places relatively to each other. No doubt there is some effect of this kind, but it is an insignificant one, and need not at present concern us. The essential point to be noticed is, that the stars which happen to lie in the vicinity of the Pole would have a changed relation to the Pole in consequence of the fact that this latter point is itself in incessant movement. At the present time the Pole is advancing in such a direction that it is getting nearer to the Pole Star, so that the actual circle which the Pole Star is describing is becoming less and less. The time will come when the circle which this star performs will have reached its lowest dimensions, but the Pole will still be moving on its way, and then, of course, the dimensions of the circle traversed by the Pole Star will undergo a corresponding increase. As hundreds of years, and thousands of years roll by the Pole will retreat further and further from the Pole Star, so that in the course of a period as far in the future as the foundation of Rome was far in the past, the Pole will be no longer sufficiently near the Pole Star to enable the latter to render to astronomers the peculiar services which it does at present.
Looking still further ahead, we find that in the course of about twelve thousand years the Pole will have gained a position as remote as it possibly can from that position which it now occupies. This most critical point in the heavens will then lie not far from the star Vega, the brightest point in the northern sky, and then it will commence to return, so that after the lapse of about twenty-five thousand years the Pole will be found again in the same celestial neighbourhood in which it is to-night, having, in the meantime, traversed a mighty circle through
