Every flower, every ray of light, every drop of dew, each flake of snow, the curling smoke, the lowering cloud, the bright sun, the pale moon, the twinkling stars, speak to us in eloquent language of the great Hand that made them. But millions lose the grand lesson which Nature teaches, because they can attach no meaning to what they see or hear.
"THE REASON WHY" is offered as an interpreter of many of Nature's utterances. Great care has been taken that these interpretations may be consistent with the latest knowledge, obtained from the highest sources. If the author finds that his work if accepted for the good of those who seek not only to know, but to _understand_, he will make it his constant care to read the Book of Nature, and to add to the pages of this volume whatever interpretations the progress of enquiry and discovery may demand and supply.
[Pointing hand symbol] _The numbers refer to the Questions. The Index Lessons do not correspond with the Chapters, but are designed to bring together in their alphabetical connection, all the Questions and Answers upon each particular subject included in the work._
Acids, vegetable, whence are they obtained, 1256
Actinism, what effect has it upon vegetation, 559
Actinism, at what season of the year is it most abundant, 560
Air, what is its state after it has been breathed, 13
Air, is that sent from the lungs light or heavy, 14
Air, is it a good or bad conductor of heat, 150
Air, why is a still summer said to be sultry, 171
Air, why does it feel cooler when in motion, than when still, 175
Air, when is it hot enough to destroy life, 179
Air, why is it often excessively hot in chalk districts, 219
Air, is it heated directly by the sun's rays, 221
Air, why does it fly through the doors and windows towards the fire-place, 241
Air, what does the motion of it in our rooms illustrate, 242
Air, why does it become charged with watery vapour, 346
Air, when is it said to be saturated with vapour, 430
Air, what proportion of water is air capable of holding in the form of vapour, 431
Air, what is its weight relative to that of water, 647
Air, which is heavier, dry or vaporised, 697
Air-pistol (or pop-gun), why does pressure applied to the handle propel the cork, 854