50 



MAT H E M 



AND 



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After the obfervatioa of the contads, I applied myfelf 

 to the micrometer to meafure the diameters of the Sun and 

 Venus, and thcdiftance of their limbs at fundry times du- 

 ring the tranfit. I had indeed frecpently meafured tlie 

 ■equatorial diameter of the Sun before the day of the tranfit, 

 and always found it to be 6 fcconds Ms than what is given 

 in the nautical almanac. The mean of 6 mcafures on that 

 day is 31'. 3i".6, which differs but o",3 or three-tenths 

 of a fccond from what is given in the faid almanac leffened 

 as above. Therefore I have ftated it at 3 1 ' . 3 1 ".3 in the 

 following reduftions and calculations. 



Six meafures of the diameter of Venus on the Sun made 

 it 58 fcconds. I attempted to meafure it both ways, with 

 the beginning of the divifions of the vernier advanced on 

 the fcaie of the micrometer and the contrary, that the er- 

 ror of adjaftment might have been thereby taken away. 

 But the micrometer did not admit of it, the diameter of 

 Venus being a fmall matter too large for this operation. 

 However I took fome meafures this way, but they gave 

 the diameter no more than 55 ".4, which appearing too 

 fmall Vv'ere therefore rejeQed. 



About .20 minutes after the contads, 1 began to mea 

 fure the nearcft diftanceofthelimbs of Venus and the Sun, 



and continued unllU the Sun was fo low, that the meafures 

 could not be made with Aifficicnt accuracy any longer. 

 Some of the meafures appear to difagrce too much with 

 the others, and therefore Ihoukl not be depended on; but 

 I could' not prevail upon myfelf lo negled the inferting of 

 them ; leaft the unufual agreement among fo great a num- 

 ber fliould raifc a fufpicion, in the minds of aftronomers, 

 that they had not been honeftly tranfcribcd from our mi- 

 nutes j efpecially as there are enough, to anfwer all the 

 purpofcs defigned by them, which agree in giving the 

 nearell diflance of the centers with fufficient precilion. 

 Although thefe meafures are fetdown in the following ta- 

 ble with the parts of a fecond, we would not therefore be 

 fuppofed to afFea an impoffible accuracy in them ; but they 

 are fuch as the micrometer has given them when properly 



reduced. 



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