PRECESSION: AND THE PYRAMIDS 



453 



can never differ greatly from what we know them now. They can 

 neither be materially accentuated nor proportionately reduced. 



Though the obliquity of the ecliptic is oscillatory, the motion of the 

 ecliptic pole keeps persistently, though unsteadily, on always in the 

 same sense. Its wanderings trace out an elliptic spiral which never 

 returns into itself. Its vagaries resemble as much as anything an un- 

 evenly bent spring carelessly coiled about a mid-position from which 

 it never far departs. 



Meanwhile our own pole pursues its relatively sedate march around 

 the other, permitting its position to be calculated at any past epoch not 

 too remote. We can plot its path and thus see near which stars it 

 passed, stars which had the earthly distinction once upon a time of being 

 our cynosure. In this manner we discover that 4,690 years ago, or in 

 2780 B. c, the pole passed within 3' of arc of the star a Draconis. Prac- 

 tically the star was the pole, and it was the last bright star the pole 

 approached before reaching Polaris. In the time of Hipparchus, 140 

 B.C., the pole lay undistinguished in a waste region of the sky. A of the 

 dragon is now a star between the second and third magnitudes, but there 

 is evidence to show that in ancient times it was brighter. It must 



Map of the Northern Part of the Axciext Pyramid Field in Egypt. 



