OUTLINES OF NATURAL PHILOSOPHY. 



If the star is in the pole of the ecliptic, it describes a 

 circle, with the radius 20'.232, having the pole 

 for its centre. 



If the star is in the ecliptic, it describes a straight 

 line in that plane, and extending 20".232 on each 

 side of the star. 



The purposes of practical astronomy require, that 

 the change made by the aberration on the longi- 

 tude and latitude, and on the right ascension and 

 declination of a star, should be computed. 



. If L be the longitude of the sun at any 

 time, and L' the longitude of a star, the aberra- 

 tion of the star in longitude is 



Q0".23<2 x cos (I/ L) m 

 cos Lat. 



and the aberration in latitude is 



x sin (L' L) sin Lat. 



These formulas were first given by CLAIRAUT. Mem. 

 Acad. de Scien. 1737. 



See also CAGNOLI, Trig. 1529. LA LANDE, 2823. 

 and DE LAMBRE, Ast. legon 19. 20, 21. &c. 



213. If A be the right ascension, and D the 

 declination of a star, L being the sun's longi* 



tude, 



