OF ARTS AND SCIENCES. 



69 



Observations on the Comet of March 4th, 1847. 



3Iade at Camhridge Observatory. Long. 4''- 44™- 32'-. 

 Corrected for refraction, and referred to the Mean Equinox of Jan. 1st 1847. 



" March 4th. The comet was first seen at 7 o'clock, in close 

 proximity to a star of the 10, 11 magnitude ; in brightness it appears 

 to be but just beyond the limit of unassisted vision. It has no visible 

 nucleus, and but slight condensation of light towards its centre. Faint 

 traces of a tail are suspected in a direction nearly opposite to the sun. 

 The observations this evening are made with the annular micrometer. 



" March 5th. From this date up to the 24th, the spider-line mi- 

 crometer was employed, the field being illuminated with red light. 



" March 6th. The comet is brighter than heretofore, showing a 

 tail of 20' in length, of a conical outline, its axis being directed 

 towards the sun. The head of the comet is very irregular, its light 

 is somewhat concentrated, but there is no well-defined nucleus, which 

 circumstance in some degree affects the accuracy of the observations. 



" March 8th. To-night, for the first time, the comet is visible to 

 the naked eye, as a star of the fifth or sixth magnitude. The angle 

 of position of the tail is n. f. 76° 30' ; consequently it is not exactly 

 in a direction opposite to the sun. The estimated diameter of the 

 light surrounding the head was four or five minutes of arc. 



" March 12th. In the comet-seeker the tail may be traced two or 

 three degrees. Angle of position of its axis is 81° n. f. 



" March 15th. The rough and irregular outline of this comet re- 

 minds one of the figures of Hevelius. Length of the tail four or five 

 degrees. 



" March 24th. The altitude of the comet at this observation 



