92 UNIVERSITY OF VIEGINIA PUBLICATIONS 



errors. Six of the stars, however, show differences which, I do not think, 

 arise from this cause. They are 612, 618, 623, 636, 686, and 688, and 

 may be studied in pairs. 612 and 618 are a pair of stars, just below the 

 trapezium, of sufficient brightness to permit Professor Bond to make two 

 measures of position in addition to several diagrams. The differences in 

 the case of these two stars would seem to indicate a northward proper 

 motion in declination of between 4" and 5" a century. 



The differences in right ascension in the cases of 622 and 636 can be 

 largely explained by assuming that these stars are physically connected with 

 the trapezium and share in its motion. This assumption is not improbable, 

 as both the stars are within 30" of the trapezium. The residuals in right 

 ascension would then reduce from 



— 1."0 to 0."2 in the case of 622, and 

 — 1. 3 to 0. in the case of 636. 



There still remain, however, small residuals in declination which cannot be 

 explained in this way, and there is need for more accurate measures upon 

 which to base a discussion of this motion. 



The cases of 686 iand 688 are peculiar. The only basis of comparison in 

 each case is a single estimate of position given by Prof. Bond, from which 

 the following residuals were obtained : 



686 

 688 



Evidently either something is wrong or these stars have large proper 

 motion. The stars themselves are distinctly visible with the 36-inch 

 equatorial on any night with the seeing 4 on a scale of 5. There are no other 

 stars in the immediate viciaity except 671 and 676, and certainly none in the 

 positions given by Professor Bond. These must be the stars which he has 

 catalogued, but unless they are affected by large proper motions, Professor 

 Bond's positions must be erroneous. It may be of interest ten years hence to 

 measure the positions of these two stars in order to see if any great change 

 of position is indicated. 



Part VI contains a few notes which may be of interest to any one who 

 is working on the Nebula of Orion. 



I wish to thank Professor Stone for the use of the Leander McCormick 

 equatorial and for the many helpful suggestions which he has given me 

 throughout this work. 



Ealph E. Wilson. 



