Physical Geography

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D. Appleton, 1877 - Physical geography - 119 pages
 

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Page 2 - ... dimmed. The few clouds which were to be seen at first have grown large, and seem evidently gathering together for a storm. And sure enough, ere breakfast is well over, the first ominous big drops are seen falling. You cling to the hope that it is only a shower which will soon be over, and you go on with the preparations for the journey notwithstanding. But the rain shows no symptom of soon ceasing. The big drops come down thicker and faster; little pools of water begin to form in the hollows...
Page 18 - Carbonic acid gas is also one of the invisible substances of the atmosphere, of which, though it forms no more than four parts in every ten thousand, yet it constitutes an important ingredient. You will understand how important it is when you are told that, from this carbonic acid in the air, all the plants which you see growing upon the land extract nearly the whole of their solid substance (see Chemistry Primer, Art.
Page 44 - To realize clearly how this takes place, let us follow a particular drop of water from the time when it sinks into the earth as rain, to the time when, after a long journeying up and down in the bowels of the earth, it once more reaches the surface. It soaks through the soil together with other drops, and joins some feeble trickle, or some more ample flow of water, which works its way through crevices and tunnels of the rocks. It sinks in this way to perhaps a depth of several thousand feet ''V FIG.
Page 109 - Now when you reflect upon these various changes you will see that through the agency of this same internal heat land is preserved upon the face of the earth. If rain and frost, rivers, glaciers, and the sea were to go on wearing down the surface of the land continually without any counterbalancing kind of action, the land would necessarily in the end disappear, and indeed would have disappeared long ago. But owing to the pushing out of some parts of the earth's surface by the movements of the heated...
Page 104 - PRIMERS. the base of the rough red and yellow cliffs which form its sides, lies a pool of some liquid, glowing with a white heat, though covered for the most part with a black crust like that seen on the outside of the mountain during the ascent. From this fiery pool jets of the red-hot liquid are jerked out every now and FIG.
Page 16 - By the motion of rotation, time is divided into days and nights, by that of revolution it is marked off into years. So that in this way the earth is our great time-keeper. THE AIR. I. What the Air is made of. 39. When we begin to look attentively at the world around us, one of the first things to set us thinking is the air. We do not see it, and yet it is present wherever we may go. At one time it blows upon us in a gentle breeze, at another it sweeps along in a fierce storm. What is this air ? 40.
Page 6 - ... snow fall, and the rivers solidly frozen-over, would you be surprised if he showed great astonishment ? If he asked you to tell him what snow is, and why the ground is so hard, and the air so cold, why the streams no longer flow, but have become crusted with ice — could you answer his questions ? And yet these questions relate to very common, everyday things. If you think about them, you will learn, perhaps, that the answers are not quite so easily found as you had imagined. Do not suppose...
Page 4 - You saw that the water was moving along the channel always from the same quarter. And now when the channel is filled with this rolling torrent of dark water, you see that the direction of the current is still the same. Can you tell why this should be ? Again, yesterday the water was clear, to-day it is dark and discoloured. Take a little of this dirtylooking water home with you, and let it stand all night in a glass. To-morrow morning you will find that it is clear, and that a fine layer of mud has...

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