92 



JAMIN ON METALLIC UEFLEXION. 



light; and finally, it determines the angle sought (a), not by 

 measuring the azimuth of polarization of a ray, which is always 

 very uncertain, but the azimuth for which two tints are equal, 

 which is infinitely more exact and more sensible. 



Mirror-metal. — Ratio of the square roots of the intensities of the 

 reflected light ( y- ) • 



T shall terminate this chapter by some remarks on the pub- 

 lished labours of M. de Senarmont [Annates de Chimie et de 

 Physique, 2^ serie, tome Ixxiii. page 337)*. 



This experimenter caused to be reflected from metal a ray 

 polarized in any azimuth whatever ; he received it afterwards on 

 a plate of mica of such a thickness, that the two principal rays 

 acquired in traversing it, a difference of route equal to a quarter 



* In the Memoir of M. de Seiiavmont not one of the names of his predeces- 

 sors in this inquiry is mentioned except that of Mains ! — Ed. 



