190 On the Stars /arming the Pleiades. 



of the mural circle at the observatory (placed there by La Hire 

 in 1682); t/iose being all he could distinguish with the telescope 

 attached to that instriime?it* : and from the positions of these, 

 thus determined, he deduced, with a telescope of 32 inches 

 focus, the positions of the remaining fifty-five. Under these 

 circumstances it cannot be expected that the positions are 

 given with that degree of accuracy which distinguishes more 

 modern observations: nevertheless they are more accurate 

 than those of any of his predecessors. And as no observa- 

 tions on this remarkable cluster of stars have been made since 

 his time (or if made, have not been recorded) I present them 

 as the best that I can procure ; under the hope that some of 

 our present observers will turn their attention to this subject, 

 and favour die world with a more correct and comprehensive 

 catalogue. With a view to assist the observer, and to enable 

 him to identify the several stars here alluded to, I have caused 

 a chart to be engraved, with their several positions laid do^vn, 

 as given in the table f. I have not in the chart paid any 

 attention to M. Jeaurat's magnitudes, as they are evidently 

 erroneous : but have adopted a scale more corresponding with 

 their present appearance. Those given by M. Jeaurat, in the 

 table, are in most cases much too great: and it is singular 

 that so considerable an error in their comjmrative brightness 

 should have arisen, when most of the stars must have been in 

 the field of the telescope at one and the same moment. More- 

 over, the magnitudes, represented on his chart, do not at all 

 correspond with those mentioned in the catalogue. I ought 

 also to notice his singular suspicion that Pleione has a proper 

 motion, from east to west, round Alcyone, at the rate of one 

 degree in 100 years ! ! ! Above two- thirds of that period has 

 elapsed since the observations of Bradley ; and Pleione still 

 retains its relative position J. 



In the column of sj^nonyms, those numbers, to which the 

 letter P is affixed, refer to Piazzi's catalogue. The letter M 

 denotes Mayer's. The other numbers are Flamsteed's. 



* And yet No. 9 (a ftar of the 8th magnitude) was one of these : although 

 there are several others of the 4th and 5th magnitude recorded in the 

 list ! ! ! 



f This chart, Mr. Baily has kindly permitted us to print, for the present 

 Number of this Journal. — Edit. 



X The presumed proper motion of many other stars would (I conceive) if 

 nicely examined, vanish in a similar manner. Good obsei-vations compared 

 with bad ones, or even with good ones improperly or imequally reduced, 

 are very inadequate tests of the proper motion of a star : and I fear the 

 major part are in this situation. Many stars, however, have unquestion- 

 ably a motion, the principles of which cannot be explained : and this, by 

 general consent, is called a proper motion. I do not object to the term, so 

 long as a correct idea is affixed to it. 



Mean 



