Reviews, and Notices respecting New Books. 371 



much interest in the present stage of our knowledge of physi- 

 cal operations. 



[To be continued.] 



LXIII. Note on Mr. Potter's Reply. By William R. Ha- 

 milton, Esq. Andrews' Professor qf Astronomy in the Uni- 

 versity of Dublin, and Royal Astronomer of Ireland*. 



TpROM Mr. Potter's Reply, published in the April Num- 

 *■ ber of the London and Edinburgh Philosophical Magazine, 

 I collect some additional facts respecting his experiment of 

 prismatic interference, which do not seem to have been stated 

 in his first account of that experiment. In Mr. Potter's first 

 paper, the stress of his objection to the undulatory theory of 

 light seemed to be laid on the observed direction of a certain 

 deviation ; to which he opposed his calculated decrease of a 

 certain hyperbolic ordinate. I showed that this observed fact, 

 of deviation in the observed direction (towards the thickness 

 of the prism), could be accounted for by the prismatic aber- 

 ration of figure, which changed the decreasing hyperbolic or- 

 dinate to an increasing ordinate of a certain other curve. But 

 I was of course aware that this prismatic aberration, though 

 a cause acting in the observed direction, might not be ener- 

 getic enough to account for the whole, or even for the greatest 

 part of the observed effect ; and that whether aberration was, 

 or was not, an adequate as well as a real cause (on the undu- 

 latory theory of light), must depend on the comparison of my 

 calculated formulae with the observed magnitude of the devia- 

 tion, of which Mr. Potter had not given any measure, or even 

 any estimate. I am happy to have been the means of indu- 

 cing Mr. Potter to bring forward some additional testimony 

 on this important point : and willingly admit, that according 

 to this new testimony, there remains, after allowing for my 

 suggestions, a large residual phasnomenon. 

 Dublin, April 13, 1833. 



LXIV. Reviews, and Notices respecting New Books. 



Journal of the Asiatic Society of Calcutta, Nos. 1 , 2, and 3 ; with 

 Plates. Calcutta, 1832. 



WE are particularly desirous of calling the attention of our readers 

 to this valuable monthly periodical, which we are afraid is by no 

 means so well known in Europe as its merits entitle it to be. The present 

 Numbers form the continuation of a scientific journal, published also 



* Communicated by the Author. 

 3B2 



