OP ARTS AND SCIENCES. 3 



The right ascensions so obtained are amply sufficient both in quan- 

 tity and quality to replace the excluded " Hauptsterne," although not 

 quite equal to the latter for their own proper epoch, 18G5. The 

 greater nearness of these stars to the pole in certain right-ascensions 

 renders them better for instrumental errors than, for example, such 

 as 7 Urste Minoris, whose right ascension is both uncertain and erro- 

 neous at the present time ; and in fact better than ( Urste Minoris, 

 which is some degrees nearer, equally uncertain, but actually not 

 quite so much in error, so far as I can judge. 



It has not been yet necessary to employ any stars whose right 

 ascensions are not given in one or more ephemerides ; so that the 

 following corrections to the apparent places of these ephemerides 

 are currently employed to bring the instrumental corrections into 

 harmony with the Pulcova system, as modified by Auwers. 



Two of Auwers's right ascensions are also corrected ; Draconis 

 1 H., as stated in my previous paper; and 76 Draconis, in conse- 

 quence of an error of sign in the proper motion, which has been 

 since corrected in the Jahrbuch, , 



In extending my scheme southward, I have, as will be seen, in- 

 serted the doubtful Hauptsterne, and all the Zusatzsterne, so far as 

 ray zone now goes, into my working list. The doubt refers almost 

 exclusively to right ascension ; hence this co-ordinate will be deter- 

 mined, while at present the catalogue declination is used to find the 

 equator-point. 



During the present year I hope to begin a series of experiments 

 with the Rittenhouse* collimator, for the purpose of showing how far 



* It seems to be certain that our countryman, David Rittenhouse, was the 

 first to employ an object-glass of small curvature with a meridian mark in its 

 focus. It is quite possible that this application preceded that of an ordinary 

 telescope as a collimator; but the latter is practically a different instrument. 



