CHANGE OF THE LINE OF APSIDES. Ill 



equator, to pass between the zenith and the southern horizon, 

 about as far from being 1 vertical at noon there, as it is to us at 

 the time of summer solstice. ' Hence, an observer there, looking 

 directly overhead, might imagine the equator a line marked in 

 the heavens extending from east to west, like the line E W; Z 



being the zenith, or point directly overhead, and A B the sun's 

 path, along which it would appear to move; being at Z, at the 

 time of the equinoxes, rising directly east and setting directly west, 

 and at B at the time of the slimmer solstice, describing, by the 

 diurnal motion of the earth, the tropic Cancer, and at A at the 

 time of winter solstice, its diurnal path being the tropic of 

 Capricorn. 



We have thus, at some length, explained the phenomena of the 

 seasons, and will now, for a few moments, consider what will be 

 the effect of the precession of the equinoxes. The earth's axis, 

 at present, is inclined towards the sign Cancer, which is located 

 in the constellation- Gemini. In the course of about 6000 years, 

 it will still be inclined towards the sign Cancer, but that sign will 

 be in the constellation Pisces. And in 6000 years more, towards 

 the constellation Sagittarius. In consequence of this change, 

 the seasons will all, really, be misplaced about six months, although 

 the various contrivances for retaining the names of the months, 

 as indicative of the several seasons, will doubtless, then, as now, 

 make the 21st of March the commencement of spring, or time 

 of vernal equinox. There is, however, a more important change 

 than this, which will affect our seasons The major axis of the 

 earth, or line a b, see figure on page 78, has not a fixed direction 

 in space, but is slowly moving from west to east, i. e. in the order 

 of the signs, at such a rate that it will require about 100,000 years 

 to make a complete revolution. The earth arrives at its perihelion 



