COMETS. 551 



short period, 6| years in its revolution, has separated into 

 two comets of similar figure though unequal dimensions, 

 both having a head and tail. So long as they could be ob- 

 served, they did not unite again, and proceeded on their 

 course separately, almost parallel with each other. Hind 

 had, on the 19th of December, 1845, already remarked a kind 

 of protuberance towards the north; but on the 21st there 

 was, according to Encke's observation in Berlin, still no 

 signs of a separation visible. The subsequent separation was 

 first detected in North America on the 29th of December, 

 1845 ; in Europe, not until the middle and end of January, 

 1846. The new smaller comet proceeded towards the 

 north. The distance of the two was at first 3', after- 

 wards (February 20th), according to Otto Struve's interesting 

 drawing, 6'. M The luminous intensity varied in such a 

 manner that the gradually increasing secondary comet for 

 some time exceeded the principal comet in brightness. The 

 nebulous envelopes which surrounded each of the nuclei had 

 110 definite outlines : that of the larger comet indeed showed 

 a less luminous protuberance towards S.S.W. ; but the space 

 between the two comets was seen at Pulkowa quite free from 

 nebulous matter. 26 A few days later. Lieutenant Maury in 

 Washington remarked, with a nine-inch Munich refractor, 

 rays which proceeded from the larger older comet to the 

 smaller new one, so that a kind of bridge-like connection was / 



25 The subsequent (5th of March) increase of distance seen 

 to the extent of 9 19' was, as Plantamour has shown, merely 

 apparent and dependent upon the approximation to the Earth. 

 Both parts of the double comet remained at the same distance 

 from each other from February until the 10th of March. 



26 " Le 19 Fevrier, 1846, on ape^oit le fond noir du ciel 

 qui separe les deux cometes." Otto Struve, in the Bulletin 

 pliysico-mathematique de VAcad. des faiences de St. Peters- 

 lourg, torn. vi. no. 4. 



