vitality of nature. And associated with this law is a law which seems at first sight opposed to it, a law indicative of the prodigality, and even of the destructiveness, of nature's dealings with living races-the law by which races not adapted, or rather less adapted than others, to the conditions around them gradually perish. We say that this law seems opposed to the other, because it involves a want of adaptation to those very conditions with respect to which the other law implies the most perfect adaptation. Yet, in reality, the two laws are correlative. It is through the action of one law that the other law prevails. The conditions of habitability are at each moment slowly changing, and Nature is careful neither of the individual nor of the type in changing, pari passu, the qualities of the living creatures which subsist under these varying conditions

Hitherto we have confined our attention to systems which, however their members may differ from the members of the solar system, yet resemble that system in this general respect, that they circle around a single central sun. But I must now touch on the possible existence of life under circumstances which do not

even present this feature of resemblance to those with which alone we are familiar.

Around the double, triple, and multiple stars there doubtless travel systems of worlds crowded with living creatures. How strangely must the conditions under which these creatures subsist differ from those which characterise life upon our earth! To begin with, consider the complexity of the motions which must result under the action of gravity, when, instead of a single centre, the planets which form the system dependent on a double or multiple star are subject to the attractions of two or more bodies which are themselves continually in motion around each other. The mathematicians in those dependent worlds should be far better than ours, if they are to deal successfully with the problems thus presented to them; and the remarkable climatic changes which must result from these complex motions seem to involve the necessity that the inhabitants of these worlds must have strong constitutions to enable them to bear in safety such important variations. Then again, where the suns are differently coloured, there must result those curious interchanges of light suggested by Sir John Herschel-'a green or a red day, for example, alternating with darkness or with white light.' He terms them 'pleasing contrasts and grateful vicissitudes,' and doubtless they are so to the inhabitants of those worlds: yet we on earth should hardly find such vicissitudes agreeable to us. The great law of adaptation exerts its influence, however,

in these parti-coloured systems as elsewhere; and whatever doubts we may have respecting the actual habitudes prevailing there, we may be sure that they are fully as well suited to the wants of the inhabitants of those systems as are terrestrial habitudes to the wants of the inhabitants of earth.

The nebulæ again afford an interesting subject of speculation. Some of these objects have been shown by spectroscopic analysis to shine with true stellar light, while others are simply immense masses of glowing gas. It is a moot point amongst astronomers whether we are to regard nebula of the former sort as belonging to our own sidereal system, or as lying far beyond it-forming, in fact, to use the expressive verbiage of German astronomers, vast island universes' scattered throughout the sea of space.' Nor does it greatly signify, so far as our present subject is concerned, which view we take. For if it should be proved that no outlying universes have yet been seen by man, yet every astronomer who recognises the true teaching of his science holds that our sidereal system is no more to be regarded as the only sidereal system of the universe, than our sun is to be regarded as the only sun in the sidereal system. Beyond that system, then, we look into the outlying spaces, and still the mental eye sees myriads of worlds richly stored with endless forms of life.

What opinion we are to form respecting the gaseous nebulæ, or respecting their correlatives in our solar system-the comets-it would at present be difficult to

say. Until we know the purposes which these objects subserve in the economy of the universe, it would not be easy to indicate their association with the question of other inhabited worlds. Our knowledge respecting the actual nature of these bodies is too recent to permit us to speculate respecting their functions.

The St. Paul's Magazine, March 1869.

THE ROSSE TELESCOPE SET TO
NEW WORK.

THE great Rosse telescope, with its monster tube down which a tall man can walk upright, and with a lightgathering power so enormous that even by day the stars seen through it shine like miniature suns, has not remained idle since the lamented death of the astronomer who constructed it. Not only has the work to which Earl Rosse devoted it-the delineation of those strange stellar cloudlets that fleck the dark vault of the heavens -been continued with unremitting assiduity, but its unrivalled powers have been devoted to aid the progress of those new and subtle modes of research which have recently been invented. The task was no simple one. The gigantic tube, with its ponderous six-feet mirror, had been poised so skilfully that a child could guide its movements. But for the new work which it was to be called on to perform much more was wanted. A new power had to be given to the telescope-a power of self-motion so exactly regulated that the gigantic eye of the telescope might remain steadily fixed on any given star or planet, notwithstanding the swift rotation of the earth, by which, in the ordinary condition of the tube, the celestial objects are carried in a few moments across its field