iMi 



i66 



MATHEMATICAL a n r» 



Let the place be Norriton, at 2'. 12'. 50", the moment 

 of the firft external eonta£t. 



Then, in the fpherical triangle ZVP, we have two lides, 



and the included angle, viz. 



ZP,=:40''- 50' • '^9"' ^^^^ co-latitude _ 

 VP,^67. ^4-. I7> the co-declination. 



^ "^ ^ ■' ". the time turned into 



ZPV=33. 12. 30=2". 12 .50 . 



deg. &c. 



Hence we get the angle ZVP 



And the zenith diftance of o's center ZV =33. 9. 

 Subtraa for ? higher than O's center, 1 5 



49'- 55'- 33" 



42 i 



. 18 



Remains the zenith dift. of 9's lower limb, 32. 54. 24:: 

 Complement of which is the height 9'P 



lower limb above the horizon, 



57- S- 35-r 



Affuming now any number for the Sun's horizontal pa- 

 rallax on the tranfxt day, let us fay 8",52 1 2 (the nearer ta 

 the true parallax the better); then the horizontal parallax 



of Venus will be to that of the Sun, inverfely as their dii- 



tancesfrom the earth; that is 



28887: ioi5i2::8",52i2;29".9444=':Iiehor. paral- 

 lax of ?. Subtrad Sun's parallax "" —-- 



8. 5212 



horizontal 



The remainder 21. 4232 

 parallax of Venus from the Sun on the tranfit day. ^ 



Then, Radius is to the Sine of the zenith dift. of Venus, 

 as her horizontal parallax from the Sun, is to her parallax 



at the altitude aforefaid ; viz. ^^^ ^^^^, ^^ 



Rad: S. 32%54',24;-- 2i",4232: II '^^^y=^\'^'^',;^ 



Moreover, in the right-angled fpherical triangle CVD, 

 we have two fides, viz. 



/ 



CV the Sun's longitude 



DV the declinations 22°. 25'. 43 



2'. If. 20 



r ..It 



3i"=73<'.2o'.3i". 



"Whence we get UU^yi". SS' 



32> 



And likewife the meridian angle CVD:zz82^'54' 



21 



(f 



The 



