iT 4 SOME TECHNICAL EXPLANATIONS. 



It is in the plane, or oblique circle, 6 xDxXos Xogo's, as 

 Ptolemaeus called it, that eclipses occur, owing to the rela- 

 tive positions of the sun, earth, and moon ; and it is for this 

 reason modern astronomers have denominated it the Ecliptic. 

 The Ecliptic is the Equator of the oblique sphere (ffpa/'ga, 

 JyxsxX/A&yugv?]), properly so called, as the Equator is that of the 

 sphere of the world, or the right sphere (ffpofioa, oodfy. The 

 circles parallel to the Ecliptic, which continue to diminish in 

 diameter up to the poles of the oblique sphere, bear the 

 name of parallels of latitude ; and we give that of meridians 

 of longitude or oblique ascensions (avapooai Xoja/) to the great 

 circles which cut the first rectangularly as they all pass 

 through the axis and the poles of the Ecliptic. The same 

 division by circles cutting each other rectangularly has been 

 made on the right sphere, or sphere of the world. Only, 

 there the latitudes are named declinations, and the longitudes 

 right ascensions. The general diurnal movement is a move- 

 ment in right ascension; it is measured upon the Equator. 

 The individual annual movement of the sun is a movement 

 in longitude ; it is measured upon the Ecliptic. 



The zone, or belt, which the sun seems to trace in its 

 annual march, from the limit of its southern excursion (the 

 winter solstice) to the limit of its boreal excursion (the summer 

 solstice), and in returning from that limit to the other, after 

 having twice passed through the equinoctial line (or Equator), 

 this zone is marked on the firmament by a belt of con- 

 stellations known as the Zodiac. 



These constellations are named, according to the figurative 



