Book II chapter 9

On the Æquinoctial Circle of the Earth and of a Terrella.

As conceived by astronomers¹ the æquinoctial circle is equidistant from both poles, cutting the world in the middle, measures the motions of their primum mobile or tenth sphere, and is named the zone of the primum mobile. It is called æquinoctial, because when the sun stands in it (which must happen twice in the year) the days are equal to the nights. That circle is also spoken of as æquidialis, wherefore it is called by the Greeks ἰσημερινός. In like manner it is also properly called Æquator, because it divides the whole frame of the earth between the poles into equal parts. So also an æquator may be rightly assigned to a terrella, by which its power is naturally divided, and by the plane of which permeating² through its centre, the whole globe is divided into equal parts both in quantity and strength (as if by a transverse septum) between verticities on both sides imbued³ with equal vigour⁴.

1 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

2 permeating   

弥漫( permeate的现在分词 )； 遍布； 渗入； 渗透

参考例句：

• His grace was more permeating because it found a readier medium. 他的风度因为有人赏识显得更加迷人。 来自英汉文学 - 嘉莉妹妹
• Thoughts are a strangely permeating factor. 思想真是一种会蔓延的奇怪东西。 来自英汉文学 - 嘉莉妹妹

3 imbued   

v.使（某人/某事）充满或激起（感情等）( imbue的过去式和过去分词 )；使充满；灌输；激发（强烈感情或品质等）

参考例句：

• Her voice was imbued with an unusual seriousness. 她的声音里充满着一种不寻常的严肃语气。
• These cultivated individuals have been imbued with a sense of social purpose. 这些有教养的人满怀着社会责任感。 来自《简明英汉词典》

4 vigour   

（=vigor）n.智力，体力，精力

参考例句：

• She is full of vigour and enthusiasm.她有热情，有朝气。
• At 40,he was in his prime and full of vigour.他40岁时正年富力强。