50 



ASTRONOMICAL PROGEESS AND PHENOMENA. 



of these bodies have been discovered. Fol- 

 lowing is the list, with their numbers, the 

 dates of their discovery, and the names of their 

 discoverers. Nos. 249 and 250 belong to last 

 year's list, but were then unnamed : 



Comets. The following-named comets have 

 been discovered since the last report. They 

 are enumerated, as all comets should be, in the 

 order of their discovery, thus saving much 

 confusion and alteration of numbers. 



Name of discoverer. Date of discovery. 



Fabry Dec. 1, 1835. 



Barnard Dec. 3, 1885. 



Brooks Dec. 26, 1885. 



Brooks (1) April 27, 1886. 



Brooks (2) May 1, 1886. 



Brooks (4) May 22, 1886. 



Winnecke's periodic, by Finlay Aug. 19, 1886. 



Finlay Sept. 26, 1886. 



Barnard Oct. 4, 1886. 



The first two were remarkable in respect to 

 the brilliancy to be attained about the time of 

 perihelion passage, but, unfortunately, both at 

 that time were so near the sun as to be seen 

 with difficulty, notwithstanding their intrinsic 

 brightness. According to the ephemeris of 

 Dr. S. Oppenheim, the theoretical brightness 

 of Fabry's comet on May 1, 1886, was 461, its 

 brightness at discovery being taken as unity, 

 and that of Barnard's 371. The prediction 

 that the world was to be treated to the un- 

 heard-of spectacle of two comets simultane- 

 ously visible, which in splendor would prob- 

 ably surpass any seen in recent times, aroused 

 great curiosity, which was followed by disap- 

 pointment correspondingly great at the failure 

 of its accomplishment. It is not always that 

 comets appear as bright as theory demands, 

 and, owing to the position relative to the sun 

 and the earth, they sometimes are not seen at 

 all, even with the telescope. For a like reason, 

 a comet that has for its period a mixed num- 

 ber of years, as five and a half, six and a half, 

 etc., can ordinarily be seen only at alternate 

 apparitions. As a late instance, Swift's peri- 

 odic comet of 1880, whose period is about five 

 and a half years, was seen in 1 869, but escaped 

 detection at its approach to pevihelion in 1874, 

 and also in 1886. In 1891 it will be on the 

 same side of the sun as the earth, and will, 

 therefore, be in the best position possible for 

 observation and early detection. At its peri- 

 helion passage in May, 1886, its theoretical 



brightness was only 0-086, that of 1880 equal 

 to unity. 



Winnecke's periodic comet was detected by 

 Finlay at the Cape of Good Hope on Aug. 19, 

 1886. This comet was first seen by Pons on 

 June 12, 1819, and not again observed until 

 rediscovered by Winnecke on March 8, 1858. 

 At its next return it again escaped detection, 

 but was refound by Wiunecke in 1869. In 

 1875 it again eluded observation. This is its 

 fifth observed return. Its periodic time is 5*64 

 years, subject to some variation by the influ- 

 ence of Jupiter. It is now visible in the even- 

 ing sky, low in the south, as a very faint nebu- 

 lous object. 



In the last volume, the number of periodic 

 comets was given as sixteen, counting Biela's 

 lost divided comet as two. The later discov- 

 eries increase this number to eighteen, viz., 

 Brooks's third and Finlay's, which is a return 

 of De Vice's lost comet of 1844 (?). Of course, 

 Brooks's comet has not been seen to return to 

 perihelion ; but there is among astronomers 

 such a close agreement in regard not only to 

 periodicity, but also to its length of period, 

 that there can be little doubt of the fact. And 

 the same may be said of Barnard's, Wolf's, and 

 Denning's comets. The following are the el- 

 liptic elements of Brooks's periodic comet, by 

 Dr. S. Oppenheim: 



Time of perihelion passage = T June, 6.815958 (Ber- 

 lin mean time). 

 Distance from node to perihelion = it Q, 176' 50' 13'3". 



Longitude of node = O '.. 525'56-2". 



Inclination = i 13" 23' 48'0". 



Logarithm of perihelion distance = q 0' 133357 



Logarithm of eccentricity = 9 -836962 



Logarithm of mean distance = a 0- 637824 



Period 9'05 years. 



Motion direct = + 



The elements of Finlay's comet, by Dr. A. 

 Krueger, are : 



T = 



TT n = 



Lon.fi = 



4 = 



Log. a = 



Period... 



Motion 



1886, Nov.. 22-234427 Berlin mean time. 



316 4' 15-7". 



58' 11' 49 -4". 



2" 59' 24- 6" 



0.11116 



5ft years. 



Prof. Boss, who first suggested the identity 

 of Finlay's comet with De Vico's, has com- 

 puted for it another set of elements, making 

 its period 4'32 years. If this be confirmed, it 

 becomes, except Encke's, the shortest period 

 comet known. 



During 1885, seven comets, including one 

 periodic (Tuttle's) were seen and carefully 

 observed ; while one, a well-known periodic 

 (Tempel's, 1867, II) was not found. It was a 

 faint object, and unfavorably situated for ob- 

 servation. It has a period of almost exactly 

 six years. Thus far in 1866 (Dec. 5) six have 

 been discovered, including one periodic (Win- 

 necke's), while another periodic (Swift's) has 

 eluded search. For the past two years the 

 number has been above the yearly average. 

 The greatest number ever seen in any calendar 

 year is eight, and that only three times, viz., 

 in 1846, 1858, and 1881. Olbers's comet of 



