[ 177 3 
count given by Mr. Mallet, the interval of time be- 
tween the true and apparent ingrefs, when the limbs 
appeared perfedtly to coincide, and when the ligament 
was obferved to be broken, did not exceed"" 53 
according to Mr. Melander’s obfervation, and amount- 
ed to 56^', according to Mr. Wargentin. This ap- 
pearance, in all probability, is occafioned by the re- 
fradtion which the rays of the Sun fuffered in palling 
through the high and denfe atmofphere of the Planet, 
and was perhaps rendered more fenfible by the va- 
pours near the horizon j as a limilar appearance was 
obferved at the fecond internal contadf, in 1761, at 
very conliderable altitudes, though in a fmaller ’de- 
gree. But it will, I fear, occalion a much greater 
uncertainty in the quantity of the Sun’s parallax de- 
ducible from thefe obfervations, than was reafonably 
expected . 
By a mean of fix obfervations, I found the Planet’s 
diameter —58'^,!;. being not greater than 59^^o 
from four of the obfervations, all agreeing precifely 
to the fame part of a fecond i nor lefs than 56'^ 9 by 
the lead: of the other two. 
About nfteen minutes after the internal contadl, a 
very thick and black cloud, which moved towards 
the eaft, with a flow motion, along the fkirts of the 
horizon, prevented any further obfervations. 
Phe next morning, the flcy being perfedtly clear, 
and the limb of. the Sun undulating but in a fmall 
degree, I made the following oblervations of the. 
Sun’s eclipfe. 
* Phil. Tranf. 1766, p. 77. 
VoL-. LVllJ, A a -^PP* 
