4 BARNARD— PHOTOGRAPHIC OBSERVATIONS [April 23, 



morning sky — the nucleus was as bright as a first magnitude star. 

 Singularly enough, the comet developed its most interesting changes 

 a month or more before perihelion passage. When near perihelion, 

 which occurred September 3, there were few changes in its appear- 

 ance from morning to morning. At that time there seemed to be 

 a uniform unbroken flow of the tail-forming particles, so that what 

 streams there were, were not individually prominent or striking. 



In the second half of July separate streams of matter were 

 frequent and formed a most interesting feature of the tail. These 

 were specially beautiful on July 17 and 19. On the first of these 

 dates the tail, where it joined the head, was made up of some five 

 broad, diverging streams, which gave it a splendid and symmetrical 

 appearance. This is really the handsomest photograph I have ever 

 seen of a comet. 



Comparatively few observatories obtained photographs of this 

 comet, which was a great pity, for it was worthy of far more atten- 

 tion from a photographic standpoint than it received. Several, 

 however, succeeded in getting results that are important. Excellent 

 photographs were obtained by Mr. W. A. Cogshall at the Kirkwood 

 Observatory at the State -University, Bloomington, Indiana, with 

 a small reflecting telescope made by himself. Though these, from 

 the limitations of the reflector, do not show a great length of tail, 

 they are specially beautiful and valuable for the structural details. 

 A good series was also obtained at Greenwich. Dr. Max Wolf 

 secured some specially valuable photographs with the 30-inch re- 

 flector, whose large scale showed the tail near the head, on several 

 dates, to be made up of a great number of thin rays. 



An excellent series of photographs of the comet was made by 

 Mr. Duncan at the Lick Observatory. Though the time interval 

 between these last and those of the Yerkes Observatory is roughly 

 only two hours, there are decided changes shown in the tail when 

 these pictures are compared with those made at the Yerkes Observa- 

 tory. Unfortunately the changes in the comet are such that there 

 are no definite markings that can be measured on the photographs 

 to determine the motion of the tail-producing particles, with per- 

 haps one exception — that of July 11. There are twelve dates that 



