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. 1900 edition. Excerpt: ... the rocks, might have been anticipated by a process of reasoning. It has long been known that the heat of the earth is greater at the bottom of a mine than it is near the surface. Observations made in many regions show that, after a level down to which the temperature is affected by the heat of summer and the ...
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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. 1900 edition. Excerpt: ... the rocks, might have been anticipated by a process of reasoning. It has long been known that the heat of the earth is greater at the bottom of a mine than it is near the surface. Observations made in many regions show that, after a level down to which the temperature is affected by the heat of summer and the cold of winter--a depth of a few feet only in England--the temperature steadily rises to the extent of i F. for every 5o or 6o feet. This proves that the more superficial strata are losing heat which they receive by conduction from strata placed more deeply. The earth is shedding heat into space. Lord Kelvin has calculated the amount of heat which is dissipated yearly, and has estimated the time which has elapsed since the surface of the earth was so hot that all water upon it must have been in the form of steam. This, 1 he says, was the condition of the globe less than loo million I years ago. Lastly, the physicist attacks the problem from quite a different side. Having determined the outside limit of the age of the earth, he turns to the sun and asks, How old is that? How long has the sun been pouring forth the force which keeps plants and animals alive? What is the source of his energy? It cannot come from the same source from which we commonly obtain it, combustion. Had the whole sun been made of coal with an infinite atmosphere of oxygen in which to burn, it would have gone out in a few thousand years. When this fact was recognized it was suggested that the great mass of the sun might attract meteors, fragments of broken-up worlds, which would rush towards it with such velocity as to set free, when they struck it, the energy which the sun disperses as heat. But for the supply of the sun's heat in this way meteors equal in size, in the...
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