RErORTS OF ASTRONOMICAL OBSERVATORIES. 72") 



Tliis redetermination will result in the formation of a catalogue of 

 1,210 stars, in which the positions will he laid down with a prohal. It- 

 error of about ^ second in each co-ordinate (tlie rectaseension i»roh;il.ly 

 more accurate). Most of the required observations were made by Mr. 

 LiNDiTAGEN, and the series is nearly conii)lete. The second series, 

 unfortunately, will have to be delayed, owiuii^ to necessary repairs of 

 the meridian circle, which exhibits trac<'s of old a.ue. - - •• 



From the results obtained by comparison in diiforent positions, the 

 the probable error of a single declination determination is estimated as 

 0".5 to 0".C, which may be still reduced. 



Up to the present time the polar distances have been coiiii)uted tem- 

 porarily from observations of the Jfautical Almanac stars, with a].i)lica- 

 tionof the dechnation estimated hi the fundamental catalo.mie for zone 

 observations in the N. sky. Predominating^, though not exclusive, use 

 havino- been made of extreme northern stars, it is presumable tiiat the 

 uidcnown inclination of the instrument has exerted quite an intluence on 

 the results obtained. It is, however, evident from the coincidence of the 

 polar positions obtained in both situations of the ol)jective and ocular 

 that the inclination coefficient, Avhich appears as multiidied by the sine 

 of the zenith distance, cannot be very large. - - - 



The second series is intended to furnish a contribution to the knowl- 

 edge of the mean distances of the stars. Mention of this work has l)een 

 made in former reports, an<l an account of the progress made during 

 the past year is here presented. 



Of the stars previously mentioned as to be observed for parallax, two 

 have been omitted, namely, a Aurigji', and 'V Persei; the former on ac- 

 count of the difference of brilliancy between the i)riucipal star and a 

 comparison star, the latter on account of the ditlerence of declination 

 of the comjjarison stars. These were substituted by a Corona', and 

 I UrsjB Majoris. In consequence of the brilliancy of the former the 

 observations will be rather diflicult and probably somewhat incorrect. 

 I propose, however, to continue them for some time yet, in ordei- to test 

 whether the parallax may be confined to satisfactory limits by a multi- 

 plication of the observations. The same is the case with a Persei and 

 /5 Audromedse, notwithstanding their insuflicient accuracy. 



In observing t Ursa Majoris use could be made of only one compai^ison 

 star; a second one, at iirst designed to be included, proving too indis- 

 tinct. The former, however, is in every respect satisfactory. This star 

 moves on the same parallel with the principal star and oO.J seconds 

 ahead, and its magnitude, according to Argelander, is 8.0. The consid 

 erable brilliancy of this star admits of its observation even during un- 

 favorable state of the atmosphere, and it has not been neglected not- 

 withstanding the sometimes very unsatisfactory impression obtained. 



It is thereby intended to arrive at another result in addition to the de- 

 termination of the parallax, namely, the collecting of material for the 

 estimation of the relative accuracy which may be exi)e(!ted at the contact 

 of the cross-wire and right-ascension diftercnces during a favorable or 

 unfavorable condition of the atmospiiere. Although the results obtained, 

 until now, in reference thereto are not by any means conclusive, the}' 

 are regarded as worth communicating. 



As the results of observations are computed, Avith but few exceptions, 

 from four transits, the probable error ± 0^017 is to be expected. In 

 close conformity there is deduced from the 10 observations of i Ursa ex- 

 tant at present the probable error ± O^OKJ. 



This result appears to be very satisfactory. Even if the probable 

 error of a result of observations were ± 0^020, 30 or 40 nights adequately 



