PHYSICAL AND LITERARY. ^^ 



to be the par. lat. D ^ ; the vlf. lat. being 

 the fame when obferved at B or C. 



5. In any other pofition of the moon, if its 

 diftance from the point v exceeds not one de- 

 gree, which it can never do in the time of an 

 eclipfe J the parallaxes, to a fpeftator at the 

 point V of the difk, will continue nearly the 

 fame as before, without any fenfible alteration. 

 Let /be the place of the moon, Id, If, perpen- 

 diculars to c ;z, c ey and let^ /, v a, be pro- 

 duced till they meet in the point g, and let Id 

 meet with "u*^ in the point / ; the vif. Ion. ^ 

 a ©, will be nearly the fame at the points 

 g and /. Therefore the vif. long D a O, ob- 

 ferved at V, is the angle under which the 

 arch 1;^ is feen from that point. But the arch 

 '^g will be feen nearly under the fame angle 

 from the points V and C ; and confequently it 

 is the meafure of the vif. Ion. 1) a 0. But the 

 true Ion. is dl'=:ag'. therefore vg—ag — va 

 is the par. Ion. 2> ^ 0. Again, adzzlg-rz vif. 

 lat. 5 /^ } and c^=://= tr. lat. : therefore 

 V b — a c — a d -\- dc — pzr. ht. D a (D. 



6. But thefe parallaxes va, vif, and the 

 vif Ion. and lat. vg, vf, fuppofe the fpeftator 

 at the point V" on the difk ; whereas his 



true 



