224- Royal Astronomical Society. 



serve the first contact of the solar eclipse, by placing that part of the 

 sun's limb (then very indistinct) which the moon would first touch, 

 between the parallel threads of the micrometer, applied to the nine- 

 feet equatoreal, with a power of ninety- six times. 



" As the time of contact approached the sky somewhat cleared, 

 and the moon's first impression took place at 23 h 14™ 37 s, 8 sidereal 

 time, or 20 h 18 m 24 s * 17 mean time at the observatory. During the 

 greatest part of the obscuration the sky was very cloudy, but towards 

 the end it cleared, and the last contact was well observed at l h 33 m 

 48 s, 9 sidereal, or 22 h 37 m 12 s, 45 mean time. No phenomena be- 

 yond what is usual occurred ; nor was there, to my senses, any per- 

 ceptible diminution of light on the landscape. 



" May 8. For the transit of Mercury the appearances a short time 

 before it began were still more unpromising. During the forenoon 

 we had several showers, with a most gloomy sky ; and even as late 

 as half-past three p.m. we had a smart shower of close, small rain. 

 A little change for the better occurred shortly before four, and I had 

 just time to set the micrometer by the sun's limb after he became 

 visible, and get settled at the telescope, when the first notch was cut 

 out by the planet. The sun's limb was beautifully sharp, but occa- 

 sionally obscured by passing clouds. From the time, however, of 

 the first impression until the planet had advanced about two of its 

 diameters upon the disc of the sun, it was generally unclouded, and 

 the atmosphere remarkably tranquil. The first contact took place 

 at 7 h 13 m 36 s, 3 sidereal time, or 4 h 8 m 12 s 36 mean time. The in- 

 ternal contact, or complete immersion of the planet, took place at 

 7 h 16 m 48 3, 7 sidereal, or 4 h ll m 24 s, 24 mean time. Both times were 

 carefully and, I believe, accurately noted. Whilst the planet was 

 traversing the edge of the sun, an apparent distortion took place, the 

 parts of the sun's edge, or limb, in contact with the planet, appear- 

 ing rounded off; and a moment or two before the complete immer- 

 sion of the planet, an appearance analogous to Mr. Baity' s beads 

 took place, — the planet apparently breaking contact two or three 

 times with the sun's limb before the final separation occurred. Mer- 

 cury had also, to my eye, somewhat of a pear-like shape previously 

 to his entering quite within the sun's disc. When he had advanced 

 two or three of his diameters, the clouds rapidly thickened, and 1 

 saw him no more. 



" I take this opportunity of stating, that a late redetermination of 

 the longitude of my Observatory depending upon the lately deter- 

 mined longitude of the Liverpool Observatory, inclines me to adopt 

 finally ll m 47 s- 34 as my longitude west of Greenwich, which differs 

 scarcely a quarter of a second from that given in my paper contained 

 in the forthcoming volume of the Society's Memoirs. 



" The latitude I have also redetermined lately by transits of seven 

 stars over the prime vertical, giving 53° 25' 3"*5 as the mean re- 

 sult." 



Observations of the Transit of Mercury made at Aylesbury by 

 Thomas Dell, Esq. Communicated by Dr. Lee. 



" Transit of Mercury. — The first contact of the two limba was in- 



