[ 66 ] 
broken, though faintly. Another circumftancc was, 
that the limb of Venus, near the point of contact, 
left its circular form. But the inftant of time when 
the thread of light was broken being the objedt in 
view, I omitted a detail of thofe particulars. 
In the late tranfit, June 3d, 1769 , 1 carefully ob- 
ferved feveral circumftances attending that pheno- 
menon, which feem to me abfolutely neceflary to 
be attended to, in order to the exadt determination 
of the time when the internal contadt happened 3 a 
particular account of them is as follows 3 viz. _ 
Receiving an invitation from the prefent Aftronomer 
Royal to be at the Royal Obfervatory at Greenwich, 
at the time of the late tranfit, I determined to be 
there, rather than any where elfe, thinking that the 
experience which I had had of the former tranfit 
would enable me to make fuch an obfervation as 
might be acceptable to poflerity. 
The time came, and the weather proved favour- 
able for making that obfervation, with all the exadt- 
nefs that could be wifhed for or defired. Several 
hours before the tranfit, having a very diftindt idea 
of the circumftances which appeared in forming the 
internal contact of Venus with the fun’s limb, June 
6, 1761, and being almoft certain fomething of the 
fame kind would now happen, I drew out fmnll cir- 
cular diagrams, reprefenting Venus at feveral near 
diftances within the fun’s difc, with the like obfcu- 
rity near the point of contadt as I had obferved in 
the tranfit of 1761, and requeued Mr. Hirft, Mr* 
Dollond, and Mr. Nairne, who were likewife to 
obferve, to ufe their utmcft endeavours for de- 
termining whether any fach impediment occurred 
or 
