I n the universe of nature that marvellous provision of its Maker1 should be noticed, whereby the principal bodies are restrained within certain habitations and fenced in, as it were (nature controlling them). For this reason the stars, though they move and advance, are not thrown into confusion. Magnetical rotations2 also arise from a disposing influence, whether in greater and dominating quantity, or in a smaller, and compliant4 quantity, even though it be very small. For the work is not accomplished5 by attraction, but by an incitation6 of each substance, by a motion of agreement toward fixed7 bounds, beyond which no advance is made. For if the versorium dipped by reason of an attractive force, then a terrella made from a very strong magnetick stone would cause the versorium to turn toward itself more than one made out of an average stone, and a piece of iron touched with a vigorous loadstone would dip more. This, however, never happens. Moreover, an iron snout placed on a meridian8 in any latitude9 does not raise a spike10 more toward the perpendicular11 than the stone itself, alone and unarmed; although when thus equipped, it plucks up and raises many greater weights234. But if a loadstone be sharper toward one pole, toward the other blunter, the sharp end or pole allures12 a magnetick needle more strongly, the blunt, thick end makes it rotate more strongly; but an orbicular stone makes it rotate strongly and truly, in accordance with magnetick rules and its globular form. A long stone, on the other hand, extended from pole to pole, moves a versorium toward it irregularly; for in this case the pole of the versorium always looks down on the pole itself. Similarly also, if the loadstone have been made in the shape of a circle, and its poles are on the circumference13, whilst the body of it is plane, not globular, if the plane be brought near a versorium, the versorium does not move with the regular magnetick rotation3, as on a
terrella; but it turns looking always toward the pole of the loadstone, which has its seat on the circumference of the plane. Moreover, if the stone caused the versorium to rotate by attracting it, then in the first degrees of latitude, it would attract the end of a short versorium toward the body itself of the terrella; yet it does not so attract it that they are brought into contact and unite; but the versorium rotates just so far as nature demands, as is clear from this example. For the cusp of a versorium placed in a low latitude does not touch the stone or unite with it, but only inclines toward it. Moreover, when a magnetick body rotates in dipping, the pole of the versorium is not stayed or detained by the pole of the earth or terrella; but it rotates regularly, and does not stop at any point or bound, nor point straight to the pole toward which the centre of the versorium is advancing, unless on the pole itself, and once only between the pole and the æquator; but it dips as it advances, according as the change of position of its centre gives a reason for its inclination14 in accordance with rules magnetical. The declination of a magnetick needle in water also, as demonstrated in the following pages, is a fixed quantity; the magnetick needle does not descend15 to the bottom of the vessel16, but remains17 steady in the middle, rotated on its centre according to its due amount of declination. This would not happen, if the earth or its poles by their attraction drew down the end of the magnetick needle, so that it dipped in this way.
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1 maker | |
n.制造者,制造商 | |
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2 rotations | |
旋转( rotation的名词复数 ); 转动; 轮流; 轮换 | |
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3 rotation | |
n.旋转;循环,轮流 | |
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4 compliant | |
adj.服从的,顺从的 | |
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5 accomplished | |
adj.有才艺的;有造诣的;达到了的 | |
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6 incitation | |
刺激,激励 | |
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7 fixed | |
adj.固定的,不变的,准备好的;(计算机)固定的 | |
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8 meridian | |
adj.子午线的;全盛期的 | |
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9 latitude | |
n.纬度,行动或言论的自由(范围),(pl.)地区 | |
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10 spike | |
n.长钉,钉鞋;v.以大钉钉牢,使...失效 | |
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11 perpendicular | |
adj.垂直的,直立的;n.垂直线,垂直的位置 | |
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12 allures | |
诱引,吸引( allure的第三人称单数 ) | |
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13 circumference | |
n.圆周,周长,圆周线 | |
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14 inclination | |
n.倾斜;点头;弯腰;斜坡;倾度;倾向;爱好 | |
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15 descend | |
vt./vi.传下来,下来,下降 | |
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16 vessel | |
n.船舶;容器,器皿;管,导管,血管 | |
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17 remains | |
n.剩余物,残留物;遗体,遗迹 | |
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