14 On Light. 
coincides with the plane of the meridian, and that the reflected ray, 
is vertical. Then, if we make the second inclined plate revolve, it. 
will turn around the reflected ray, forming always with it thesame> 
angle ; and the plane in which the second reflection takes place, 
will necessarily be directed towards the different points of the ho- 
tizon, in different azimuths. This being arranged, the following 
phenomena will be observed. 
When the second plane of reflection is directed in the meridian, 
and consequently coincides with the first, the intensity of the light 
reflected by the second glass is at its maximum. 
In proportion as the second plane, in its revolution, deviates 
from its parallelism with the first, the intensity of the reflected 
light will diminish. 
Finally, when the second plane of reflection is placed in the 
prime vertical, that is east and west, and consequently perpen- 
dicular to the first, the intensity of the reflection of light is ab- 
solutely null on the two surfaces of the second glass, and the ray 
is entirely transmitted. 
Preserving the second plate at the same inclination to the ho- 
rizon, if we continue to make it revolve beyond the quadrant now 
described, the phanomena will be reproduced in the inverse or- 
der; that is, the intensity of the light will increase, precisely as 
i¢ diminished, and it will beconie equal, at equal distances from 
the east and west. Hence, when the second plane of reflection 
returns once more to the meridian, a second maximum of inten- 
sity equal to the first recurs. 
From these experiments it appears, that the ray reflected by 
the first glass, is not reflected by the second, under this incidence, 
whei it is presented to it by its east and west sides; but that it is 
reflected, at least in part, when itis presented to the glass by any 
two others of its opposite sides. Now, if we regard the ray as an» 
infinitely rapid succession of a series of luminous particles, the faces 
of the ray are merely the successive faces of these particles.. We 
must hence conclude, that these particles possess faces endowed .. 
with different physical properties, and that, in the present cireum- 
stance, the first reflection has turned towards the same sides of 
space, similar faces, or faces equally endowed at least with the 
property under consideration. It is this arrangement of its mole- 
cules which Malus named the polarization of light, assimilating 
the effect of the first glass to that of a magnetic bar, which would 
turn a series of magnetic needles, all in the same direction. 
Hitherto we have supposed that the ray, whether incident or 
reflected, formed with the two mirror plates, an angle of 35° 25’; 
for it is only under this angle that the phenomenon is complete. 
Vithout changing the inclination of the ray to the first plate, if 
we 
