142 ON THE COMET OF SEPTEMBER 1862. No. 1. 



The line connecting the two nuclei appeared to be nearly coin- 

 cident with a parallel of declination, having, in fact, the same 

 direction as the major axis of the large elliptical nucleus of the 

 preceding evening. On the evening of the 3rd the nucleus was 

 scarcely distinguishable, in consequence partly of the increase 

 of the moon's light, partly of the increase of the comet's distance 

 from both the earth and the sun, and partly of the haziness of 

 the atmosphere. The evening of the 4th was very cloudy. The 

 clouds broke once and revealed the comet, but it again clouded 

 over before I could make any observation. Some good observa- 

 tions were made on the 5th, but the stars of comparison cannot 

 be identified with any in the catalogues in my possession. The 

 comet's nucleus on this occasion was much more sharply denned, 

 and presented a very interesting appearance. It appeared single, 

 but there extended from it a narrow beam of light in the direc- 

 tion of the sun. The beam gradually increased in breadth as it 

 extended from the nucleus, and resembled that seen on July 4th, 

 1861, in the great comet of that year, by the Rev. T. W. Webb, 

 of Hardwick, Herefordshire, England. I estimated it to be 

 about two minutes of arc in length. The physical changes of the 

 comet during the first week of September were remarkable, and 

 an account of them will be awaited with interest from those 

 possessed of more powerful instrumental means. The nebulosity 

 surrounding the nucleus was pretty extensive, being upwards of 

 six or eight minutes in diameter. The observations of the first 

 three evenings being carefully reduced, a process rather trouble- 

 some, owing to the rapid movement of the comet in declination, 

 the calculation of the orbit was immediately proceeded with. Mr. 

 Hawkins of Goulburn, published an approximation on the 13th, 

 which, though based on rough observations, was sufficiently ac- 

 curate to show that the comet was not to be identified with any 

 whose elements had hitherto been computed. On the 16th, my 

 first approximation appeared as deduced from the observations of 

 the first three evenings. [See the set of elements marked I., at 

 the end of this paper.] These were found to represent the obser- 

 vations of the 7th within a few seconds of arc ; those of the llth, 

 within about three minutes ; and, finally, on the 1 7th, the dis- 

 crepancy between the observed and computed places amounted 



