ABE 



In any other position of the earth, aberration in longitude is 

 20" x cos. earth's distance from syzygy 



cos. star's lat. 

 Hence aberrat. in long, is a max. when the eartli is in syzygy with 



the star, and l_ _-.. 



cos. star s lat. 



Aberration in Decimation. 

 Aberration in declination o, when tang, earth's disk from syzygy 



tan, position 

 sin. star's lat. ' 



In any other position of the earth, let d= dist. of the earth, at the time 

 of observation, from the position it had when aberrat. in declin. o, D 

 = earth's dist. from syzygy at the same time, found by the last Ar- 

 ticle, then aberrat. in declination is 



20" x sin, d X sin, position 



sin. D 

 Hence aberration in declination is a max" 1 , when d = 90. and then 



2Q// X sin, position. 

 shiTD 



Aberration in Right Ascension. 



Aberration in right ascension o, when the tang, earth's distance from 

 - rotan - position 

 sin. star's lat. ' 



In any other position of the earth, let d= dist. of the earth, at the time 

 of observation, from the position it had when aberration in right ascen- 

 sion = o, D =. earth's distance from syzygy at the same time, found 

 by last Art. ; then aberrat. in right ascension is 

 2Q 7/ sin. d x cos. position 

 cos. decl. X sin. D 



Hence aberrat. in right ascension is a max. when d = 90, and 

 20" cos, posit 



cos. dec. X sin. D* 



4. The following are the Formulae given by M. Cagnoli, in his Trigo- 

 nometry, as being the most convenient for practice, and from which M. 

 de Lambre has computed his Tables on Aberration. ( See Vince $ Play, 

 fair.) 



If L be the longitude of the sun at any time, and L' the longitude of a 

 star, the aberration of the star in lat. is 



20". 232 x sin. (L' L) X sin. lat. 



