THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JULY 1852. 



I. Remarks on Lord Brougham's " Experiments and Obser- 

 vations on the Properties of Light," <^-c. inserted in the Phil. 

 Trans. 1850, Part I. Bt/ the Rev. Baden Powell, M.A., 

 F.R.S, i^c, Savilian Professor of Geometry, Oxford"^. 



THE publication of Lord Brougbam's optical researches, in 

 which a number of experimental facts connected with the 

 phajnomena now usually called " diffraction," are viewed accord- 

 ing to a peculiar theory of certain new properties of light, and in 

 some respects held to be irreconcileable with the principle of in- 

 terference, seems to render desirable some examination into the 

 actual bearing of the results on the theory of undulations, by 

 which not only all the phtenoraena of diffraction, hitherto known, 

 have been so perfectly explained, but which has also been applied 

 so extensively to other large classes of facts, as to render it unphi- 

 losophical to resort to theories assumed on independent grounds 

 to meet apparent exceptions in limited classes of phsenomena. 



These researches having been briefly alluded to by the Astro- 

 nomer Royal in his opening address to the British Association 

 at Ipswich t^ and having also myself made a few observations on 

 the subject at the same meeting J, my object in the present com- 

 munication is to follow up the question in somewhat more detail ; 

 and without pretending to enter on any controversy as to the 

 author's theory, to examine merely the experimental evidence ad- 

 duced, and inquire how far it seems accordant or not with the 

 undulatory theory. 



During the summer of last year I took the opportunity of 



* Communicated by the Autlior. t Sec Athemcinn, No. 123G. 



X See Ibid. No. 12;i7. 



Phil. May. S. 4. Vol. 4. No. 22. July 1852. B 



