[ * 5 * ] 
XII. Obfervations on a Comet. In a Letter from William 
Herfchel, LL.D. F. R. S. to Sir Jofeph Banks, Bart » 
P. R. S, 
Read April 2, 1789. 
S I R, Slough, March 3, 1789, 
T HE laft time I was in town, you expreffed a wifh to : fee 
my obfervations on the comet which my lifter, Caro* 
line Herschel, difcovered in the evening of the 21ft of laft 
December, not far from /3 Lyrae. 
As (he immediately acquainted the Rev. Dr. Maskelyne, 
and feveral other gentlemen, with her difcovery, the comet 
was obferved by many of them. The Aftronomer Royal, in 
particular, having, I find, obtained a very good fet of valuable 
obfervations on its path, it will be fufficient if 1 communicate 
only thofe particulars which relate to its firft appearance, and 
a few other circumftances that may perhaps deferve to be 
noticed. 
December 21, 1788, about 8 o’clock, I viewed the comet 
which my fifter had a little while before pointed out to me with 
her fmall Newtonian fweeper . In my inftrument, which was a 
ten-feet refle&or^ it had the appearance of a confiderably 
bright nebula ; of an irregular, round form ; very gradually 
brighter in the middle ; and about five or fix minutes in dia- 
meter. The fituation was low, and not very proper for inftru- 
ments with high powers. 
2 
December 
