Dr. Herschel’s Objervatlons on a Comet. 
alfo of the parallel can hardly err fo much as fifteen feconds of 
a degree. 
This, and feveral evenings afterwards, I viewed the comet 
again with fuch powers as its diluted light would permit, but 
could not perceive any fort of nucleus, which, had it been a 
fingle fecond in diameter, I think, could not well have efcaped 
me. This circumftance feems to be of fome confequence to 
thole who turn their thoughts on the inveftigation of the na- 
ture of comets ; elpecially as I have alio formerly made the 
fame remark on one of the comets difcovered by M. Mechain 
in 1787, a former one of my lifter’s in 1786, and one of Mr. 
Pigott’s in 1783; in neither of which any defined, folid 
nucleus could be perceived. 
I have the honour to remain, &c. 
If 7 1 
WILLIAM HERSCHEL. 
