古代中国与古希腊回归年长度测算中若干问题的比较研究

回归年是历法中的一个重要参数。在古代中国和古希腊非常受重视．通过探讨回归年在中国和希腊不同的发展历史．比较了它们发展的异同，认为它们都遵循了测量和计算相结合的测算原则，在测量中都有时间间隔愈长得到的年长愈准．以及日影关于冬至点对称的思想．但它们也有差异：古希腊明确建立了基本的空间几何概念，形成了判断和逻辑严密的论证．比较重视建立一套由观测出发的公理化系统，整套思想方法被近代科学所继承；古代中国比较重视经验和具体细节．关于回归年的测算精度不逊于古希腊。说明其采用的方法和对于晷影的认识是科学的．此外．根据现有资料认为何承天论及的新的回归年值与古希腊的回归年值相等，从而推测它们之间可能存在某种联系．

A comparison study on some problems of the observation and calculation of the Solar year in ancient China and Greece

The Solar year is an important parameter on which was paid much attention in ancient China and Greece. By discussing their various history of the development,based on the observation and the calculation,they thought the accuracy of the Solar year was related to the interval of time and the shadow of the sun symmetrical about the winter solstice. Moreover, the Greek set up the geometrical models and used them to practice, but the Chinese emphasized the experiment and the details of the observation and acquired the nearly same accuracy as the Greek. Furthermore,the length of the Solar year mentioned by He Chengtian was same as one of the Greek,which guess there was a possible relation between them.