Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1883 Excerpt: ...air in the room, of course," replied Charlie. "Ah, now I see what you mean; the colder air rushes in to the wanner. But why does it?" ""When air is warmed, it expands, becomes lighter, and is forced upward by the colder and heavier air around it. "A few weeks ago I bought you a red balloon. Do you. remember that when you held it near the fire, it swelled out, and became larger and tighter, until it burst? "When the sun' shines, it warms the ground. The air above that ground also becomes wanner and lighter, and is pushed upward by colder air flowing from where the sun is not shining. You know that after sunset, when it becomes dark, it also becomes colder. "Just as the air is always coming through the keyhole into a room warmed by fire. so a breeze, coming from cooler regions, is always moving to places where the air is warmed. Change from heat to cold, then, makes air move--that is, causes wind. "When air takes up much dampness it also becomes lighter than dry air. So both dampness and drought cause wind. If air did not move freely, we could not live. We must have fresh air for every breath. Air once breathed is unfit to breathe again." While Charlie and his father were talking Vbout wind, they were walking up the hill behind the cottage. On reaching the top, they sat down to rest awhile. The wind blew softly in their-faces. Overhead, clouds were scudding quickly along, but moving in a different direction from the wind which fanned their cheeks. Seeing this, the little boy touched his father's arm, and pointed upward. "I am glad you notice that," said his father; "the upper and the lower air do not always move the same way at the same time. Those clouds are not more than two miles above our he...
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