登封四丈高表与圭表测影

登封四丈高表是元朝郭守敬创制的大型天文仪器,它反映了元初天文观测领域的高超技艺。本文结合相关研究和史料,首先对登封四丈高表的构造进行介绍,同时回顾和探讨其历史和影响；之后对四丈高表测影进行分析,归纳出三个创新点,并在此基础上解释高表表高定为四丈的原因；最后将高表测影置于世界图景下进行比较研究,展示和总结中国古代圭表测影的特性。

Dengfeng 40-chi-high Gnomon and Gnomon Shadow Measurements

Dengfeng 40-chi-high Gnomon is a large astronomical instrument created by Guo Shoujing in the Yuan Dynasty. It reflects the superb skills in the field of astronomical observation in the early Yuan Dynasty. Combined with relevant research and historical data, this paper firstly introduces the structure of Dengfeng 40-chi-high gnomon. And at the same time the history and influence of Dengfeng 40-chi-high gnomon is reviewed. Then, this paper summarizes three innovations of measurements with 40-chi-high gnomon. On this basis, the paper explains the reason why Guo Shoujing set the height of the gnomon at 40 chi. Finally, putting high gnomon measurements under the world picture for comparative study, this paper displays and summarizes the characteristics of gnomon shadow measurements in ancient China.