    Dyeing, direct, 245.
      home, 247.
      indirect, 247.
      variety of color, 247.

    Dyes, 218, 244, 245.

    Dynamo, 346.
      alternating current, 349.
      source of energy, 346-347.

    Ear, in man, 301-303.
      care of, 303.

    Earth, conductor of electricity, 326.

    Echo, 277.

    Economy in buying food, 66-69.

    Effort, muscular, 155, 160.

    Electric, battery, 311.
      bell, 319-321.
      bread toasters, 314.
      conductors and non-conductors, 321-322.
      cost of, energy, 352.
      current, 306, 312.
      flatiron, 313.
      heating pad, 314.
      lights, 314.
      street cars, 337.

    Electricity, heat, 312-315, 339.
      as a magnet, 319, 331-333.
      practical uses of, 312-317.

    Electrodes, of cell, 308.

    Electrolytic metals, 317.

    Electromagnets, 319.

    Electromotive force, 308.
      unit of, 344.

    Electroplating, 315.

    Electrotyping, 317.

    Elements, 102-103.

    Emulsion, 224.

    Energy, conservation of, 58, 59.
      transformations of, 58, 59.

    Engine, steam, 183-185.
      gas, 185-186.
      horse power, 173.

    Erosion, 73-74.

    Essential colors, 139-140.

    Evaporation, 35-39.
      cooling effect, 35-36.
      effect of temperature on, 35, 36.
      effect of air on, 38.
      freezing by, 98.
      heat absorbed, 36.
      of perspiration, 38.

    Expansion, of air, 10, 11.
      cooling effect of, 97.
      disadvantage and advantage of, 11-13.
      of liquids, 9-11.
      of solids, 10, 11.
      of water, 9, 10, 11, 12. 
    Eye, 122-125.
      headache, 124, 125.
      how focused, 122, 123.
      nearsighted and farsighted, 123.
      strain, 125.

    Fahrenheit thermometer, 15.

    Fats, 65.
      in soap making, 223.

    Fermentation, 232-236.
      by yeast, 234-236.

    Ferric compounds, 248.

    Fertilizers, 262-265.
      nitrogen, 262.
      phosphorus, 263, 264.
      potash, 263-265.

    Field magnet, 336.

    Filings, iron, 329.

    Film, photographic, 129.