liked. He chose to run it through the Fortunate Islands (now called the Canary & Madeira Islands) off the north-west coast of Africa. Later mapmakers moved the prime meridian to the Azores and to the Cape Verde Islands, as well as to Rome, Copenhagen, Jerusalem, St. Petersburg, Pisa, Paris, and Philadelphia, among other places, before it settled down at last in London. As the world turns, any line drawn from pole to pole may serve as well as any other for a starting line of reference. The placement of the prime meridian is a purely political decision.
然而，托勒密可以随心所欲地铺设他的本初子午线，即零度经线。他选择了穿越非洲西北海岸的幸运群岛(现在叫做加那利和马德拉群岛)。后来，地图绘制者把本初子午线移到亚速尔群岛和佛得角群岛，以及罗马、哥本哈根、耶路撒冷、圣彼得堡、比萨、巴黎和费城等地，最后在伦敦安顿下来。当世界转动时，从一极到另一极所画的任何线都可以作为起点参考线。本初子午线的位置纯粹是一个政治决定。
Here lies the real, hard-core difference between latitude and longitude – beyond the superficial difference in line direction that any child can see: The zero-degree parallel of latitude is fixed by the laws of nature, while the zero-degree meridian of longitude shifts like the sands of time. This difference makes finding latitude child’s play, and turns the determination of longitude, especially at sea, into an adult dilemma – one that stumped the wisest minds of the world for the better part of human history.
这就是经纬度之间真正的、核心的差别——超越了任何孩子都能看到的表面的线向差别:纬度的零度纬线是由自然规律决定的，而经度的零度子午线则像时间的流沙一样移动。这种差异使得寻找经度变成了小孩子的游戏，并将经度的测定，尤其是在海上，变成了成年人的难题——这个难题难倒了世界上最聪明的人，让他们对人类历史的大部分都感到困惑。
Any sailor worth his salt can gauge his latitude well enough by the length of the day, or by the height of the sun or known guide stars above the horizon. Christopher Columbus followed a straight path across the Atlantic when he “sailed the parallel” on his 1492 journey, and the technique would doubtless have carried him to the Indies had not the Americas intervened.
任何称职的水手都能根据一天的长短、太阳的高度或地平线上已知的导航星来判断纬度。1492年，克里斯多弗·哥伦布在“平行航行”时，沿着一条笔直的路线横跨大西洋，如果没有美洲的干涉，这项技术无疑会把他带到印度。
The measurement of longitude meridians, in comparison, is tempered by time. To learn one’s longitude at sea, one needs to know what time it is abroad ship and also the time at the home port or another place of known longitude – at the very same moment. The two clock times enable the navigator to convert the hour difference into a geographical separation. Since the Earth takes 24 hours to complete one full revolution of 360 degrees, one hour marks 1/24 of a spin, or 15 degrees.
相比之下，经度经线的测量是随时间而调整的。要想在海上知道自己的经度，你需要知道国外船只的时间，同时也要知道在本国港口或另一个已知经度的地方的时间——在同一时刻。两个时钟时间允许导航器将小时差转换为地理分隔。由于地球完成一次360度的完整公转需要24小时，所以1小时等于自转1/24，即15度。
And so each hour’s time difference between the ship and the starting point marks a progress of 15 degrees of longitude to the east or west. Every day at sea, when the navigator resets his ship’s clock to local noon when the sun reaches its highest point in the sky, and then consults the home port clock, every hour’s discrepancy between them translates into another 15 degrees of longitude.
因此，船和起点之间每小时的时差标志着东经或西经15度的变化。在海上的每一天，当航海家在太阳到达天空的最高点时，把船上的时钟调到当地的中午，然后再参考母港的时钟，他们之间每小时的偏差就转换成另一个15度的经度。
Those same 15 degrees of longitude also correspond to a distance traveled. At the Equator, where the girth of the Earth is greatest, 15 degrees stretch fully one thousand miles. North or south of that line, however, the mileage value of each degree decreases. One degree of longitude equals four minutes of time the world over, but in terms of distance, one degree shrinks from 68 miles at the Equator to virtually at the Poles.
