1S9S.] Mr Leathern, On the possibility of deducing, etc. 531 



It was necessary to compare the modified scheme thus obtained 

 with experimental knowledge : and the calculations given in this 

 paper show that in fact it does not represent the phenomena. 

 The paper is only a summary of the actual calculations, because 

 since they were completed the author has shown (On the Magneto- 

 optic Phenomena of Iron, Nickel and Cobalt, Phil. Trans. 1897) 

 that the other rigorous theory formulated as an alternative by Mr 

 Larmor (loc. cit.), which leads to an analytical scheme practically 

 the same as those advanced on various hypotheses by Fitzgerald, 

 Gold hammer, Basset, Drude, and others, is in much more satis- 

 factory agreement with experiment. This brief history of the 

 subject shows the desirability of the examination of the conse- 

 quences involved in the former method of explanation : the result 

 is however what was to be expected by those who adhere to the 

 more recent formulation (Larmor, A Dynamical Theory of the 

 Electric and Luminiferous Medium, Part ill., Phil. Trans. 1898) 

 of optical theory which treats a material medium as free sether 

 pervaded by discrete molecules involving in their constitution 

 electrons considered as nuclei of intrinsic oethereal strain. On 

 such a view a continuous energy function is not the starting- 

 point, and the influence of these discrete nuclei could hardly be 

 conceived to modify the propagation in the intervening aether in 

 so fundamental a manner as an electromotive pressure would 

 demand. 



(5) On the solutions of the equation (V 2 -f- k 2 ) yjr = in elliptic 

 coordinates and their physical applications. By R. C. Maclaurin, 

 B.A., St John's College. 



[Printed in the Transactions, Vol. xvn. Pt. I.] 



(6) On the interpretation of divergent solutions of the hyper- 

 geometric equation. By Mr W. M C F. Orr, Professor at the Royal 

 College of Science, Dublin. 



42—2 



