OBSERVATIONS. 



clvi 



a. OBSERVATIONS OF MARS I. WITH THE CAMBRIDGE EQUATORIAL. 



A comparatively large number of observations of right-ascension only are given in the present 

 volume ; as these however not only have no relation to the problem before us, but are incapable, 

 under any circumstances, of furnishing a trustworthy value for the parallax, (s. Astronomical 

 Journal, N. 103,) they have not been critically examined. To the observations for declination 

 the following corrections or modifications have been applied : 



Page 453, November 15, 16. The "unknown star" is the comparison-star of the preceding day. (Bessel Z. 348.) 

 454, " 16,17. The comparisons were evidently with the south limb, not the north. 

 457,, December 17. Mean it, for 3' 34". 69 read 0' 34". 69. 

 458, " 27. The planet was tauth of Bessel Z. 405, not north. 



458, " 29,30. There is some undetected error here.- 



459, January 1. The comparisons are neither accordant with one another nor with the mean. The second 



series, upon reduction, gives A(5 = 0' 34". 10 0". 02 = 0' 34". 08 ; but even then the 

 . difference between the north and south limb is nearly twice the diameter of the planet. 

 The comparisons will, if used as follows, give nearly the average accordance with the 

 Ephemeris : 



Mars, S. limb, N. of Bessel 405. 

 Corr. Sid. time. Microm. 



Adopted 

 zero. 



460, 

 460, 



Chron. 



1A. 54m. 40s. 8. 59s. 4. 1A. 53m. 41s. 4. 



and the values have been assumed. 



' 5, results, line 1, Mean A<>, for V 45". 19 read 2' 4". 10. 



3, " " 1 45 .01 " 2 4 .01 



' 5, " 3, Microm. " ST. 394 " 18r. 394 



' Micrometer 

 Kev. Arc. 



Oorr. 



53r.428. 50r. 034. 3r. 394 33". 26 0. 02 33. 24 



The Cambridge series will then be as follows : 



MA Us I. 



Observations with the Cambridge Equatorial. 



