A Catechism of Familiar Things; - Their History, and the Events Which Led to Their Discovery. - With a Short Explanation of Some of the Principal Natural Phenomena. For the Use of Schools and Families. Enlarged and Revised Edition. by Anonymous
page 302 of 365 (82%)
page 302 of 365 (82%)
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path by gravitation.
Do we experience this attraction upon our earth? Yes; because our earth is carried around the sun by it; and, further, the tides show it very clearly. What are the Tides? The ebbing and flowing of the sea, which regularly takes place twice in twenty-four hours. The cause of the tides is the attraction of the sun, but chiefly of the moon, acting on the waters of the ocean. What is Gravity? Gravity is the attraction between the earth and the bodies on the earth, which makes what we call weight of bodies. What do you understand by specific weight or gravity? It means the weight of a body as compared with the weight of an equal bulk of some other body taken as a standard--commonly water. Why do we say that certain metals--as, for example, platina or gold--are heavier than others, say, lead or iron? |
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