^ 

 ^ 



48 



MATHEMATICAL and 



per, many times in a minute, and examine the limb of the 

 Sun ftridtly, in hopes of difcovering the atmofphere of 

 Venus approach, lb as to give an opportunity of taking the 

 contads of the limbs to a great certainty. In pafEng my 

 eye along the limb of the Sun, I difcovered a fmall imper^ 

 fedion, which I thought muft be the ftroke of the atrnof-- 

 phere, but in four feconds I difcovered it to be the limb of 

 Venus, the atmofphere not being vifiblc on the Sun. The 

 time therefore that I note for my external contad is, when 

 I firil difcovered that impcrfedion on the Sun's limb, 

 which was at 2'\ 13'. 42'' apparent time. When the bo- 

 dy of Venus was fomething more than one third on the 

 Sun, 1 faw hereaftern atmofphere very diftindly refleding 

 the light of the Sun fo ftrongly on the limb of Venus, as 

 to fliew it well defined; but as it came on the Sun, it was 

 entirely loft. The time, I note for my internal contad, 

 was, when the thread of light was diftindly feen all round 

 the body of Venus, which was at 2^ 31', 28^' apparent 



I: 



tune. 



Mr. James Pearfon, having obferved the external con- 

 tad at ^ 2\ 13' . 50" apparent time, with a fmall telefcope, 



belonging to the honorable proprietaries of this province, 

 whofe magnifying power is about 60 times; Mr. Charles 

 Thompfon obferved the internal contad with the fame te- 

 lefcope, of which he gave the following account, viz, 



" At 2\ 29'. 11^' mean time, or 2\ 3I^ 26". apparent 

 time, I faw fome tremulous rays of light pafs from the up- 

 per or eaftcrn limb of the Sun to the eye, acrofs, and fo as 

 juft to touch the upper limb of Venus. Marking that 

 down therefore as the time of contad, I counted four fe- 

 conds, at which time I faw a continued thread of light, like 

 a filver lace, but ftill with a tremulous motion, round the 

 eaftcrn limb of Venus, whereby it appeared to me that the 

 whole body of Venus was then within thedifk of the Sun. 

 The tremulous appearance of the rays of light, I at firft at- 

 tributed to my telefcopc refting againft the fide of the ob- 

 crvatory, but afterwards apprehended might be owing to 

 their pafting through the atmofphere of Venus.'* The 



15" 





l^f 





fr.- 



i 



r-_^--n lIJ^IJ 



MSi yt t r .z-^v^n-t^si^iljriii^ 



-^ -^^LVJv :^l■^^^ ^Amaij _ri\ 



—. r. 'm_ 



n—r. ^ ^1 L ^ix -r 



J L-x ^_u_HJiM-' L a-^r L\K-^ u 



