CONSTRUCTION OF COM£f% &C, 295 
It will be necessary to mention that in the calculations be- 
longing to this comet, I have used the elements of Mr, Ga/us, 
with a small correction of the longitude of the perihelion, 
which I found would answer the end of giving the observed 
place with sufficient accuracy from the 1st of January to the 
20th. These calculations may however be repeated, if here- 
after we should obi a n elements improved by additional obser- 
vations, made with fixed 'instruments ; but the result, I may 
venture to say, will not be materially different. 
The distance of the comet from the earth, the 20th of Ja- and its dm-* 
nuary, when its apparent diameter was determined,, was 1 ,0867* 
the mean distance of the earth from the sun being 1 5 whence 
we deduce a very remarkable consequence, which is, that the 
real diameter of its nucleus cannot be less than 2037 miles. 
The Chevelure of the Comet. 
Instead of that bright appearance, which in the first comet Examination 
has been considered as the head, there was about the nucleus 0£ tiie 
of the second a faint whitish scattered light, which may be 
called its chevelure. 
Jan. 1. Examining the chevelure of the comet with a 10 
feet reflector, I found that it surrounded the nucleus, not in 
the form of a head consisting of gradually much condensed 
nebulosity, but had the appearance of a faint haziness, which 
although of some extent, was not much brighter near the 
nucleus than at a distance from it. 
Jan. 2. I viewed the two comets alternately. The first 
could only be distinguished from a bright globular nebula by 
the scattered light of its tail, which was still 2 ' 20' long. The 
* second comet, on the contrary, had nothing in its appearance 
resembling such a nebula : it consisted merely of a nucleus, 
surrounded by a very faint chevelure j and had it not been for 
an extremely faint light, in a direction opposite to the sun, it 
would hardly have been entitled to the name of a comet $ 
faint object to measuring it with, a micrometer, which requires light 
to show the wires, and a high magnifying power to give an image 
[ sufficiently large for mensuration ; neither of which conditions the 
present comet would adjnit, 
O 2 
having 
