Does our Sun gravitate around an immense sun whose attraction extends to it and controls its destinies as it controls that of the planets? Do investigations in sidereal astronomy lead us to believe that a star of such magnitude can exist in a direction situated at right angles with our course towards Hercules? No; our Sun is influenced by sidereal attraction, but no one star appears to overpower all the others and reign sovereign over our central star.

Although it may be perfectly admissible, or rather certain, that the sun nearest to ours, the star Alpha Centauri, and our own Sun feel their mutual attraction; although this star may be situated at about 90 degrees from our tangent towards Hercules, and, more than that, in the plane of the principal stars, passing by Perseus, Capella, Vega, Aldebaran, and the Southern Cross; and although the proper motion of this neighboring sun may be turned sensibly in the opposite direction from ours,—yet we could not consider these two systems as forming one couple analogous to that of the double stars; in the first place, because all the known double-star systems are composed of stars much nearer to each other, and then because in the immensity of the orbit described, according to this hypothesis, the attraction of the neighboring stars could not be considered as remaining without influence; and lastly, because the actual rates of speed with which these two suns are moved are much less great than those which would result from their mutual attraction.

The little constellation of Perseus, especially, might very well exert a more powerful action than that of the Pleiades, or than any other group of stars, and be the fixed point, the centre of gravity, of the motions of our Sun, of Alpha Centauri, and the neighboring stars, inasmuch as the cluster of Perseus is not only at right angles with the tangent of our movement towards Hercules, but also in the great circle of the principal stars and precisely at the intersection of this circle with the Milky Way. But here another factor comes in, of more importance than all the preceding ones,—this Milky Way, with its eighteen millions of suns, of which it would assuredly be audacious to seek the centre of gravity.

But what is the whole entire Milky Way, after all, compared with the milliards of stars which our mind contemplates in the bosom of the sidereal universe? Is not this Milky Way itself moving like an archipelago of floating islands? Is not every resolvable nebula, each cluster of stars, a Milky Way in motion under the action of the gravitation of other universes, which call to it and appeal to it through the infinite night?

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Our thoughts are transported from star to star, from system to system, from region to region, in the presence of unfathomable grandeurs, in sight of celestial motions whose speed we are but just beginning properly to value, but which already surpasses all conception. The proper annual motion of the sun Alpha Centauri exceeds 188 millions of leagues per year. The proper motion of the 61st of Cygnus (second sun in the order of distances) is equivalent to 370 millions of leagues per year, or about one million of leagues per day. The star Alpha Cygni comes to us in a direct line at a speed of 500 millions of leagues per year. The proper motion of the star 1830 of Groombridge's Catalogue rises to 2,590 millions of leagues per year, which represents seven millions of leagues per day, 115,000 kilometres per hour, or 320,000 metres per second! These are minimum estimates, inasmuch as we certainly do not see perpendicularly, but obliquely, the stellar displacements thus measured.

What projectiles! They are suns thousands and millions of times heavier than the Earth, launched through the unfathomable void with giddy rates of speed, revolving in immensity under the influence of the gravitation of all the stars of the universe. And these millions and thousand millions of suns, planets, clusters of stars, nebulæ, worlds in their infancy, worlds near their end, rush with equal velocity towards goals of which they are ignorant, with an energy and intensity of action before which gunpowder and dynamite are like the breath of sleeping babes.

And thus everything hurries on through all eternity perhaps, without being able ever to reach the unexisting limits of infinity.... Motion, activity, light, life everywhere. Happily so, without doubt. If all these innumerable suns, planets, earths, moons, comets, were fixed and immovable, petrified kings in their eternal tombs, how much more formidable, but also more mournful, would be the aspect of such a universe! Can you imagine the whole creation stopped, benumbed, mummified? Is not such an idea unbearable? Is there not something funereal about it?

What causes these motions? What maintains them? What regulates them? Universal gravitation, invisible force, which the visible universe (what we call matter) obeys. A body attracted from infinity by the Earth would attain a velocity of 11,300 metres per second; just as a body thrown from the Earth with that speed would never fall again. A body attracted by the Sun from the infinite would attain a speed of 608,000 metres; and a body thrown by the Sun with that swiftness would never return to its point of departure. Clusters of stars may give us velocities much more remarkable still, but which are explained by the theory of gravitation. A glance at a map of the proper motions of the stars is enough to make one understand the variety and grandeur of these motions.

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