Appearance of Comet II. at Paris. 221 



to become ten times brighter, will probably offer appearances 

 which, will assist in the study of the physical constitution of 

 these bodies. 



SECOND NOTE FEOM M. CHACORNAC, ON THE SECOND COMET 



OF 1862. 



In continuing to describe the changes which hare occurred in 

 the present comet's head since the 10th of August, it may be 

 said that four distinct aigrettes have become disengaged from 

 the nucleus by a succession of phenomena, analogous to those 

 which were seen in Donates Comet at the time of the disen- 

 gagement of its envelopes. 



When a new aigrette is about to be developed, the nucleus 

 of the present comet assumes an elongated form, in the direc- 

 tion of the radius vector, and its extremity, turned towards the 

 sun, is terminated by a feeble tuft, ( f ''houppe") which gives it 

 the aspect of a burning torch. Some hours later, the nucleus 

 extends in the same direction, and the part facing the sun 

 becomes more diffused in enlarging. Next day, a long ray, 

 which may be compared to those observed around the sun at 

 the moment of a total eclipse, may be seen turned towards that 

 luminary, but no longer following the direction of the radius 

 vector ; it deviates therefrom by a certain angle, opposed to 

 the proper movement of the comet. Other rays, of about half 

 the size, visible on each side of that first mentioned, complete 

 the aigrette. The nucleus, then, is seen as a clearly-defined 

 luminous centre, occupying the apex of the cone formed by the 

 aigrette. These objects being sufficiently well-marked in out- 

 line, can be perceived through the vast nebulosity which 

 envelops them ; and from this nebulosity escape feeble particles 

 of cometary matter, which go to form the tail, in the direction 

 opposite to the sun. 



Later, the outlines of the rays and of the aigrette become 

 less clear, and the principal ray continues to be inclined on the 

 axis of the tail in a direction opposed to the movement of the 

 comet, in the same shape in which a flame is inflected when 

 exposed to a current of air. 



While thus inclining, the ray augments the amplitude of 

 the aigrette. When it comes to form an angle of only about 

 100 degrees with the then direction of the tail, it is extremely- 

 diffused, enlarges along with the aigrette, and their much- 

 weakened light becomes confounded at the borders with that of 

 the nebulosity. Then the nucleus again becomes oval ; a new 

 ray, a new aigrette are prepared to pass successively through a 

 set of phases similar to those we have just described. 



Thus, from the 12th to the 17th of August, we have seen 

 three rays and three aigrettes detached from the nucleus. 



