Book IV chapter 3

The variation in any one place is constant.

Inclination⁶ of a versorium toward a second magnet." alt="Inclination of a versorium toward a second magnet." src="https://ebooks.adelaide.edu.au/g/gilbert/william/on-the-magnet/figures/illo145.jpg" />
 

unless there should be a great dissolution of a continent and a subsidence of the land such as there was of the region Atlantis of which Plato and the ancients tell, the variation will continue perpetually immutable¹; the arc of the variation remains² the same in the same place or region, whether it be at sea or on land, as in times past a magnetick body has declined toward the East or the West. The constancy of the variation and the pointing of the versorium to a definite point on the horizon in individual regions is demonstrated by a small versorium placed over a terrella the surface of which is uneven³: for it always deviates⁴ from the meridian⁵ by an equal arc. It is also shown by the inclination of a versorium toward a second magnet; although in reality it is by the turning power of the whole, whether in the earth or in a terrella. Place upon a plane a versorium whose cusp is directed toward the north A: place beside it a loadstone, B, at such a distance that the versorium may turn aside toward B to the point C, and not beyond. Then move the needle of the versorium as often as you will (the box and the loadstone not being moved), and it will certainly always return to the point C. In the same manner, if you placed the stone so that it may be truly directed toward E, the cusp always reverts⁷ to E, and not to any other point of the compass. Accordingly, from the position of the land and from the distinctive⁸ nature of the highest parts of the earth (certain terrene and more magnetick eminences⁹ of the regions prevailing), the variation indeed becomes definite in one and the same place, but diverse and unæqual from a change of place, since the true and polar direction originating in the whole terrestrial globe is diverted somewhat toward certain stronger eminences on the broken surface.

1 immutable   

adj.不可改变的，永恒的

参考例句：

• Nothing in the world is immutable.世界没有一成不变的东西。
• They free our minds from considering our world as fixed and immutable.它们改变着人们将世界看作是永恒不变的观点。

2 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。

3 uneven   

adj.不平坦的，不规则的，不均匀的

参考例句：

• The sidewalk is very uneven—be careful where you walk.这人行道凹凸不平—走路时请小心。
• The country was noted for its uneven distribution of land resources.这个国家以土地资源分布不均匀出名。

4 deviates   

v.偏离，越轨( deviate的第三人称单数 )

参考例句：

• The boy's behavior deviates from the usual pattern. 这个男孩子的举止与一般人不同。 来自《简明英汉词典》
• The limit occurs when the ordinate deviates appreciably from unity. 这个限度发生在纵坐标明显地从单位1偏离的时候。 来自辞典例句

5 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。

6 inclination   

n.倾斜；点头；弯腰；斜坡；倾度；倾向；爱好

参考例句：

• She greeted us with a slight inclination of the head.她微微点头向我们致意。
• I did not feel the slightest inclination to hurry.我没有丝毫着急的意思。

7 reverts   

恢复( revert的第三人称单数 )； 重提； 回到…上； 归还

参考例句：

• The mind reverts to the earliest days of colonial history. 我们回想到早期的殖民地历史。
• Macau reverts to Chinese sovereignty at midnight on December19. 澳门主权于十二月十九日零时回归中国。

8 distinctive   

adj.特别的，有特色的，与众不同的

参考例句：

• She has a very distinctive way of walking.她走路的样子与别人很不相同。
• This bird has several distinctive features.这个鸟具有几种突出的特征。

9 eminences   

卓越( eminence的名词复数 )； 著名； 高地； 山丘

参考例句：

• Both are truly grey eminences who have become accustomed to the exercise of influence. 两个人都是真正的幕后操纵者，他们已习惯于用其影响进行幕后操纵。