OF ARTS AND SCIENCES. 



169 



Mr. Bond also presented the subjoined 

 Observations on Mauvais's Comet of July 4th, 1847. 



^^ July I4th. The comet was first seen at IP- 45"- P. M- ; but 

 after watching its position for some time, we could detect no indication 

 of motion relatively to the neighbouring stars, so that it was not recog- 

 nized as a comet until six days after. Its position, as given above, 

 was taken from the circles of the five-foot equatorial. 



" July 20th. The comet was observed to-night with the five-foot 

 equatorial, using the annular micrometer for the comparisons. It 

 disappears sharply behind the ring, with almost as much certainty as a 

 star ; indicating a sudden condensation of light at the centre. This 

 was afterwards confirmed, on examination v/ith the great refractor 

 recently mounted in the dome of the Observatory. With the full ap- 

 erture of fifteen inches, a very minute stellar point is visible in the 

 centre of the comet, with a sparkling light, easily distinguishable from 

 the diffused nebulosity which surrounds it. 



" July 23d. The observations were made this evening with the great 

 equatorial, by differentiating with the hour and declination circles. 

 In high declinations this method allows the comparisons to be oftener 

 repeated than is otherwise practicable. In declination the comparisons 

 have a better mutual agreement than we have been able to obtain 

 when using the annular micrometer. 



" July 24:th. The comet does not sensibly increase in brightness. 

 The stellar point is visible through strong moonlight. 



" Sept. 3rf. The comet still shows a star-like nucleus. A faint tail is 

 visible, of six or eight minutes in length. 



" October llth. The differences of right ascension this evening 

 are somewhat uncertain, the altitude being too low for accurate obser- 

 vations. 



" It seems necessary to remark, that the above places of the comet 



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