70 LIGHT SCIENCE FOR LEISURE HOURS. 



like the apparent advance and retrogression of planets 

 which, nevertheless, are travelling in a common direc- 

 tion around a common centre. 



But precisely because the difficulties which surround 

 the problem of the stellar motions are so stupendous, 

 we must so much the more carefully examine every 

 feature which observation may reveal to us. To do 

 otherwise were to abandon the problem as altogether 

 hopeless. 



Now it cannot but be recognised that in this respect 

 the new method of research is peculiarly promising. 

 For whereas all former methods have dealt only with 

 apparent motion, this method tells us of the real rate 

 of stellar displacements. We have seen how it has 

 disposed of the inferences which had been formed as to j 

 the sun's velocity, and the average velocities of stellar 

 motion ; let us inquire what has been its bearing on 

 the views of astronomers respecting the stellar universe 

 regarded as a scheme or system. 



Other methods of dealing with the motions of the 

 stars had related chiefly to the question of the sun's 

 journey through space, until Madler was led to inquire 

 whether the motions of the stars might not afford the | 

 means of determining where the centre of the stellar 

 system may lie. Limiting his range of inquiry, in the 

 first instance, by certain preliminary considerations, he 

 proceeded to examine the direction of the apparent 

 stellar motions in a particular region of the heavens. 

 It seemed likely to him that the centre of the universe 

 would be near the Milky Way, and probably on that 



