The Babylonian astr onomers also observed that the successive vernal (or autumnal) equinoxes follow each other at intervals of a few seconds less than a year. 李贝.西洋科学史.
The time of the rising is now, owing to the precession of the equinoxes, different from what it was then (July 1st). 佚名.神奇的知识之书.
And as a third important factor there is what is called the _precession of the equinoxes_. 赫伯特·乔治·威尔斯.世界史纲.
They calculated the angle of the ecliptic and the precession of the equinoxes. 赫伯特·乔治·威尔斯.世界史纲.