68^ PHILOSOPHICAL TRANSACTIONS, [aNNO 176Q. 



cerning, at the same place, a very small indentation of Venus. He thinks he 

 may put the external contact about 3* sooner. 



At 7^ 28'" 8^* the planet seemed quite entered on the disk, her upper limb 

 being tangential to that of the sun : but instead of a thread of light, which he 

 expected immediately to appear between them, he perceived Venus to be still 

 conjoined to the sun's limb by a slender kind of tail, nothing near so black as her 

 disk, and shaped like the neck of a Florence flask. 



At 7^ 28™ 17* the said tail vanished at once, and, for a few seconds after, the 

 limb of Venus, to which it had been joined, appeared more prominent than her 

 lower limb, somewhat like the lesser end of an egg, but soon resumed its ro- 

 tundity. 



In a few minutes more the whole circumference of Venus became very ill de- 

 fined, and beset with asperities. These were amazingly agitated by a sort of 

 curling quick motion, not easily to be described. A gentleman of his acquaint- 

 ance fancied Venus, in this circumstance, to resemble a black wafer on the head 

 of a beaten drum. In the transit of Venus, in 1761, which Dr. B. observed at 

 Savile-house, he saw not the least of such appearance at the exit. The planet 

 was then perfectly circular and well defined. The sky, though for the most part 

 of the day clouded over, was all this while very fine. 



At 1 8*^ S^*" l6» the sun's eclipse began, perhaps, 2 or 3' sooner. 



At 20'' 22*" 33* the eclipse ended, very exact. 



XXVl. Observations of the Transit of Fenus, June 3, 1769, and of the Eclipse 

 of the Sun the next Morning. By John Canton, M.J., FIR.S. p. 192. 



About half a minute before the total ingress, when the bright cusps of the sun 

 were at some distance' from each other, there appeared a faint light between 

 them, a little lower than the cusps, or nearer to the centre of the planet : this 

 increased till the time of the internal contact; which fully convinced Mr. C. that 

 there is an atmosphere about Venus. The longitude of Spital-square, west of 

 the royal observatory, Mr. C. formerly found by Rocque's survey, to be l6«-J- of 

 time; and lately, by observing the explosions of rockets, it was found to be 17'-tV- 

 He therefore adds 17» to his time, to bring it to that of Greenwich. The mag- 

 nifying power of his telescope was 95. 



1st external contact at 7" 8- 28'J | ^^^^ ^.^^ 



1 St internal contact at 7 2o 59^ J 



Duration of the ingress 18 31 



Equation of time 2 15| add 



ist external contact at 7 10 ^^Ug t ti^^. 



1st internal contact at 7 29 1 34 J i^*^ 



Tlie diameter of the sun, from 3 observations, was 31' 35"J 



Venus, from 4 observations 59 



At 7* 38" 31', apparent time, the right ascension of $ was greater than that of the O by 8' 7". 



