Book V chapter 9

Demonstration¹ of direction, or of variation from the true direction, at the same time with declination, by means of only a single motion in water, due to the disposing and rotating virtue².

Fix a slender iron wire of three digits³ length through a round cork⁴, so that the cork may support the iron in water. Let this water be in a good-sized glass vase or bowl. Pare the round cork little by little with a very sharp knife (so that it may remain round), until it will stay motionless one or two digits below the face of the water; and let the wire be evenly balanced. Rub one end of the wire thus prepared on the boreal end of a loadstone and the other on the southern part of the stone (very skilfully⁵, so that the cork may not be moved ever so little from its place) and again place it in the water; then the wire will dip with a circular motion on its own centre below the plane of the horizon, in proportion to the latitude⁶ of the region; and, even while dipping, will also show the point of variation (the true direction being perturbed). Let the loadstone (that with which the iron is rubbed) be a strong one, such as is needed in all experiments on magnetick declination. When the iron, thus put into the water and prepared by means of the loadstone, has settled in the dip, the lower end remains⁷ at the point of variation on the arc of a great circle or magnetick meridian⁸ passing through the Zenith or vertex, and the point of variation on the horizon, and the lowest point of the heavens, which they call the Nadir⁹. This fact is shown by placing a rather long magnetick versorium on one side a little way from the vase. This is a demonstration of a more absolute conformity¹⁰ of a magnetick body with the earth's body as regards unity¹¹; in it is made apparent, in a natural manner, the direction, with its variation, and the declination. But it must be understood that as it is a curious and difficult experiment, so it does not remain long in the middle of the water, but sinks at length to the bottom, when the cork has imbibed¹² too much moisture.

1 demonstration   

n.表明，示范，论证，示威

参考例句：

• His new book is a demonstration of his patriotism.他写的新书是他的爱国精神的证明。
• He gave a demonstration of the new technique then and there.他当场表演了这种新的操作方法。

2 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。

3 digits   

n.数字( digit的名词复数 )；手指，足趾

参考例句：

• The number 1000 contains four digits. 1000是四位数。 来自《简明英汉词典》
• The number 410 contains three digits. 数字 410 中包括三个数目字。 来自《现代英汉综合大词典》

4 cork   

n.软木，软木塞

参考例句：

• We heard the pop of a cork.我们听见瓶塞砰的一声打开。
• Cork is a very buoyant material.软木是极易浮起的材料。

5 skilfully   

adv. (美skillfully)熟练地

参考例句：

• Hall skilfully weaves the historical research into a gripping narrative. 霍尔巧妙地把历史研究揉进了扣人心弦的故事叙述。
• Enthusiasm alone won't do. You've got to work skilfully. 不能光靠傻劲儿，得找窍门。

6 latitude   

n.纬度，行动或言论的自由(范围)，(pl.)地区

参考例句：

• The latitude of the island is 20 degrees south.该岛的纬度是南纬20度。
• The two cities are at approximately the same latitude.这两个城市差不多位于同一纬度上。

7 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。

8 meridian   

adj.子午线的；全盛期的

参考例句：

• All places on the same meridian have the same longitude.在同一子午线上的地方都有相同的经度。
• He is now at the meridian of his intellectual power.他现在正值智力全盛期。

9 nadir   

n.最低点，无底

参考例句：

• This failure was the nadir of her career.这次失败是她事业上的低谷。
• The demand for this product will reach its nadir within two years.对此产品的需求在两年内将达到最低点。

10 conformity   

n.一致，遵从，顺从

参考例句：

• Was his action in conformity with the law?他的行动是否合法？
• The plan was made in conformity with his views.计划仍按他的意见制定。

11 unity   

n.团结，联合，统一；和睦，协调

参考例句：

• When we speak of unity,we do not mean unprincipled peace.所谓团结，并非一团和气。
• We must strengthen our unity in the face of powerful enemies.大敌当前，我们必须加强团结。

12 imbibed   

v.吸收( imbibe的过去式和过去分词 )；喝；吸取；吸气

参考例句：

• They imbibed the local cider before walking home to dinner. 他们在走回家吃饭之前喝了本地的苹果酒。 来自《简明英汉词典》
• Hester Prynne imbibed this spirit. 海丝特 - 白兰汲取了这一精神。 来自英汉文学 - 红字