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fuppofed to be the period of its being vifible, at leaft 
through the Newtonian telefcope of 4 ^ foot, which 
I have made ufe of, and which magnifies the dia- 
meter of objecfts about 66 times. I have once more 
been able to compare the nucleus with a ftar of the 
6th magnitude, which is the 27th of the fextant 
according to Flamftead’s catalogue. Its pofition for 
the prefent time is fet down in the firft Table. 
I looked again for the comet the following days, 
but in vain j fo that the 3d of June put a period to 
my obfervations of this comet. The duration of 
its appearance has been 134 days, reckoning from 
the 2ifl of January, when I firfl faw it from the ma- 
rine Obfervatory. All the obfervations of the comet 
have been taken with the Newtonian telefcope, to 
which was adapted a micrometer with filken threads, 
which could be inclined every way, fo that it was an 
eafy matter to bring one of the threads to the pa- 
rallel of the comet j another parallel thread ferved to 
take the differences of declination between the comet 
and the Ifar to which it was compared. At another 
thread, perpendicular to thefe, I obferved the differ- 
ences of the paffages in right afcenfion of the ffars 
and the comet. The field of the telefcope was about 
53 minutes of a great circle. 
By this account it appears, that the comet has had 
three feveral appearances above our horizon, which 
M. De I’lfle and I had calculated as foon as I had 
made my firfi: obfervations, that is, as early as the 
month of February. 
The firfi; appearance of the comet was in the 
evening from the 2ifi; of January, to the 14th of 
February, when I ceafed feeing it by reafon of its 
r entrance 
