明制简仪上地平日晷时间刻线的偏差与地理经度差修正问题的考证

发布时间：2018-07-21 20:40

【摘要】：在著名的明制简仪(现今保存于南京紫金山天文台)上有一架按西法建造的地平日晷。对于此日晷来历,百余年来的大多数学者都认为是清代加上去的。此晷面上的刻线有一个迄今未解的重大疑问:晷盘时间刻线的午正线方向相对于方位盘刻线的子午线北侧为何有着一个向东二度左右的偏离角?文章对这一问题作了多方面的考证,认为:这一偏离角正相应于南京和北京的地理经度之差,是当时的设计制造者有意为之的。由于在整个明代所用的官方标准时间并非北京的地方时间(顺天之数),而是南京的地方时间(应天之数),为了在北京的观测能在此日晷刻线上直接读取相应于南京的地方时时刻,必须作两地经度差的改正。而这一向东二度左右的偏离角,正是相应于南京和北京经度差的改正角。在明代末期,中国天文学家也已经了解了关于地理经度和经度差的某些概念。由此,可以认为该地平日晷最迟在明代末期已经建造于北京了。
[Abstract]:There is a flat sundial built according to Xifa on the famous Ming Dynasty simple instrument (now preserved in Nanjing Zijinshan Observatory). For more than a hundred years most scholars believed that the sundial had been added in the Qing Dynasty. The line on the dial faces has one major question that has not yet been solved: why does the midday line of the dial mark have a deviation angle of about two degrees to the east relative to the northern side of the meridian line of the azimuth dial mark? This paper makes a lot of textual research on this problem, and holds that the deviation angle is corresponding to the difference of the geographical longitude between Nanjing and Beijing, which was deliberately carried out by the designers at that time. Because the official standard time used throughout the Ming Dynasty was not the local time in Beijing (the number of days), but the local time in Nanjing (the number of days to be taken), in order to observe Beijing, it could be read directly from the sundial line in this sundial. The local time in Beijing, A correction must be made to the longitude difference between the two places. This deviation angle, which has always been about two degrees east, is the correction angle corresponding to the longitude difference between Nanjing and Beijing. In the late Ming Dynasty, Chinese astronomers had also known some concepts about geographical longitude and longitude difference. Therefore, it can be assumed that the flat sundial was built in Beijing by the end of Ming Dynasty at the latest.
【作者单位】：中国科学院紫金山天文台;
【基金】：国家自然科学基金(项目编号:11020302)
【分类号】：P111.1

【共引文献】