仰仪

仰仪是中国古代的一种天文观测仪器，由元朝天文学家郭守敬设计制造。

An ancient astronomic instrument for observation ， the projection semi-sphere was a creation by Guo Shoujing ， an astronomer of the Yuan Dy-nasty .

仰仪是采用直接投影方法的观测仪器，非常直观、方便。例如，当太阳光透过中心小孔时，在仰仪的内部球面上就会投影出太阳的映像，观测者便可以从网格中直接读出太阳的位置了。

Employing projection ， the instrument is simple and convenient for observation.For example ， when the sun-light goes through the hole ， it will project the image of the sun onto the internal spherical surface.Then the observer can read the sun 's position from the grids .

尤其在日全食时，利用仰仪能清楚地观看日食的全过程，连同每一个时刻，日面亏损的位置、大小都能比较准确地测量出来。因此，仰仪是一种很受古代天文爱好者喜爱的天文观测仪器。

Par-ticularly ， during a total solar eclipse ， the whole process of the solar eclipse can be observed with the instrument . Moreover , both the exact position and size of the e-clipse at different times can also be measured . Therefore ， the projection semi-sphere was greatly loved by astronomy lovers .

仰仪的主体是一只直径约三米的铜质半球面，好像一口仰放着的大锅，因而得名。仰仪的内部球面上，纵横交错地刻划出一些规则网格，用来量度天体的位置。

The main body of the projection sphere is a bronze semi-sphere with a diame-ter of three meters ， like an upturned pot ， hence its name " Yang Yi " ( Upturned Sphere ) . Inside the spherical surface ， there are drawings of many orderly grids that are used for measuring the position of celestial bodies .