Comet 1887 IV: 

 = Comet e 1887. 



ASTRONOMY- 151 



wards the north and west; hist observed on April 10, at Orwell Park. 

 The ordinary formula for brightness, which assumes that the comet 

 shines by retieoted suiili<;ht only, seems to have failed in this case, as in 

 many others; in the middle of March, when its theoretical brightness 

 was 0.12 that at the time of discovery, it was apparently as well seen as 

 during- the first days of its appearance. 



Barnard's third comet of 1887 was discovered at 

 11 o'clock on the evening of May 12, in right as- 

 cension 15'', declination— 31°. On May 13 it was described by Boss as 

 having a star like nucleus of the 11.5 magnitude. It increased some- 

 what in brightness till about the middle of June, developing a tail 

 which attained a length of 5'. It moved rapidly north, and on account 

 of its brightness and favorable situation was well observed, till August 

 11. Mr. Muller has already completed a definitive orbit, and finds that 

 the observations arc represented by an ellipse somewhat better thau 

 by a parabola. 

 Comet 1887 V: Found by W. R. Brooks, of Phelps, ^ew 



=Comet/ 1887. York, on August 24, 1887. (See comet Olbers.) 



^Couiet 1«15. 



= 01beis' comet. 



=01beis-Brooks comet. 



Comet 1888 I : 

 = Comet « 1838 



Discovered by Sawerthal, at the Cape of Good 

 Hope, on February 18, 1888, or the early morning 

 of February 19, civil reckoning, the comet being readily seen with the 

 naked eye, with sharply defined nucleus of the seventh magnitude in 

 right ascension 19'', declination -560; a tail 2^ in length was visible 

 with an opera glass. The rapid northerly motion brought it, by the 

 12th of March, into view in the northern hemisphere, where it was fol- 

 lowed until September, being reported visible to the naked eye until 

 the first part of May. Thome, at Cordoba, described it as a fine naked- 

 eye object, with a tail, at its maximum, 5° in length and a nucleus of 

 three and one-half magnitude. Remarkable fluctuations occurred in 

 the brightness of the head, during the months of March aiul May, re- 

 sembling the phenomena noted in the great September comet of 1882 

 and the Pons-Brooks comet of 1881. 



On the 19th of ^Nlarch the main eighth magnitude nucleus was seen to 

 have an eleventh magnitude companion, and on the 27th of the month 

 a third faint nucleus was detected; the triple nucleus was last seen 

 on the 4th of June. Between the 19th and 21st of May it became five 

 or six times brighter than during the days immediately i)receding, and 

 from the nucleus two bright streamers were shot out, curving backward 

 on either side of the nucleus into the tail. This sudden outburst is all 

 the more difficult to account for as it occurred two months after peri- 

 helion ; it is to be regretted that no spectroscopic observations were 

 obtained at this criti(;al period. The spectroscopic observations made 

 in March and April showed a faint, broad, continuous spectrum, in ad- 



