NOMOS. 151 



and mysterious as the appearance. Sometimes there 

 is more than one tail, and sometimes the tails project 

 from different parts of the body ; but there is much 

 obscurity upon this and upon several other matters 

 in connection with the general history of comets ; 

 and it is better, therefore, to leave generalities, and 

 speak of the particular changes which were observed 

 in Halley's comet in 1835, for these may be said to 

 be the only particulars which are absolutely authen- 

 ticated. 



Halley's comet, then, long eagerly anticipated, 

 became visible as a small round tail-less nebula with 

 a spot brighter than the rest placed eccentrically 

 within it. On the 2d of October, 1835, the tail be- 

 gan to project from the part most removed from the 

 sun; on the 20th of the same month the tail had 

 reached its greatest length ; on the 5th of November 

 it had nearly disappeared. Concurrently with these 

 changes there was an ejection of nebulous matter 

 from the part nearest to the sun, and this ejection 

 continued at intervals for several days. On the 8th 

 of November, according to M. Schwabe, a process 

 like a " second tail " pointed towards the 

 sun. At the same time the luminous 

 nucleus underwent changes of form which J et m 

 reflected in some manner the changes of 

 the entire comet, tail-like processes being given out 

 on one side or the other, or on both sides at once, or 

 two processes on one side, and generally in a direc- 

 tion more or less backwards from the sun. The 

 comet made its first appearance after perihelion on 

 the 24th of January, 1836. At this time it was 



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