STELLAR ASTRONOMY 421 



It is this fact which has restrained me till now from publishing 

 anything about these systematic motions, which in the main have 

 been known to me for two years. 



If I do not hesitate to publish them now, it is in the hope of elicit- 

 ing these spectroscopic data, without which a further development 

 of the theory had perhaps better come to a standstill. 



If these spectroscopic observations confirm the theory, we may 

 safely go on. 



If they do not? they will undoubtedly help to find the true explan- 

 ation of the dissymmetries summarized in our figures, the real exist- 

 ence of which is out of the question. Further labor devoted to a false 

 theory would be thrown away. 



In the mean while it seems well worth the trouble to see what 

 evidence can already be got on the question, even from the scanty 

 materials which have become public property. 



Unfortunately we here meet with some difficulties, which singu- 

 larly diminish the value of any conclusions that might otherwise 

 still have considerable weight. 



First, we have to exclude a relatively large number, which, prob- 

 ably or certainly, do not give a fair idea of the whole. As such I con- 

 sider the stars only observed because of their excessive astronomical 

 proper motion, or selected from a larger list on account of excep- 

 tionally large velocity. Further, the Orion stars which seem to be 

 nearly at rest in space; their relation to the system must be some- 

 what exceptional. 



What remains are 78 stars. I have added 46 spectroscopic binaries, 

 though the true velocity of their centres of gravity has been deter- 

 mined only in a few cases. I was mostly compelled to adopt as such 

 the mean of the greatest and smallest of observed velocities. 



Small though the collection be, it still offers one formidable diffi- 

 culty: Great part of it belongs to the very brightest stars in the sky. 

 For these Campbell has discovered the most important fact that they 

 have smaller motions than the mean of the fainter stars. 



What may be the cause? 



Light will be thrown thereon if more ample data confirm what I 

 found from my scanty store, apparently even more decisively than 

 Campbell's phenomenon, viz., that these stars also lead to a very 

 small velocity of the solar system. For this would make us conclude 

 that the stars nearest to the solar system partly participate in its 

 motion. The conclusion is strengthened by various considerations 

 into which time does not allow me to enter now.- On the other hand, 

 there are very serious though perhaps not insuperable objections, 

 which would rather make us seek an explanation in quite another 

 quarter and which at least compel us to wait for further confirm- 

 ation. 



