POLE OF THE ECLIPTIC. 



89 



pole of the heavens, or that part of the heavens towards which 

 the pole of the earth points, at the top, directly where the line VI- 

 XVIII crosses the outermost circle drawn around the pole of 

 the ecliptic, and which is the little circle represented in the figure, 

 (page 59), with the radius T S, or T Z. The pole of the earth, as 



it revolves around the pole of the ecliptic, passes, in succession, 

 through each point of this circle, moving, as represented in the 

 map, towards the left. This circle we have graduated into spaces 

 of ten degrees each, and drawn meridians from the pole of the 

 ecliptic through them, the pole of the heavens moves over one of 

 these spaces in about 718 years. The meridian VI, XVIII, is the 

 only one which passes through the two poles, consequently when 

 Polaris comes to this meridian, its distance from the pole will be 

 the least possible. In the course of 2100 years, as will be perceived, 



