有声英文阅读-为什么把地图画成北方朝上？

Why Are Maps Drawn 1 with North at the Top?

     Now it is hard to visualize 2 a map that does not feature north at the top, but this was not always so.
     The oldest known map in the accepted sense of the word was drawn about 3,800 BC, and represents the river Euphrates flowing through northern Mesopotamia, Iraq. This, and others that followed it, were little more than rough sketches 3 of localized features; it was not until many centuries later that the ancient Greeks placed the science of map-making on a sound footing.
     At the fore 4 front of the pioneers in the field was the Greek mathematician 5 and philosopher Claudius Ptolemaeus (c. AD 90~168), more popularly known to history as Ptolemy. The last great scientist of the classical period, he was the first to draw a map that was based on all available knowledge, rather than guess or imagination. Earlier, the Babylonians had attempted to map the world, but they presented it in the form of a flattened 6 disc rather than a sphere, which was the form adopted by Ptolemy.
     Given the state of knowledge of those times, he got things wrong; for example, his estimate of China and the Atlantic Ocean was far from being accurate. Nevertheless, it was a useful effort, and the map remained a word of reference for over a thousand years. In fact, Christopher Columbus used a version of it when he set sail in search of the New World - which caused him some navigational problems, since Ptolemy had calculated wrongly the size of the Atlantic and was unaware 7 that the Pacific Ocean existed.
     The really important thing about Ptolemy's map was that north was at the top. The reason for this was that he decided 8 to orientate 9 the map in the direction of the Pole Star since Polaris was the immovable guiding light in which the voyagers of that era placed their trust.
     North at the top remained the accepted arrangement until the early Middle Ages, when the Church began to interfere 10 seriously with the advance of science. In accordance with the orders of the Church, maps were still produced in accordance with Ptolemy's principles - but now Jerusalem was the central feature, as it was held to be the center of the Christian 11 faith, and east was moved to the top.
     These maps are often called "T" Maps because they show only three continents - Europe, Asia and Africa - separated by the "T" formed by the Mediterranean 12 Sea and the River Nile. From a navigational point of view, they were almost useless.
     More accurate maps began to appear in the 14th century, with the spread of trade and increasing reliance on the compass. Once again, north assumed its rightful place at the top of maps.

为什么把地图画成北方朝上？

     现在很难设想，若绘制地图不以北方作为地图的上方。可是过去可并不总是这样绘制的。
     现在已知的被公认为世上最古老的地图绘制于公元前3800年，这幅地图描绘的是流经伊拉克北部的美索不达米亚平原的幼发拉底河。这张地图，以及从这以后绘制的一些地图，最多也只不过算做是一些局部地区的很粗略的一些草图而已；直到很多世纪以后，古希腊人才把绘制地图这门科学置于坚实合理的基础之上。
     在绘制地图这一专业先驱者当中，处于最前列最古的地位的就是古希腊的数学家兼哲学家克劳迪o托勒密尤斯，即历史上广为人知的托勒密。他，作为古典时期的最后一位伟大的科学家，以当时的知识水平为基础，而不是凭猜测或想象，是绘制出地图的第一个人。在这以前更早的时候，巴比伦人曾经企图绘制世界地图，但是巴比伦人绘制成一个扁平的圆盘形，而不是绘制像托勒密所绘制的球形。
     由于那个时代的知识水平有限，所以他把一些情况搞错了，例如：他对中国和大西洋的看法，远远不够精确。尽管如此，他努力绘制的地图还是很有用处的。他所绘制的地图在从那时起的一千多年的时间内仍不失为一份重要参考资料。事实上，克里斯托佛o哥伦布在扬帆前去寻找新世界的时候，所用过的就正是托勒密所绘制的地图版本--这就是造成了哥伦布在航海中产生了一些问题的那个版本。因为托勒密对大西洋的范围有多大计算错了。再加上他就不知道还有个太平洋。
     托勒密所绘制的地图有一点是十分重要的，那就是他把北方置于地图的上方。他之所以要这样做就是因为他决定以北极星的方向来确定地图的方位。因为北极星是一盏不动的导航灯，那个时代的航海家们主要依靠北极星来导航。
     直到中世纪初期为止基督教会开始严重地干涉科学的进步和发展。在中世纪初期以前一致公认的依然是把北方置于地图的上方。依照教会的命令，地图的绘制依然要遵循托勒密的原则原理--但当时耶路撒冷具有中心的特征，因为基督教的信仰认为耶路撒冷是中心，结果就把东方移成了地图的上方。
     这种地图通常被叫做"丁"字形地图，因为这些地图上只表明了三大洲--欧洲、亚洲和非洲--的情况，这三大洲被地中海和尼罗河所形成的"丁"字隔开了。从航海的观点看来，这种地图几乎是没有用处的。
     随着贸易的扩张及越来越依靠罗盘，在14世纪开始出现了更加精确的地图。北方再一次被摆放到地图上的正确的位置--地图的上方。