PHYSICAL PROPERTIES OF POLARIZED LIGHT. 143 



The hypothesis therefore is, that every ray of ordi- 

 nary light consists of two rays vibrating in different 

 planes; and that these rays, separated one from the 

 other, have the physical conditions which we call 

 polarized. 



The most transparent bodies may be regarded as 

 being made up of atoms arranged in certain planes. 

 Suppose the plane of lamination of any substance to be 

 vertical in position, it would appear that the ray which 

 has a vertical motion passes it freely, whereas if we 

 turn the body round so that the planes of lamination 

 are at right angles to the plane of vibration of the ray, 

 it cannot pass. 



That some action similar to that which it is here 

 endeavoured to express in popular language does take 

 place, is proved by the correctness of the results deduced 

 by rigid mathematical analyses founded on this hy- 

 pothesis. 



There are two other conditions of the polarization of 

 light called circular and elliptical polarization. The 

 first is produced by light when it is twice reflected from 

 the second surface of bodies at their angle of maximum 

 polarization, and the second by reflexions from the sur- 

 faces of metals at angles varying from 70 45' to 78 30'. 

 The motion of the wave in the first is supposed to be 

 circular, or to be that which is represented by looking 

 along the centre of a corkscrew as it is turned round. 

 At every turn of the medium effecting circular polari- 

 zation the colour of the ray of light is changed after a 

 uniform order. If turned in one direction, they change 

 through red, orange, yellow, green, and violet ; and if 

 in the other direction, the colours appear in the contrary 

 order. 



The variety of striking effects produced by the polari- 

 zation of light ; the unexpected results which have 

 sprung from the investigation of the laws by which it 

 is regulated ; and the singular beauty of many of its 



