Book II Chapter 33

On the Varying Ratio of Strength, and of the Motion of coition, within the orbe of virtue¹.

S hould a very large weight, which at a very small distance is drawn² towards a loadstone, be divided into ever so many equal parts, and should the radius³ of the orbe of magnetick attraction be divided into the same number of parts, the like named parts of the weight will correspond to the intermediate parts of the radius.

The orbe of virtue extends more widely than the orbe of motion of any magnetick; for the magnetick is affected⁴ at its extremity⁵, even if it is not moved with local motion, which effect is produced by the loadstone being brought nearer. A small versorium also is turned when a good distance off, even if at the same distance it would not flow towards the loadstone, though free and disengaged from impediment.

The swiftness of the motion of a magnetick body to a loadstone is dependent on either the power of the loadstone, on its mass, on its shape, on the medium, or on its distance within the magnetick orbe.

A magnetick moves more quickly towards a more powerful stone than towards a sluggish⁶ one in proportion to the strength, and [as appears] by a comparison of the loadstones together. A lesser⁷ mass of iron also is carried more quickly towards a loadstone, just as also one that is a little longer in shape. The swiftness of magnetick motion towards a loadstone is changed by reason of the medium; for bodies are moved more quickly in air than in water, and in clear air than in air that is thick and cloudy.

By reason of the distance, the motion is quicker in the case of bodies near together than when they are far off. At the limits of the orbe of virtue of a terrella a magnetick is moved feebly and slowly. At very short distances close to the terrella the moving impetus⁸ is greatest.

A loadstone which in the outmost part of its orbe of virtue hardly moves a versorium when one foot removed from it, doth, if a long piece of iron is joined to it, attract and repel⁹ the versorium more strongly with its opposite poles when even three feet distant. The result is the same whether the loadstone is armed or unarmed. Let the iron be a suitable piece of the thickness of the little finger.

For the vigour¹⁰ of the loadstone excites verticity in the iron and proceeds in the iron and through the iron much further than it extends through the air.

The vigour proceeds even through several pieces of iron (joined to one another end to end), not so regularly, however, as through one continuous solid.

Dust of steel placed upon paper rises up when a loadstone is moved near above it in a sort of steely hairiness; but if the loadstone is placed below, such a hairiness is likewise raised.

Steel dust (when the pole of a loadstone is placed near) is cemented into one body; but when it desires coition with the loadstone, the mass is split and it rises in conglomerated parts.

But if there is a loadstone beneath the paper, the mass is split in the same way and many portions result, each of which consists of very many parts, and remains¹¹ cemented together, as individual bodies. Whilst the lower parts of these pursue greedily the pole of the loadstone placed directly beneath, even they also are raised up as magnetick wholes, just as a small iron wire of the length of a grain or two grains of barley¹² is raised up, both when the loadstone is moved near both beneath and above.

1 virtue   

n.德行，美德；贞操；优点；功效，效力

参考例句：

• He was considered to be a paragon of virtue.他被认为是品德尽善尽美的典范。
• You need to decorate your mind with virtue.你应该用德行美化心灵。

2 drawn   

v.拖，拉，拔出；adj.憔悴的，紧张的

参考例句：

• All the characters in the story are drawn from life.故事中的所有人物都取材于生活。
• Her gaze was drawn irresistibly to the scene outside.她的目光禁不住被外面的风景所吸引。

3 radius   

n.半径，半径范围；有效航程，范围，界限

参考例句：

• He has visited every shop within a radius of two miles.周围两英里以内的店铺他都去过。
• We are measuring the radius of the circle.我们正在测量圆的半径。

4 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

5 extremity   

n.末端，尽头；尽力；终极；极度

参考例句：

• I hope you will help them in their extremity.我希望你能帮助在穷途末路的他们。
• What shall we do in this extremity?在这种极其困难的情况下我们该怎么办呢？

6 sluggish   

adj.懒惰的，迟钝的，无精打采的

参考例句：

• This humid heat makes you feel rather sluggish.这种湿热的天气使人感到懒洋洋的。
• Circulation is much more sluggish in the feet than in the hands.脚部的循环比手部的循环缓慢得多。

7 lesser   

adj.次要的，较小的；adv.较小地，较少地

参考例句：

• Kept some of the lesser players out.不让那些次要的球员参加联赛。
• She has also been affected,but to a lesser degree.她也受到波及，但程度较轻。

8 impetus   

n.推动，促进，刺激；推动力

参考例句：

• This is the primary impetus behind the economic recovery.这是促使经济复苏的主要动力。
• Her speech gave an impetus to my ideas.她的讲话激发了我的思绪。

9 repel   

v.击退，抵制，拒绝，排斥

参考例句：

• A country must have the will to repel any invader.一个国家得有决心击退任何入侵者。
• Particles with similar electric charges repel each other.电荷同性的分子互相排斥。

10 vigour   

（=vigor）n.智力，体力，精力

参考例句：

• She is full of vigour and enthusiasm.她有热情，有朝气。
• At 40,he was in his prime and full of vigour.他40岁时正年富力强。

11 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

12 barley   

n.大麦，大麦粒

参考例句：

• They looked out across the fields of waving barley.他们朝田里望去,只见大麦随风摇摆。
• He cropped several acres with barley.他种了几英亩大麦。