58 Royal Astronomical Society. 



III. Observation of the Lunar Occultation of Venus on September 

 11, 1841, at Mr. Bishop's Observatory, in the Regent's Park. 



The occultation of Venus by the moon was observed here, but 

 not under favourable circumstances. The morning was clear, but 

 the wind easterly. The equatoreal telescope was charged with a 

 power of 105. Venus was badly defined in general, the air being 

 in a very disturbed state. The enlightened edge of the moon com- 

 pletely hid the planet at about 18 h 31 m 21 s , Greenwich mean astro- 

 nomical time. The time was not accurately noted, the observer's 

 attention being principally directed to the phenomena of the occul- 

 tation. No projection on the moon's limb, nor any distortion of the 

 form of Venus, was perceivable. The edge of the moon was well 

 seen, and sharply defined on the planet's disc. 



The commencement of the reappearance at the unenlightened edge 

 was not well caught, the planet becoming visible at some distance 

 from the centre of the field. This being instantly rectified, the dark 

 edge was well seen on the planet, which did not appear in the least 

 distorted. The reappearance was complete at about 19 h 41 m 54 s , 

 Greenwich mean time, and was observed with the power 105. The 

 air had become very smoky, and vision was extremely bad. 



IV. Notice of the Occultation of Venus on the morning of the 

 12th of September, 1841. Observed at Malta by Capt. Basil Hall, 

 R.N. Communicated by Capt. Beaufort, R.N. 



" The beginning of this interesting occultation was observed at 

 Valetta within a second of time, I think I may venture to say. An 

 unlucky cloud prevented my observing the planet's reappearance. 

 Telescope magnifying sixty times. 



" The following are the times by chronometer : — 

 First contact of the north limb of Venus with the 



south limb of the moon (civil reckoning) 



Instant when the centre of Venus appeared cut by "] 



the enlightened limb of the moon, as nearly as I >6 46 26 



could judge J 



Contact of the eastern, or enlightened, limb of Venus 1 „ > fi "\(\-c\ 

 with the eastern, or enlightened, limb of the moon J 



Chronometer slow of Malta mean time 1 6 33*2 



Mean time at Malta of the disappearance of the "1 



eastern limb of Venus behind the east limb of >7 53 9*2 



the moon J 



Difference of longitude 58 x l*8 



Mean time at Greenwich of the disappearance of 1 fi -- ,.. 



the eastern limb of Venus behind the moon. ... J 

 " The time was ascertained by equal altitudes of the sun, and, I 

 think, may be considered correct to about a second. The differ- 

 ence of longitude is taken from the Table No. 8. in Lieut. Raper's 

 recently published work, in which you will observe that the obser- 

 vatory (which is no longer an observatory) on the palace is placed 



in 14° 30' 42" = 58 m 2 s -8. But 



my house lies west of the palace 1 



Consequently the difference of longitude is 58 1 '8 



| 6 45 54 



