494 M, A. Berlin on Circular Mametic Polarization. 



2. Experiments mth the Jlint-glass of Mr. Faraday, thickness 

 38-9 millims. 



Experiments mth the Jlint-glass of Matthiessen, thickness 

 44 millimetres. 



Distance from 



the flint- glass to 



the coil. 





 10 

 20 

 30 



40 



Rotation 

 observed. 



7 40 

 6 20 

 5 00 

 3 40 

 2 50 



Relation of the 

 rotations. 



y' 



0-8261 

 0-7895 

 0-7333 

 0-7727 



Calculated 



rotation. 



2/j'=z/. 0-7823.3. 



00 

 6 1 

 4 56 

 3 53 

 2 53 



Difference. 



yi'-y'- 



-19 

 - 4 



+14 

 + 3 



This law may be represented by a very simple formula. 

 On expressing by A the rotation produced by the flint-glass 

 in contact with the coil, if Ar is the rotation produced by the 

 same flint-glass at the distance of 1 millimetre, the action of 

 the coil at a distance x millimetres will be y — Ai-^. 



This formula proving true for all thicknesses, it must be 

 concluded that it represents the elementary action of a pole 

 upon any stratum whatsoever; for instance, upon a stratum 

 of 1 millimetre. It may consequently lead us to the law con- 

 necting the rotation with thickness, if in every instance each 

 of the different sections of a substance receives an impression 

 as if it were a single one. To convince myself of this, I placed 

 two flint-glasses in contact between the two poles in certain 

 positions, and observed the rotations produced by the two 

 flint-glasses collectively, and by each of them singly, in the 

 position which it first occupied. 



The following experiments show that the first rotation is 

 always the sum of the two others. 



