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6 MATHEMATICAL and 



The apparent time of the ecliptical conjundion of the 

 Sun and Venus, as feen from the center of the earth, 1769, 



J 



4' 43", 



as reckoned at Philadelphia, 5^. o' 



32^' weft from Greenwich. The place of the Sun and 

 Venus, at the time of the tranfit, is 2' 13'' 26' 2>^"' The 

 placeof herdefcendingnode is 8* 14'' 35' 27'^ at that time. 

 The geocentric latitudeofVenusatthat timeis lo' i6''.295 

 The Sun's femidlamctcr is i c' ac".6c. The femi- 



is 



15' 45"-65. 

 Their fum 16' i^",6y^ 



<liameter of Venus o' 29 



Their difference is 15' 16''. 65. Venus's horary motion 

 from the Sun 3' 57". 43. The angle made by the axis of 

 the earth and ecliptic, as feen from the Sun, 7* 3' 16". 

 The angle made by the axis of Venus's vifible path and 



'^f^ 



the axis of the ecliptic, is 8" 34 



' 17"; 



the angular point 



or node being i* 8' SS" ^^^ ^^ ^^^ Sun. The angle made 

 by the earth's axis and the axis of Venus's vifible path is 

 equal to the fum of thefe, 15"* 37' ^^". The horizontal pa- 

 rallax of the Sun on the day of the tranfit is 8".5204, 

 when his diftance from the earth is 101521.2, his paral- 

 lax at his mean diftance 1 00000 beingfuppofedtobe8'',65> 



as found at the laft tranfit, 1761. The horizontal 



parallax of Venus on the day of the tranfit 29".9348, 

 when her diftance from the Sun 72626.3, her mean dif- 

 tance being according to her periodic time 72333. The 

 difference of thefe, viz. 2i'^4i44, is the horizontal pa- 

 rallax of Venus from the Sun on the faid day. The tran- 

 fit begins, asfeenfrom the earth's center, at 2% 17' 2o".48, 

 and ends at 8". 41' 46^.72. The total ingrefs at 2\ 

 36' 3 1 ''-38; the beginning of egrefsat 8\ 22' 35^82; fo 

 that the wliole duration between the internal contads will 



be 5% 46 



' 4"44 



But thefe times will be confiderably al- 



tered by the parallaxes of Venus in longitude and latitude, 

 as obferved from different parts of the earth. The whole 

 effed: of the parallaxes of longitude and latitude at the time 

 :of the external contaft to haften it, being 3^ 31", the time 

 of it, as feen from Philadelphia, is at 2% 13' 49" 28''^ 



M 



And the time of total ingrefs at Philadelphia is 



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