Book IV chapter 8

On the construction of the common mariners¹' compass225, and on the diversity of the compasses of different nations.



I n a round226 hollow wooden bowl, all the upper part of which is closed with glass, a versorium is placed upon a rather long pin which is fixed³ in the middle. The covering prevents the wind, and the motion of air from any external cause. Through the glass everything within can be discerned. The versorium is circular, consisting of some light material (as card), to the under part of which the magnetick pieces of iron are attached. On the upper part 32 spaces (which are commonly called points) are assigned to the same number of mathematical intervals⁵ in the horizon or winds which are distinguished⁶ by certain marks and by a lily indicating the north. The bowl is suspended in the plane of the horizon in æquilibrium in a brass⁷ ring which also is itself suspended transversely in another ring within a box sufficiently⁸ wide with a leaden weight attached; hence it conforms to the plane of the horizon even though the ship be tossed to and fro by the waves. The iron works are either a pair with their ends united, or else a single one of a nearly oval shape with projecting ends, which does its work more certainly and more quickly. This is to be fitted to the cardboard circle so that the centre of the circle may be in the middle of the magnetick iron. But inasmuch as variation arises horizontally from the point of the meridian⁹ which cuts the horizon at right angles, therefore on account of the variation the makers¹⁰ in different regions and cities mark out the mariners' compass in different ways, and also attach in different ways the magnetick needles to the cardboard circle on which are placed the 32 divisions or points. Hence there are commonly in Europe 4 different constructions and forms. First that of the States on the Mediterranean¹¹ Sea, Sicily, Genoa, and the Republick of Venice. In all these the needles are attached under the rose or lily on the cardboard versorium, so that (where there is no variation) they are directed to the true north and south points. Wherefore the north part marked with the lily always shows exactly the point of variation when the apex¹² itself of the lily on the movable circle, together with the ends of the magnetick wires attached below, rests at the point of variation. Yet another is that of Dantzig, and throughout the Baltic Sea, and the Belgian provinces; in which the iron works fixed below the circle diverge¹³ from the lily ¼ of a rumbe to the east. For navigation to Russia the divergency is ⅔. But the compasses which are made at Seville, Lisbon, Rochelle, Bordeaux, Rouen, and throughout all England have an interval⁴ of ½ a rumbe. From those differences most serious errors have arisen in navigation, and in the marine² science. For as soon as the bearings of maritime¹⁴ places (such as promontories¹⁵, havens¹⁶, islands) have been first found by the aid of the mariners' compass, and the times of sea-tide or high water determined¹⁷ from the position of the moon over this or that point (as they say) of the compass, it must be further inquired in what region or according to the custom of what region that compass was made by which the bearings of those places and the times of the sea-tides were first observed and discovered. For one who should use the British compass and should follow the directions of the marine charts of the Mediterranean Sea would necessarily wander very much out of the straight course. So also he that should use the Italian compass in the British, German, or Baltic Sea, together with marine charts that are made use of in those parts, will often stray from the right way. These different constructions have been made on account of the dissimilar variations, so that they might avoid somewhat serious errors in those parts of the world. But Pedro Nuñez seeks the meridian by the mariners' compass, or versorium (which the Spanish call the needle), without taking account of the variation: and he adduces many geometrical demonstrations¹⁸ which (because of his slight use and experience in matters magnetical) rest on utterly¹⁹ vicious foundations. In the same manner Pedro de Medina, since he did not admit variation, has disfigured his Arte de Navegar with many errors.

1 mariners   

海员，水手（mariner的复数形式）

参考例句：

• Mariners were also able to fix their latitude by using an instrument called astrolabe. 海员们还可使用星盘这种仪器确定纬度。
• The ancient mariners traversed the sea. 古代的海员漂洋过海。

2 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

3 fixed   

adj.固定的，不变的，准备好的；(计算机)固定的

参考例句：

• Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗？
• Once the aim is fixed,we should not change it arbitrarily.目标一旦确定，我们就不应该随意改变。

4 interval   

n.间隔，间距；幕间休息，中场休息

参考例句：

• The interval between the two trees measures 40 feet.这两棵树的间隔是40英尺。
• There was a long interval before he anwsered the telephone.隔了好久他才回了电话。

5 intervals   

n.[军事]间隔( interval的名词复数 )；间隔时间；[数学]区间；（戏剧、电影或音乐会的）幕间休息

参考例句：

• The forecast said there would be sunny intervals and showers. 预报间晴，有阵雨。
• Meetings take place at fortnightly intervals. 每两周开一次会。

6 distinguished   

adj.卓越的，杰出的，著名的

参考例句：

• Elephants are distinguished from other animals by their long noses.大象以其长长的鼻子显示出与其他动物的不同。
• A banquet was given in honor of the distinguished guests.宴会是为了向贵宾们致敬而举行的。

7 brass   

n.黄铜；黄铜器，铜管乐器

参考例句：

• Many of the workers play in the factory's brass band.许多工人都在工厂铜管乐队中演奏。
• Brass is formed by the fusion of copper and zinc.黄铜是通过铜和锌的熔合而成的。

8 sufficiently   

adv.足够地，充分地

参考例句：

• It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。
• The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。

9 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。

10 makers   

n.制造者，制造商（maker的复数形式）

参考例句：

• The makers of the product assured us that there had been no sacrifice of quality. 这一产品的制造商向我们保证说他们没有牺牲质量。
• The makers are about to launch out a new product. 制造商们马上要生产一种新产品。 来自《简明英汉词典》

11 Mediterranean   

adj.地中海的；地中海沿岸的

参考例句：

• The houses are Mediterranean in character.这些房子都属地中海风格。
• Gibraltar is the key to the Mediterranean.直布罗陀是地中海的要冲。

12 apex   

n.顶点，最高点

参考例句：

• He reached the apex of power in the early 1930s.他在三十年代初达到了权力的顶峰。
• His election to the presidency was the apex of his career.当选总统是他一生事业的顶峰。

13 diverge   

v.分叉，分歧，离题，使...岔开，使转向

参考例句：

• This is where our opinions diverge from each other.这就是我们意见产生分歧之处。
• Don't diverge in your speech.发言不要离题。

14 maritime   

adj.海的，海事的，航海的，近海的，沿海的

参考例句：

• Many maritime people are fishermen.许多居于海滨的人是渔夫。
• The temperature change in winter is less in maritime areas.冬季沿海的温差较小。

15 promontories   

n.岬，隆起，海角( promontory的名词复数 )

参考例句：

16 havens   

n.港口，安全地方( haven的名词复数 )v.港口，安全地方( haven的第三人称单数 )

参考例句：

• Your twenty havens would back out at the last minute anyhow. 你那二十个避难所到了最后一分钟也要不认帐。 来自辞典例句
• Using offshore havens to avoid taxes and investor protections. 使用海面的港口避免税和投资者保护。 来自互联网

17 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。

18 demonstrations   

证明( demonstration的名词复数 )； 表明； 表达； 游行示威

参考例句：

• Lectures will be interspersed with practical demonstrations. 讲课中将不时插入实际示范。
• The new military government has banned strikes and demonstrations. 新的军人政府禁止罢工和示威活动。

19 utterly   

adv.完全地，绝对地

参考例句：

• Utterly devoted to the people,he gave his life in saving his patients.他忠于人民，把毕生精力用于挽救患者的生命。
• I was utterly ravished by the way she smiled.她的微笑使我完全陶醉了。