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of the Sun’s altitude at that time, made the limb To 
very ill defined and undulating, that it is poflible 
{here may be an error of five or fix feconds, at Icaft, 
*n the time' of the external contadl ; being anxious, 
iherefore, of having the internal contadf as exadt as 
pofiiblc, I changed the magnifying power of my 
telefcope from that of 125 times, recommended by 
yourfelf, to that of 55 times, the leaft of all, which 
lucceeded beyond expedlation ;; for by this means 
that undulating motion of the Sun’s limb was 
greatly reduced, though not entirely taken away, 
appearing much better defined than before, as did 
likewife that of the Planet Venus ; infomuch that 
the error, if any, in the time of the internal 
contadl, by which I mean the completion of the 
thread of light formed by the Sun’s circumference, 
cannot exceed three feconds. The obferving of the 
two contadls with fo different magnifying powers as 
that of 125 times and that of 55 times, muff: occa 
fion fome difference in the times, and duration be- 
tween the two contadfs, to what they would have 
been, had they both been obferved with the fame 
magnifying power ; which is to be allowed for. 
Venus appeared remarkably protuberant on hef 
upper limb, both before and at the time of her in- 
ternal contadf, which went gradually off foon after, 
but did not, though I earneffly attended to it, ob- 
ferve any thing like an atmofphere about her. 
Be pleafed. Sir, to accept of my bed thanks 
for the ufe of your glafs roof and tranfit-inftrument, 
as likewife for your very obliging and ufeful 
communications, at different times, on the prefent 
fubjcdt, 
