THE 



LONDON AND EDINBURGH 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



DECEMBER 183G. 



LXXVI. Facts relating to Optical Science. No. IF. 

 By H. F. Talbot, Esq., F.R.S,*' 



% 1. Experiments on the Interference of Light. 



A LTHOUGH so much lias been explained in optical sci- 

 -^*- ence by the aid of the undulatory hypothesis, yet when 

 any •well-marled phcenomena occur which present unexpected 

 peculiarities, it maybe of importance to describe them, for the 

 sake of comparison with the theory. 



Such appears to me to be the case with those which I am 

 about to mention, in which, by means of a remarkable 

 compensation of some kind or other, common solar light ap- 

 pears to play the part of homogeneous light, and to achroma- 

 tize itself, if I may use such an expression, in a very high de- 

 gree of perfection. 



Sir William Herschel was, I believe, the first who took 

 notice of the very beautiful coloured bands which are seen 

 by looking through two prisms placed in contact. Thus, let 

 A B C, A D C be two equal right-angled glass prisms in con- 

 tact. We will suppose the sides A B, B C to be equal, and 

 the thickness of the prisms to be equal to A B, in which case 

 the combination of the two will form a cube. Let the two 

 prisms be gently pressed together by their face A C, which 

 must be previously well cleaned from any adhering dust, and 



• Communicated by the Author. 

 Third Series. Vol.9. No. 56. Dec. 1836. 3 B 



