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- Celestial Ｒuler and Kamal: A Note on the Navigation Instruments of Ancient China and the Arabs
| Jounal : | Studies in the History of Natural Sciences |
| Author : | CHEN Xiaoshan |
| YEAR : | 2018 |
| Vol. : | 37 |
| No. : | 2 |
| Page : | 139-155 |
| Abstract : | In pre-modern times， there were some nautical instruments used by medieval maritime navigators． Chinese used rulers， while Arabs used the kamal． Sailors used these instruments to determine the altitude of circumpolar stars， following which they could sail along the same latitude． This article analyzes and discusses several important problems about these instruments， and demonstrates that the bamboo ruler from the Southern Song Dynasty ship unearthed in Quanzhou in 1974 was not a special navigation tool， and that there is no evidence to show that there were special local celestial navigation tools and measurement units in ancient Chinese navigation． Ｒegarding the purpose of rulers and the kamal as navigation tools， this paper considers their main function to be to record the height of stars rather than to calculate geographical latitude． The different technical principles of rulers and the kamal shows the difference of the scientific and technological traditions between mediaeval China and the Arab world， and reflects the influence of regional differences on practical technology． |