282 On Polarization of Light by Reflexion. 
PLATE GLASS. 
Inclination of Plane of Polarization 
Angle of Angle of to Plane of Reflexion. 
Incidence. _ Refraction. Observed. Computed. Difference. 
BBO ae OS. Oe ABO LO! CLARO 10) ee 
BS ie wath: 28. wk ABO Ao GAD AO. ioc ar 
BG ap cake Ai MCs suivoi AO AD cso S Ge. te doe” 
BA uc iA Di WOvieiae te aA VA Ne jg ee oe iY 
S12 Cen ee: 3 ONG MMP 312 am FS RS tae Mea 
GO ce a0 AB ee Ve gO LOW ce a2 Oy MOnee okie 
BO ie 6 OE Our oe OL OF oo OO) heen 
BO ie a OL OB. OQ OO Oa ae 
46 ee 28. 29° 2S NG Baa 2. 16 Si ee 
AO) a 25 42. OF a.) 2S ee 
BOD ay foie 19) ABH el). py 8225. ao. Bd. 195 3 
AO. 2 18 200 BORO) a. AO: 4. as eee 
10s, 6, 44. 44 Oo ao 49. 
These results, obtained in every part of the quadrant, completely 
establish the accuracy of the formula. The differences are all with- 
in the limits of the errors of observation, and amount, at an average, 
to 324’ on each observation. pe 
It is a curious circumstance, which I believe has not before been 
remarked, that at an incidence of 45° the deviation produced by re- 
fraction, or i—7’, is, in every substance, the complement of the an- 
gle of refraction 7 to 45°; and in the action of all substances 
upon polarized light at an incidence of 45°, the rotation of the plane of 
polarization of a pencil polarized + 45°, or — 45°, is equal to the 
the angle of refraction; while the inclination of the plane of polari- 
zation to the plane of reflexion, or 9,, is equal to the deviation 2 —2’. 
In order to establish the accuracy of the formula for different de- 
grees of refractive power, I made the following experiments on Dia- 
mond, in which the index of refraction was 2.440. 
