222 GENERAL MOVEMENT OF THE STARS. 



In the first part of the great work on this subject, which was pub- 

 lished in 18-17 and 1848, he subjected to a detailed examination all 

 the observations made by himself and others relative to double stars 

 and the orbits they describe, with a view to ascertain if there were 

 among these or other stars any central body competent by its mass 

 to exert a preponderant attractive action on all the other stars, so as 

 to be controller of the general system, or central sun, in the literal 

 sense of that word, as is our sun for the partial system which it governs. 

 The result was to negative any such hypothesis — a result which no 

 one has contested. 



In the second portion of the work, the author has shown that the 

 idea of a distribution of the stars into simply partial systems, without 

 any general connexion among themselves, is not admissible, inasmuch 

 as it fails sufficiently to account for the proper movements already 

 ascertained. This idea once eliminated, there remained for M. 

 Mtedler, while admiting the law of universal gravitation, no other 

 assumption but the existence of a general system without a pre- 

 dominant central body, or of a globular system in which the stars 

 all revolve about their common centre of gravity, according to 

 a force directly proportional to their distance from the central point. 

 With this assumption as a basis, the investigation turns upon the 

 question whether the observed movements proper to the stars satisfy 

 the conditions which result from it. 



The conditions which the central point and the neighboring region 

 of the heavens ought to satisfy are the following: 



1. The central point should have no real movement proper, and its 

 apparent movement, though to lie taken in the opposite direction, 

 would represent that of the sun. 



2. If around the central point there be any group of stars physi- 

 cally connected with it, the proper real movements of the stars of 

 that group should be very small and equal as regards one another. 



3. If we describe around the central point C a concentric sphere, 

 whose radius, C S, is equal to the distance of our sun from that point, 

 all the stars situated within the interior of such sphere should have 

 a real movement proper, smaller than that of the sun, and so much the 

 smaller as they are nearer to C; the real movements proper should 

 increase in departing from C to the circumference of a. great circle 

 described with C as a pole. 



4. The point of the heavens towards which the sun is directing 

 itself should be some 90 degrees from the centre C. 



5. If we denote by <f the -angle of direction of the proper move- 

 ment of any observed star, ami by </< the angle of direction of the 

 proper movement of the sun, the difference <p — <p of those two angles 

 should be null at the centre, and should increase in all directions at 

 departing from that point, without ever exceeding 90 degrees within 

 the interior zone. 



G. The region of the heavens when the central point is determined 

 should be the only one in regard to which the whole of the above con- 

 ditions is fulfilled. 



