[ 3*2 ] 
thread of light was formed at the internal contadl, 
but noted the time, when they judged it was juft 
ready to be formed. The 34. feet achromatic te- 
lefcopes were thofe made with 3 objedt-glaffes. 
The differences between the different obfervations 
feem pretty confiderable, and greater than I expected, 
confidering that all the telefcopes may be reckoned 
pretty nearly equal, excepting the 6 feet rcfledtor, 
which is much fuperior to them all ; and to its greater 
excellence and diftindtnefs I principally attribute the 
difference of 26" by which Mr. Hitchins faw the in- 
ternal contadl before me; as I can depend upon his 
obfervations. Poffibly the greatnefs of the differ- 
ences might arife from the low altitude of the Sun and 
Venus ; and then the like differences would not be fo 
much to be feared in places where the obfervation 
may be made at higher altitudes ; otherwife the 
fun’s parallax will not be deducible from the tranfit of 
Venus with that accuracy which has been expedted. 
The other appearances about Venus, noted by the 
fix obfervers, which they have communicated to me, 
are as follows : 
Mr. Hitchins remarks, that, at the firft contadl, 
though there was a tremulous motion in the Sun’s 
limb, yet that part of it which the planet entered 
was very well defined, and the firft impreffion of Ve- 
nus appeared to be inftantaneous, and as a black, 
fliarp point. At the internal coincidence of circum- 
ferences, the fluctuation of the Sun’s limb was in- 
creafed, and the limb of Venus being affedted in like 
manner, there was an uncertainty of about io A ' in 
effimating the faid coincidence ; but at the breaking 
in of the thread of light between the limbs, there was 
not 
