L 337 ] 
vertical diameter than he expefted it, but in the very 
pohit, however, where it was clearly feen imnie- 
diately alter. 
h ' n 
W Wllfon. •[ 54 28 
|_ iiuernal ccntad "] \z z\. 
My fon dehrcs me to remark, that his firfl obfer- 
vation Ihould be confidered as no. other but a pofterior 
confirmation of Dr. Wiiiiamfon’s and Dr. Reid’s ex- 
ternal contadf ; the fact was, that when thefe gentle- 
men perceived the firlf contadt, their keennefs made 
them call out, and it was not till then that he faw 
the pha^nomenon with perfedl certainty. He was 
confcious, however, that he fludtuated concerning 
the reality of the appearance for about twelve feconds 
before that time, during which his determinations 
were fufpended, through an apprehenfion of antici- 
pating the real time, which was heightened by fo 
clofe a neighbourhood with the other obfervers, all of 
whom he could not help being fenfible were hill ex- 
pelling the phaenomenon. Upon the whole, he is 
rather of opinion that he would have put down the 
external contadl at lead eight feconds fooner had he 
been obferving apart. His fecond obfervation, by 
which he means the inftant when the interval be- 
tween Venus and the Sun’s limb fird appeared ob- 
vious, was taken down without the lead knowledge 
of what was pading among the other gentlemen who 
obferved. Dr. Irvine has been out of town for fome 
confiderable time pad, and forgot to lodge his obfer- 
vations with me, but I remember certainly that he 
made the external contadl three feconds fooner than 
the red j but his internal contadl was fome feconds 
Voi,. LIX. X X later, 
