O wing to the loadstone being supposed (amongst the crowd of philosophizers) to seize and drag, as it were, magnetick bodies; and since, in truth, sciolists have remarked no other forces than those so oft besung of attractive ones, they therefore deem every motion toward the north and south to be caused by some alluring2 and inviting3 quality. But the Englishman, Robert Norman, first strove to show that it is not caused by attraction: wherefore, as if tending toward hidden principles, he imagined a point respective224, toward which the iron touched by a loadstone would ever turn, not a point attractive; but in this he erred4 greatly, although he effaced5 the former error about attraction. He, however, demonstrates his opinion in this way:
Let there be a round vessel6 filled with water: in the middle of the surface of the water place a slender iron wire on a perfectly7 round cork8, so that it may just float in æquilibrium on the water; let the wire be previously9 touched by a magnet, so that it may more readily show the point of variation, the point D as it were: and let it remain on the surface for some time. It is demonstrable that the wire together with the cork is not moved to the side D of the vessel: which it would do if an attraction came to the iron wire by D: and the cork would be moved out of its place. This assertion of the Englishman, Robert Norman, is plausible10 and appears to do away with attraction because the iron remains11 on the water not moving about, as well in a direction toward the pole itself (if the direction be true) as in a variation or altered direction; and it is moved about its own centre without any transference to the edge of the vessel. But direction does not arise from attraction, but from the disposing and turning power which exists in the whole earth, not in the pole or in some other attracting part of the stone, or in any mass rising above the periphery12 of the true circle so that a variation should occur because of the attraction of that mass. Moreover, it is the directing power of the loadstone and iron and its natural power of turning around the centre which cause the motion of direction, and of conformation, in which is included also the motion of the dip. And the terrestrial pole does not attract as if the terrene force were implanted only in the pole, for the magnetick force exists in the whole, although it predominates and excels at the pole. Wherefore that the cork should rest quiescent13 in the middle and that the iron excited by a loadstone should not be moved toward the side of the vessel are agreeable to and in conformity14 with the magnetick nature, as is demonstrated by a terrella: for an iron spike15 placed on the stone at C clings on at C, and is not pulled further away by the pole A, or by the parts near the pole: hence it persists at D, and takes a direction toward the pole A; nevertheless it clings on at D and dips also at D in virtue16 of that turning power by which it conforms itself to the terrella: of which we will say more in the part On Declination.
1 rotation | |
n.旋转;循环,轮流 | |
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2 alluring | |
adj.吸引人的,迷人的 | |
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3 inviting | |
adj.诱人的,引人注目的 | |
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4 erred | |
犯错误,做错事( err的过去式和过去分词 ) | |
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5 effaced | |
v.擦掉( efface的过去式和过去分词 );抹去;超越;使黯然失色 | |
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6 vessel | |
n.船舶;容器,器皿;管,导管,血管 | |
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7 perfectly | |
adv.完美地,无可非议地,彻底地 | |
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8 cork | |
n.软木,软木塞 | |
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9 previously | |
adv.以前,先前(地) | |
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10 plausible | |
adj.似真实的,似乎有理的,似乎可信的 | |
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11 remains | |
n.剩余物,残留物;遗体,遗迹 | |
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12 periphery | |
n.(圆体的)外面;周围 | |
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13 quiescent | |
adj.静止的,不活动的,寂静的 | |
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14 conformity | |
n.一致,遵从,顺从 | |
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15 spike | |
n.长钉,钉鞋;v.以大钉钉牢,使...失效 | |
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16 virtue | |
n.德行,美德;贞操;优点;功效,效力 | |
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