VOL. LIX.] PHILOSOPHICAL TRANSACTIONS. 631 



Mr. Horsley likewise obtained from his brother, Mr. John Horsley, a mi- 

 nute of his observation made at Greenwich with an excellent refractor of Mr. 

 Dollond's, which magnified, however, only 50 times. His brother assured him, 

 that he did not see the ligament above described, though it was seen by Mr. 

 Maskelyne and by others, at Greenwich. He set down, however, two different 

 dates of the total ingress. One, which he called close contact without any light, 

 appearing between the limbs of Venus and the sun, at 7'' 28™ ] 5% apparent time 

 at Greenwich. Another, which he marked thus : ' a thread of light, fine as you 

 can imagine, appearing between,' at "J^ 29" 28'. Here is an interval of 73' be- 

 tween the close contact and the appearance of light. The time of the appearance 

 of the light being reduced to mean time, and to the meridian of Oxford (reckon- 

 ing the meridian of Oxford 3"" 4' west of Greenwich, as it is stated in Mr. Mas- 

 kelyne's Tables), was 7*^ 22™ 9% which is only 3* earlier than Mr. H.'s observa- 

 tion of the detachment of the ligament. Now hence he concludes, that though 

 the magnifying power of the telescope, which his brother used, was too small to 

 show him the shape of the ligament, yet the ligament had its effect with respect 

 to obstructing the sun's light, which he perceived about the same time as others, 

 who used glasses of greater force ; which seems to be a strong confirmation of 

 the reality of what he saw: or that there actually was a part of the sun's disk, 

 which remained obscure for several seconds after the limbs of the planet and the 

 sun were separated. 



XXV. Observations of the last Transit of Venus, and of the Eclipse of the Sun 



the next Day ; made at the House of Joshua Kirby, Esq., at Kew.* By J. 



Bevis, M.D., F.R.S. p. I89. 



In the morning of June 2, 1769, Dr. B. fixed his equal altitude instrument, 

 and carefully rectified it; and applying the proper correction to the fore and after- 

 noon's corresponding altitudes of the sun, he found that Mr. Kirby's clock, 

 whose rate of going was well regulated to mean solar time, at noon was 2™ 5' be- 

 fore the mean time; whence he deduced the apparent times of his observations. 

 June 3, in the evening, he was alone in a room where he had a very commodious 

 view of the sun. His telescope was a very good reflector, of about 3 feet and a 

 half focal length, with an aperture of near fi inches, and a magnifying power of 

 120 times; it was steadily supported, and governed by rack-work, and he had a 

 stop-watch in his hand. Mr. Kirby at the clock. 



June S'' 7'' 9™ 59' apparent time, was perceived a sudden boiling or tremor 

 at the very summit of the sun's limb, very diflferent from what is usually called 

 an undulation of his limb : 8 or 9' after which. Dr. B. called out now ! on dis- 



* Mr, Kirby's house is exactly 4'| of time east of his majesty's domestic observatory, and l" 1 4' w. 

 of the royal observatory at Greenwich. — Orig. 



