174 



MATHEMATICAL akd 



PHILAT)ELPHIA, and Ten Places in EUROPE, 



External Contact, 



H. m. foe. iecoiids. 



%. 13, 46,6 Philacklpliia mean of 5 obferv. 403,853 mean parallax for the lo places, 



5. II, 5^,95 ^=meari diiT. merld, 215,12 parallax for Philadelphia. 



7. %$. 39,55==time for the I© places? diiT, i88,733==calculatcdeffe<5l of parallax. 



without parallax, 5 

 ■7. %%, 30, 25=mean ofthe obfcrved times. 



f c/',567. 



i)iif. 3. 9, 3^==iS9'^3— mean ohfcrved effedt of parallax, 



W\\^\\i:t, 188^^,733 : l89",3 :: 8''',52i2 : 8'',5468=^g5's parallax on tranfit day.- 



1 1, m. 



2. 31. 

 5. II. 



Internal Contact. 

 fee. fcconds. 



28. Philadelphia mean of 5 obferv. 422,817 mean parallax for the 10 places, 



^^a,95=c:::iiiean dift^ merid. 



237,94 parallax for Philadelphia. 



7- 43- ao,95 

 7. 40. 37,8^ 



=^tinie for the 10 places 7 

 without parallax. 3 

 :mean of the obferved times. 



Diff. i84,877^:::calculatcd cfTciSt of parallax. 



■2i/'737 



I)JiF.2. 43,i5=i63'^l5 mean obferved parallax. 



WheiicCj 184^^877 : i63",l5 :: 8",52I2 : 7'',5i98z=gj'sparallax on tranfit day, 



Thus, by the External ContaBy wc have the Sun's Parallax— 



feconds. 

 Prom the Philadelphia Obfcrvations 8,5468 



And from the Norril«:>n Obfervations 84060 



16,9528 

 The Mean of both is,. —— —— —8^^4764. 



In like manner^ by the Internal ContaB, we have the Sun's Parallax- 



feconds. 



Prom the Norriton obfer-7 7j74 comparifon, reg. circumf. in contact. 



vations. J 7*^^ comparifon, thread of light complete 



From Philadelphia obfer-7 « t *t, j n* 1 i. i . 



•t'ons * ^^^ companion thread ol light com|ilete.' 



\ 



The Mean of thcfe is. 



a'^,34 



^hh7 



! 



7 ',447- 



Now the mean parallax thus got by the compariibn of 

 all the ten external contads in the above table, with thofe 

 of Philadelphia and Norriton, being ^"^^y6/[. on the tran- 

 fit day, is nearly the fame that was got by the beft obferva- 

 tions in 1 76 1, and gives 8^^6045 for the Sun's horizonta 

 parallax at the mean diftance. And there is reafon to 

 think, that is as large as perhaps any good obfervations 

 will give it, 



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