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researches of the universe of God. Time, and space and number, and distance, have all been set at defiance. No limits have been sufficiently great to circumscribe its movement. For more than six thousand years, onward ! has truly been the word. And here might very well pause, and rest content in the exhibi,
. tion of the absolute and actual triumphs of human genius; but as the rays of the rising sun penetrate the darkness of night, and scattering the gloom, dimly reveal the scenes of earth which are soon to be flooded with splendor, so the light of human knowledge breaks over the boundaries which divide the known from the unknown, and faintly reveals what yet lies far beyond in the dark profound.
Guided by this light, we shall ask your attention to one of the most sublime speculations to which the mind of man has ever risen. I refer to the supposed discovery of the great centre about which it is presumed the myriads of stars composing our mighty Milky Way are all revolving.
M. Maedler, the author of the recent investigations with reference to the Central Sun, has long been known to the astronomical world as the successor of M. Struve in the direction of the observatory at Dorpat. His computations of the orbitual movements of the double stars have given to him a deservedly high celebrity, and the great theory which he has propounded is only given to the world after a long and patient examination, extending through seven years.
The extension of the law of gravitation to the fixed stars, now absolutely demonstrated in the revolutions of the binary systems, settles forever the fact, that in thu grand association of stars composing our cluster,
or, as we shall hereafter call it, our astral system, there must be a centre of gravity, as certainly as there is ono to the solar system. In the organization of the solar system we find a central body of vast size, surrounded by small and subordinate satellites. Again, among the planets, we find their magnitude very great, when compared with the moons which circulate around them. Extending this analogy, early astronomers conceived that this principle of a great central pre ponderating globe would, in all probability, obtain in all the higher orders of physical organization.
This idea, apparently so well founded, was entirely destroyed by the discovery of the binary stars.
Here we find the next higher organization above our solar system, but instead of finding in the bodies thus united a vast preponderance in magnitude of one over the other, there are many examples in which the two suns thus united by gravitation are, in all respects, equal. In many others the difference is only slight, yet in all these higher systems there must exist a common centre of gravity.
With the mind cleared, by these views, from all prejudice in favor of the necessary existence of some stupendous central globe, as far exceeding in magnitude the myriads of fixed stars by which it is surrounded as does the sun all the satellites of its system, we are prepared to inquire into the actual exigtence or nonexistence of such a body.
Admitting its invisibility, either in consequence of its distance or nonluminous character, there are yet remaining the means, not only of detecting its existence, but of discovering its position in space. In case such a body exists, the stars located nearest to it will be most completely subjected to its influence, and will show their proximity by the swiftness of their motion. Since it is possible to penetrate space in every direction, in case the stars of any particular region were endowed with a more rapid motion than all others, these would not fail to be discovered. But no such rapid motions have ever been detected, and hence it is now fair to conclude that such motions do not exist, and consequently no vast central globe can ever be found, because there is no evidence that such a body has any locality in space.
The question resolves itself, then, into a research for the common centre of gravity of all the stars composing our astral system, and the data for such an examination must be found in the direction of the solar motion, and in that of the proper motion of the fixed stars. Difficult as this research undoubtedly is, Maedler's sagacity detected various guides which limited his more minute examinations to a comparatively small portion of the heavens. Since our great astral system has been shown to take the form of a layer or stratum whose thickness is small compared with its extent, we cannot fail to perceive that the centre of gravity of a mass of stars thus arranged must be found somewhere within the limits of the Milky Way, when seen by an eye located not very distant from the centre. But it is seen that our sun does not occupy the absolute centre of this stratum. In case it did, then would the bright circle of the Milky Way divide the heavens into two equal hemispheres. Since there is a manifest difference between the two parts into which the heavens is divided, the snaller portion will be the more distant from us, and
in this smaller part we must look for the centra, point. But, from the soundings of both the Herschels it is certain that our sun lies nearer the southern half of the Milky Way than the northern. Hence, in our researches for the centre of gravity, we may confine our examinations to the northern half of the smaller of the two parts into which the Milky Way divides the heavens.
One more approximation may be made. knew that our sun, in its presumed revolution about this great centre, described a circle, and if we knew the plane of this circle, and the direction in which the sun was now moving, a line drawn in that plane from the sun, and in a direction perpendicular to its line of motion, would pass directly through the centre about which it is revolving, and would point us directly to it. Now the direction of the sun's motion is alone determined; but since the centre of gravity must be found somewhere in a line perpendicular to the direc tion, we must give to this perpendicular all possible positions in space, which will cause it to cut from the celestial sphere the circumference of a great circle, within which the centre of gravity must be found.These limiting considerations brought the distinguished astronomer to a region of the heavens in and about the constellation Taurus.
Here the examination took a more definite and more strictly scientific form. The proper motion of the stars in this region could be anticipated and known, at least in character and direction. The great centre would probably be located within the limits of some rich cluster. All the stars composing this cluster as well as those within 20° or 30°, would appear to move in the same direction. Those im mediately proximate to the central sun or star would appear to move with the same velocity due to that star, and the entire group would sweep, apparently, through space without parting company.
Having, by such like considerations, narrowed down the limits of research, Maedler commenced his individual examinations. Among other objects subjected to rigid scrutiny, was the brilliant star Aldebaran, in the eye of the Bull. This being the brightest star in this region, and being, moreover, in the midst of a group of smaller stars, seemed, in the outset, to fulfill some of the conditions required of the central sun. But a more rigid examination proved conclusively that this star could not occupy the centre. Its own proper motion far exceeded that of the sur. rounding stars, and demonstrated its near proximity to our own system, and its mere optical connection with the stars surrounding it.
Thus did this great astronomer move from point to point, from star to star, subjecting each successively to the severest tests, until, finally, a point was found a star was discovered, fulfilling, in the most remarka ble manner, all the requisitions demanded by the nature of the problem. All are familiar with the beautiful little cluster, called the Pleiades, or seven stars. Clustered around the brilliant star Alcyone, which occupies the optical centre of the group, the telescope shows fourteen conspicuous stars. The proper motions of all these have been determined with great exactitude. These are all in the same direction, and are all nearly equal to each other; and, what is still more ipuportant, the mean of their proper motions differs