这些相同的经度15度也对应着走过的距离。在地球周长最大的赤道处，15度的温度可达1000英里。然而，在这条线的北面或南面，每度的里程值都在下降。1度经度相当于世界上4分钟的时间，但就距离而言，1度经度从赤道的68英里缩小到两极。
Precise knowledge of the hour in two different places at once – a longitude prerequisite so easily accessible today from any cheap pair of wristwatches – was utterly unattainable up to and including the era of pendulum clocks. On the deck of a rolling ship, such clocks would slow down, or speed up, or stop running altogether. Normal changes in temperature encountered en route from a cold country of origin to a tropical trade zone thinned or thickened a clock’s lubricating oil and made its metal parts expand or contract with equally disastrous results. A rise or fall in barometric pressure, or the subtle variations in the Earth’s gravity from one latitude to another, could also cause a clock to gain or lose time.
要同时在两个不同的地方精确地掌握时间是完全不可能的，直到钟摆时代也是如此。在一艘滚动的船上，这样的时钟会慢下来，或加速，或完全停止运行。在从一个寒冷的原产国到一个热带贸易区的途中，温度的正常变化使钟表的润滑油变薄或变厚，使钟表的金属部件膨胀或收缩，其后果同样是灾难性的。气压的上升或下降，或地球重力从一个纬度到另一个纬度的微妙变化，也可能导致时钟的增加或减少时间。
For lack of a practical method of determining longitude, every great sea captain in the Age of Exploration became lost at sea despite the best available charts and compasses. From Vasco da Gama to Vasco Nunez de Balboa, from Ferdinand Magellan to Sir Francis Drake – they all got where they were going willy- nilly, by forces attributed to good luck or the grace of God.
由于缺乏测定经度的实用方法，在探险时代，每位伟大的船长都在海上迷失了方向，尽管他们有最好的海图和罗盘。从瓦斯科·达·伽马到瓦斯科·努涅斯·德·巴尔博亚，从费迪南德·麦哲伦到弗朗西斯·德雷克爵士——不管他们是运气好还是上帝的恩惠，他们都毫无把握地到达了目的地。
Unit 8 Active reading (2) / P165 The storm
Wind? Out of all my experience I could not have believed it possible for the wind to blow as it did. There is no describing it. How can one describe a nightmare? It was the same way with that wind. It tore the clothes off our bodies. I say tore them off, and I mean it. I am not asking you to believe it. I am merely telling something that I saw and felt. There are times when I do not believes it myself. I went through it, and that is enough. One could not face that wind and live. It was a monstrous thing, and the most monstrous thing about it was that it increased and continued to increase.
风吗?在我所有的经验中，我不可能相信风会这样吹。没有描述它。怎样才能描述噩梦呢?风也是如此。它把我们身上的衣服撕下来。我说把它们撕了，我是认真的。我不是要你相信。我只是在讲述我所看到和感觉到的东西。有时候我自己都不相信。我经历了，这就够了。一个人不可能在风中生存。这是一种可怕的东西，最可怕的是它在不断地增长。
Imagine countless millions and billions of tons of sand. Imagine this sand tearing along at 90, 100, 120, or any other number of miles per hour. Imagine, further, this sand to be invisible, impalpable, yet to retain all the weight and density of sand. Do all this, and you may get a vague inkling of what that wind was like.
想象一下，有无数的沙子。想象一下，这些沙子以每小时90英里、100英里、120英里或任何其他数英里的速度前进。再想象一下，这些沙子是看不见的，摸不着的，却保留着所有的重量和密度。做所有这些，你可能会得到一个模糊的概念，风是什么样的。
Perhaps sand is not the right comparison. Consider it mud, invisible, impalpable, but heavy as mud. Nay, it goes beyond that. Consider every molecule of air to be a mudbank in itself. Then try to imagine the multitudinous impact of mudbanks. No; it is beyond me. Language may be adequate to express the ordinary conditions of life, but it cannot possibly express any of the conditions of so enormous a blast of wind. It would have been better had I stuck by my original intention of not attempting a description.