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millionth of the whole. This is the entire fraction of the Sun's force intercepted by the Earth, and we convert but a small fraction of this fraction into mechanical energy. Multiplying all our powers by millions of millions, we do not reach the Sun's expenditure. And still, notwithstanding this enormous drain in the lapse of human history, we are unable to detect a diminution of his store. Measured by our largest terrestrial standards, such a reservoir of power is infinite; but it is our privilege to rise above these standards, and to regard the Sun himself as a speck in infinite extension -a mere drop in the universal sea. We analyse the space in which he is immersed and which is the vehicle of his power. We pass to other systems and other suns, each pouring forth energy like our own, but still without infringement of the law which reveals immutability in the midst of change, which recognises incessant transference or conversion, but neither final gain nor loss. The law generalises the aphorism of Solomon, that there is nothing new under the Sun,' by teaching us to detect everywhere, under its infinite variety of appearances, the same primeval force. To Nature nothing can be added; from Nature nothing can be taken away; the sum of her energies is constant, and the utmost man can do in the pursuit of physical truth, or in the applications of physical knowledge, is to shift the constituents of the nevervarying total. The law of conservation rigidly excludes both creation and annihilation. Waves may change to ripples and ripples to waves-magnitude

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be substituted for number and number for magnitude--asteroids may aggregate to suns, suns may resolve themselves into flora and faunæ, and flora and faunæ melt in air-the flux of power is eternally the same. It rolls in music through the ages, and all terrestrial energy-the manifestations of life, as well as the display of phenomena-are but modulations of its rhythm.'

CHAPTER IX.

THE SUN AMONG HIS PEERS.

WE have hitherto regarded the Sun with reference to his position in the solar system—as ruler, fire, light, and life of that wonderful scheme whose real magnificence and complexity has but recently begun to be recognised by astronomers. We have now-but very briefly, for already the space allotted to our subject has been exceeded-to consider him as a member of the sidereal system. What he is to the scheme of dependent worlds we have seen; it remains that we should endeavour to form some conception of his position among his peers. We have to contemplate him as a Sun among many suns, exerting an influence indeed over his fellow orbs, but, swayed in like sort by their attractions, still surrounded-as when we considered him with reference to the solar system-by orbs travelling with enormous velocity, but no longer at rest, or almost at rest, amidst a scheme of moving worlds. We are to see him taking part in a scheme of movement too wondrously complicated to be as yet interpreted by astronomers.

We must not pause here to consider the processesinteresting though their history may be-by which

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astronomers have been enabled to determine the distances of certain stars, and so to form a general estimate of the scale on which the sidereal system is constructed. Let it suffice to mention that the fundamental fact on which our estimate of the distances of the fixed stars from us and from each other has been based, is the circumstance that while our Earth sweeps round the Sun on an orbit more than 180,000,000 miles in diameter, the stars remain all but unchanged in their apparent position, all the powers of our modern instruments only revealing in a very few instances the minutest conceivable displacement. Setting this fact clearly before us, the grandeur of the sidereal system becomes more real and present to our minds. From the nearest fixed star, the vast orbit of our Earth is reduced to little more than a point, to a circle so minute that 2,000 such circles could be placed side by side along the apparent diameter of the Sun or Moon. But the great majority of the stars lie at distances far vaster: so vast indeed, that the Earth's orbit is reduced to a mere point as viewed from beyond the vast abysms which separate us from those orbs. Nor is it likely that in general, the distance of star from star, of any star in the heavens, for instance, from the nearest of its neighbours, falls short of the distance by which our Sun is separated from the nearest of his fellow orbs.

We are thus brought face to face with a problem full of interest but enormously difficult-a problem which belongs perhaps rather to the astronomy of the

future than to that of our day. How are men to determine the figure and dimensions of the sidereal system, to understand its structure and complexities, to trace out the motions taking place within its limits, when as yet they seem to have scarce any means of even attempting to solve these problems? Yet here, unless I mistake, is a work from which future astronomers will not shrink, a problem whose solution (for it will be solved) cannot but reveal results altogether surpassing in interest any which astronomers have yet obtained. It is true that if we consider the means we have for attacking this noble problem, they seem ineffective indeed; if we look at the results of past research we find little to encourage present confidence. Yet it is only necessary to consider the amazing interest of the problem to set doubt and irresolution on one side, and at least patiently to test the means we have at our disposal.

I have elsewhere* pointed out reasons for regarding the views hitherto accepted respecting the sidereal system as unsatisfactory. The results obtained by Sir William Herschel, and apparently confirmed by the labours of Sir John Herschel, the elder Struve, and others, seem, according to the evidence I have adduced, to be self-contradictory and not accordant with other equally reliable researches. I confess I can no longer entertain any doubt that there is an error in the

* In Other Worlds than Ours, and more especially the second edition, where additional, and, I think, conclusive arguments are brought forward..

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