ASTRONOMY. 



By Prof. Edward S. Holden, 



Director of the Washburn Obstrvatory. 



The following record of the progress of astronomy during the year 

 J 883 is in continuation of those of previous years, and it is given in es- 

 sentially the same form. Abstracts of some of the most important pa- 

 pers of the year are arranged under their appropriate heads. To the 

 professional astronomer the record may serve as a convenient collection 

 of reviews and notes. It is, however, primarily intended for the large 

 and increasing class of those who are interested in astronomy but whose 

 acquaintance with it is more general than special. The writer has made 

 free use of reviews and abstracts of astronomical papers which have ap- 

 peared in the various scientific journals, more especially in Nature, The 

 Observatory, Science, and the Sidereal Messenger. 



CONSTITUTION OF THE STELLAR SYSTEM. 



In a masterly review of Dreyer's recent work on the constant of pre- 

 cession, Dr. Sehonfeld has sketched the form of a wider investigation 

 into the question of the existence of a stellar system properly so called. 



"If we do not start with the assumption that the true motions of the 

 stars completely neutralize each other for some reason or other, in which 

 case they cannot influence the constant of precession, it is hardly pos- 

 sible, in spite of the commonly-asserted irregularity of their lines of 

 motion, to avoid the assumption that these motions bear some relation 

 to that plane in which the greater part of the stars is accumulated. We 

 may here call this plane the Milky Way, though it does not fully coin- 

 cide with the central line of the visible Milky Way, especially when we 

 take into consideration the accumulation of nebulae distant from the 

 Milky Way, and perhaps also the possibly somewhat eccentric posi- 

 tion of our solar system. 



" The relations which these motions bear to the plane may be conceived 

 of in many ways ; the most evident, however, is that the motions of 

 individual stars occur in planes whose inclination to the Milky Way is 

 small aud in directions accordingly which among themselves are nearly 

 parallel to the Milky Way. 



"Without this assumption of 'rotation in the plane of the Milky 



Way,' as J. Herschel culls it, it is hardly possible to explain the exist- 



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