鄭和「過洋牽星圖」及丁得把昔與沙姑馬山地理定位之研究

Study on the Navigation Charts of Zheng-he’s Expedition and Geographical Positioning of Dandi Baxi and Sha-Gu-Ma-San

徐勝一(Sheng-I Hsu) ； 陳有志(Yau-Zhih Chan)

《地理研究叢書 氣候與人文 歷史氣候、鄭和航海、客家文化》 第46號 (2016/03) Pp. 90-108

摘要

600年前鄭和下西洋，帶領龐大船隊從南京龍江闖出發抵達波斯灣的忽魯謨斯。途經數十個國家，除了靠沿岸陸標導航外，在橫跨浩茫險阻的大海時還要靠牽星來過洋。本文藉助《武備志》「自寶船廠開船從龍江關出水直抵外國諸番圖」及其中所附四幅「過洋牽星圖」，作為深入探討的主要根據資料。前者記載從南京到忽魯謀斯沿途航線上的山川地勢與邊沿島嶼及針路；後者則記載船隊從蘇門答臘至忽魯謨斯間，渡橫渡孟加拉灣及阿拉伯海時，所倚靠各方星辰的導航圖。這兩類航海圖，顯示鄭和當年是參合著陸標與天文兩種方式來完成這項遠程的航海任務。本研究欲解決的問題有三：1、為何北辰星與燈籠星是搭對出現的，而兩者仰角和是為15.5 指? 2、指仰角到底等於幾度? 3、長期沒能定位的丁得把昔及沙姑馬山，其究竟為何?根據《順風相送》所載古里牽星仰角指數以及其為11.3°N的確實地理位置，求得當時一指仰角等於1.57°的換算值。藉此結論推估丁得把昔、沙姑馬山、及南巫里洋諸地之緯度，分別為16.40°N、22.6 0°N、及7.20°N。此外，也對鄭和船隊橫渡阿拉伯海兩岸起銷點的「丁得把昔」及「沙姑馬山」進行地輿位置的考釋，因為這兩地之位置在當時的海洋交通上是具有特殊意義的。

關鍵字

鄭和 ； 陸標航海 ； 天文航海 ； 指與角 ； 丁得把昔 ； 沙姑馬山

並列摘要

Zheng-he sailed across Gulf of Bengal and Arabian Sea many times in the early 15th century. Each expedition involved thousands of crewmen and hundreds of ships and visited tens of countries. The fleet took off from Nanjing to Hormuz by means of terrestrial navigation and astronomical navigation. Official records about Zheng-he’s expedition are sparse and meager, the valuable documents used for revealing the secrete of ancient navigation techniques include two types of sea charts as appeared in Wu-Bei-Zhih. The first type named ＂Land mark navigation chart＂ which covers 40 consecutive maps that sketched out the land marks of mountains, rivers, islands, buildings and temples along the sea routes. These maps also recorded the compass direction and the depth of sea floor on the routes from Nanjing to Hormuz, these maps are regarded as terrestrial navigation maps. While the second type named ＂Star map＂ that recorded the star elevation angles as observed at Calicut, Tondavali (Dandi Baxi), Sha-Gu-Ma-San (Mountain Sham), and are regarded as astronomical navigation maps. The major stars used for positioning the ships include Polaris, Gacrux, Vega, Pollux, Procyon, and etc. Research results are summarized as follows: 1. With 3.8° polarization of Polaris in 1433, latitudinal positioning required to observe both Polaris and Gacrux at the time when the sum of the elevation angles is equivalent to 15.5 ‘fingers’. 2. One ‘finger’ elevation is estimated as 1.57° in accordance to the Calicut’s latitude and its star observing record. 3. Places of Dandi Baxi, Sa-Gu-Ma-San, and Nan-Wu-Li-Yang are located at 16.4°N, 22.6°N, and 7.2°N respectively.

並列關鍵字

Zheng-he ； land mark navigation ； astronomical navigation ； sea charts

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