ORBIT ELEMENTS COMET 1, 1899 (SWIFT). 177 



ORBIT ELEMENTS COMET I., 1899 (SWIFT). 

 By C. J. Merfield, f.ra.s. 



[Bead before the Royal Society of N. 8. Wales, December 6, 1899.'] 



Introduction. — This comet was discovered by Prof. Lewis Swift 

 of the Lowe Observatory, on the date 1899 March 3, in the con- 

 stellation Eridanus. The comet was described as bright and 

 visible to the naked eye, and having a short tail. During the 

 second week of March this apparition appeared to the writer as a 

 nebulous object of about the 6th magnitude. 



During March the comet was well placed in the western sky 

 for southern observers, and Mr. John Tebbutt, f.r.a.s., was 

 successful in obtaining twenty-six differential measures, between 

 the dates 1899 March 7, 1899 March 31, at his private observatory 

 Windsor, New South Wales. Many northern observers obtained 

 measures also, but the comet was not so well placed for them 

 during this period of visibility. Throughout the month of April 

 the comet was in proximity to the sun so that observations could 

 not be obtained. 



The comet arrived at perihelion during mid-day on April 13, 

 and about May 5 it was plainly visible to the naked eye as a 

 morning object in the eastern sky, its brightness having consider- 

 ably increased, and was well placed for observatories of both 

 latitudes. From this date forward until the end of July it has 

 been well observed by most of the leading observatories. For the 

 latitudes of the southern half of Australia the comet was just 

 below the horizon from May 27 to June 2, but Mr. Tebbutt again 

 commenced observing on June 28, and concluded a fine series of 

 observations on the evening of July 13. 



Towards the end of June the comet still remained well denned 

 as seen in large telescopes, and permitted accurate observations 

 to be made, but its distance from the earth was increasing rapidly 

 and was out of reach of ordinary telescopes during August. 



L— Dec. 6, 1899. 



