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ASTRONOMICAL PAPERS. 



89 



the contad to take place, a fmall impreflion, which prov- 

 ed to be the limb of Venus in contad with the Sun. All 

 the limb of the Sun which appeared at that time in the 

 jBeld of the telefcope had a fmall undulatory motion, which 



I apprehended was occafioncd by the afcent of denfe va- 



pours at this place (being 



the fea). On the firft ap- 



pearance of Venus, it was like one of thefe fmall waves 

 on the limb of the Sun, enlarged in fo fmall a proportion, 

 that I remained doubtful for feveral feconds, whether it 

 was any thing befides. It continued making a deeper im- 

 prcffion with tliat tremulous motion for about 10 feconds,. 

 w^hen the tremor difappeared where Venus was in contact, 

 and the indenture became truly circular with an even ter- 

 mination. 



My abfence from my telefcope, juft before the conta(£l: 



occurred, deprived me of the opportunity of judging, 

 whether there was any appearance of an atmofphere pre- 

 ceding the vveftern limb of Venus as it came in contact;, 

 but when Venus had entered near one half her diameter 

 on the difl^ of the Sun, my companion and I both faw a 



luminous crefccnt, which enlightened that part of Veaus's 

 circumference which was off the Sun^ fo that the whole, 

 of her circumference was vifible;. but it did not continue 

 fo, until the firft internal contad took place. 



At the time of the internal contad, agreeable to what 

 was noted by fome of the obfervers at the tranfit 1761J; 

 « the eaftern limb of Venus feemed to be united to the 

 limb of the Sun by a black protuberance or ligament, 

 which was not broke by the entrance of the thread of 

 lio-ht," until 4 feconds after the regular circumference of 

 Venus feemed to coincide with the Sun's. 



For this obfervationi ufcd a refleaing telefcope, mag- 

 nifying about 150 times, which was in exceeding good or- 

 der at the time, and defined the limb of the Sun, andfpots 

 on its diflc, very nicely. I had applied a polar axis to it, 

 and had altered the rack work, by which I could keep the 

 fame part of the limb in the field with eafe. 



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