288 Vaniation in the Obliquity of the Ecliptic. [July, 
That the changes in the latitude of stars in one part of 
the heavens, and an opposite change in another part of the 
heavens, indicate that the pole of the ecliptic has moved 
during past times in any particular direction is not true. 
This assertion we can bring to the test of recorded facts. 
The star catalogues of Ptolemy, Tycho Brahe, Hevelius, 
Halley, and others, can be compared with modern cata- 
logues, and it will be found, by any fair and impartial inves- 
tigator, that those persons who have so boldly asserted that 
the proof did exist are more remarkable for their zeal in 
endeavouring to support a popular theory than they are for 
that unprejudiced love of truth and fact which should alone 
be the desire of the man of Science. 
The statement that the pole of the heavens always traces 
an arc at right angles to the arc joining the pole of the 
heavens with the pole of the ecliptic is a theory. To decide 
whether the pole of the heavens traces an arc at right 
angles to the arc joining the pole of the heavens with the 
pole of the ecliptic, or at right angles to the arc joining the 
pole of the heavens with the point C 6° from the pole of 
the ecliptic, is a problem almost impossible to decide by the 
actual changes in North Polar distance of stars near 24 and 
12 hours right ascension. The means, however, by which it 
could be discovered which course is pursued we have pointed 
out in detail in our work ‘‘ The Motion of the Fixed Stars,” 
pages I12 to 170. 
The important fact, however, remains,—viz., that if the 
pole of the heavens trace an arc at right angles to that by 
which it may be joined to the pole of the ecliptic, then, to 
account for a decrease in the obliquity, it must be proved 
that the pole of the ecliptic does move annually towards the 
pole of the heavens 45’ per century now, and at a more 
rapid rate formerly, as is shown by recorded observations. 
Yet no such evidence can be adduced. 
Again, suppose it could be shown that the pole of the 
ecliptic has moved towards that part of the heavens in which 
are stars having from 5 to 7 hours’ right ascension, we still 
have the stubborn fact before us, that the actual curve 
traced by the earth’s axis is part of a circle having for its 
centre a point 6° from the pole of the ecliptic, and that if 
the pole of the ecliptic move towards that part of the 
heavens occupied for the time being by the pole of the 
heavens, still we have to account for the curve being such 
as itis; for to assert that it is a ‘‘ strange coincidence ” that 
during historical records this curve should coincide with 
such a circle is little better than a mere subterfuge to 
