OBSERVATIONS OF A COMET. 7^ 



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. 20. "With a 7 feet reflector, and power only 75, I 

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

 more than a mere point. 



Of the Head of the Comet. 



When the comet is viewed with an inferior telescope, or if Head of the 

 the magnifying power, with a pretty good one, is either much comet - 

 too low, or much too high, the very bright rays immediately 

 contiguous to the nucleus will seem to belong to it, and 

 form what may be called the head. 



Oct. 19. I examined the head of the comet with an indif- 

 ferent telescope, in the manner I have described, and found 

 it apparently of the size of the planet Jupiter, when it is< 

 viewed with the same telescope and magnifying power. 



With a good telescope, I saw in the centre of the head a 

 very small well defined round point. 



Nov. 20. The head of the comet is now less brilliant than 

 it has been. 



Of the Coma of the Comet, 



The coma is the nebulous appearance surrounding the Us coma, 

 head. 



Oct. 19. By the field of view of my reflector, I estimate, 

 the coma of the comet to be about 6 minutes in diameter. 



Dec. 6. The extent of the coma, with a mirror of 24 inches 

 diameter, is now about 4' 45". 



Of the Tail of the Comet. 



Oct, 18. 7h. With a night glass, which has aiield of view Its tail, 

 of nearly 5°, I estimated the length of the tail to be 3 Q |; 

 but twilight is still very strong, which may prevent my see- 

 ing the whole of it. 



Nov. 20. The tail of the comet is still of a considerable 

 length, certainly not less than 2§ degrees. 



Oct. 



