Among the many striking contrasts between the seeming and the real suggested by the study of astronomy, there is none more startling than the contrast which exists between the apparent repose of the heavens and what is really taking place among the star-depths. On a calm clear night -

When all the winds are laid, And every height comes out, and jutting peak And valley, and the immeasurable heavens Break open to their highest the stars seem set as emblems of eternal fixity and rest. As such they have been regarded in all ages by the poet; nor has science, so far as it has been directed to the apparent movements of the stars, taught any other lesson. It has, indeed, shown that the stars are even more steadfast than they seem, in so far as it teaches that their diurnal and annual motions are but apparent, while the great precessional swaying of the star-sphere is but the reflexion of the earth's gyration. More and more just, so far as these motions are concerned, has appeared the title of 'the fixed stars,' assigned by astronomers to the suns which people space.

Yet the depths displayed to our view in the stillness of the calmest and clearest night are, in reality, astir with the most stupendous activity. The least of the orbs we see - some star so faint that it is only discerned by momentary gleams - is the abode of forces whose action during a single instant surpasses in effect all the forces at work upon the earth during a decade of years. All the wonderful processes taking place within and around the globe of our own sun have their analogues in that distant orb. Let it be remembered also that our sun himself presents an aspect which in no sense suggests his real condition. If we would picture him as he actually is, we must consider the uproar and tumult which prevail where, to our ordinary perceptions, all seems at perfect rest. The least movement on that glowing photosphere represents the action of forces so tremendous that they would be competent to destroy in an instant this earth on which we live. The most hideous turmoil, outvying a million-fold the roar of the hurricane or the crash of the thunderbolt, must prevail for ever in every part of the solar atmosphere. And in whatever respects other suns may differ from our own, in this at least we know that they resemble him. It is the very charter of their existence as suns-as real living centres of energy to schemes of circling worlds-that they should thus continually pulsate with their own vitality. Each is the central engine on whose internal motions the life of a system of worlds depends and each must, with persistent activity, work out its purpose, until the fuel which supplies its forces shall be exhausted.

All the evidence as yet obtained points to the conclusion that our own sun, wonderful as is his structure and stupendous his energy, is yet very far inferior in splendour and power to most of his fellow suns. Placed where Sirius is, the sun would appear but as a third-rate star, less bright than hundreds of the stars visible to the unaided eye. But removed to the distance of Alde-baran, or Castor, or Betelgeux, our sun would certainly not shine more brightly than the fourth-magnitude stars, while it is probable that his lustre would be so reduced that he would be barely discernible. There can be little doubt that of all the stars seen on the clearest and darkest night, there are scarce fifty which are not far larger suns than ours, and consequently the scene of more tremendous processes of change.

But when we turn from the consideration of the energy and vitality of individual stars to inquire into the movements taking place within the star system, we are yet more startlingly impressed by the contrast between the apparent rest prevailing in the star-depths and the inconceivable activity really present there. It seems incredible that all those orbs which look so still are speeding through space with a velocity compared with which every form of motion familiar to us on earth must be regarded as almost absolute rest. This appears even more surprising when we consider that during all those centuries with which history deals, during the rise and fall of the nations of antiquity, during the darkness of the Middle Ages, during the more familiar scenes of recent centuries, the stars have presented an aspect so constant that if the Chal-daean astronomers could be restored to life, they would recognise scarce any change in the positions of the stars forming the ancient constellations. Yet there are no astronomical facts more thoroughly established than those which relate to the motions of the stars. The giant orb of Sirius, exceeding our sun a thousand times in volume, Capella and Procyon, the glories of Orion, the clustered Pleiads, Arcturus, Vega, and Aldebaran, all the stars known to the astronomer, are urging their way with inconceivable velocity, each on its own course, though doubtless all these motions are subordinated to some as yet unexplained system of movements whereby all the stars of the galaxy are made to form parts of one harmonious whole.

Until lately it had only been by one method of observation that the astronomer could assure himself that these motions were taking place. That method is the simplest conceivable. If a star's place were accurately determined, either with respect to neighbouring stars or to the imaginary circles and points on the sphere which are determined by the earth's movements of rotation and revolution, then, if the star be really in motion, a change of place must in the long run manifest itself, not indeed to ordinary vision, but to the piercing scrutiny and to the yet more remarkable measuring powers of the astronomical telescope. A hundred years may elapse before the motion is measure-able, yet the astronomer can none the less certainly assure himself that the motion is taking place, since he has the records of those who have gone before him, and the means of satisfying himself that those records are trustworthy.