A SYNOPSIS 



PRACTICAL PHILOSOPHY. 



ABERRATION of LigJit.(Woodhousc t Vince.) 



1. If two lines be drawn from the earth, one in the direction of its rao 

 tion, which will be a tangent to its orbit, and the other through the star,, 

 the angle they form is called the / of the earth's ivay ; and the aberra- 

 tion will wholly take place in the plane passing through these two lines ; 

 which is .". called the plane of aberration. 



2. The greatest effect of aberration = 20". 232, or in round numbers 

 20" ; and generally the aberration in its own plane 20" x sin. of the 

 / of the earth's way. 



The velocity of the earth C the velocity of light ', '. sin. 20" I rad. : : 1 : 

 10324. 



3. This aberration will affect the apparent position of the stars both 

 in latitude, and longitude j declination, and right ascension. Hence the 

 following Formulae : 



Aberration in Latitude, 

 Aberrat. in lat. o, when the earth is in syzygy with the star. 



In any other position of the earth, aberration in lat. is 



20" X sin. of earth's distance from syzygy X sin. star's lut 



Hence the aberration in lat. is a max. when the earth is in quadrat v.rc 

 with the star, and then = 20" x sin. star's lat. 



Aberration in Longitude, 



Aberrat. in long. o, when the earth is in quadratures with the star, 

 1 A 



rj 



A 



