applying to Light under the action of Magnetism. 473 

 Y',=Y', V'^Y"; 2J X = 71, Z", = Z": 

 in the second experiment let 



Y' 2 =-Y', Y" 2 =-Y", Z' 2 =Z', Z" 2 =Z". 

 Then, 

 in the first experiment, for Ray No. I., 



2 



Y' — a. cos 



T 



Z' = a.sm^(t-0; 

 and Prof. MacCullagh's equations become 

 -^^cos-^^-^^-A^^-ja.cos^^-^ 



+ B 15 -^j«.cos T ^-^, 



4*r 2 . 2f/ x\ . 4tt 2 /1\ 2 . 2*/. *\ 



-^«.sin-(/-^ = -A.-^.^«.sin- r ^-^j 



which agree in giving 



W)t= 1+B £(4r 



for Ray No. II., 



Y»^.cos^(,-^), 



The equations become 



4w* Sir/! a?\ A 49T 2 / 1 \ 2 2tt/ ar\ 



_ 87T 3 / 1 \ 3 2tt/ x \ 



4* 2 . 1iz( x\ 1 4tt 2 / 1 \« . 2tjV #\ 



. -r. 8^/1 \ 3 . 2-w/, a:\ 



Phil. Mag. S. 3. Vol. 28. No. 189. Jmw* 1846. 2 K 



