Prof. Kelland on the explanatmi of Dispersion. 37 S 



2;(A^.0"^) = 2s(A^sin2^).0 = A^ 



I omit the part involving \^a~ — ^\ because it is not linear 

 with regard to J. In a similar manner we may put 



and v(„,^;F^.^-^A E?. 



V ax a;: / 



And proceeding in the same way to obtain the equations of 

 motion with regard to the forces respectively parallel to the 

 axes of J/ and z, we finally obtain, 



<^/?= -A^-Frj-Er, 



^;,,= -F0-B>!-D?, 



These then are the general equations for the transmission of 

 common light through any transparent medium whatever. 

 As I have already occupied a considerable portion of your 

 valuable space, I shall reserve my inferences from these equa- 

 tions for a future Number of your Journal. 

 March 12, 1842. 



LIV. Remarks on a paper by Mr. O'Brien relative to the ap- 

 plication of the Ujidulatori/ Theory to the explanation of 

 Dispersion. By the Rev. P. Kelland, M.A., F.R.SS. L. 

 <^' E., F.C.P.S., SfC., Prof essor of' Mathematics in the Univer- 

 sity of Edinbnrgiiy late Fellow and Tutor of Queen's College, 

 Cambridge. 



To Richard Taylor, Esq. 

 My dear Sir, 

 Vl/'ILL you do me the favour to insert in your Magazine 

 * * a few remarks on a paper which has just appeared 

 (Phil. Mag. for March, page 201), the object of which is 

 to investigate the influence which material particles exert on 

 the vibrations of the molecules of aether? The result of the 

 investigation is the establishment of a relation between the 

 velocity of transmission and the length of a wave of light, 

 without introducing the hypothesis of a finite ratio between 

 the mutual distance of two consecutive particles of the lumi- 

 niferous aither, and the length of an undulation. I have hi- 

 therto abstained from taking a part in the discussions which 

 have arisen since tlie appearance of my publication on the 



