THE GREAT COMET OF 1858. 



9 



< 



T 



b) 



Q 



log? 

 logo 



p 



1858, Sept. 29.970971 ± O d .00008GO Paris Mean Time. 



O f II n 



129 6 41.21 

 165 19 12.71 

 116 58 10.55 

 85 3 55.22 

 9.7622804 

 2.19331 

 1949.7 years. 



± 0.348 



± 0.611 f Mean Equinox and Kcliptir 1858." 



± 0.290 



± 19.10 



± 0.000000616 



± 6 y .25 



The normals are represented by these elements with the following residuals 



(Ob 



rui \ 





■mi., 











A 



a cos S 



June 



14 





—0.43 



July 



13 





—0.07 



Aug. 



11 





—0.40 



Aug. 



23 





+0.30 



AS 



A a cos 8 



AS 



Sept. 5 

 Sept. 17 

 Sept. 28 



Oct. 



8 



+1.23 

 +0.32 

 +0.08 

 0.66 



+0.39 

 +0.35 

 0.89 

 0.49 



+0.93 

 +0.60 



0.44 

 0.39 



Oct. 19 



Nov. 1 



Nov. 16 



Dec. 1 



Dec. 16 



Jan. 



3 



Jan. 30 

 Feb. 26 



—0.17 



0.96 

 +0.11 



+0.3'. I 

 .32 

 +0.00 

 +0.41 

 1.21 



0.11 



+0.19 

 +0.70 



+1.97 



+0.27 



+1.42 



+0.73 

 0.22 



These residuals, although they appear quite small, do not indicate a completely 

 satisfactory solution. For the probable error derived from them is much larger than 

 that obtained from the consideration of the observations themselves. The latter 

 quantity being + 0".27, while the former, as stated above, is ±0".487. The principal 

 cause of this difference is doubtless to be sought in the small systematic errors of the 

 observations which arise from the idiosyncrasy of the observer in selecting the proper 

 point to be observed, influenced perhaps, in some degree by the size of the instrument 

 he used. In Vol. III. p. 329, of the Annals of Harvard College Observatory, will be 

 found the statement of the opinion that the observations have a tendency to place 

 the comet too near the Sun, and the smaller the telescope the nearer the Sun. Let 

 us see whether the observations confirm this supposition. Taking the comparisons in 

 declination of the best observations which go to form our normal of Sept. 17, when 

 the effect of such a tendency lies almost wholly in declination, and arranging them 

 under the head of the different observatories and in the order of the size of the tele- 

 scopes, we have the following table. The numbers beneath the names of the observa- 

 tories denote the aperture of the telescope in inches. 



vol. ix. 



16 



