82 POL SEIZED LIGHT AND ITS APPLICATION TO THE MICKOSCOPE. 
polarizing plane, almost equal to the original intensity, and but 
a feeble intensity in the other polarizing plane. But there will 
also be vibrations very nearly coinciding with each of the polari- 
zing planes, so that the sum of the resulting vibrations in 
each polarizing plane, will be exactly equal. 
The rays polarized in each plane will be represented in inten- 
sity by the sum of all the resultants in that plane. 
Figure 44 is designed to represent a transverse section of a 
ray of common light, vibrating in an infinite number of planes, 
and at right angles to the direction of the ray. 
Fig. 44. Fig. 45. Fig. 46. 
Figure 45 is designed to represent this vibrating ray, resolved 
into vibrations in two directions at right angles to each other, 
as when a ray of common light undergoes double refraction 
and polarization by passing through Iceland spar. 
Figure 46 shows another and more common method of repre- 
senting the two rays, produced by double refraction, polarized 
in the planes A B and C D, the fine lines in A B and C D, in- 
dicating the condensation and combination of resultant vibra- 
tions, entirely separated from the vibrations in the other plane 
of polarization. 
107. Polarizing effect of Iceland Spar. Thus tlie polari- 
zing action of Iceland spar, and all doubly refracting substan- 
ces, is to separate a ray of common light, whose vibrations are 
in every plane passing through the direction of the ray, into 
two parallel polarized rays, whose vibrations are in planes at 
right angles to each other. 
The preceding illustrations may aid in understanding that if 
a 'polarized ray falls upon another polarizing medium, in 
J. & W. GRUNOW & GO’S ILLUSTRATED 
