with Remarks on the Construction of its different Parts . 121 
its light appeared to be greenish, or bluish green. Its appear- 
ance was certainly very peculiar. 
The disposition of the light of the head was likewise ac- 
companied with some remarkable circumstances; for notwith- 
standing a general accumulation about the middle, there 
seemed to be a greater share of it towards the sun, than a 
portion in that situation of the circumference was entitled to, 
had it been uniformly arranged ; and if we look upon the head 
as a coma to the planetary point, the eccentricity of its light 
will be still more evident ; for this point was constantly more 
or less farther from the sun than the middle of the greatest 
brightness of the light surrounding it. The eccentricity of 
the head was indeed so considerable, that considering the dif- 
ficulty of seeing the point, it might easily have escaped the 
notice of one who locked for it in the centre of the head. 
The apparent and real Magnitudes of the Head. 
With an intention to ascertain the dimensions of the various 
parts of the comet, I viewed the head in the 7, 10, and 20 feet 
telescopes, and estimated its size by the proportion it bore to 
the known fields of the eye-glasses that were used. I shall 
only mention two estimations : September 29, the 10 feet gave 
its apparent diameter f o". With the 20 feet Oct. 6 , it was 
3 ' 45". 
From a calculati n of the 20 feet measure, which I prefer, 
it appears that the real diameter of the head at this time was 
about 127 thousand miles. 
MDCCCXII. 
R 
