10 OBSERVATIONS OF A COMET. 



met, in order to ascertain the cause of this appearance; in 

 consequence of which I perceived several small stars shining 

 through the nebulosity of the coma. 



Jan. 14. 7 feet. " Bright, pretty large, irregular round, 

 brighter in the middle.'* 



Feb. 2. 10 feet, 24 inch aperture. " Very bright, large, 

 irregular round, very gradually much brighter in the mid- 

 dle." There is a very faint diffused nebulosity on the north 

 preceding side; I take it to be the vanishing remains of the 

 comet's tail. 



Feb. lj). Considerably bright; about \ of the field — 

 3' 26 " " in diameter, gradually brighter in the middle.'' 

 The faint nebulosity in the place where the tail used to be 

 still projects a little farther from the centre than in other 

 directions. 



Feb. 21. Less bright than on the 19th; nearly of the same 

 size*, gradually brighter in the middle. The nebulosity still 

 a little projecting on the side where the tail used to be. 



Result of the foregoing Observations. 



General infer- From the observations which are now before us, we may 

 ences. draw some inferences, which will be of considerable import- 



ance with regard to the information they give us, not only of 

 the size of the comet, but also of the nature of its illumina- 

 tion. 

 It is a solid A visible, round, and well defined disk, shining in every 



bo<1 . v » part of it with equal brightness, elucidates two material cir- 



cumstances; for since the nucleus of this comet, like the 

 body of a planet, appeared in the shape of a disk, which was 

 experimentally found to be a real one, we have good reason 

 to believe, that it consists of some condensed or solid body, 

 the magnitude of which may be ascertained by calculation. 

 For instance, we have seen, that its apparent diameter, the 

 19th of October, 6h. 20', was not quite so large as that of 

 the third satellite of Jupiter. In order therefore to have 

 some idea of the real magnitude of our comet, we may ad- 

 mit, that its diameter at the time of observation was about 

 l", which certainly cannot be far from truth. The diameter 

 of the 3d satellite of Jupiter, however, is known to have a 

 permanent disk, such as may at any convenient time be 



measured 



