132 Dr. Herschel’s Observations of a Comet, 
and irregular, especially towards the end ; it is also shorter 
than the south-preceding one. 
The shape of the unequal length of the sides of the tail, 
when attentively viewed, is visible in a night glass, and even 
to the naked eye. 
Oct. 31. 10-feet reflector. The tail continues to be better 
defined on the south-preceding than on the north-following 
side. 
Dec. 6 . The length of the tail is now reduced to about 23' 
of a degree. 
Of the Density of the Coma and Tail of the Comet. 
Many authors have said, that the tails of comets are of so 
rare a texture, as not to affect the light of the smallest stars 
that are seen through them. Unwilling to take any thing 
upon trust that may be brought to the test of observation, I 
took notice of many small stars that were occasionally covered 
by the coma and the tail, and the result is as follows. 
Oct. 2 6, 6 h 13'. Large 10-feet reflector, 24 inches aper- 
ture. A small star within the coma is equally faint with two 
other stars th&t are on the north-following side of the comet, 
but without the coma. 
7 h 30'. The coma being partly removed from the star, it is 
now brighter than it was before. 
Oct. 31, 6 h 5'. 10-feet reflector. A star in the tail of the 
comet, which we will call a, is much less bright than two 
others, b and c, without the tail. 
Two other stars, d and e, towards the south of b and c, are 
in the following skirts of the tail, and are extremely faint. 
7 h 2 o'. The star c is now considerably bright, the tail having 
