[ 30 ? ] 
weather became perfectly clear in lefs than the fpace 
of one hour, and continued the day following, as 
well as the day of the tranfit, in fuch a hate of fe- 
renity, Iplendor of funfhinej and purity of atmo- 
fphere, that not the leah appearance of cloud was to 
be feen in the vvhole heavens. 
June 2, and the forenoon of June 3, were fpent 
in- making the neceffary preparations j fuch as, exa- 
mining and marking the Jhd of the telefcopes, parti- 
cularly the refledlor with and without the micrometer^ 
and in its different powers. The refiedor was alfo placed 
on a polar axis j and fuch fupports were contrived 
for refting the ends of the refradors, as might give 
them a motion as nearly parallel to the plane of the 
equator as fuch haffy preparations, would permit. 
Several diameters of the Sun were taken during this 
time, and the micrometer examined by fuch other 
methods as the time would allow. 
The Sun was fo intenfely bright on the day of 
the tranfit, that it was found beflj early in the fore- 
noon, to lay afide the coloured glalfes, brought with 
the refleding telefcope from England ; and to put on 
deeply-fmoaked glaffes, which Mr. Lukens prepared, 
in their room j and which gave a much more beau- 
tiful and well-defined appearance of the Sun. 
Mr. Rittenhoufe, on a fuppofition of the Sun’S 
horizontal parallax being but 8'^, had, in one of his 
calculations of the time of the tranfit, made in Sep- 
tember, 1768, brought out the firfl external contadj 
at Philadelphia, to be June 3, 2^ i T, mean time. 
It happened, that he was not many feconds wrong in 
this, although moft other calculations made it from 
6 ' to 8' later for Philadelphia. 
R r a 
Wc 
