304 



M. Struve on the 



as the precise point to be observed in determining the place of 

 the comet. The figures in the accompanying wood-cuts shew 



Fig. III. 7th Dec. 



Fig. IV. 14th Dec. 



the eccentricity of this point, as seen on the 7th and 14th of 

 December. These two figures, from the first having been 

 drawn under unfavourable circumstances, and the latter whilst 

 the moon was shining, do not quite accord in shape with the 

 correct representations in the lithographic plate. 



IV. On the 7th of November, the whole nebulous mass had 

 a diameter of eighteen minutes, and on the 30th of November 

 it had lessened to nine minutes, although, during the interval, 

 the comet had approached nearer to the earth, and although, 

 from its increased vicinity to the sun, its light should have 

 been twice as strong as on the 7th of November, and conse- 

 quently its extent and limits more clearly visible. The fact 

 of the contraction of the whole nebulous mass was further con- 

 firmed by the coincidence, on the 30th of November, of the 

 limit of the whole mass with the boundary of the more lumi- 

 nous included spot ; whereas, on the 7th of November, the 

 boundary of the spot was considerably withinside that of the 

 nebulous envelope. M. Struve is positive in the recollection 

 of his surprise at the diminished size of the comet on the 30th 

 of November, at which time he had expected to have found it 

 much larger than on the 7th ; particularly as, from its increased 

 light, it had become visible to the naked eye as a star of the 

 6th magnitude. 



