18-A. 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 forefront 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 Bahylonians 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 work 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 Vole 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.
【課文譯文】
為什麼地圖以北為上
今天，人們難以想像地圖的上方指的不是北方。但過去並不總是這樣的。
現在已知的最古老的被人們認可的地圖是於大約公元前3800年繪製的。地圖描繪的是流經伊拉克美索不達米亞北部的幼發拉底河。這幅地圖以及隨後出現的一些地圖無非都是些區域性地貌的草圖。直到許多世紀以後，古希臘人才把地圖繪製學置於堅實的基礎上。
這一領域的先驅中最早的是希臘數學家和哲學家克勞迪?托勒密(約公元90年～168年)，歷史上多稱他托勒密。作為古典文化藝術時期的最後一位偉大的科學家，他是把地圖繪製建立在當時所有可獲得的知識上，而不是建立在猜想或想像之上的第一人。在這之前，巴比倫人曾試圖繪製世界地圖，但他們把它繪成平盤狀而不是托勒密採用的球體狀。
鑑於當時人們的知識水平，他把一些事情搞錯了。例如，他對中國及大西洋的估計遠不夠精確。儘管如此，這仍是一次有用的嘗試，這幅地圖一千年以來一直作為一種參考。其實，克里斯長弗?哥倫布當時尋找新大陸時就使用該版本——這使他在航海中出了些問題，因為托勒密錯誤地計算了大西洋的面積，而且不知道太平洋的存在。
關於托勒密的.地圖最重要的一點是北方為上方。其原因是他決定以北極星的方向來確定地圖的方向，因為北極星是固定不動的航燈，那時的航海者依賴它進行航行。
在中世紀早期以前，人們一直接受北在上方的佈局。此後，教會嚴重地妨礙了科學的發展。根據教會的命令，地圖仍然按托勒密的原則進行繪製——但當時是以耶路撒冷為中心，因為它被認為是基督徒信仰的中心，所以東方成了地圖的上方。
這些地圖常被稱為“T”形地圖，因為它們只顯示了三個大洲——歐洲、亞洲和非洲——由地中海和尼羅河形成的“T”字形將它們分開，從航海的觀點看，這些地圖幾乎沒什麼用處。
14世紀，隨著貿易的發展以及人們對指南針的日益依賴，出現了更精確的地圖。北方又一次恢復了它在地圖上方的正當位置。
