292 On Polarization of Light by Reflexion. 
two kinds of light.is marked by most distinctive characters, and will 
be found to show itself in some of the more complex phanenene of 
interference. 
In my paper of 1815, already referred to, I was led by a distant 
view of the phenomena which I have now developed, to consider com- 
mon light as composed of rays in every state of positive and negative 
polarization* ; and upon this principle the whole of the phenomena 
described in this paper may be calculated with the same exactness 
as upon the supposition of two oppositely polarized pencils. Nothing 
indeed can be simpler than such a principle. The particles of light 
have planes, which are acted upon by the attractive and repulsive 
forces residing in solid bodies; and as these planes must have every 
possible inclination to a plane passing through the direction of their 
motion, one half of them will be inclined — to this plane, and the 
other half +. When light in such a state falls upon a reflecting 
surface, the — and the + particles have each their planes of polar- 
ization brought more or less into a state of parallelism with the plane 
of reflexion, in consequence of the action of the repulsive foree upon 
one side or pole of the particle through which the plane passes; while 
in the particles which suffer refraction, the same sides or poles are by 
the action of the attractive force drawn downwards, so.as to increase 
the inclination of their planes relative to the plane of incidence, and 
bring them more or less into a state of parallelion with a plane perpen- 
dicular to that of refraction. 
The formule already given, and those for refracted light which are 
contained in another paper, represent the laws according to which the 
repulsive and attractive forces change the position of the planes of 
polarization ; and as we have proved that the polarization is the ne- 
cessary consequence of these planes being brought into certain posi- 
tions, we may regard all the various phenomena of the polarization of 
light by reflexion and refraction, as brought under the dominion of 
laws as well determined as those which regulate the motions of the 
planets. 
Allerly, December 25, 1829. 
*M. Biot has followed me in this opinion. See Traité de Physique, tom. iv. p. 304. 
ie 
