23-4 



SCIENCE. 



[Vor,. U., No. 29. 



in tlie report, it is not quite clear upon what autliority 

 they rest. The worlc assigned to the Pulkova observa- 

 tory by the zone commission was the exact determi- 

 nation of tlie places of the stars of this list. The 

 observations were undertaken by Gromadski Tvith 

 the Repsold meridian circle. In accordance with the 

 plan adopted, each star was observed eight times, — 

 four times in each position of the instrument. The 

 observations were differential with respect to the 

 hauptsterne. 



The results were published by Struve in 1876; and 

 the places there given were used in the first reduction 

 of the Harvard-college observations for 1874-75, and 

 perhaps in some other cases. 



About this time a change seems to have been made 

 in the original plan with respect to the formation of 

 the final catalogue of fundamental stars, of which I 

 have been unable to find a clear account. The origi- 

 nal intention was to make the positions depend en- 

 tirely upon the observations at Pulkova. The zone 

 commission established by the gesellschaft, however, 

 committed the formation of this catalogue toAuwers; 

 and it is to liim that we owe the most complete and 

 the most perfect catalogue of fundamental stars yet 

 published. The Pulkova system forl8G.5was adopted 

 as the basis; but, in order to obtain greater freedom 

 froyn accidental errors for hidividual stars, the final 

 catalogue was obtained by combining with the Pul- 

 kova series, the Greenwiclr observations from 18.36 

 to 187(5, the Harvard-college observations for 1871-72, 

 the Leipsic observation^, in declination only, between 

 1866 and 1870, and tlie Leiden observations in declina- 

 tion between 1864 and 1870. Before this combination 

 was made, however, these observations were all re- 

 duced to the Pulkova system. 



The following observatories have taken part in the 

 zone observations : — 



The zone between —2° and -H° was originally un- 

 dertaken at Palermo, that between -1-1° and +4° at 

 Neuchalel, that between -|-4° and -|-10° at Mannheim, 

 and that between -|-3.5° and -1-40° at Chicago. 



In the latter case, the great fire at Chicago crippled 

 the resoui-ces of the observatory to such an extent, 

 that Safford was compelled to relinquisli the work, 

 which was at that time quite far advanced. 



The chief items of interest in connection with this 

 work are found in the following tabular statement: — 



[Table omitted.] 



Attention was called, at an early date, to the im- 

 portance of continuing the survey of the northern 

 heavens beyond the southern limit fixed by Argelan- 



der. The preparation necessary for the execution of 

 this work consisted in the extension of the Durch- 

 musterung to the tropic of Capricorn. This was 

 undertaken by Schiinfeld at Leipsic. 



In the report to the gesellschaft at the meeting held 

 at Stockholm in 1877, lie has given an account of this 

 work, in which he stated that it was suflBciently near 

 completion to invite the consideration of the question 

 of the meridian circle determinations of the places of 

 stars to the ninth magnitude. The lack of southern 

 fundamental stars whose positions were well deter- 

 mined was still a hinderance to the immediate com- 

 mencement of the work. Relatively more stars of 

 this class are required than in tlie northern observa- 

 tions, in Older to eliminate the inequalities liue to 

 refraction. Schonfeld stated, that, while the burden 

 of the determination of the places of these southern 

 fundamental stars must rest mainly upon southern 

 observations, it seemed necessary to connect thera 

 with the Pulkova system by a connecting link (mit- 

 telglied), through observations at some observatory 

 well situated for this purpose. At this meeting Sande 

 Bakhuysen, at Leiden, gave notice of intention to 

 take part in this worlc. Gylden urged the importance 

 of securing the co-operalion of Melbourne ; and Pe- 

 ters suggested the advantage of securing Washington 

 as an additional 'mean term' (V. J. S. 1877, p. ^65). 



The next refeience to this work is contained in 

 tlie vierteljahrsscbrift for 1881, xv. p. 270. A list of 

 303 southern stars is here given, whose exact places 

 were at that time being determined at Leiden and at 

 the Cape of Good Hope. This list was selected by 

 Schiinfeld and Sande Bakhuysen, in a way to meet 

 the requirements referred to in previous discussions. 



A final catalogue of 83 southern fundamental stars 

 by Auwers appears in this number of the vierteljalirs-. 

 schritt. The places depend upon tlie same authorities 

 as for the northern stars, with the addition of the Cape 

 of Good Hope catalogue for 1860, Williamstown, Mel- 

 bourne for 1870, and Harvard college (Safford) for 

 1864. For stars not observed at Pulkova, the general 

 catalogue of Yarnall (1858-1861), .and the Washing- 

 ton observations, with the new meridian circle be- 

 tween 1872 and 1875, were employed. As in the case 

 of the northern stars, these observations are all re- 

 duced to the Pulkova system for 1865. It is under- 

 derstood that the co-ordinates of the list of 303 stars 

 are to deperid upon this extension of the general 

 system of publication xiv. to the limits required by 

 the southern Durchmusterung of Schonfeld. 



It would be surprising if all the conditions of suc- 

 cess were fulfilled in the first execution of a work 

 having the magnitude, and involving the difficulties, 

 of the sclieme of observations undertaken under the 

 auspices of the gesellschaft. The extent of the dis- 

 cordances which are to be expected between the 

 results obtained by different observers can only be 

 ascertained when Ihe observations by which tbe dif- 

 ferent zones are to be connected have been reduced. 

 Each observer extended the working-list of his own 

 zone 10' north and south; and it is expected that a 

 sufficient number of observations of this kind has 

 been made to determine the systematic relations 



