The Earth |
PART ONE THE NATURAL EARTH The center of gravity of the Earth [1.1] When you study a body, whatever shape it might have, with a scrutinizing mind and eye, you will easily and quickly notice that three features can be observed, namely first its visual outer shape, i.e. its form with all its natural attributes, for example its circumference, its surface extending to all sides and the coloring of this surface; secondly, you will essentially perceive a certain volume that has some diameter in its length, width, and height; and this volume of the body shows, according to its nature, some weight or gravity notably toward a certain direction. [1.2] If, for example, you observe any stone, or any other regular or irregular lump, it will soon become apparent that it's center of gravity is not equally evident on all parts of it; In particular, you can see this most easily with a somewhat misshapen wooden peg by placing it on water, where it will always sink it's center of gravity deepest into the water. This would be the second point, which everyone can easily find with every object. [1.3] The third point of a body is it's real center - which, however, is never to be confused with the center of gravity of a body; and therefore every body has two centers, namely one of gravity and one of it's physical measure. You may also examine bodies of whatever kind, and you will never find that the center of gravity and the center of the body measure coincide completely in one; not even with a perfectly mathematically correct cast metal sphere, and that because absolutely nobody consists of such perfectly equal parts, according to which the center of gravity could coincide with the actual center of the body measure in completely one. [1.4] If, for example, you take pure steel as one of the most solid metal bodies of all metals, break such a steel bar in two, you will easily recognize the crystalline structure at the white fracture, which will appear to the unaided eye to be strikingly uniform; but observed with a microscope, this fracture surface will get an appearance like the sight of one discovering all kinds of larger and smaller elevations from a high mountain below. But if such a difference can be perceived in the crystalline structure of one of the most solid metal bodies, how much greater is such a difference with those far less solid bodies, whose crystalline structure is often easily perceptible to the naked eye between large and small, dense and less dense; and it is therefore all the more perfectly true that the center of gravity and the center of the body-measure can never coincide. |
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