ASTRONOMICAL PAPERS. 



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parallax being 8"55204 on the day of the tranfit. From 

 this, the Sun's horizontal parallax is found either greater 

 or lefs, as the calculated effcQ of parallax is greater or 

 lefs, than what is obferved. 



The parallax of Venus in longitude at Greenwich, at 

 the time of the firft external conta£l was i6'',9, which haft- 

 ened the contact there 4'. i6'',5, and her parallax in lati- 

 tude at the fame time was 12'', 97, which deprefTed her on 

 the diik of the Sun, lengthened her vifible path, and acce- 

 feratcd the contact 2^. 34'',5, fo that the total effed of her 

 parallax was to haften the contadT; 6^ .51'' of time. In like 

 manner her parallax in longitude at the internal contact 

 was i6'^6, which haftened it 4'. 12" of time; and her 

 parallax in latitude being I2'''i^2 at that time, for the fame 

 reafon haftened the faid contaCt 2'. 40'^; and therefore the 

 total effed; of parallax to accelerate the internal contact at 

 Greenwich h 6^ 52''. 



At Philadelphia her parallax in longitude being io'',74 

 at the external conta£l, haftened it 2'. 43"; and her paral- 

 lax in latitude being 4'S43, lengthened her vifible path on. 



the Sun and haftened the contact 53'' of time; whence its 

 total eff'ed: was 3'. 36^' of time. In like manner her pa- 

 rallax in longitude at the internal contad: being ii^S95 



haftened it 3^. i'^ of time, and her parallax in latitude be- 

 ing 4'\49 lengthened the tranfit line, and haftened the con.- 



and therefore the total cffrft of her parallax 



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at that time to haften the internal contadl was 4^ 4". 



Now as the total eflx.^£t of parallax both at Greenwich 

 and at Philadelphia confpired to haften the contacts at botli 

 thefe places, with refpeil to the center of the earth, their 

 diff'erence is the whole eff'ed: they have on abfolute time 

 viz. 3'. 15'' at the external contad, and 2'. 48'^ at the 

 internal contacl. 



The contads were obferved at Greenwich at the appa- 

 rent times mentioned in the following table, according to 

 their meridian. 



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