60 Ohservations of a Comet. 



altitude, I examined it with 289, and having but very lately 

 reviewed my globules, T judged its diameter to be not only 

 less than my second globule, but also less than the third : 

 that is, less than 2"'4 7. 



Oct. 6. The 20-feet reflector, notwithstanding its great 

 light, does not show the nucleus of the comet larger than 

 the ten-feet, with an equal magnifier, makes it. 



Oct. 28. My large ten-feet telescope, with the mirror of 

 24 inches in diameter, dots not increase the size of the nu- 

 cleus. 



Oct. 6. Being fullv aware of the objections that may be 

 made against the method of comparing the magnitude of 

 the nucleus of the comet with objects that cannot be seen 

 together, I had recourse to the satellites of Jupiter for a more 

 decisive result, and with my seven-feet telescope, power 202, 

 I viewed the disk of the third satellite and of the nucleus of 

 the comet alternately. They were both already too low to be 

 seen very distinctly ; the diameter of the nucleus however 

 appeared to be less than twice that of the satellite. 



Oct. 18. With the ten-feet reflector, and the power 221, 

 a similar estimation was made ; but the light of the moon 

 would not permit a fair comparison. 



Oct. 19. I had prepared a new ten-feet mirror, the deli- 

 cate polish of my former one having suffered a little from 

 being exposed to damp air in nocturnal observations. This 

 new one being uncommonly distinct, and the air also re- 

 markably clear, I turned the telescope from the comet to 

 Jupiter's third satellite, and saw its diameter very distinctly 

 larger than the nucleus of the comet, i turned the telescope 

 again to the comet, and as soon as I saw it distinctly round 

 and well defined, I was assured that its diameter was less 

 than that of the satellite. 



6h. 20'. I repeated these alternate observations, and al- 

 ways found the same result. The night is beautifully clear, 

 and the moon has not yet risen to interfere with the light of 

 the comet. 



Nov. $0. With a seven-feet reflector, and power only 75, 

 I can also see the nucleus; it is extremely small, being little 

 more than a mere point. 



Of 



