有聲英文閱讀-為什么把地圖畫成北方朝上？

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Why Are Maps Drawn with North at the Top?

Now it is hard to visualize 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 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 front of the pioneers in the field was the Greek mathematician 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 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 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 to orientate 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 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 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 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.

為什么把地圖畫成北方朝上？

現(xiàn)在很難設(shè)想，若繪制地圖不以北方作為地圖的上方。可是過去可并不總是這樣繪制的。
現(xiàn)在已知的被公認為世上最古老的地圖繪制于公元前3800年，這幅地圖描繪的是流經(jīng)伊拉克北部的美索不達米亞平原的幼發(fā)拉底河。這張地圖，以及從這以后繪制的一些地圖，最多也只不過算做是一些局部地區(qū)的很粗略的一些草圖而已；直到很多世紀以后，古希臘人才把繪制地圖這門科學置于堅實合理的基礎(chǔ)之上。
在繪制地圖這一專業(yè)先驅(qū)者當中，處于最前列最古的地位的就是古希臘的數(shù)學家兼哲學家克勞迪o托勒密尤斯，即歷史上廣為人知的托勒密。他，作為古典時期的最后一位偉大的科學家，以當時的知識水平為基礎(chǔ)，而不是憑猜測或想象，是繪制出地圖的第一個人。在這以前更早的時候，巴比倫人曾經(jīng)企圖繪制世界地圖，但是巴比倫人繪制成一個扁平的圓盤形，而不是繪制像托勒密所繪制的球形。
由于那個時代的知識水平有限，所以他把一些情況搞錯了，例如：他對中國和大西洋的看法，遠遠不夠精確。盡管如此，他努力繪制的地圖還是很有用處的。他所繪制的地圖在從那時起的一千多年的時間內(nèi)仍不失為一份重要參考資料。事實上，克里斯托佛o哥倫布在揚帆前去尋找新世界的時候，所用過的就正是托勒密所繪制的地圖版本--這就是造成了哥倫布在航海中產(chǎn)生了一些問題的那個版本。因為托勒密對大西洋的范圍有多大計算錯了。再加上他就不知道還有個太平洋。
托勒密所繪制的地圖有一點是十分重要的，那就是他把北方置于地圖的上方。他之所以要這樣做就是因為他決定以北極星的方向來確定地圖的方位。因為北極星是一盞不動的導(dǎo)航燈，那個時代的航海家們主要依靠北極星來導(dǎo)航。
直到中世紀初期為止基督教會開始嚴重地干涉科學的進步和發(fā)展。在中世紀初期以前一致公認的依然是把北方置于地圖的上方。依照教會的命令，地圖的繪制依然要遵循托勒密的原則原理--但當時耶路撒冷具有中心的特征，因為基督教的信仰認為耶路撒冷是中心，結(jié)果就把東方移成了地圖的上方。
這種地圖通常被叫做"丁"字形地圖，因為這些地圖上只表明了三大洲--歐洲、亞洲和非洲--的情況，這三大洲被地中海和尼羅河所形成的"丁"字隔開了。從航海的觀點看來，這種地圖幾乎是沒有用處的。
隨著貿(mào)易的擴張及越來越依靠羅盤，在14世紀開始出現(xiàn)了更加精確的地圖。北方再一次被擺放到地圖上的正確的位置--地圖的上方。