l6 PHILOSOPHICAL TRANSACTIONS. [aNNO 1770- 



thread of light was not yet formed, for still 3 or 4 broad parts of the ligament 

 never had yet broken from the sun, and therefore the thread of light was not yet 

 formed. He carefully examined the sides of those black cones connected with 

 the limb of the sun, and saw the fissures or spaces between them to be filled 

 with a steady illumination, of the colour of twilight compared with the light of 

 the sun; and while steadily attending to these circumstances, he saw the pure 

 and genuine light of the sun break in between some of those fissures like streaks 

 of lightning, which made the partial light become in 2 or 3 secomls of time, of 

 the same colour as the light of the sun, yet still the undulating ligament, though 

 reduced, was not broken. And now, 



In an instant, the northern part of the divided ligament withdraws itself from 

 the sun's limb about half way towards Venus, and instantly but gently it returns 

 and again unites the limbs of the sun and Venus; instantly after, another less 

 northern part of the ligament does the like, and then breaks off again, and so 

 does each part of the divided ligament, till 7*' 29™ 5V apparent time, when the 

 ends or vertexes of the black cones between Venus and the sun's limb appear to 

 be separated from the sun's limb, retreating to that of Venus, and dissolving or 

 dying away like a drop of tinge thrown into water, and now the thread of light 

 becomes complete. 



The internal contact being past, and Venus being wholly on the sun, Mr. D. 

 examined the space surrounding Venus, and saw such a lucid annulus around the 

 planet as appeared in 1761. The part of this annulus next to the limb of Venus 

 appeared a little dusky, but much more clear than in 1761, when it appeared 

 more confused, and as a penumbra ; but that part of the annulus farthest off 

 from the circumference of Venus appeared a little tinged with blue. The 

 breadth of the annulus about 5 or 6 seconds. On hearing a gentleman in the 

 lower apartment call out to be showed the atmosphere of Venus, Mr. D. now 

 left his telescope, went down stairs to Mr. Nairne and Mr. Dollond, and desired 

 them to be attentive at their telescopes, and they would see this shining annulus, 

 which they attended to, and after a little while saw it plainly, though for some 

 time they could not perceive any such thing. Then the other gentlemen present 

 also saw it. 



These observations being made, Mr. D. states the first external contact at 7*' 

 jgrn 37s apparent time for Greenwich. Circular contact internally at 7^ "29™ 23^ 

 Completion of the thread of light at 7^ 29™ 48% under the circumstances above 

 described. 



Though he would not willingly form any hypothesis from the aforementioned 

 phenomena, there is one of them, namely, the appearance of the well defined 

 streaks of light between the fissures, which seems accountable for thus. The 

 partial light which preceded it, he takes to be rays scattered by refraction and 



