348 Dr. Herschel’s Observations of a Comet , 
telescope is a little tinged with red ; but less so than that of 
Arcturus to the naked eye. 
Magnitude of the Nucleus. 
Oct. 26. In order to see the nucleus as small as it really 
is, we should look at it a long while, that the eye may gra- 
dually lose the impression of the bright coma which surrounds 
it. This impression will diminish gradually, and when the 
the eye has got the better of it, the nucleus will then be seen 
most distinctly, and of a determined magnitude. 
Oct. 4. With a 7-feet reflector I estimated the diameter of 
the nucleus of the comet at first to be about five seconds, but 
soon after I called it four, and by looking at it longer, I sup- 
posed it could not exceed three seconds. 
Oct. 6. 10-feet reflector, power 221. The apparent disk 
of the comet is much less than that of the Georgian planet, 
which being an object I have seen so often with the same in- 
strument and magnifying power, this estimation from memory 
cannot be very erroneous. 
Oct. 5. Micrometers for measuring very small diameters, 
when high magnifying powers cannot be used, being very 
little to be depended upon, I erected a set of sealing wax glo- 
bules upon a post at 2422 inches from the object mirror of 
my 10-feet reflector, and viewed them with an eye-glass, 
which gives the instrument a power of 221, this being the 
same which I had found last night to show the nucleus of the 
comet well. I kept them in their place all the day, and reviewed 
them from time to time, that their magnitudes might be more 
precisely remembered in the evening, when I intended to 
compare the appearance of the nucleus with them. 
