AT HUDSON OBSERVATORY. 



147 



comet into the middle of the field, and, by rapidly turning the screw of the de- 

 clination circle, brought it to the margin of the field. The graduation, which 

 is to 10", was then read off. I performed the same operation with the star of 

 comparison, and repeated the process several times. These observations occu- 

 pied nearly the whole of the evening that the comet could be conveniently ob- 

 served. I thus obtained differences of right ascension and declination between 

 the comet and known stars. The following table exhibits a summary of the 

 observations. The place of a Arietis is from the Nautical Almanac; of 0' Arietis 

 from Pond's Catalogue of 1112 Stars; and of yi and t^ Arietis from the Astro- 

 nomical Society's Catalogue. 





Sideiial Time 

 at Hudson. 







Apparent Places of the Stars. 



Comet minus Star. 1 



1840. 



Star. 



Mag. 



A 



E. 



Dec. 



A. E. 



Obs. 



Dec. 



Obs. 



March 18 



7h 45°^ 28^67 

 7 56 12.98 



a Arietis 



3 



li» 58"' 



9».76 



-1-22° 



42' 16".3 



+ 



32^80 



5 



+ 7'30".9 



2 



19 



7 39 15,25 







1 58 



9.76 







+ 140 .94 



8 









7 40 38.96 











4-22 



42 16 .2 









— 25 14 .2 



3 



21 



8 11 13.89 

 7 39 26.77 



ri Arietis 



6 



2 3 



50.54 



-1-20 



27 20 .6 



+ 



12,80 



10 



+ 47 11 .8 



3 



25 



8 7 43.76 

 8 29 19.58 



9' Arietis 



6 



2 9 



14.21 



+ 19 



9 34 .9 



+ 



85.80 



5 



+ 5 48 .2 



4 



April 18 45 10.65 



\ Arietis 



6 







+ 16 



59 44 .1 









— 51 42 .9 



1 



2 8 49 41 .00 







2 22 



2.12 







+ 



38.00 



3 







8 24 21 .01 











+ 16 



59 44 .2 









— 77 29 .3 



2 



From these data we obtain the apparent places of the comet affected by 

 parallax, and the difference of refraction of the comet and stars of comparison. 

 In the following table these corrections are applied, and the times reduced to 

 Berlin Observatory, by adding 6'' 19" 22'.3 for difference of longitude. 



1840. 



Berlin Mean Time. 



Comet's A. E. 



Comet's Dec. [ 



March 18 



14h Igm 



12^34 



29° 



40' 43", 8 









14 28 



54.89 







+ 22° 



49' 51",8 



19 



14 8 



4,04 



30 



7 45 .1 









14 9 



27.52 







22 



17 5 .9 



21 



14 32 



5.63 



31 



1 2 .5 









14 



23.72 







21 



14 49 ,0 



25 



14 12 



52.44 



32 



40 7 .8 









14 34 



24.72 







19 



15 35 ,1 



April 1 



14 22 



41 .82 







16 



7 29 .7 



2 



14 23 



15,53 



35 



39 25 .0 









13 57 



59.69 







15 



42 2 .0 



