I *46 ] 
where I expe&ed the Moon would make the fir ft im- 
preffion; and at 8 h 59' 33" apparent time, faw a 
very flight alteration on the Sun’s limb, which I flat- 
ter myfelf may be confldered as the time of the be- 
ginning of the eclipfe very accurately afcertained ; 
lince a gentleman then prefent, with a reflecting te- 
elefcope of 1 8 inches, faw that the eclipfe was begun 
about 6 " later by the fame clock. 
As the eclipfe advanced, I propofed to meafure 
both chords and the quantity of the -lucid parts with 
a reflecting telefcope of 9 inches, armed with a mi- 
crometer executed by Mr. Dollond himfelf,and which 
was very obligingly left me for that purpofe by my 
worthy collegue the reverend Mr. Blifs. >And ac- 
cordingly at 9 h 37' 1.7" apparent time (as are all the 
times hereafter mentioned) I meafured the chord of 
the part eclipfed and found it = 25' 45", 8. At 
9 h $o / 2.4!' the unobfcured part of the Sun was — 
13' 17", 7; and at io h 3' 39" = 8' 33", 8. At 
the time of which obfervation the colour of the fky 
was remarkably changed. 
At io h 19' 15" I determined, by the old micro- 
meter applied to the 1 2 foot tube, the quantity of the 
lucid parts to be 3' 45" : but, as I found fuch mea- 
furements could not be taken with that inftrument, 
without great difficulty, I immediately endeavoured 
to determine, by the other micrometer, the quantity 
of the Moon’s horizontal diameter as feen upon the 
Sun, and found it, by a mean of three obfervations, 
hardly differing from each other, to be 29' 45 // , 1. 
It was formerly a difpute among the aftronomers, 
whether the Moon’s diameter did not appear lefs 
when viewed upon the Sun, than when feen upon a 
darker 
