Book I chapter 13

Chap. xiii.

Wrought¹ iron has in itself certain parts Boreal and Austral: A magnetick vigour², verticity, and determinate vertices, or poles.

I ron settles itself toward the North and South; not with one and the same point toward this pole or that: for one end of the piece of ore itself and one extremity³ also of a wrought-iron wire have a sure and constant destination to the North, the other to the South, whether the iron hang in the air, or float on water, be the iron large rods or thinner wires. Even if it be a little rod, or a wire ten or twenty or more ells in length; one end as a rule is Boreal, the other Austral. If you cut off part of that wire, and if the end of that divided part were Boreal, the other end (which was joined to it) will be Austral. Thus if you divide it into several parts, before making an experiment on the surface of water, you can recognize the vertex86. In all of them a Boreal end draws an Austral and repels⁴ a Boreal, and contrariwise, according to the laws magnetical. Yet herein wrought iron differs from the loadstone and from its own ore, inasmuch as in an iron ball of any size, such as those used for artillery⁵ or cannon⁶, or bullets used for carbines or fowling-pieces, verticity is harder to acquire and is less apparent than in a piece of loadstone, or of ore itself, or than in a round loadstone. But in long and extended pieces of iron a power is at once discerned; the causes of which fact, and the methods by which it acquires its verticity and its poles without use of a loadstone, as well as the reasons for all the other obscure features of verticity, we shall set forth⁷ in describing the motion of direction.

1 wrought   

v.引起；以…原料制作；运转；adj.制造的

参考例句：

• Events in Paris wrought a change in British opinion towards France and Germany.巴黎发生的事件改变了英国对法国和德国的看法。
• It's a walking stick with a gold head wrought in the form of a flower.那是一个金质花形包头的拐杖。

2 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。

3 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？

4 repels   

v.击退( repel的第三人称单数 )；使厌恶；排斥；推开

参考例句：

• His manner repels me. 他的举止让我厌恶。 来自《简明英汉词典》
• Her callous attitude repels me. 她冷酷无情的态度引起我的反感。 来自《简明英汉词典》

5 artillery   

n.(军)火炮，大炮；炮兵(部队)

参考例句：

• This is a heavy artillery piece.这是一门重炮。
• The artillery has more firepower than the infantry.炮兵火力比步兵大。

6 cannon   

n.大炮，火炮；飞机上的机关炮

参考例句：

• The soldiers fired the cannon.士兵们开炮。
• The cannon thundered in the hills.大炮在山间轰鸣。

7 forth   

adv.向前；向外，往外

参考例句：

• The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
• He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。