Comet 1886 I : 



=Comet d 18S5. 

 :=Fabry's comet. 



ASTRONOMY. 121 



esting observations of the tail, accompanied by numerous sketches, are 

 found in vol. i of the Publications of the McCormick Observatory, the 

 observers being Messrs. Leavenworth and Jones. 



Comets of 1886. — Nine comets passed perihelion in 1886 ; three of them 

 visible to the naked eye. One was a well-known periodic comet return- 

 ing at the appointed time, and two of the new-comers appear to be 

 periodic, one of them identical possibly with De Vico's lost comet of 

 1814. Olbers's comet of 1815 was not detected, but as an uncertainty of 

 some three years exists in the period of revolution, it may be picked up 

 during the coming year. The Tempel-Swift comet due at perihelion on 

 May 9 seems to have escaped notice on account of its excessive faint- 

 ness. Of these nine comets, three belong to Barnard, three to Brooks, 

 two were found by Finlay, and one by Fabry ; two were discovered in 

 1885, one in 1887 ; leaving six discovered in 1886. Comet 1886 IX was 

 picked up by three observers independently, on three successive morn- 

 ings in October, showing what a careful watch is kept by comet hunt- 

 ers. Warner prizes to the amount of $800 were paid for the captures. 

 This comet, as noted in laj>t year's report, was dis- 

 covered on December 1, 1885, at Paris. From a 

 faint little patch of nebulosity it grew steadily in 

 size and brightness, and on March 29, 1886, Fabry described it as hav- 

 ing a diffused nucleus about 15" in diameter, comparable with a star of 

 the seventh magnitude ; a tail about 20' long and 4' broad, was thrust 

 out in a i)osition angle of 325°, while the nebulosity extended about 1'. 5 

 beyond the head. It became rapidly more prominent, and on April 3 

 was visible without difficulty to the naked eye. On April 23 the head 

 was as bright as a third-magnitude star, and the tail 4° long. The 

 greatest length of the tail was probably about 9°, but the comet was not 

 a very conspicuous object on account of its slight elevation above the 

 horizon before sunrise, and also on account of the moon light. It is said 

 to have remained visible to the naked eye from the early part of April 

 to beyond the middle of May. Observations were continued in the 

 southern hemisphere until about the end of July. 



The determination of the orbit presented some difficulties, and the 

 elements from early observations were not entirely accordant. Dr. S. 

 Oppenheim's elements (Astrou. Nachr., 2722), derived from observa- 

 tions extending to March 28, placed perihelion passage on April 5, 1886 ; 

 the nearest point to the earth and greatest brilliancy (about four hun- 

 dred and seventy-five times as bright as when discovered) were reached 

 about May 1. 



The spectrum was studied by Trepied, Perrotin, Kayet, Vogel, and 



others. The three bands common to comets and hydrocarbons were 



found — the central band, perhaps, somewhat intensified ; and besides 



these bands there was also a continuous spectrum. 



Dr. MuUer, of Potsdam, has published in the Nachrichten (ISTo. 2733) 



