ANNALS 



OF 



PHILOSOPHY. 



FEBRUARY, 1814. 



Article I. 



Memoir 07i New Optical Phenomena. By M. Malus. Read before 

 the French Institute on the 11th March, ISll. * 



I ANNOUNCED, at the end of 1808, that light reflected by all 

 opaque or diaphanous bodies acquired new and very extraordinary 

 properties, which distinguished it essentially from light diiectly 

 transmitted from luminous bodies. 



The observations which I now have the honour to report to the 

 Class, are the suite of those which have been already communi* 

 cated. I shall begin therefore with recapitulating, in a few words, 

 the principal phenomena, in order to throw more light on the nevf 

 experiments, and new results, which I am about to describe. Let 

 us, by means of a hcliostate, throw a ray of solar light in the 

 plane of the meridian, so that it makes with the horizon an angle 

 of 19° 10'. Let us, then, fix a mirror glass not silvered, so that 

 it shall reflect this ray vertically downwards. If we place below 

 this first glass and parallel to it a second glass, this second glass will 

 make with the descending ray an angle of 35° 25', and will reflect 

 it anew, parallel to its first direction. In this case we shall not 

 observe any thing remaikable ; but if we turn round this second 

 glass in such a manner that its face shall be directed towards the 

 west or towards the east, without changing its inclination with 

 respect to the vertical ray, it will no longer reflect a single particle 

 of light either at its first or second surface. If (still preserving the 

 same inclination with respect to the vertical ray) we turn its face to 

 the south, it will begin anew to reflect the usual proportion of tLe 



• Traiislatc<« from the Monitcur of the 13th March, 1811. 



Vor.. 111. Noll. F 



